Q&A: Hanno Sander on Robotics

I met Hanno Sander in 2008 at the Embedded Systems Conference in San Jose, CA. At the time, Hanno was at the Parallax booth demonstrating a Propeller-based, two-wheeled balancing robot. Several months later, we published an article he wrote about the project in issue March 2009. Today, Hanno runs HannoWare and works with school systems to improve youth education by focusing technological innovation in classrooms.

Hanno Sander at Work

The March issue of Circuit Cellar, which will hit newsstands soon, features an in-depth interview with Hanno. It’s an inspirational story for experienced and novice roboticists alike.

Hanno Sander's Turing maching debugged with ViewPort

Here’s an excerpt from the interview:

HannoWare is my attempt to share my hobbies with others while keeping my kids fed and wife happy. It started with me simply selling software online but is now a business developing and selling software, hardware, and courseware directly and through distributors. I get a kick out of collaborating with top engineers on our projects and love hearing from customers about their success.

Our first product was the ViewPort development environment for the Parallax Propeller, which features both traditional tools like line-by-line stepping and breakpoints as well as real-time graphs of variables and pin I/O states to help developers debug their firmware. ViewPort has been used for applications ranging from creating a hobby Turing machine to calibrating a resolver for a 6-MW motor. 12Blocks is a visual programming language for hobby microcontrollers.

The drag-n-drop style of programming with customizable blocks makes it ideal for novice programmers. Like ViewPort, 12Blocks uses rich graphics to help programmers understand what’s going on inside the processor.

The ability to view and edit the underlying sourcecode simplifies transition to text languages like BASIC and C when appropriate. TBot is the result of an Internetonly collaboration with Chad George, a very talented roboticist. Our goal for the robot was to excel at typical robot challenges in its stock configuration while also allowing users to customize the platform to their needs. A full set of sensors and actuators accomplish the former while the metal frame, expansion ports, and software libraries satisfy the latter.

Click here to read the entire interview.

 

Zero-Power Sensor (ZPS) Network

Recently, we featured two notable projects featuring Echelon’s Pyxos Pyxos technology: one about solid-state lighting solutions and one about a radiant floor heating zone controller. Here we present another innovative project: a zero-power sensor (ZPS) network on polymer.

The Zero Power Switch (Source: Wolfgang Richter, Faranak M.Zadeh)

The ZPS system—which was developed by Wolfgang Richter and Faranak M. Zadeh of Ident Technology AG— doesn’t require battery or RF energy for operation. The sensors, developed on polymer foils, are fed by an electrical alternating field with a 200-kHz frequency. A Pyxos network enables you to transmit of wireless sensor data to various devices.

In their documentation, Wolfgang Richter and Faranak M. Zadeh write:

“The developed wireless Zero power sensors (ZPS) do not need power, battery or radio frequency energy (RF) in order to operate. The system is realized on polymer foils in a printing process and/or additional silicon and is very eco-friendly in production and use. The sensors are fed by an electrical alternating field with the frequency of 200 KHz and up to 5m distance. The ZPS sensors can be mounted anywhere that they are needed, e.g. on the body, in a room, a machine or a car. One ZPS server can work for a number of ZPS-sensor clients and can be connected to any net to communicate with network intelligence and other servers. By modulating the electric field the ZPS-sensors can transmit a type of “sensor=o.k. signal” command. Also ZPS sensors can be carried by humans (or animals) for the vital signs monitoring. So they are ideal for wireless monitoring systems (e.g. “aging at home”). The ZPS system is wireless, powerless and cordless system and works simultaneously, so it is a self organized system …

The wireless Skinplex zero power sensor network is a very simply structured but surely functioning multiple sensor system that combines classical physics as taught by Kirchhoff with the latest advances in (smart) sensor technology. It works with a virtually unlimited number of sensor nodes in inertial space, without a protocol, and without batteries, cables and connectors. A chip not bigger than a particle of dust will be fabricated this year with the assistance of Cottbus University and Prof. Wegner. The system is ideal to communicate via PYXOS/Echelon to other instances and servers.

