Measurement Theory and Experimental Study of Fault-Tolerant Fully Pre-Stressed Parallel Six-Component Force Sensor

To meet the high reliability requirement under complicated environment and overcome the disadvantages of parallel structure six-component force sensor with traditional spherical pairs, the design concepts of fault-tolerance and fully prestressing are proposed to the design of parallel six-component force sensor. A kind of fault-tolerant and fully prestressed parallel structure force sensor using modified spherical pairs is proposed. The structural characteristics of the sensors are analyzed in comparison with traditional Stewart platform-based sensor. The complete mathematic model including the models with and without signal fault is established using screw theory and considering the relations of stiffness and force distribution. The mathematical expression to obtain the lower bound of prestressed force is determined. The static calibration experimental study of a sensor prototype is carried out, and the experimental results prove the superiority of the structure and the correctness of theoretical analysis. Besides, a fault diagnosis method is proposed and verified with a tracking task, which provides a basis for the applied research of the fault-tolerant sensor.