Research on a novel parallel spoke piezoelectric 6-DOF heavy force/torque sensor

A novel parallel spoke piezoelectric 6-DOF heavy force/torque sensor by using adjustable load sharing devices is presented in this paper. Measuring methods of piezoelectric quartz crystals and structure of the force/torque sensor are introduced. Load sharing principle on parallel spoke piezoelectric 6-DOF heavy force/torque sensor is researched in vertical, horizontal, moment, and torque directions. Related theoretical structural models are constructed, interpreted, and modified. Moreover, main parameters influencing on load sharing effects in six directions are obtained. By using FEM analysis and verification tests, validity and reliability of load sharing principle are verified. Relationships between load sharing ratio and defined parameters are built, in order to provide reference basis for design of parallel spoke piezoelectric 6-DOF heavy force/torque sensor. Static calibration experiments for fabricated piezoelectric 6-DOF heavy force/torque sensor are designed and carried out. Results of verification experiment show that the load sharing ratios calculated by equations are consistent with those of experiments. Relative errors of load sharing ratio in vertical and horizontal forces are 2.24% and 4.37%, respectively. 6-DOF heavy forces and torques can be measured by the fabricated sensor. The linearity errors and repeatability errors are all less than 1%. By changing the parameters of load sharing device, variable range loads can be measured by using the same sensor. The cost and volume are greatly decreased, and design efficiency is improved. This paper will provide theoretical reference basis for product formation of this kind force/torque sensor.

► A novel parallel spoke piezoelectric 6-DOF heavy force/torque sensor is presented.
► Models of load sharing principle in 6 directions is built and calculated.
► Variable range loads can be measured by changing parameters of load sharing device.
► The linearity errors and the repeatability errors of fabricated sensor are all less than 1%.
► The cost and the volume are decreased, and design efficiency is improved.