Question

In an admittance control scheme, what physical variable does the robot measure at the end-effector to command a corresponding change in its position?

Accepted Answer

In an admittance control scheme, the robot measures the external force applied to its end-effector as the physical variable to command a corresponding change in position. The end-effector is the device or tool located at the very end of a robotic arm that interacts with the environment, such as a gripper or a sensor. Admittance control functions by sensing these external forces, typically using a force-torque sensor mounted at the wrist, and converting those force values into a commanded movement through a mathematical model. This model mimics a mass-spring-damper system, which defines how the robot should behave in response to being pushed or pulled. For example, if a human pushes the end-effector, the robot calculates the desired acceleration, velocity, and finally the position offset based on the measured force and the programmed stiffness or damping parameters. By adjusting its position to minimize the difference between the measured force and a target state, the robot allows for compliant motion, meaning the robot moves easily when touched or guided by a human operator.

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In an admittance control scheme, what physical variable does the robot measure at the end-effector to command a corresponding change in its position?