I’ve spent a lot of my spare lab time messing around with a robot wheel mechanical concept, and an electronic design that controls a pair of DC motors and 4 RC servos. Here’s an update.
The ongoing design effort to create a dual DC motor controller that can also read radio control servo pulses and output those same pulses has progressed over the last few months. The design idea started when I created an Arduino clone that incorporated 2 motor controller ICs. I had hoped to use the Arduino to read and write servo signals as well as provide PWM signals to drive the motors. Unfortunately, the many macros created for the Arduino that handle things like PWM and pulse generation don’t work well together. In order to maintain the Arduino functionality, I decided to move the motor control and servo overhead to a PIC microcontroller.
At this stage of the design I have the PIC code written and about 90% tested. I’m ready to move the design off of the breadboard, and onto a custom PCB (shown next to the PIC). When that’s done we’ll sell the controller as an open source design and provide the source code (written in C). The same design will also be added to an Arduino clone, whose PCB I’ve already completed. The image below shows the breadboard I’ve been using to wire up and test the dual motor and servo controller (DMSC). I’m also using our BM010 USB to serial converter (red LED board) to interface a Visual Studio 2010 program to the PIC. This allows me to test the serial and control interface.
In the video I’m using the Visual Studio software to send servo position commands to the breadboard PIC. Right now its slow because I type in each position. I’ll add some slide bars or other controls to make it a little more smooth.
In addition to this electronic design I’ve been creating a mechanical wheel design. That effort has progressed some brass prototypes to an acrylic design I created in SketchUp. The mechanical concept allows the robot to change stance. This week I received in an order from Ponoko that includes the wheel arm parts and the servo holder parts. At the end of the video above you can see a single “wheel-arm” under control of our new electronic design.
I’m not sure when I’ll have time to put it all together. When I do I’m sure there will be some hurdles to get past. But it’s definitely been a fun design effort, and I think I can see light at the end of the tunnel.