Designing Wireless Data Gloves

Kevin Marinelli, IT manager for the Mathematics Department at the University of Connecticut, recently answered CC.Post’s newsletter invitation to readers to tell us about their wearable electronics projects. Kevin exhibited his project,  “Wireless Data Gloves,” at the World Maker Faire New York in September. He spoke with Circuit Cellar Managing Editor Mary Wilson about the gloves, which are based on an Adafruit ATmega32U4 breakout board, use XBee modules for wireless communication, and enable wearers to visually manipulate data and 3-D graphics.

MARY: Tell us a little bit about yourself and your educational and professional background.

KEVIN: I am originally from Sydney, Nova Scotia, in Canada. From an early age I have

Kevin Marinelli

Kevin Marinelli

always been interested in taking things apart and creating new things. My degrees are a Bachelor’s in Computer Science from Dalhousie University in Halifax, Nova Scotia, and a Master’s in Computer Science from the University of New Brunswick in Fredericton, New Brunswick. I am currently working on my PhD in Computer Science at the University of Connecticut (UConn).

My first full-time employment was with ITS (the computer center) at Dalhousie University. After eight years, I moved on to an IT management position the Ocean Mapping Group at the University of New Brunswick. I am currently the IT manager for the Mathematics Department at  UConn.

I am also an active member of MakeHartford, which is a local group of makers in Hartford, Connecticut.

MARY: Describe the wireless data gloves you recently exhibited at the World Maker Faire in New York. What inspired the idea?

KEVIN: The idea was initially inspired 20 years ago when using a Polhemus 6 Degree-of-Freedom sensor for manipulating computer graphics when I was at the University of New Brunswick. The device used magnetic fields to locate a sensor in three-dimensional space and detect its orientation. The combined location and orientation data provides data with six degrees of freedom. I have been interested in creating six degrees of freedom input devices ever since. With the Arduino and current sensor technologies, that is now possible.

Wireless data gloves on display at World Maker Faire New York. (Photo: Rohit Mehta)

Wireless data gloves on display at World Maker Faire New York. (Photo: Rohit Mehta)

MARY: What do the gloves do? What applications are there? Can you provide an example of who might use them and for what purpose?

KEVIN: The data gloves allow me to use my hands to wirelessly transmit telemetry data to a base station computer, which collects the data and provides it to any application programs that need it.

There are a number of potential applications, such as manipulating 3-D computer graphics, measurement of data for medical applications, remote control of vehicles, remote control of animatronics and puppetry.

MARY: Can you tell me about the data gloves’s design and the components used?

KEVIN: The basic design guidelines were to make the gloves self-contained, lightweight, easy to program, wireless, and rechargeable. The main electronic components are an Adafruit ATmega32U4 breakout board  (Arduino Leonardo software compatible), a SparkFun 9d0f sensor board, an XBee Pro packet radio, a LiPo battery charger circuit, and a LiPo battery. These are all open hardware projects or, in the case of the battery, are ordinary consumer products.

The choice of the ATMega32U4 for the processor was made to provide a USB port without any external components such as an FTDI chip to convert between serial and USB communications. This frees up the serial port on the processor for communicating with the XBee radio.

For the sensors, the SparkFun 9dof board was perfect because of its miniscule size and

Top of glove

Top of glove

because it only requires four connections: two connections for power and two connections for I2C. The board has components with readily available data sheets, and there is access to working example code for the sensor board. This reduced the design work greatly by using an off-the-shelf product instead of designing one myself.

The choice of an 800-mAh LiPo battery provides an excellent lightweight rechargeable power supply in a small form factor. The relatively small battery powers the project for more than 24 h of continuous use.

Palm of glove

Palm of glove

A simple white cotton glove acts as the structure to mount the electronics. For user-controlled input, the glove has conductive fabric fingertips and palm. Touching a finger to the thumb, or the pad on the palm, closes an electrical pathway, which allows the microcontroller to detect the input.

For user-selectable input, each fingertip and the palm of the hand has a conductive fabric pad connected to the Adafruit microcontroller. The thumb and palm act as a voltage source, while the fingertips act as inputs to the microcontroller. This way, the microcontroller can detect which fingers are touching the thumb and the palm pads. Insulated wires of 30 gauge phosphor bronze are sewn into the glove to connect the pads to the microcontroller.

MARY: Are the gloves finished? What were some of the design challenges? Do you plan any changes to the design?