Pyxos networks helps to bring wireless ZPS sensor data over distances to external instances, nets and servers. With the advanced ECHELON technology even AC Power Line (PL) can be used.

As most of a ZPS server is realized in software it can be easily programmed into a Pyxos networks device, a very cost saving effect! Applications start from machine controls, smart office solutions, smart home up to Homes of elderly and medical facilities as everywhere else where Power line (PL) exists.”

Inside the ZPS project (Source: Wolfgang Richter, Faranak M.Zadeh)

For more information about Pyxos technology, visit www.echelon.com.

This project, as well as others, was promoted by Circuit Cellar based on a 2007 agreement with Echelon.

Robot Nav with Acoustic Delay Triangulation

Building a robot is a rite of passage for electronics engineers. And thus this magazine has published dozens of robotics-related articles over the years.

In the March issue, we present a particularly informative article on the topic of robot navigation in particular. Larry Foltzer tackles the topic of robot positioning with acoustic delay triangulation. It’s more of a theoretical piece than a project article. But we’re confident you’ll find it intriguing and useful.

Here’s an excerpt from Foltzer’s article:

“I decided to explore what it takes, algorithmically speaking, to make a robot that is capable of discovering its position on a playing field and figuring out how to maneuver to another position within the defined field of play. Later on I will build a minimalist-like platform to test algorithms performance.

In the interest of hardware simplicity, my goal is to use as few sensors as possible. I will use ultrasonic sensors to determine range to ultrasonic beacons located at the corners of the playing field and wheel-rotation sensors to measure distance traversed, if wheel-rotation rate times time proves to be unreliable.

From a software point of view, the machine must be able to determine robot position on a defined playing field, determine robot position relative to the target’s position, determine robot orientation or heading, calculate robot course change to approach target position, and periodically update current position and distance to the target. Because of my familiarity with Microchip Technology’s 8-bit microcontrollers and instruction sets, the PIC16F627A is my choice for the microcontrollers (mostly because I have them in my inventory).

To this date, the four goals listed—in terms of algorithm development and code—are complete and are the main subjects of this article. Going forward, focus must now shift to the hardware side, including software integration to test beyond pure simulation.

SENSOR TECHNOLOGY & THE PLAYING FIELD
A brief survey of ultrasonic ranging sensors indicates that most commercially available units have a range capability of 20’ or less. This is for a sensor type that detects the echo of its own emission. However, in this case, the robot’s sensor will not have to detect its own echoes, but will instead receive the response to its query from an addressable beacon that acts like an active mirror. For navigation purposes, these mirrors are located at three of the four corners of the playing field. By using active mirrors or beacons, received signal strength will be significantly greater than in the usual echo ranging situation. Further, the use of the active mirror approach to ranging should enable expansion of the effective width of the sensor’s beam to increase the sensor’s effective field of view, reducing cost and complexity.

Taking the former into account, I decided the size of the playing field will be 16’ on a side and subdivided into 3” squares forming an (S × S) = (64 × 64) = (26, 26) unit grid. I selected this size to simplify the binary arithmetic used in the calculations. For the purpose of illustration here, the target is considered to be at the center of the playing field, but it could very well be anywhere within the defined boundaries of the playing field.

Figure 1: Squarae playing field (Source: Larry Foltzer CC260)

ECHOES TO POSITION VECTORS
Referring to Figure 1, the corners of the square playing field are labeled in clockwise order from A to D. Ultrasonic sonar transceiver beacons/active mirrors are placed at three of the corners of the playing field, at the corners marked A, B, and D.”

The issue in which this article appears will available here in the coming days.

