Inspiration
Always wanted to build a quadruped (A four legged walker). This hackathon provided a great opportunity to get started on this project!
How it works
Twelve servos actuate the four legs of McHackBot, which is how it walks around. On board is a Teensy 3.1 microcontroller, and a Bluetooth dongle running in slave mode to accept incoming commands. Commands are send from a host PC, which aggregates data from a range of sensors, smooths it using a low pass filter and other digital signal processing techniques, and finally transmits the joint angles to McHackBot.
For this project, I wanted to use a Myo to control McHackBot. By flexing your forearm, the Myo would do its thing and provide raw data to the host PC. The host PC would be running a script to convert the raw data into movement commands for the quadruped. Then its just a matter of sitting back, and with the flick of your wrist, taking over the world.
Challenges I ran into
- Did not bring all the necessary tools to make the physical portion of the project. I had to MacGyver my way around many limitations. From soldering my own breakout board, to powering the microcontroller with an unregulated voltage, and leaving both the motor and microcontroller to be powered from the same source.
- Bluetooth dongle had an error in manufacturing, whereby a diode meant to protect against reverse polarity and parasitic power consumption, actually led to a diminished signal, producing far too much noise. This was fixed in software by switching the receive pin to a high impedance state.
- My project was very dependent on 3D printing parts. I came prepared with the robots chassis, which was 3D printed (Didn't want to take any chances that there wasn't going to be a printer here -- and there wasn't, so it turned out to be a good call). However, the remaining portion of my project needed several other parts.
- Time. 24 hours is a very very short amount of time, when you consider that I was working alone on this project. Being a hardware and software oriented project, there was double the amount of work. From soldering a breakout board, to assembling the chassis, and then testing electrical connections, finally to writing software to allow the robot to communicate with the outside world (PC, mobile), and interfacing with various other hardware -- the Myo in my case.
Accomplishments that I'm proud of
Was approached by several other hackers inquiring about my project. Several others also asked to borrow my soldering iron, wire stripper and other tools; have a length of wire; or even asked me to solder a component for them. And also advice on how they should approach their hardware problems.
What I learned
Its good to come prepared. If I hadn't brought my soldering iron, I would be dead in the water. I also learned its better to form a team beforehand, and work out an idea, than to leave things to chance when you arrive. With most hackers focusing on a software-centric idea, being one of the few hardware/software hybrid hackers left me working alone (which is entirely fine btw). In fact most of my friends ended up working on their own ideas individually.
What's next for McHackBot
The first step is to redesign a proper breakout board for the teensy. One that fits the contours of the robot, much like a good suit, where it will serve to both look and function better. Second, is to 3D print the remaining parts for the sensor interface. Finally, writing a smoothing algorithm to translate raw, noisy coordinates to smooth movements for McHackBot.
Oh, and one more thing. A laser. Every robot must come equipped with a laser.
Cheers, Dustin
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