The Future of Intelligent Robots

Robots have been around for over half a century now, making constant progress in terms of their sophistication and intelligence levels, as well as their conceptual and literal closeness to humans. As they become smarter and more aware, it becomes easier to get closer to them both socially and physically. That leads to a world where robots do things not only for us but also with us.

Not-so-intelligent robots made their first debut in factory environments in the late ‘50s. Their main role was to merely handle the tasks that humans were either not very good at or that were dangerous for them. Traditionally, these robots have had very limited sensing; they have essentially been blind despite being extremely strong, fast, and repeatable. Considering what consequences were likely to follow if humans were to freely wander about within the close vicinity of these strong, fast, and blind robots, it seemed to be a good idea to isolate them from the environment by placing them in safety cages.

Advances in the fields of sensing and compliant control made it possible to get a bit closer to these robots, again both socially and physically. Researchers have started proposing frameworks that would enable human-robot collaborative manipulation and task execution in various scenarios. Bi-manual collaborative manufacturing robots like YuMi by ABB and service robots like HERB by the Personal Robotics Lab of Carnegie Mellon University[1] have started emerging. Various modalities of learning from/programming by demonstration, such as kinesthetic teaching and imitation, make it very natural to interact with these robots and teach them the skills and tasks we want them perform the way we teach a child. For instance, the Baxter robot by Rethink Robotics heavily utilizes these capabilities and technologies to potentially bring a teachable robot to every small company with basic manufacturing needs.

As robots gets smarter, more aware, and safer, it becomes easier to socially accept and trust them as well. This reduces the physical distance between humans and robots even further, leading to assistive robotic technologies, which literally “live” side by side with humans 24/7. One such project is the Assistive Dexterous Arm (ADA)[2] that we have been carrying out at the Robotics Institute and the Human-Computer Interaction Institute of Carnegie Mellon University. ADA is a wheelchair mountable, semi-autonomous manipulator arm that utilizes the sliding autonomy concept in assisting people with disabilities in performing their activities of daily living. Our current focus is on assistive feeding, where the robot is expected to help the users eat their meals in a very natural and socially acceptable manner. This requires the ability to predict the user’s behaviors and intentions as well as spatial and social awareness to avoid awkward situations in social eating settings. Also, safety becomes our utmost concern as the robot has to be very close to the user’s face and mouth during task execution.

In addition to assistive manipulators, there have also been giant leaps in the research and development of smart and lightweight exoskeletons that make it possible for paraplegics to walk by themselves. These exoskeletons make use of the same set of technologies, such as compliant control, situational awareness through precise sensing, and even learning from demonstration to capture the walking patterns of a healthy individual.

These technologies combined with the recent developments in neuroscience have made it possible to get even closer to humans than an assistive manipulator or an exoskeleton, and literally unite with them through intelligent prosthetics. An intelligent prosthetic limb uses learning algorithms to map the received neural signals to the user’s intentions as the user’s brain is constantly adapting to the artificial limb. It also needs to be highly compliant to be able to handle the vast variance and uncertainty in the real world, not to mention safety.

Extrapolating from the aforementioned developments and many others, we can easily say that robots are going to be woven into our lives. Laser technology used to be unreachable and cutting-edge from an average person’s perspective a couple decades ago. However, as Rodney Brooks says in his book titled Robot: The Future of Flesh and Machines, (Penguin Books, 2003), now we do not know exactly how many laser devices we have in our houses, and more importantly we don’t even care! That will be the case for the robots. In the not so distant future, we will be enjoying the ride in our autonomous vehicle as a bunch of nanobots in our blood stream are delivering drugs and fixing problems, and we will feel good knowing that our older relatives are getting some great care from their assistive companion robots.

[1] http://www.cmu.edu/herb-robot/
[2] https://youtu.be/glpCAdKEWAA

Tekin Meriçli, PhD, is a well-rounded roboticist with in-depth expertise in machine intelligence and learning, perception, and manipulation. He is currently a Postdoctoral Fellow at the Human-Computer Interaction Institute at Carnegie Mellon University, where he leads the efforts on building intuitive and expressive interfaces to interact with semi-autonomous robotic systems that are intended to assist elderly and disabled. Previously, he was a Postdoctoral Fellow at the National Robotics Engineering Center (NREC) and the Personal Robotics Lab of the Robotics Institute at Carnegie Mellon University. He received his PhD in Computer Science from Bogazici University, Turkey.

This essay appears in Circuit Cellar 298, May 2015.

Security Agents for Embedded Intrusion Detection

Knowingly or unknowingly, we interact with hundreds of networked-embedded devices in our day-to-day lives such as mobile devices, electronic households, medical equipment, automobiles, media players, and many more. This increased dependence of our lives on the networked-embedded devices, nevertheless, has raised serious security concerns. In the past, security of embedded systems was not a major concern as these systems were a stand-alone network that contained only trusted devices with little or no communication to the external world. One could execute an attack only with a direct physical or local access to the internal embedded network or to the device. Today, however, almost every embedded device is connected to other devices or the external world (e.g., the Cloud) for advanced monitoring and management capabilities. On one hand, enabling networking capabilities paves the way for a smarter world that we currently live in, while on the other hand, the same capability raises severe security concerns in embedded devices. Recent attacks on embedded device product portfolios in the Black Hat and Defcon conferences has identified remote exploit vulnerabilities (e.g., an adversary who exploits the remote connectivity of embedded devices to launch attacks such as privacy leakage, malware insertion, and denial of service) as one of the major attack vectors. A handful of research efforts along the lines of traditional security defenses have been proposed to enhance the security posture of these networked devices. These solutions, however, do not entirely solve the problem and we therefore argue the need for a light weight intrusion-defense capability within the embedded device.

