Impedance Control vs. Position Control

The human body moves with a natural fluidity. When developing an exoskeleton for intimate human interactions, or more specifically for rehabilitation, it is vital for the technology to work with a human’s natural, soft movements. This video depicts two types of robotic control––impedance control vs. position control. Both arms are programmed to complete the same movement, however, the stiffness in Harmony SHR’s left arm is set to the highest level in order to mimic position control. The right arm of the exoskeleton is dialed into a softer setting of impedance control. Notice how the left arm is stiff, rigid and challenging to interrupt. It completes the movement, as programmed, with little distraction from the human attempting to disrupt the intended path of movement. Meanwhile, the same disruptions (force and direction) are applied to the right arm. Notice how the right arm ‘gives in’ to these forces in a soft, spring-like manner and can easily be disrupted from completing the movement.