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pantor / ruckig

Motion Generation for Robots and Machines. Real-time. Jerk-constrained. Time-optimal.
https://ruckig.com
MIT License
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Trajectory generation with only current position and velocity in Ruckig #119

Closed zipping-suger closed 2 years ago

zipping-suger commented 2 years ago

I'd like to implement Ruckig on a robot arm for online trajectory generation. However, I can not get current acceleration feedback. I have seen that Type II Reflexxes Motion Library offered (OTG) algorithm for the second-order system with only current position and velocity as input in the figure I wonder if Ruckig offers similar features? If not, is it possible to use estimated current acceleration? How sensitive the algorithm is to the acceleration input?

pantor commented 2 years ago

In comparison to Reflexxes Type II, Ruckig does also constraint the jerk and does therefore need to know the current acceleration (similar to Reflexxes Type IV). If you don’t care and don’t know the acceleration state of your robot, you could set the current and target acceleration to zero and use a very high jerk limit (however within the supported numerical range). This should work without problems.

In general, we think that jerk limitation is essential for smooth and non-vibrating robot motions. As such, we don’t plan to offer a second-order system (although it is technically implemented for the velocity control mode) and recommend to use a reasonable jerk limit instead.