In particular, we observe that the networking capability of embedded devices can indeed be leveraged to provide an in-home secure proxy server that monitors all the network traffic to and from the devices. The proxy server will act as a gateway performing policy based operations on all the traffic to and from the interconnected embedded devices inside the household. In order to do so, the proxy server will implement an agent based computing model where each embedded device is required to run a light weight checker agent that periodically reports the device status back to the server; the server verifies the operation integrity and signals back the device to perform its normal functionality. A similar approach is proposed Ang Cui and Salvatore J. Stolfo’s 2011 paper, “Defending Embedded Systems with Software Symbiotes,” where a piece of software called Symbiote is injected into the device’s firmware that uses a secure checksum-based approach to detect any malicious intrusions into the device.

In contrast to Symbiote, we exploit lightweight checker agents at devices that merely forward device status to the server and all the related heavy computations are offloaded to the proxy server, which in turn proves our approach computationally efficient. Alternatively, the proposed model incurs a very small computational overhead in gathering and reporting critical device status messages to the server. Also, the communication overhead can be amortized under most circumstances as the sensor data from the checker agents can be piggybacked to the original data messages being transferred between the device and the server. Our model, as what’s described in the aforementioned Cui and Stolfo paper, can be easily integrated with legacy embedded devices as the only modification required to the legacy devices is a “firmware upgrade that includes checker agents.”

To complete the picture, we propose an additional layer of security for modern embedded devices by designing an AuditBox, as in the article, “Pillarbox,” by K. Bowers, C. Hart, A. Juels, and N. Triandopoulos. It keeps an obfuscated log of malicious events taking place at the device which are reported back to the server at predefined time intervals. This enables our server to act accordingly by either revoking the device from the network or by restoring it to a safe state. AuditBox will enforce integrity by being able to verify whether the logs at the device have been tampered with by an adversary who is in control of the device and covertness by hiding from an attacker with access to the device whether the log reports detection of malicious behavior. To realize these requirements, AuditBox will exploit the concept of forward secure key generation.

Embedded systems security is of crucial importance and the need of the hour. Along with the advancement in embedded systems technology, we need to put an equal emphasis on its security in order for our world to be truly a smarter place.

RESOURCES
K. Bowers, C. Hart, A. Juels, & N. Triandopoulos, “Pillarbox: Combating Next-Generation Malware with Fast Forward-Secure Logging,” in Research in Attacks, Intrusions and Defenses, ser. Lecture Notes in Computer Science, A. Stavrou, H. Bos, and G. Portokalidis (Eds.), Springer, 2014, http://dx.doi.org/10.1007/978-3-319-11379-1_3.

A. Cui & S. J. Stolfo, “Defending embedded systems with software symbiotes,” in Proceedings of the 14th international conference on Recent Advances in Intrusion Detection (RAID’11), R. Sommer, D. Balzarotti, and G. Maier (Eds.), Springer-Verlag, 2011, http://dx.doi.org/10.1007/978-3-642-23644-0_19.

DevuDr. Devu Manikantan Shila is the Principal Investigator for Cyber Security area within the Embedded Systems and Networks Group at the United Technologies Research Center (UTRC).

 

Marten van DijkMarten van Dijk is an Associate Professor of Electrical and Computing Engineering at the University of Connecticut, with over 10 years research experience in system security both in academia and industry.

 

Syed Kamran HaiderSyed Kamran Haider is pursuing a PhD in Computer Engineering supervised by Marten van Dijk at the University of Connecticut.

 

This essay appears in Circuit Cellar 297 (April 2015).

The Future of Flexible Circuitry

The flexible circuit market has been growing steadily for the last three decades. This trend will continue into the foreseeable future as flexible circuitry supports many of the same industries and many of the same applications that have been around for more than 30 years. Past and current industries include military and avionics with most of these applications being high layer count, high-density rigid flex, and also consumer electronics, telecom, and automotive applications with flex circuit designs that are typically less complex than those of mil/aero. Medical diagnostic applications will continue to grow as new equipment is developed and older equipment is refurbished or redesigned. But if I had to sum up an answer to the question “where is flex going in the near future?” my answer would be simply “on you.”

The wearable electronics market has absolutely exploded in the last few years with new applications emerging almost daily. If an electronic device is going to be worn on the body comfortably, it has to be flexible. So what better way to provide interconnects for these types of devices than a flex circuit? Here are just a few of the current and emerging wearable products that contain flexible circuitry.

Wrist-Worn Activity and Body Function Monitors: Electronic watches were some of the first wearable electronics, so it was just a natural progression to include more advanced functionality than just time keeping. Wrist-worn activity monitors are light weight and use multiple axis accelerometers and other sensors to detect motion and body functions. They can capture and record daily activity levels as well as sleep cycles. This data is stored in on-board memory in the device until it can be downloaded to the user’s mobile phone. Since the human hand is larger than the wrist, these monitoring bands need to be able to expand when the user is putting it on or taking it off. Flexible circuits allow the band to flex while maintaining connectivity across flexing sections.

