Teleoperation Success!
There were two issues that I ran into upon integration testing the frame housing that prevented locomotion:
- The space between the front plate and the wheel attachment piece was too large, and it caused the wheel to twist and get caught on itself when spun. This was fixed by increasing the thickness of the bottom front plate ring to hold the wheel piece down. I thought having more would be okay with the wheel holding it on the other side, but then it would have been more friction as the wheel being the primary method of holding it in place would drag much more.
- The gear train required too much torque from our motors. As a run down of the diagnostics: a) the friction was minimal with PLA on PLA (after fixing issue 1). b) The rods we used were very form fitting with the gears spinning very nicely (I had made another little piece with various hole sizes to test which would be best before making the full print). c) The spacing between gears was all correct, as the gears could spin well using our hands, but it was difficult to spin them. So the solution for this was to change the gear ratio between the gears. I made the motor gear smaller, and the corresponding one larger to match, so the design didn’t have to change much and we could still use the rest of the print we already had.
Old: New:
(there are also a few other issues that were addressed, that weren’t strictly necessary, but just make the bot better to work with. 1) Some holes were hard to screw into, so I made them slightly larger. 2) the sensor frame holder broke, so while duct-tape does work, I went ahead and made the frame a little thicker with more support. 3) the 3D model from online didn’t match the motors perfectly in length, so the snug fit works, but is slightly misaligned and required some physical *ahem* adjustments to mitigate that.
And now it works!! We have minimal media space for our website, so linked below is a full teleoperation integration test over WiFi using our keyboard and ROS topics:
Next Steps
Mainly, print our second bot with the now fully verified design. Then as that prints, also to help the team in refining our algorithms for the actual movement (and getting our actual full system documentation together). At the moment, it just maxes the voltage output forward, backward, left, right based on arrow key presses. This isn’t too conducive for autonomous or waypoint following. We have begun this process already, and Adrian talks to it more in his report.