Design and Fabrication of a Novel Force Sensor for Robot Grippers

Force sensors using strain gauge have been widely applied in mechanical systems. They usually possess a structure consisting of a simple cantilever beam and two strain gauges attached to two opposite beam surfaces. However, this structure shows severely distorted stress in the implementation of smart robot grippers with lateral offsets, which is usual in limited-space applications. In order to overcome the limitation and to reduce the nonlinearity of the gauge sensor, a novel hinged-joint cantilever beam sensor structure is proposed. An analytical model is derived to predict the force sensitivity and force linearity. The simple cantilever beam sensor and the hinged-joint sensor are analyzed and compared with the conducting finite-element-method simulation. Signal processing circuits are designed and implemented. A hinged-joint prototype force sensor is fabricated for calibration and testing. Experiments show that the proposed hinged-joint sensor possesses a high quality of linearity and excellent sensitivity, which can be applied to diverse fields including smart robot grippers.