Foot-Worn Sensors: I have seen a lot of applications recently for electronics that are worn on the foot or inside the shoe. Foot-worn electronics monitor everything from steps taken when running or walking to stride irregularities that can contribute to back problems. These sensors need to be very thin in order to be comfortable and also very robust to survive in what I would consider a pretty hostile environment. Flexible circuitry is thin enough to lay on the sole of a shoe and be almost undetectable to the wearer.

Wearable Baby Monitors: Baby monitors are one of the newer products in the wearable electronics market. New parents no longer have to rely on a simple walkie talkie system to keep tabs on their little ones while they sleep. These monitors can be worn on the baby’s leg or in their clothing and can keep track of breathing, heartbeat, body temperature, etc. If the device senses that there is a problem, an alert is sent to the parents phone to wake them. It is almost like having a private nurse watching the child all night long.

Medical Sensors: This is an area that has been growing rapidly, and I predict that the trend will continue at an accelerated rate. With today’s push to get patients out of the hospital as quickly as possible, electronic home monitoring of the patient is going to be necessary. There are currently sensors that can be worn by the patient for several days at a time, while keeping tabs on heart functions continuously during this time. Just like the baby monitor referred to earlier, these devices can send alerts to the patient’s physician if any abnormalities are detected. These devices will allow a patient to recover from heart attack or surgery in the comfort of their own home while still having continuous monitoring of their state of health.

Pet Monitors: Even Rover gets to wear electronics these days. Training collars have been around for a while, but now thanks to shrinking electronics there are collars that contain GPS and mobile phone capabilities. Today a lost pet can use the GPS to figure out where he is and call his owner for a ride home! Not really, but if your pet is wearing one of these devices he is never truly lost. The mobile phone module is used to transmit the GPS coordinates to tracking service, where the owner can log on and track the pet’s location to within a few feet.

Clothing Worn Electronics: This is an area that is just starting to emerge, and new technology is being developed to support these applications. Standard flex circuitry is constructed from a combination of polyimide film, thermo-setting film adhesive, and copper foil. Unfortunately, flex circuits fabricated with these materials will not survive the crumpling that they would be exposed to in a washing machine. I have seen several applications where flex has been incorporated into clothing that does not need to be machine washed (e.g., flexible heaters in winter gloves). The key to making this type of wearable application machine washable is to make the flex circuit not only flexible, but also stretchable. This means that both conductors and dielectrics must be developed that will allow the finished product to stretch and still maintain electrical continuity. This technology is not mainstream yet, but it is on its way.

These examples are just a small sampling of the applications that are currently on the market, and there are many others in development. As more and more of these applications emerge, flexible circuitry will continue to be the interconnect method of choice.


Mark Finstad is a Senior Application Engineer at Flexible Circuit Technologies in Minneapolis, MN. He is a nationally recognized expert in the design, fabrication, and test of flexible and rigid flex printed circuits with more than 30 years of experience in the flexible PCB industry.

This article appears in Circuit Cellar 296 (March 2015).

The Future of Embedded Linux

My first computer was a Cosmac Elf. My first “Desktop” was a $6,500 HeathKit H8. An Arduino today costs $3 and has more of nearly everything—except cost and size—and even my kids can program it. I became an embedded software developer without knowing it. When that H8 needed bigger floppy disks, a hard disk, or a network, you wrote the drivers yourself—in assembler if you were lucky and machine code if your were not.

Embedded software today is on the cusp of a revolution. The cost of hardware capable of running Linux continues to decline. Raspberry Pi (RPi) can be purchased for $25. A Beagle Bone Black (BBB) costs $45. An increasing number of designers are building products such as Cubi, GumStik, and Olinuxino and seeking to replicate the achievements of the RPi and BBB, which are modeled on the LEGO-like success of Arduino.

These are not “embedded Linux systems.” They are full-blown desktops—less peripherals—that are more powerful than what I owned less than a decade ago. This is a big deal. Hardware is inexpensive, and designs like the BBB and RPi are becoming easily modifiable commodities that can be completed quickly. On the other hand, software is expensive and slow. Time to market is critical. Target markets are increasingly small, with runs of a few thousand units for a specific product and purpose. Consumers are used to computers in everything. They expect computers and assume they will communicate with their smart phones, tablets, and laptops. Each year, consumers expect more.

There are not enough bare metal software developers to hope to meet the demand, and that will not improve. Worse, we can’t move from concept to product with custom software quickly enough to meet market demands. A gigabyte of RAM adds $5 to the cost of a product. The cost of an eight-week delay to value engineer software to work in a few megabytes of RAM instead, on a product that may only ship 5,000 units per year, could make the product unviable.

Products have to be inexpensive, high-quality, and fast. They have to be on the shelves yesterday and tomorrow they will be gone. The bare metal embedded model can’t deliver that, and there are only so many software developers out there with the skills needed to breathe life into completely new hardware.

That is where the joy in embedded development is for me—getting completely new hardware to load its first program. Once I get that first LED to blink everything is downhill from there. But increasingly, my work involves Linux systems integration for embedded systems: getting an embedded Linux system to boot faster, integrating MySQL, and recommending an embedded Linux distribution such as Ubuntu or Debian to a client. When I am lucky, I get to set up a GPIO or write a driver—but frequently these tasks are done by the OEM. Today’s embedded ARMs have everything, including the kitchen sink integrated (probably two).

