Sensor Block Type Joint Torque Sensor Insensitive to Crosstalk Error

For collision detection and force control, collaborative robots working in human environments are often equipped with joint torque sensors instead of an expansive force/torque sensor. However, such torque sensors suffer from the issue of crosstalk error by loads other than the torque of interest and the vibration of the harmonic drive. A cross roller bearing (CRB) can effectively minimize this crosstalk but this increases the sensor cost. In this study, we propose a sensor block type joint torque sensor (SB-JTS) that is easy to manufacture and does not require a CRB. The sensor block is a hexahedral block with eight strain gauges attached, and the support part is designed to reduce the moment load applied to the sensor block. Through FEM analysis, the attachment locations that are sensitive to the torque of interest but insensitive to other loads can be identified. A series of experiments was conducted using a manufactured SB-JTS. The results showed that the SB-JTS can effectively reduce the crosstalk due to moment load without the use of a CRB.