Design and development of a multi-axis force sensor based on the hall effect with decouple structure

Abstract

This paper investigates the design and development of a novel 3-axis force sensor for human–robot interaction purposes. Based on the characteristics of the sensing technologies proposed in the literature, the Hall effect sensor is chosen according to its linearity, low-cost and appropriate range for voltage output. Then, by properly positioning the hall effect sensors, an asymmetric structure for the force sensor is presented. The proposed structure is inspired by an gyroscope’s architecture which provides an independent output on the sensor’s axes. As a result, each axis of the sensor, independently, creates a relationship between force and displacement which is covered by a silicon structure. Therefore, the Jacobian matrix of the proposed structure becomes an identity matrix for which the least-squares estimation is used to identify the force/displacement relationship. The developed force sensor has the ability to measure the force along the three cartesian axes Xˆ, Yˆ, Zˆ with the resolution of 2 mN, 1.5 mN, and 0.2 N, respectively. In order to illustrate the performance of the proposed multi-axis force sensor, an interactive simple control is carried out which is performed by attaching the sensor to the end-effector of a parallel robot, the so-called Tripteron robot, and enable to have a safe reaction in the case of occurring a collision in an environment.