Modern embedded products are being produced with client server architectures by developers writing in Ruby, PHP, Java, or Python using Apache web servers and MySQL databases and an assortment of web clients communicating over an alphabet soup of protocols to devices they know nothing about. Often, the application developers are working and testing on Linux or even Windows desktops. The time and skills needed to value engineer the software to accommodate small savings in hardware costs do not exist. When clients ask for an embedded software consultant, they are more likely after an embedded IT expert, rather than someone who writes device drives, or develops BSPs.

There will still be a need for those with the skills to write a TCP/IP stack that uses 256 bytes of RAM on an 8-bit processor, but that growing market will still be a shrinking portion of the even faster growing embedded device market.

The future of embedded technology is more of everything. We’ll require larger and more powerful systems, such as embedded devices running full Linux distributions like Ubuntu (even if they are in systems as simple as a pet treadmill) because it’s the easiest, most affordable solution with a fast time to market.


LaneTTFDavid Lynch owns DLA Systems. He is a software consultant and an architect, with projects ranging from automated warehouses to embedded OS ports. When he is not working with computers, he is busy attempting to automate his house and coerce his two children away from screens and into the outdoors to help build their home.

 

Seven Engineers on the Future of Electrical Engineering

The Circuit Cellar staff thought it would be interesting to kick off 2015 by asking several long-time contributors about the future of electrical engineering and embedded systems. Here we present the responses we received to the following questions: What are your thoughts on the future of electrical engineering? What excites you? Is there something in your particular field of interest that you think will be a “game changer”?

STEVE CIARCIA: Frankly speaking, if I was smart enough to accurately predict the future, I wouldn’t be doing all this again. Seriously, “What excites me in the future?” shouldn’t be the question I’m answering here. Instead, it should be  how much does all this embedded stuff we’re seeing and talking about today look like a classic case of déją vu to me. Circuit Cellar started 40 years ago in BYTE to promote my enthusiasm for professional-level DIY computer applications (albeit mostly embedded). The names have changed to Maker this and that and Raspberry Pi whatever, but what once was, still is. Solder fumes aside, Circuit Cellar has always been about nurturing the talented engineer who designs the game changer. (Steve is an electrical engineer who founded Circuit Cellar in 1988.)

DAVID TWEED: Embedded technology is becoming more pervasive, appearing in more and more places in our lives. Embedded processors have become as powerful as desktop machines were just a few short years ago, and the their ability to connect to the world at large through high-bandwidth wireless communications has grown to match this. This is both exciting and scary, because it becomes a powerful enabler for both positive and negative changes in how we live our lives. Take the ubiquitous “smart phone” as an example. It can process two-way audio, video, GPS data, and an Internet connection simultaneously in real time. This enables powerful applications such as GPS-based route finding that can give you verbal and pictorial directions to get you where you want to go. But, as anyone who watches the popular crime drama N.C.I.S. knows, that same technology can be used to track your phone’s location, along with everything it can “see” and “hear,” including the phone calls you have made. While that kind of surveillance can be used it positive ways, such as to aid you in an emergency, it can also be used to invade your privacy. Can you really be sure that everyone in law enforcement and other areas of government has only your best interests in mind when accessing your data? The increased power of embedded systems means that autonomous mechanisms gain capabilities they didn’t have before. Fully-autonomous vehicles—cars, trucks, trains, and aircraft—will be able to carry people and goods long distances over arbitrary routes. Factory automation will become more generic, because complex general-purpose mechanisms will be as easy to use as purpose-built mechanisms that only do one thing, because the software will manage all of the low-level details of “training” the system. Machine vision will be an important part of this, giving the system the feedback it needs to interact with objects and people. “With great power comes great responsibility.” This has never been more true. I’m excited by the possibilities that increasingly powerful embedded technology will open up for us, but let’s make sure that it is used responsibly! (David is a professional electrical engineer and long-time Circuit Cellar author and technical editor.)

ROBERT LACOSTE: I think the most significant change in embedded systems these last years is the nearly mandatory inclusion of Internet connectivity. It’s called the Internet of Things (IoT). Just enter those three words in Google and the 752 million results you get will show it’s a quite hot topic. When a customer meets with us to discuss a potential new product (whatever it is), the question is no longer: “Should it be connected?” The question is: “How should it be connected?” Having said that, the key difficulty is the long list of wireless protocols trying to become the ubiquitous solution for IoT: Wi-Fi, Bluetooth, Bluetooth Low Energy, ZigBee, Zwave, 6LowPan, and a hundred others. Bluetooth seems the clear winner for smartphone-based products, but what about the other applications like home automation, logistics, smart metering, or dog tracking? Which protocol(s) will be the winner(s)? Which one will be natively supported on our Internet access gateways or even rolled-out worldwide? Will it be Thread, sponsored by Google itself? Or will it be another derivative of Bluetooth, due to its huge predominance? (The overall sales of Bluetooth-capable chips already exceed four times the human population on earth.) Or could it be one of the machine-to-machine variants of 3G/4G cellular standards being studied? Or perhaps it will be one of the solutions proposed by one of the many startups working on the technology? Or maybe it will be a completely new protocol that we’ll invent? I don’t know the answer, but the result will be the next game changer! (Robert is an electrical engineer and Circuit Cellar columnist. In 2003, he founded ALCIOM, an electrical engineering firm near Paris, France.)

