EncoderBot - VEX Robotics Chassis

thingiverse

Chassis for a two motored, four wheeled, programmable robot using VEX EDR components. Extendable by attaching to the microcontroller's mounting points. This project was the latest of my attempts at completely replace VEX metal structural components with 3D printed plastic. And also teaching myself SketchUp Make. I attempted to make it as compact as possible within the given parameters, so I placed the largest motors possible (393s with integrated encoder modules) back to back, and worked out from there. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator (5th Generation) Rafts: Yes Supports: Yes Resolution: High Infill: Defaults Notes: Print so that the flat top of the chassis is upside down, against the build plate Post-Printing Just printed. Cleanup I used a letter opener and a razor blade to scrape off excess support structure plastic. Cleaned up a bit. Needed parts Parts 1 VEX Cortex Microcontroller with accompanying mounting screws and nuts. (The old PIC microcontroller should also fit fine, but there's no convenient mount points for its radio receiver; I'd suggest using stand-offs and mounting above the microcontroller.) 2 VEX 2-wire motors (393) with Integrated Encoder Modules with accompanying mounting screws. (Any other VEX EDR motors should also fit fine, the integrated encoders are completely optional.) 1 7.2V robot battery with a couple of long-enough twist ties. 6 square shafts; 4 3" shafts and 2 2" shafts. 6 36-tooth gears. 12 nylon washers. 10 lock collars 4 2.75" wheels. 4 black plastic spacers. All VEX EDR parts are available through VEX: http://www.vexrobotics.com/vexedr/products/accessories Assembled the wheel gear assemblies. Hung battery off chassis with twist ties. Programming a manual control loop Having plugged the left motor into motor port 1 and the right motor into motor port 10, I used the Purdue Robotics Operating System IDE http://purdueros.sourceforge.net/doc/ to program the Cortex brain. It reads the driver's controller's left and right joysticks' y axes to control the robot in a "tank drive" or "skid steering" mode by adding the following code to a brand new PROS project's opcontrol.c's operatorControl() function: void operatorControl() { while (1) { delay(20); motorSet(1,joystickGetAnalog(1,3)); motorSet(10,-joystickGetAnalog(1,2)); } } Completely assembled and running. Extending the chassis: Line tracking sensor bundle added using stand-offs on the underside of the microcontroller's mounting points. How I Designed This I used SketchUp Make 2016 to design this object from scratch. Design This is the latest (1/21/2016) of my self-directed exploration of SketchUp Make for creating objects to be used with VEX robotics components.