Calibrate guarded contact tool fails when homing finds incorrect range hardstop #75
Description
The REx_calibrate_guarded_contact.py tool fails when the joint hasn't been homed correctly. Often, the arm or lift won't home correctly because the homing threshold is too low. This causes the arm or lift to incorrectly assume it's hardstop positions. I assumed the REx_calibrate_guarded_contact.py tool could help with this by running through the joint range and finding new thresholds. However, instead the joint never gets to where it think the joint range ends because it actually ends earlier. This causes the tool to freeze, waiting for the joint to complete moving. No errors are emitted, but the tool doesn't continue executing. Additionally, the joint pressing against the hardstop emits a harsh noise.
How to reproduce
Lower the lift's homing threshold. Running lift homing, and the lift should incorrectly detect a hardstop below where the actual head shell is. So the lift thinks it's range starts from there and it's hard stops aren't where it expects it to be. Now run REx_calibrate_guarded_contact.py on the lift joint. It will fail to reach the bottom of its range and emit a harsh noise.