CHRIS COULSTON: While tech will companies continue to evolve existing technologies to offer more features, with lower power and at a lower cost, I think that the most exciting and revolutionary technology is to be found in the Internet of Everything (IOE) concept. Hardware supporting the IOE offers up the tantalizing potential to free our designs from physical interconnects, giving our designs world wide access, allowing us to interact with our designs in real time, and allowing our design to access the almost unlimited diversity of services available on the Internet. I am excited to explore a design space that enables me to connect something trivial like my key-ring to the Internet. The Raspberry Pi was the first breakthrough with companies like Intel redefining the cutting edge with their Edison module. There are several limiters to the IOE concept including power consumption and standardization. As these issues are addressed, the potential of the IOE concept will only be limited to the creativity of engineers and makers everywhere. (Chris is a professor of electrical and computer engineering at Penn State, Behrend. He’s also technical reviewer for Circuit Cellar.)

GEORGE NOVACEK: Embedded controllers are essential components of automatic systems. Without  automation, many products could not even be manufactured. Machines, such as aircraft, medical equipment, power generators, etc. could not be operated without the assistance of smart control systems. Until some, not yet invented, technology makes electronics obsolete, the future of embedded controllers will remain bright. In the coming years, more and more engineers will be focusing on system design, while only the brightest ones will be developing microelectronic components for those systems—more sophisticated, more integrated, faster, smaller, hardened to environment, consuming less power. There continues to be a trend towards universal embedded controllers. These, equipped with the appropriate sensors and actuators and loaded with a particular application software, could be used for fly-by-wire, or for control of an industrial machinery or just about everything else. Design engineers need to be cautious not to put powerful, yet inexpensive controllers into new products just because it  can be done. There is already a proliferation of simple  consumer products equipped, without any sensible need, with microcontrollers. This often leads to lower reliability, shorter life and, because these products are usually not repairable, to greater cost of ownership and waste. (George is professional engineer and Circuit Cellar columnist who served as president of a multinational manufacturer of embedded control systems for aerospace applications.)

ED NISLEY: The rise of the Maker Movement changes everything in the embedded systems field: Makers take control over the devices in their lives, generally by repurposing embedded hardware in ways its designers never intended. The trend becomes clear when dirt-cheap USB TV tuners become software defined radios. Embedded systems must eventually sprout exposed (and documented!) interfaces, debugging hooks, and protocols, because collaboration with Makers who want to turn the box inside-out and build something better can enrich our world beyond measure. Excluding those people won’t work over the long term: just as DRM-encumbered music became unacceptable, welded-shut embedded systems will become historic curiosities. You can make it so! (Ed is an electrical engineer and long-time Circuit Cellar columnist and contributor.)

KEN DAVIDSON: Twenty-five years ago, while developing the Circuit Cellar Home Control System (HCS) II, our group created a series of interface boards that could be placed around the house and communicate using RS-485. Tons of discrete wire running throughout buildings was the norm at the time, and the idea of running just a single twisted pair between units was novel and exciting. This all predated inexpensive Ethernet and public Internet. Today, such distributed intelligence has only gotten better, smaller, and cheaper. With the Internet of Things (IoT) everybody is talking about, it’s not unusual to find a wireless interface and embedded intelligence right down to the level of a light bulb. There was an episode of The Big Bang Theory where the guys set up the apartment lights so they could be controlled from anywhere in the world. Everyone got a laugh when the “geeks” were excited when someone from Japan was blinking their lights. But the idea of such embedded intelligence and remote access continuing to evolve and improve truly is exciting. I look forward to the day in the not-too-distant future when such control is commonplace to most people and not just a geeky novelty. (Ken is an embedded software engineer who has been contributing to Circuit Cellar for years as an author and editor.)

These responses appear in Circuit Cellar 294 (January 2015).

The Future of Temperature-Compensated Crystal Oscillators

Most modern digital and analog electronic devices require a time base to perform their intended function. Found in everything from cell phones to smart munitions, quartz crystal oscillators are widely used in many embedded applications. Quartz resonators’ high Q, excellent temperature performance, and superior long-term aging makes them the clear resonator of choice for many applications. The frequency versus temperature performance of a discrete LC oscillator will be on the order of several hundred parts per million (ppm) per °C, where a crystal oscillator (XO) will have roughly ±30 ppm over the entire industrial temperature range (–40 to +85°C). While being superior to a discrete oscillator, this temperature stability is not nearly sufficient for many modern applications.

EsterlineFigure1

Source: John Esterline

The temperature-compensated crystal oscillator (TCXO) employs the use of an open loop compensation circuit to create a correction voltage to reduce the inherent frequency versus temperature characteristic of the crystal. The crystals used in TCXOs have frequency versus temperature characteristics that approximate a third-order polynomial, as seen in the nearby figure.

The early designs for TCXOs employed a network of thermistors and resistors to create a correction voltage. By using thermistors with different slopes and properly selecting the fixed value resistors, the correction voltage can be made to have a shape factor matched to the crystal’s frequency versus temperature performance. The correction voltage is applied to a varactor in the feedback path of the TCXO. This change in capacitance in the feedback path alters the tuning of the oscillator, thus changing the output frequency and compensating it for temperature effects. Thermistor/Resistor network TCXOs can achieve frequency versus temperature stabilities of around ±1 ppm over the industrial temperature range; however, they are limited in their curve-fitting capabilities because of the nature of using discrete thermistors and resistors.

Thermistor/resistor network TCXOs are still found in specialized environments including satellite and other space applications where modern solid-state devices do not have the radiation hardness to survive. Most TCXOs manufactured today utilize an ASIC which contains the oscillator circuit and a third- or fifth-order polynomial voltage generator. The polynomial generator is an analog output voltage but also has digital registers for setting the coefficients of the polynomial. The newest generations of TCXO ASICs can provide temperature performances of ±0.1 ppm over the industrial temperature range. This is a 10-fold improvement over what is obtainable with a traditional thermistor/resistor network TCXOs and also has the advantage of a much smaller footprint (5 mm × 3.2 mm).