KEVIN: The initial glove design and second version of the prototype have been completed. The major design challenges were finding a microcontroller board with sufficient capabilities to fit on the back of a hand, and configuring the XBee radios. The data glove design will continue to evolve over the next year as newer and more compact components become available.

Initially I was designing and building my own microcontroller circuit based on the ATmega32U4, but Adafruit came out with a nice, usable, designed board for my needs. So I changed the design to use their board.

SparkFun has a well-designed micro USB-based LiPo battery charger circuit. This would have been ideal for my project except that it does not have an On/Off switch and only has some through-hole solder points for powering an external project. I used their CadSoft EAGLE files to redesign the circuit to make it slightly more compact, added in a power switch and a JST connector for the power output for projects.

The XBee radios were an interesting challenge on their own. My initial design used the standard XBee, but that caused communication complications when using multiple data gloves simultaneously. In reading Robert Faludi’s book Building Wireless Sensor Networks: With ZigBee, XBee, Arduino, and Processing, I learned that the XBee Pro was more suited to my needs because it could be configured on a private area network (PAN) with end-nodes for the data gloves and a coordinator for the base station.

One planned future change is to switch to the surface-mount version of the XBee Pro. This will reduce both the size and weight of the electronics for the project.

The current significant design challenge I am working on is how to prevent metal fatigue in the phosphor bronze wires as they bend when the hand and fingers flex. The fatigue problem occurs because I use a small diamond file to remove the Kapton insulation on the wires. This process introduces small nicks or makes the wires too thin, which then promotes the metal fatigue.

A third version is in the design stage. The new design will replace the SparkFun 9dof board with a smaller single-chip sensor, which I hope can be mounted directly on the Adafruit ATmega32U4 board.

MARY: What new skills or technologies did you learn from the project, if any?

KEVIN: Along the way to creating the gloves, I learned a great deal about modern electronics. My previous skills in electronics were learned in the ’70s with single-sided circuits with through-hole components and pre-made circuit boards. I can now design and create double-sided circuit boards with primarily surface-mounted components. For initial prototype designs, I use double-sided photosensitized circuit boards and etch them at home.

Learning to program Arduino boards and Arduino clones has been incredible. The fact that the boards can be programmed using C in a nice IDE with lots of support libraries for common programming tasks makes the platform an incredibly efficient tool. Having an enormous following makes it very easy to find technical support for solving problems with Arduino products and making Arduino clones.

Wireless networking is a key component for the success of the project. I was lucky to have a course in wireless sensor network design at UConn, which taught me how to leverage wireless technology and avoid many of the pitfalls. That, combined with some excellent reference books I found, insured that the networking is stable. The network design provides for more network bandwidth than a single pair of data gloves require, so it is feasible to have multiple people collaborating manipulating the same on the same project.

Designing microcontroller circuits using EAGLE has been an interesting experience. While most of the new components I use regularly in designs are available in libraries from Adafruit and SparkFun, I occasionally have to design my own parts in EAGLE. Using EAGLE to its fullest potential will still take some time, but I have become reasonably proficient with it.

For soldering, I mostly still use a standard temperature controlled soldering iron with a standard tip. Amazingly, this allows me to solder 0402 resistors and capacitors and up to 100 pitch chips. When I have components that need to be soldered under the surface, I use solder paste and a modified electric skillet. This allows me to directly control the temperature of the soldering and gives me direct access to monitoring the process.

The battery charger circuit on my data glove is hand soldered and has a number of 0402-sized components, as  well as a micro USB connector, which also is a challenge to hand solder properly.

MARY: Are there similar “data gloves” out there? How are yours different?

There are a number of data glove projects, which can be found on the Internet. Some are commercial products, while others are academic projects.

My gloves are unique in that they are lightweight and self-contained on the cotton glove. All other projects that you can find on the Internet are either hard-wired to a computer or have components such as the microcontroller, batteries, or radio strapped to the arm or body.

Also, because the main structure is a self-contained cotton glove; the gloves do not interfere with other activities such as typing on a keyboard, using a mouse, writing with a pen, or even drinking from a glass. This was quite handy when developing the software for the glove because I could test the software and make programming corrections without having the inconvenience of putting the gloves on and taking them off repeatedly.

MARY: Are you working on any other projects you’d like to briefly tell us about?

KEVIN: At UConn, we are lucky to have one of the few academic programs in puppetry in the US. In the spring, I plan on taking a fine arts course at UConn in designing and making marionette puppets. This will allow me to expand the use of my data gloves into controlling and manipulating puppets for performance art.

