Contact Detection

Determining whether, when, and where a robot has touched an object or its environment.

Contact detection determines whether, when, and where a robot part — a finger, gripper, tool, or the body itself — has touched an object or the environment. Signals come mainly from three sources: a change in a tactile sensor's or electronic skin's reading; a sudden jump in the force or torque read by a wrist F/T sensor; or, when no dedicated sensor is available, the residual between motor current or joint torque and what a dynamics model predicts. Vision alone is often unreliable here, since the hand frequently blocks the object right at the moment of contact. Contact detection is the trigger condition for many manipulation routines — close the gripper until contact then stop, lower until the table is touched then release, judge whether an assembly step is complete. Fixed thresholds are prone to misjudging in home settings, so some work instead fuses sound with force signals, or uses a learned detector. A legged robot's judgment of whether a foot has touched the ground is usually given its own separate name, contact estimation.

ExampleWhile lowering an arm slowly to place a cup, the wrist force sensor reads a sudden jump in vertical force past a threshold, which is taken to mean the cup's base has touched the table, and the gripper opens immediately.

Also called

Contact Sensing

Related

Tactile Sensor · Six-Axis Force/Torque Sensor · Slip Detection · Extrinsic Contact Sensing · Sensorless Force Estimation · Contact Estimation

Sources

Multimodal Contact Detection using Auditory and Force Features for Reliable Object Placing in Household Environments (arXiv 2012.01583)
Tactile sensor（Wikipedia）