Real-time reference trajectory adaptation for haptic shared control during teleoperation
S.A. Seuren (TU Delft - Mechanical Engineering)
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Abstract
Haptic Shared Control (HSC) can improve operator performance during teleoperation. HSC uses assistive forces on the master device to guide the operator's control input towards a reference trajectory. However, the reference trajectory might be incorrect due to inaccuracies in the sensed or modeled environment and thus not match the intended trajectory of the operator, resulting in force conflicts that can potentially reduce performance. This paper describes the design and evaluation of a haptic shared controller whose reference trajectory adapts in real-time to resort force conflicts. Different adaptive controllers have been designed and compared in simulation. The final controller is built on a Task Parameterized Gaussian Mixture Model and adapts using an Incremental Gaussian Mixture Model. The controller is evaluated in an experiment (n=16) where subjects performed a planar teleoperation task that involved moving the slave through a narrow corridor. The subjects were assisted by HSC with a correct reference (cHSC), HSC with a wrong reference (wHSC), HSC with a wrong reference that adapts in real-time (waHSC) and a manual condition.
The waHSC condition was expected to result in lower control effort, compared to wHSC, and induce better performance compared to wHSC and the manual condition.
Within-subjects results showed that waHSC decreases control effort compared to wHSC, while the performance remained similar. Manual control had better performance than wHSC and waHSC, and cHSC outperformed all other conditions.
Even though the conditions were tested in a balanced order, we observed a strong effect of the order of the conditions: between-subject results showed improved performance, lower control effort and better subjective results for waHSC over wHSC when wHSC was executed first. Upon first execution of waHSC, improved performance and self-reported satisfaction were realized for wHSC over waHSC. The results show that, in the event of a force conflict, an adaptive controller is a promising alternative to temporarily adjusting the HSC stiffness.