I am collaborating on designing circuit boards with a number of people in Hartford. The more interesting collaborations are with artists, where they think differently about technology than I do. Balam Soto of Open Wire Labs is a new media artist and one of the creative artists I collaborate with regularly. He is also a member of MakeHartford and presents at Maker Faires.

MARY: What was the response to the wireless data gloves at World Maker Faire New York?

KEVIN: The response to the data gloves was overwhelmingly positive. People were making comparisons to the Nintendo Power Glove and to the movie “Minority Report.” Several musicians commented that the gloves should be excellent for performing and recording virtual musical instruments such as a guitar, trumpet and drums.

For the demonstration, I showed a custom application; which allowed both hands (or two people) to interactively manipulate points and lines on a drawing. Many people were encouraged to use the gloves for themselves, which enhanced the quality of the feedback I received.

The gloves are large-sized to fit my hands, which was quite a challenge for younger children to use because their hands were “lost” in the gloves. Even with the size challenge, it was fun watching younger children manipulating the objects on the computer screen.

I look forward to the Maker Faire next year, when I will have implemented the newer design for the data gloves and will have additional software to demonstrate. I plan on trying to put together a presentation on some form of performance art using the data gloves.

Q&A: Krystal Horton, the Raspberry Pi Kid

Eben Upton and Krystal met in October at the Broadcom MASTERS

Krystal Horton is the clever kid behind the blog Raspberry Pi Kid: An 11-Year-Old’s Adventures with Raspberry Pi.  Since starting her blog in January 2013, her entries have covered everything from unpacking her first Pi, to projects she has created with the SBC, to her recent dinner with Eben Upton, founder and trustee of the Raspberry Pi Foundation, and his wife, Liz Upton, who oversees the foundation website.

Krystal met the couple in October 2013 in Washington, D.C., as one of 30 finalists competing in the 2013 Broadcom MASTERS, a national science, technology, engineering, and math competition for middle school students.  (At the competition, Krystal was named one of two Rising Stars students who will represent Broadcom MASTERS at the 2014 International Science and Engineering Fair, the world’s largest international high school science fair competition.)

“They also gave each of the finalists their own Raspberry Pi,” Krystal says in her October 2 blog entry from Washington, D.C.  “I’m hoping to have each of the finalists guest post on my blog after they’ve had a chance to try out the RPi.”

Liz Upton describes Krystal as “brilliant.” Recently, Circuit Cellar Managing Editor Mary Wilson asked the seventh-grader several questions about her interest in the Raspberry Pi and the blog she created to complement it.

Krystal and her oak borer beetle infestation science project.

Krystal and her oak borer beetle infestation science project.

MARY: Tell us a little bit about yourself and why you became interested in working with the Raspberry Pi.

KRYSTAL: I am an 11-year-old seventh-grader in Southern California. I have been interested in science and technology ever since I can remember. My cousin got a Raspberry Pi for Christmas and my uncle saw how curious I was. So, he gave me one for New Year’s. He gave me some basic lessons on how to hook it up, turn it on, and type into Vim. That and some YouTube videos, tutorials, and eBooks and I was off and running. I now blog at http://raspberrypikid.wordpress.com and sometimes I tweet through @kid_pi.

MARY: Why did you decide to start your blog Raspberry Pi Kid? What type of feedback/comments have you gotten from visitors to your site? Will you rename the blog and keep posting when you’re 12?

KRYSTAL: I’ve learned so much from other people’s blogs, but they’re written for adults and are very hard for a kid to understand. So, I thought that I could put things in kid language and in simple steps so that other kids would be inspired and learn from what I’ve done. I want to give back to the Raspberry Pi and blogging communities.

On my blog, I’m often talking about problems that I’m having (I still haven’t figured out analog to digital conversion) and a lot of people offer to help me out. Others congratulate me and wish that they’d had an RPi when they were my age. I’ve also heard from other kids my age who are learning to code. I put my dad’s email address on the account and he gets invitations for me to Skype with CoderDojos and to guest blog for people. I have over 52,000 views to my blog right now. I hadn’t even thought about whether the name would change when I turn 12, but I’ll definitely keep blogging.

MARY:  Was the SBC difficult to set up? What was the first project you worked on with it?

KRYSTAL: The only hard thing about setting it up is all of the accessories that you need. It doesn’t even come with a power supply, keyboard, or mouse. My uncle gave me some of the stuff (power supply, wireless keyboard/mouse, breadboard), I had some stuff at home (memory card, network cable), and I bought some stuff from Adafruit’s very useful website (wireless adapter, ADC chip, breadboard accessories).

