External Force Estimation for Telerobotics without Force Sensor

Abstract

Abstract. This paper establishes an approach to external force estimation through the use of a mathematical model and current sensing, without employing a force/torque sensor. The advantages and need for force feedback have been well established in the field of telerobotics. This paper presents the requirement for sensorless force estimation and comparative results between a force sensor and the presented approach using an industrial robot. The approach presents not only a cost effective solution but also a solution for force sensing in hazardous environments, especially ionizing radiation prone environments where the dose rates limit the use of sensing equipment. The paper also discusses the applications and advantages presented by this work in various fields.Keywords: Industrial robot, sensorless, remote handling, force feedback, master-slave system IntroductionIn teleoperation a human operator manipulates master device, and a slave device follows the motion while manipulating in a remote environment. Providing the operator with various information regarding the remote environment like position, orientation, contact, load, forces and others; improves the task performance and the operator understanding of the environment. This information can be viewed on display screens [1] but, it is more intuitive when provided directly, by reflecting the measured parameters like positions and torques to the master haptic device. When the operator is interacting with the slave with a haptic master then the operator is said to be kinesthetically coupled to the environment. The task being performed is said to be bilateral controlled teleoperation [2], [3]. The continued advances in these various fields of control, communications, haptic systems and others have made possible to have an integrated robotic master slave system that it is able to aid the human operator in effective task execution. The teleoperation slaves are generally controlled using bilateral control algorithms. Bilateral control algorithms main goals are stability and transparency. Stability assures expected system response for the teleoperation task. It ensures stability and prevents

External Force Estimation for Teleoperation Based on Proprioceptive Sensors

“…On a hydraulic actuator based on servo-valves, the motor torque τ m can be estimated by using the expression on (3) [36], where Kp is a constant and A P is the differential pressure between the two chambers of the hydraulic actuator:…”