Living & Working Off the Grid

Interested in engineering your own solar panel system installation? If so, you’ve likely begun researching photovoltaic technology, construction materials, and test equipment on the Internet. Have you been satisfied with the information you’ve found? Probably not. There’s simply a scarcity of reliable electronics engineering advice out there about serious solar panel installation projects. Enter Circuit Cellar. Over the past several years, we’ve published articles by professional engineers about their own installations.

Three panels are wired in series and run into the MPPT controllers. Their capacity is 170 W each, 510 W total, to charge the batteries and put off running the generator. (Source: George Martin CC218)

So, before you get sidetracked with another 3-minute video or bullet-point tutorial, do yourself a favor and read columnist George Martin’s two-part article series “Living and Working Off the Grid.” Here’s an excerpt from Part 1:

“First, I’m an engineer—and an electrical one at that (except my degree is so old that it reads “DC ONLY!”). In addition, my neighbors in New Mexico already have systems up and running. Jeff and Pat live up the road in a handmade log home. Jeff is a former engineer for General Motors (Pontiac GTO, Avanti, and Saturn to his credit). That makes for some interesting discussions about how electronics will revolutionize the car industry, but I digress. He’s a mechanical engineer who doesn’t fully embrace all of this electrical stuff. He has a minimal system with four panels of about 150 W each. Another neighbor’s system has about 3 kW of panels. Armed with the idea that it could be done, I started to match up equipment with our requirements.

The equipment I selected falls into four main categories: solar panels, inverters, charge controllers, and batteries. In fact, you could consider each independently and not get too far off an ideal system. There are, however, some areas of concern when mating equipment from different manufactures, so I stayed with one manufacturer for the control devices.

SOLAR PANELS

Solar panels convert solar energy into electrical energy. Again, there is a lot of literature available about how this is accomplished. But what about some hard code conversion details? Standard test conditions require a temperature of 25°C and an irradiance of 1,000 W/m² with an air mass of 1.5 (AM1.5) spectrum. They correspond to the irradiance and spectrum of sunlight incident on a clear day on a sun-facing 37° tilted surface with the sun at an angle of 41.81° above the horizon. This condition approximately represents solar noon near the spring and autumn equinoxes in the continental U.S. with the surface of the cell aimed directly at the sun. Thus, under such conditions, a solar cell with a 12% efficiency and a 100 cm2 (0.01 m2) surface area can be expected to produce approximately 1.2 W of power.[1] This gives you an idea of what’s involved in rating and selecting solar panels. Look at the University of Western New Mexico’s weather site for solar radiation and you’ll get a feeling for the actual solar radiation for the area.

There is another consideration when selecting a panel, namely cost per watt. If you start looking, you will find panels of different wattages and different prices. In March 2004, I started a spreadsheet listing panels from 125 to 195. Note pricing from March 2004, purchased equipment in 2005, installed in 2006–2007, and operational in October 2007. Then, I added the costs different suppliers were charging for each panel and calculated a price/watt number.

My results range from $4.35 to $4.76 per watt. I estimated that I would need 3,000 W of panels, and came up with $13,320 for the cost of the BP Solar SX 170B.

More polysilicon is currently being used in solar panel manufacturing than all other usages combined, so this is big business. It also seems that the larger-power-rating panels command a higher price per watt. It is sort of like the CPU business where chips are speed graded and priced accordingly.

My cost estimates are a bit old, so you’ll need to run the numbers with today’s prices. Let me add that I found solar panels to be in tight supply, so when you begin your design, look to secure the panels at a good price early in the game.

The 3,000 W in my design was derived from the sun’s availability in the winter. Figure 2 represents the solar radiation for an actual cloudless winter day.

Figure 2: The actual solar radiation recorded by Western New Mexico University in Silver City about 30 miles to the west of the house site. (Source: George Martin CC 216)

The peak radiation is 600 W/m2. Let’s estimate that the shape of the curve is a sine function so that the area under the curve is its average value (2/pi, or 0.6366 times the peak value) multiplied by its width. So, that is 600 W/m2 × 0.6366 × 8 h (9 A.M. to 5 P.M.), or 3,055.7 Wh/m2. Therefore: Close to 10 kWh per day is good enough for the workshop, but not enough for the house when it’s built. And 3 kW of panels is what one neighbor is using.

