Rover: allow steering to Motors beyond -1 to +1 range #8600
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each motor output handler (regular, skid, omni) becomes responsible for constraining the steering input (if required) and setting the limits flags it is possible to reduce duplicate code but I think it might be more important to keep it clear which level is responsible for the limiting and constraining of steering
This replaces the hardcoded 1m/s start point for speed scaling with a configurable value
khancyr
approved these changes
Jun 11, 2018
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@khancyr, txs for the review. In earlier versions we had the speed-scaling-of-steering done in the attitude control but now it's down in the motor library... not sure if that answers your question or not.. |
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Merged, thanks! |
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This PR attempts to resolve and issue with loss of steering control for vehicles traveling at high speeds. This issue was caused by this earlier PR which moved the speed-scaling from the attitude controller to the motors library. The potential issue was recognised and sadly now it's been confirmed during beta testing. Comments from the PR are copied below:
This PR resolved the problem by allowing the high-level steering request sent to the motors to be outside the -1 to +1 range.
Below are images before and after showing the simulated vehicle is better able to achieve the desired turn rate. In this test an Ackermann style rover (i.e. separate throttle and steering controls) was driven slowly (2m/s) but with full left steering. In master, because the speed scaling, the steering output was scaled back too far to achieve the desired turn rate. With this PR the vehicle comes much closer.
Somewhat separately this PR also adds a new parameter MOT_SPD_SCA_BASE (i.e. "Motor Speed Scaling Base") which is equivalent to the similar "Vector Thrust Scaling Base" parameter. It allows the user to specify the lowest speed that the scaling is applied. I don't expect many people to change this but it could be useful especially for very slow vehicles because it will give them better steering control below 1m/s. Very fast vehicles that spend very little time below 1m/s.
This issue is discussed here in the Rover-3.4.0-rc1 beta testing thread.