Proper Crawl

Published on 2017-07-23 in SpiderWing.

I went over the large SpiderWing and shortened its legs back to what Tote has. The idea to make coxas much longer sounded great — you get longer steps and thus higher speed, without actually increasing the load on the servos (since coxas only move in the horizontal plane anyways). However, doing that also changes the reachable area of the leg from a shape similar to a pizza slice, to one that looks more like a slice of a pineapple — with the center removed. Do it too much, and you can no longer draw a nice long straight line inside it — meaning the robot’s step has to be small.

So I shortened the coxas, but left the tibias long — that actually increases the load, but the servos can handle it. Once the changes were done, I had to replace a few faulty servos, that were catching for some reason. After that, finding the set of parameters that would let the robot move at a decent speed was much easier:

Next on the list is smoothing all those movements. Right now they are very jerky, so much so that the legs tend to slip on the floor. Unfortunately, I will probably need to rewrite most of the gait code to do that.