Integration of a Low-Cost Three-Axis Sensor for Robot Force Control

Many robot systems incorporate six-axis force/torque sensors to enable compliant interaction with the environment, even when a lower-cost three-axis sensor may be sufficient. One challenge is that a three-axis sensor may measure a coupling of the applied forces and torques; these can be decoupled with an appropriate calibration and with assumed knowledge of the location of the applied force. In this paper, we develop the method and open source software to calibrate a commercially-available three-axis sensor and verify its performance in static tests with known weights and in dynamic tests by comparison to an accurate six-axis sensor. Mean errors in static tests are less than 5% and experiments demonstrate that the sensor can be used to control the contact force applied by a robot-held ultrasound probe.