The Emergence of Multiple Movement Units in the Presence of Noise and Feedback Delay

Tangential hand velocity profiles of rapid human arm movements often appear as sequences of several bell-shaped acceleration-deceleration phases called submovements or movement units. This suggests how the nervous system might efficiently control a motor plant in the presence of noise and feedback delay. Another critical observation is that stochasticity in a motor control problem makes the optimal control policy essentially different from the optimal control policy for the deterministic case. We use a simplified dynamic model of an arm and address rapid aimed arm movements. We use reinforcement learning as a tool to approximate the optimal policy in the presence of noise and feedback delay. Using a simplified model we show that multiple submovements emerge as an optimal policy in the presence of noise and feedback delay. The optimal policy in this situation is to drive the arm's end point close to the target by one fast submovement and then apply a few slow submovements to accur...

• Type: Conference
• Year: 2001
• Where: NIPS
• Authors: Michael Kositsky, Andrew G. Barto
• Keywords: Feedback Delay, NIPS 2001, NIPS 2007, Optimal Control Policy, Optimal Policy