Development of a Cylindrical 6-axis Force Sensor with Optimal Isotropy

Abstract

In this study, a method for developing a cylindrical 6-axis force/torque (F/T) sensor with optimal sensitivity isotropy is proposed. To accommodate diverse conditions, it is desirable for a force sensor to have good isotropy. To evaluate sensitivity isotropy, voltage ratio is introduced as an index corresponding to the ratio of the sensitivity along the z-axis to those along other directions. By analyzing the cylindrical structure using material mechanics, we analytically determined the structure and the location of the gauge attachment point so that the voltage ratio 𝑓 for the force and voltage ratio 𝑔 for the moment would be equal. The maximum nonlinearity and maximum decoupling errors of the developed sensor were 2.40% and 2.23%, respectively. In addition, the average voltage ratios calculated from the measured values were determined to be 𝑓 = 0.873 and 𝑔 = 1.67. This shows that the sensitivity in the z-axis direction toward other axes has been improved compared to previous studies.