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

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 Ha l l effect sensor is chosen according to its linearity, low-cost and appropriate range for voltage output. Then, by properly positioning the hal l effect sensors, an asymmetric structure for the force sensor is presented . The proposed structure is inspired by an gyroscope's architectu r e 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 identi f y the force/displacement relationship. The developed force sensor has the ability to measure the force along the three cartesian axes X, Y, Z 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.