Building the ROS Robot: Chassis, Wiring, and Safety
Build it right, fix it less later
I stumbled on the Weddell 2 ROS Robot by user pokpong on Thingiverse, and was very impressed. It was very close to what I was after. I wanted something large enough to carry a Raspberry Pi and sensors, a reasonable battery pack and a microcontroller. I couldn’t source the motors the original device used, so I made a remix of that design that was set up for inexpensive gear motors with encoders. The modified files are here.
The chassis is printed in PETG on an Ender 3 Pro. The parts require rafts and supports to print without warping, and the supports need to be gently cut away with an hobby razor knife. Holes tend to print a little small because of the way the slicer works, so it’s best to drill them to size.
The original design used some German gear motors that I had trouble sourcing (and frankly, they look expensive). They are probably overkill for my application, so I opted to modify the baseplate to mount these inexpensive gearmotors with integrated encoders. I wanted a robot that was slow with plenty of torque, so I used a robot wheel speed calculator to figure out what RPM I needed to get the speed range I wanted.
I used OpenSCAD to modify the base STLs, by plugging the holes I didn’t need and punching new ones for the…