Some high-precision applications require frequency versus temperature stabilities better than ±0.1 ppm. To meet these challenging specifications a different methodology is implemented. An oven-controlled crystal oscillator (OCXO) uses a heater circuit and thermal insulation to keep the crystal at an elevated temperature (≈15°C above the upper operating temperature limit). By controlling the crystal’s temperature and keeping it nearly constant, the frequency deviation due to ambient temperature changes is vastly reduced. OCXOs can achieve frequency versus temperature stabilities of ±0.005 ppm. This improved performance comes at the cost of a larger footprint and increased power consumption. The TCXO’s performance limit of ±0.1 ppm is due to several factors. First, the resonators are not perfect. Their frequency versus temperature stability approximates a third-order polynomial; however, higher order effects are present. Secondly, the polynomial generator is nonideal and induces some higher order artifacts, leaving the user with residuals of ±0.1 ppm. A new methodology which uses an artificial neural network (ANN) to create the correction voltage has recently been demonstrated. The ANN is superior in that the neural network is not inherently shape limited like a third-order polynomial. If enough data is presented to the ANN, it can “learn” the crystal’s temperature performance shape and correct for it. This new methodology has been shown to provide ±0.01 ppm frequency versus temperature stability over the industrial range. The ANN algorithm can achieve OCXO temperature performance in a much smaller footprint, and without the need for the power-hungry oven.

The evolution of quartz crystal time bases over the last 70 years has seen the frequency versus temperature stability improve by a factor of several thousand. As our need for more stable oscillators in smaller packages with less power consumption grows, the development of better compensation schemes is paramount. The ANN demonstrates a technology that has much potential. Its ability to adapt and change its shape factor makes it ideal for complex compensation problems.

EsterlinePhotoJohn Esterline is the CEO of Esterline Research and Design, LLC, a Pennsylvania based start-up company. John holds an MEngEE and a BSEE from Pennsylvania State University. His research interests focus on temperature compensation algorithms for the improvement of embedded time bases. John is the inventor on two US patents (US8188800 B2, US8525607 B2), and the inventor of one patent pending (US 13/570,563). Esterline Research and Design, LLC offers consulting services in frequency control, test and automation and other subject matter in addition to its RF testing products.

 

Circuit Cellar 291 (October 2014) is now available.

Self-Reconfiguring Robotic Systems & M-Blocks

Self-reconfiguring robots are no longer science fiction. Researchers at MIT are rapidly innovating shape-shifting robotic systems. In the August 2014 issue of Circuit Cellar, MIT researcher Kyle Gilpin presents M-Blocks, which are 50-mm cubic modules capable of controlled self-reconfiguration.

The creation of autonomous machines capable of shape-shifting has been a long-running dream of scientists and engineers. Our enthusiasm for these self-reconfiguring robots is fueled by fantastic science fiction blockbusters, but it stems from the potential that self-reconfiguring robots have to revolutionize our interactions with the world around us.

Source: Kyle Gilpin

Source: Kyle Gilpin

Imagine the convenience of a universal toolkit that can produce even the most specialized tool on demand in a matter of minutes. Alternatively, consider a piece of furniture, or an entire room, that could change its configuration to suit the personal preferences of its occupant. Assembly lines could automatically adapt to new products, and construction scaffolding could build itself while workers sleep. At MIT’s Distributed Robotics Lab, we are working to make these dreams into reality through the development of the M-Blocks.

The M-Blocks are a set of 50-mm cubic modules capable of controlled self-reconfiguration. Each M-Block is an autonomous robot that can not only move independently, but can also magnetically bond with other M-Blocks to form larger reconfigurable systems. When part of a group, each module can climb over and around its neighbors. Our goal is that a set of M-Blocks, dispersed randomly across the ground, could locate one another and then independently move to coalesce into a macro-scale object, like a chair. The modules could then reconfigure themselves into a sphere and collectively roll to a new location. If, in the process, the collective encounters an obstacle (e.g., a set of stairs to be ascended), the sphere could morph into an amorphous collection in which the modules climb over one another to surmount the obstacle.  Once they have reached their final destination, the modules could reassemble into a different object, like a desk.

The M-Blocks move and reconfigure by pivoting about their edges using an inertial actuator. The energy for this actuation comes from a 20,000-RPM flywheel contained within each module. Once the motor speed has stabilized, a servomotor-driven, self-tightening band brake decelerates the flywheel to a complete stop in 15 ms. All of the momentum that had been accumulated in the flywheel is transferred to the frame of the M-Block. Consequently, the module rolls forward from one face to the next, or if the flywheel velocity is high enough, it rapidly shoots across the ground or even jumps several body lengths through the air. (Refer to www.youtube.com/watch?v=mOqjFa4RskA  to watch the cubes move.)

While the M-Blocks are capable of independent movement, their true potential is only realized when many modules operate as a group. Permanent magnets on the outside of each M-Block serve as un-gendered connectors. In particular, each of the 12 edges holds two cylindrical magnets that are captive, but free to rotate, in a semi-enclosing cage. These magnets are polarized through their radii, not through their long axes, so as they rotate, they can present either magnetic pole. The benefit of this arrangement is that as two modules are brought together, the magnets will automatically rotate to attract. Furthermore, as one and then two additional M-Blocks are added to form a 2 × 2 grid, the magnets will always rotate to realign and accommodate the additional modules.