I really like the idea of programming the computer to do things. So, the first thing I did was start programming in Python through Vim and IDLE. I got a book from the library, read tutorials online, and emailed my uncle questions.

MARY: Can you tell me about some other Pi-based projects you have finished or are working on? Do you have something you would like to do next? Where do you get your ideas? Where do you go for guidance?

Krystal and her robot

Krystal and her robot

KRYSTAL: I love playing Minecraft, so when I saw that there’s a Pi version, I installed it and blogged about it. I’ve also used the Scratch programming language to create games and blink LEDs. I’ve used RPi as a Linux computer with the Wheezy version. I just wish that Midori would play YouTube videos so that I could watch Pi tutorials on my Pi. I have also installed OpenELEC (Open Embedded Linux Entertainment Center) so that I can stream HD video to my TV. I’ve also used PuTTY to control the Pi with a laptop (my uncle showed me that one).

In the future, I want to keep working with Scratch, a free visual programming language for kids from MIT (where I want to go to college). I want to figure out analog to digital so that I can connect sensors. And I want to use the RPi to do a science fair project. I really, really want to get a 3-D printer and connect it to the Pi.  I’m planning to order a MakiBOX soon, but it’ll take six-10 weeks to arrive and then I have to build it and learn how to use it.

When I don’t know how to do something, my dad helps me find answers on YouTube or other people’s blogs. He’s a scientist, not a programmer, so he learns with me sometimes. If he can’t help me, I email my uncle who does know how to program. He has automated his house with a RasPi. If I can’t get in touch with him, then I post a question on a forum and wait for answers.

Close up view of the credit-card sized Pi

Close up view of the credit-card sized Pi

MARY: What were some of the challenges you had to overcome with the Pi? What, if anything, would you change about it?

KRYSTAL: One of the problems I’ve had is when things don’t work for me as the blogs say they should. I had a really hard time getting Wi-Fi to work even though I followed the instructions exactly.

If I could change anything, I’d label the GPIO pins right on the board. I’ve had to look up that diagram soooo many times. There are several versions now, so I’d recommend marking them to make it easier to tell which one it is when getting a case for it. I’ve read stories about people breaking off the connector where the memory card goes. That’s scary, I hope they fix that if they can.

MARY: What do you think are the SBC’s best features?

KRYSTAL: Everyone says that the price and size are the Pi’s best features and I agree. But I also like that it’s so open to let me put any kind of Linux I want on it. Some people have even put the Android Operating System on it. Not me… yet.

MARY: What new skills/tools have you learned about through your Pi?

KRYSTAL: Some of the things I’ve learned through using my Pi are: coding in Python and Scratch, basic electronics (how to use a breadboard, multimeter, LEDs, etc.), and using Linux and all of the absolutely free software for it. These are very valuable skills for anyone to learn. I’ve learned about IP addresses and using a computer without the graphical interface at times also.

MARY: What advice would you give to another kid (or adult tinkerer) who is interested in getting started with the Raspberry Pi?

KRYSTAL: The advice that I’d give is to work on fun projects. This shouldn’t feel like boring work. Also, don’t get frustrated if things don’t work right the first time. That’s just part of coding. Most big cities also have groups of computer users. Find one and connect with them.

MARY: How many other 11-year-old girls do you know who are drawn to the Raspberry Pi? Any thoughts about that?

KRYSTAL: I’ve met online several kids who are using Pi. I spoke through Skype with a group in Washington, D.C., one Saturday morning. There were probably 15 kids and many were girls. I watched a video of a girl who tests all of the Raspberry Pis that get sent back as broken.

I think that computers and technology are going to be incredibly important to my generation. It is very scary that so few (girls or boys) are learning how technology works and how to code. Coders are going to rule the future, and I want be a part of that. All kids should. And their parents need to encourage it.  Websites like code.org and adafruit.com and devices like Raspberry Pi are helping.

CC25 Is Now Available

Ready to take a look at the past, present, and future of embedded technology, microcomputer programming, and electrical engineering? CC25 is now available.

Check out the issue preview.

We achieved three main goals by putting together this issue. One, we properly documented the history of Circuit Cellar from its launch in 1988 as a bi-monthly magazine
about microcomputer applications to the present day. Two, we gathered immediately applicable tips and tricks from professional engineers about designing, programming, and completing electronics projects. Three, we recorded the thoughts of innovative engineers, academics, and industry leaders on the future of embedded technologies ranging from
rapid prototyping platforms to 8-bit chips to FPGAs.