We also need to account for cloudy days. The energy to run the workshop would need to come from the battery or backup generator. Another concern is hot summer days when the panel efficiency drops because of the heat. But the days are longer in the summer. Actually, it’s still a 24-hour day, but there is more available sunlight each day. I don’t have test results for summer generation (because I’m writing this in February 2008 after getting the system put together in October 2007), so stay tuned. The last point to watch out for in panel selection is cold weather open-circuit voltage going into the charge controller.

In the cold, with no current drawn, the open-circuit voltage of the solar panel will rise. If several panels are connected in series (for efficiency), this voltage may damage the input to the charge controller. This is a well-known situation and your equipment dealer will be able to guide you in this area.

INVERTERS

I must confess that I find inverters boring. They are not as exciting as solar panels, charge controllers, or even batteries. I thought I would not find much difference in available inverters and that probably was due to my lack of enthusiasm. I selected inverters from OutBack Power Systems. I wanted the inverter/charge controller combination to be from one manufacturer. As I looked at the literature, OutBack seemed to have covered all of the issues for my installation. I ended up with two OutBack VFX3648 inverters (see Photo 2).

Photo 2: The placement of the Outback System next to the feed into the normal house distribution panel. (Source: George Martin CC216)

They are 3.6 kW (continuous) with connections for a 48-V battery and vented. You will find vented and sealed inverters. I selected vented because they typically have a larger power rating and I’m not in a harsh environment.

Also, the inverters are located in an area that is protected from the elements. Another option is a fan on the inverter. The fan also gives you more capacity, but what will you do when the fan fails, and you know it will? Our system is a normal 220-V home application. So, there are two inverters, one for each phase. OutBack has a neat option that includes a transformer to supply the second phase so the second inverter can remain in a low-power operating mode. When the power requirements become large enough, the main inverter will signal the second (slave) inverter to start up and handle the increased load. This is a good setup for our application. We can install a normal commercial heating/cooling system and power up only the second inverter when the load is calling for it.

Click here to read the entire article series.

 

Radiant Floor Heating Zone Controller Project

Even if you aren’t interested in designing a radiant floor zoned heating system, you can study this innovative project and apply what you learn to any number of building control and automation applications. Dalibor Zaric’s Radiant Floor Heating Zone Controller is built around an NXP Semiconductors LPC2134 ARM processor that’s connected to an Echelon Pyxos chip. The project won Second Place in Echelon’s 2007 “Control Without Limits” design competition.

The heat zone controller system (Source: Echelon & Dalibor Zaric)

Zaric provides the following details in his project documentation:

“• Power supply to unit is 24VAC and controller has switching power supply to provide 24VDC for Pyxos network as well 5V for logic, there is 3.3V linear regulator as well.

• There are four relay with 24VAC output to power up thermoelectric zone valve on radiant floor heating manifold. These outputs are protected with 1.85A self resetting fuse to prevent overloading. This block has as well 24VAC/DC dry contact to provide a call for heat to boiler or optional zones pump.

• Pyxos power supply filter and Pyxos chip provides Pyxos network connection for future sensors and thermostats. Pyxos thermostat will be more cost effective than regular LONWorks sensors/thermostats.

• RS-485 driver will provide future Modbus connection for local touch screens or smart home systems with Modbus connections. There is end of line resistors enabled with the dip switches beside connector.

• 3150 Neuron board with 64K flash provides LONWorks connection to the controller.”

 

The heat zone controller diagram (Source: Echelon & Dalibor Zaric)

For more information about Pyxos technology, visit www.echelon.com.

This winning project, as well as others, was promoted by Circuit Cellar based on a 2007 agreement with Echelon.