We're currently designing a task where we 'replay' rials to participants (Human Exo) by moving their arm along the trajectory that they took previously. I've gotten this working very well using the position controller (with no intertia component in the feed-forward controller) by storing their joint position and feeding that to the position controller (at maximum sampling time 0.00025). This currently works very well, but we'd like to improve the quality of the replay further. Trying to use any of the intertial components of the feed-forward controller leads to extremely high instantaneous forces, which I gather is not unexpected since the desired joint position is changing every time step. Do you have ideas how we could further improve trajectory control?