The same cylindrical magnets that bond neighboring M-Blocks together form excellent pivot axes, about which the modules may roll over and around one another. We have shown that the modules can climb vertically over other modules, move horizontally while cantilevered from one side, traverse while suspended from above, and even jump over gaps. The permanent magnet connectors are completely passive, requiring no control and no planning. Because all of the active components of an M-Block are housed internally, the modules could be hermetically sealed, allowing them to operate in extreme environment where other robotic systems may fail.

While we have made significant progress, many exciting challenges remain. In the current generation of modules, there is only a single flywheel, and it is fixed to the module’s frame, so the modules can only move in one direction along a straight line. We are close to publishing a new design that enables the M-Blocks to move in three dimensions, makes the system more robust, and ensures that the modules’ movements are highly repeatable. We also hope to build new varieties of modules that contain cameras, grippers, and other specialized, task-specific tools. Finally, we are developing algorithms that will allow for the coordinated control of large ensembles of hundreds or thousands of modules. With this continued development, we are optimistic that the M-Blocks will be able to solve a variety of practical challenges that are, as of yet, largely untouched by robotics.

Kyle Gilpin

Kyle Gilpin

ABOUT THE AUTHOR

Kyle Gilpin, PhD, is a Postdoctoral Associate in the Distributed Robotics Lab at the Massachusetts Institute of Technology (MIT) where he is collaborating with Professor Daniela Rus and John Romanishin to develop the M-Blocks. Kyle works to improve communication and control in large distributed robotic systems. Before earning his PhD, Kyle spent two years working as a senior electrical engineer at a biomedical device start-up. In addition to working for MIT, he owns a contract design and consulting business, Crosscut Prototypes. His past projects include developing cellular and Wi-Fi devices, real-time image processing systems, reconfigurable sensor nodes, robots with compliant SMA actuators, integrated production test systems, and ultra-low-power sensors.

Circuit Cellar 289 (August 2014) is now available.

Wearable Medical Computing and the Amulet Project

Health care is one of the most promising areas for employing wearable devices. Wearable mobile health sensors can track activities (e.g., count steps or caloric expenditure), monitor vital signs including heart rate and blood pressure, measure biometric data (e.g., glucose levels and weight), and provide alerts to medical emergencies including heart failures, falls, and shocks.

Applying wearable computing to support mobile health (mHealth) is promising but involves significant risks. For instance, there are security issues related to the reliability of the devices and sensors employed, the accuracy of the data collected, and the privacy of sensitive information.

The Amulet bracelet-style prototype for developers enables users to control its settings

The Amulet bracelet-style prototype for developers enables users to control its settings

Under the federally funded Amulet project, an interdisciplinary team of Dartmouth College and Clemson University researchers is investigating how wearable devices can effectively address medical problems while ensuring wearability, usability, privacy, and security for mHealth applications. The project aims to develop pieces of “computational jewelry” and a software framework for monitoring them. This computational jewelry set comprises wearable mobile health devices collectively named Amulet. An Amulet device could be worn as a discreet pendant or bracelet that would interact with other wearable health sensors that constitute the wearer’s wireless body-area network (WBAN). The Amulet device would serve as a “hub,” tracking health information from wearable health sensors and securely sending data to other health devices or medical professionals.

The project’s goals are multifold. Regarding the hardware, we’re focusing on designing small and unobtrusive form factors, efficient power sources, and sensing capabilities. With respect to the software, we’re concentrating on processing and interpreting the digital signs coming from the sensors, effectively communicating and synchronizing data with external devices, and managing encrypted data.

Amulet’s multiprocessor hardware architecture includes an application processor that performs computationally intensive tasks and a coprocessor that manages radio communications and internal sensors. Amulet’s current prototypes contain an accelerometer and a gyroscope to monitor the wearer’s motion and physical activities, a magnetometer, a temperature sensor, a light sensor, and a microphone. To save power, the application processor is powered off most of the time, while the coprocessor handles all real-time device interactions.

By employing event-driven software architecture, Amulet enables applications to survive routine processor shutdowns. Amulet is reactive, running only when an event of interest occurs. To handle such events, programmers can define their application as a finite-state machine and set appropriate functions. Amulet’s architecture enables applications to identify the computational states that should be retained between events. Explicitly managing program state (rather than implicitly managing state in a thread’s run-time stack) enables the run-time system to efficiently save the application state to persistent memory and power down the main processor without harming applications.

Amulet provides a secure solution that ensures the accuracy and the integrity of the data sensed and transmitted, continuous availability of the services provided (e.g., data sensing and processing and sending alerts and notifications), and access to the device’s data and services only by authorized parties after their successful authentication. Two key features enable Amulet to provide security in mHealth applications: sandboxing and the authorization manager. The former enforces access control, protects memory, and restricts the execution of event handlers. The latter enables applications to run small tasks until their completion, managing all resources by receiving requests and forwarding them to a corresponding service manager.

Amulet also aims to protect privacy, enabling users to control what is sensed and stored, where it is stored, and how it is shared (with whom). Amulet devices use privacy policies to protect patients’ sensitive information, which ensures confidentiality through authorized access and controlled sharing.