The issue’s content is gathered in three main sections. Each section comprises essays, project information, and interviews. In the Past section, we feature essays on the early days of Circuit Cellar, the thoughts of long-time readers about their first MCU-based projects, and more. For instance, Circuit Cellar‘s founder Steve Ciarcia writes about his early projects and the magazine’s launch in 1988. Long-time editor/contributor Dave Tweed documents some of his favorite projects from the past 25 years.

The Present section features advice from working hardware and software engineers. Examples include a review of embedded security risks and design tips for ensuring system reliability. We also include short interviews with professionals about their preferred microcontrollers, current projects, and engineering-related interests.

The Future section features essays by innovators such as Adafruit Industries founder Limor Fried, ARM engineer Simon Ford, and University of Utah professor John Regehr on topics such as the future of DIY engineering, rapid prototyping, and small-RAM devices. The section also features two different sets of interviews. In one, corporate leaders such as Microchip Technology CEO Steve Sanghi and IAR Systems CEO Stefan Skarin speculate on the future of embedded technology. In the other, engineers such as Stephen Edwards (Columbia University) offer their thoughts about the technologies that will shape our future.

As you read the issue, ask yourself the same questions we asked our contributors: What’s your take on the history of embedded technology? What can you design and program today? What do you think about the future of embedded technology? Let us know.

CC 25th Anniversary Issue: The Past, Present, and Future of Embedded Design

In celebration of Circuit Cellar’s 25th year of publishing electrical engineering articles, we’ll release a special edition magazine around the start of 2013. The issue’s theme will be the past, present, and future of embedded electronics. World-renowned engineers, innovators, academics, and corporate leaders will provide essays, interviews, and projects on embedded design-related topics such as mixed-signal designs, the future of 8-bit chips, rapid prototyping, FPGAs, graphical user interfaces, embedded security, and much more.

Here are some of the essay topics that will appear in the issue:

  • The history of Circuit Cellar — Steve Ciarcia (Founder, Circuit Cellar, Engineer)
  • Do small-RAM devices have a future? — by John Regehr (Professor, University of Utah)
  • A review of embedded security risks — by Patrick Schaumont (Professor, Virginia Tech)
  • The DIY electronics revolution — by Limor Fried (Founder, Adafruit Industries)
  • The future of rapid prototyping — by Simon Ford (ARM mbed, Engineer)
  • Robust design — by George Novacek (Engineer, Retired Aerospace Executive)
  • Twenty-five essential embedded system design principles — by Bob Japenga (Embedded Systems Engineer, Co-Founder, Microtools Inc.)
  • Mixed-signal designs: the 25 errors you’ll make at least once — by Robert Lacoste (Founder, Alciom; Engineer)
  • User interface tips for embedded designers — by Curt Twillinger (Engineer)
  • Thinking in terms of hardware platforms, not chips — by Clemens Valens (Engineer, Elektor)
  • The future of FPGAs — by Colin O’Flynn (Engineer)
  • The future of e-learning for engineers and programmers — by Marty Hauff (e-Learning Specialist, Altium)
  • And more!

Interviews

We’ll feature interviews with embedded industry leaders and forward-thinking embedded design engineers and programmers such as:

More Content

In addition to the essays and interviews listed above, the issue will also include:

  • PROJECTS will be available via QR codes
  • INFOGRAPHICS depicting tech-related likes, dislikes, and ideas of hundreds of engineers.
  • And a few surprises!

Who Gets It?

All Circuit Cellar subscribers will receive the 25th Anniversary issue. Additionally, the magazine will be available online and promoted by Circuit Cellar’s parent company, Elektor International Media.

Get Involved

Want to get involved? Sponsorship and advertising opportunities are still available. Find out more by contacting Peter Wostrel at Strategic Media Marketing at 978-281-7708 (ext. 100) or peter@smmarketing.us. Inquire about editorial opportunities by contacting the editorial department.

About Circuit Cellar

Steve Ciarcia launched Circuit Cellar magazine in 1988. From its beginning as “Ciarcia’s Circuit Cellar,” a popular, long-running column in BYTE magazine, Ciarcia leveraged his engineering knowledge and passion for writing about it by launching his own publication. Since then, tens of thousands of readers around the world have come to regard Circuit Cellar as the #1 source for need-to-know information about embedded electronics, design, and programming.