Estimating Force/Torque Sensor Offsets and Gravity Parameters Using Only Wrench Measurements to Facilitate Human Demonstration of Robot Manipulation Tasks in Contact

In human demonstration of manipulation tasks involving contact, a tool equipped with a force/torque (FT) sensor is typically used to capture contact wrenches (i.e., forces and moments). For accurate measurements, the sensor must be properly calibrated to ensure that it only records the contact wrenches during tool-environment interactions. This estimation in our context refers to estimating the sensor offsets, as well as the gravity parameters, i.e. mass and center of mass (COM), of the rigid object mounted on the FT sensor. Proper estimation enables access to the true contact wrench, which facilitates construction of reliable task models from human demonstrations. We propose a method for estimating sensor offsets and gravity parameters using only wrench measurements. This is particularly beneficial in scenarios where orientation information is unavailable or unreliable. By relying solely on wrench data, the method mitigates motion-related noise, eliminates the need for sensor orientation calibration, and remains computationally efficient, making it well-suited for real-time applications. The method’s effectiveness is evaluated against a baseline method that utilizes both wrench and accurate orientation measurements, whereas our method relies solely on wrench data. The results show that both methods perform well, particularly when the excitation range exceeds 10°. However, the proposed method consistently outperforms the baseline across all experiments within the excitation range.