To guarantee easy wearability, the Amulet team focuses on understanding the user’s wishes, needs, and requirements and translating them into appropriate design decisions. Amulet provides a list of principles and guidelines for wearability, which will aid designers in providing high levels of comfort, aesthetics, ergonomics, and discretion in their projects.

Amulet includes a framework to support stakeholders involved in similar projects during all phases of development. It is intended to aid developers and designers from industry or academia. Amulet provides a general-purpose solution for body-area mobile health, complementing the capabilities of a smartphone and facilitating the development of applications that integrate one or more mHealth wearable devices.

Amulet also provides intuitive interfaces and interaction methods for user input and output, employing multimodal approaches that include gestures and haptics. Amulet has developed and continues to refine bracelet-style prototypes with a variety of envisioned applications, including: emergency responders (e.g., providing immediate notifications and quick responses in medical emergencies), stress monitoring, smoking cessation, diet (e.g., bite counting), and physical therapy (e.g., knee sensors).

Dr. Vivian Genaro Motti

Dr. Vivian Genaro Motti

ABOUT THE AUTHOR

Dr. Vivian Genaro Motti holds a PhD in Human Computer Interaction from the Université catholique de Louvain in Belgium. She is a Postdoctoral Research Fellow in the School of Computing at Clemson University in Clemson, SC. She works on the Amulet project, which is funded by a three-year, $1.5 million grant from the National Science Foundation’s Computer Systems Research program. As part of the Amulet project, Vivian is investigating how to properly ensure wearability and privacy in wearable applications for mobile health. Vivian has a BA in Biomedical Informatics and an MS in Human Computer Interaction from University of Sao Paulo in Brazil. Her main research interests are human computer interaction, medical applications, wearable devices and context awareness.

This appears in Circuit Cellar 288, July 2014.

The Future of Open-Source Hardware for Medical Devices

Medical technology is changing at a rapid pace, but regulatory compliance is also becoming increasingly harder. Regulatory compliance can act as a barrier to innovation, but it is a necessary check to ensure quality medical care. For small companies, aligning innovation with regulatory compliance can only help.

Fergus Dixon

When designing any new product, the FDA-recommended process is a great reference. First, the design input requirements must be written down. After the device has been designed and prototyped, verification and validation (V&V) will ensure that the device meets the design input. The device is then documented, creating the design output or device master record (DMR). Each device made is checked against the DMR and documented in the device history record (DHR). So all the details on how to make the device are contained in the DMR, and the results and traceability are recorded in the DHR.

My company recently asked an overseas company to design and manufacture an existing product. After many e-mails, the overseas company managed to build a working unit and immediately requested an order for 1,000. Before ordering even one unit, there was the matter of V&V. So what is V&V? Verification is the act of ensuring that the circuit acts as it should, as the circuit designer intended. This involves testing to a predetermined criteria, where the pass/fail is clearly defined. Testing happens by varying the inputs and checking the outputs to test the device as close to 100% as reasonably possible. When the inputs fall outside a normal range (e.g., a 10-VDC instead of 12-VDC battery voltage), the device must still work or it must provide a message showing why the device will not work (e.g., low battery light). Validation is the act of ensuring the circuit works as the customer or patient requires. This involves field testing, feedback, and rework—lots of it.

Working for medical device companies can be very rewarding. Smaller companies tend to work at the cutting edge. Larger companies are more secure and have stable products, but they can be less agile. With one company, we had a device that used smart batteries. During testing, we discovered that the batteries would not charge below 15ºC. After many meetings and e-mails to the manufacturers, the problem went to management, who decided to change the manual to say: “Do not charge below 15ºC.” Smaller dynamic companies can attract the best scientists, which is great until a connector fails and there is a roomful of highly intelligent people with no soldering iron experience. Every technology company can benefit from having at least one experienced technician or engineer. A few hours spent playing with an Arduino is a great way to get this experience.

What about open-source hardware (OSHW) for medical devices? For home hobbyists and students, OSHW is great. There is free access to working circuits, programs, and sketches. C compilers, which once cost several thousand dollars, are mostly free. For the manufacturers, the benefits are plenty of feedback, which can be used to improve products. There is one roadblock, and that involves the loss of intellectual property (IP), which means anyone can copy the hardware. Creative Commons has addressed this with an agreement that any copies must reference the original work. Closed-source hardware can also be good and present fewer issues with losing IP. Apple is a great example. Rather than use feedback to improve products, it makes smart decisions about future products. The iOS vs. Android battle can be viewed as a closed-source vs. open-source struggle that still hasn’t produced a winner. Medical devices and OSHW will have to meet up sometime.

Fergus Dixon’s embedded DNA sequencer project (Source: F. Dixon)

What about the future of medical devices? Well, the best is yet to come with brighter organic light-emitting diode (OLED) displays, a multitude of wireless connectivity options (all using the serial interface), and 32-bit ARM cores. DNA is gradually being unlocked with even “junk DNA” becoming meaningful. The latest hot topics of 3-D printing and unmanned aerial vehicles (UAVs) have direct medical applications with 3-D printed prosthetic ears and medical nanorobotics ready to benefit from UAV technology. Using a new sensor (e.g., a gyroscope) now means visiting an online seller such as Pololu, which offers ready-built development kits at reasonable prices. A recent design was a manually assisted CPR device project, which was abandoned due to lack of funding. How great would it be to have a device that could not only improve the current 10% survival rate with CPR (5% without CPR) but also could measure a patient’s health to determine whether CPR was helping and, even more importantly, when to stop administering it? Now that would be a good OSHW project.