Robust disturbance estimation for human-robotic comanipulation

Abstract

SUMMARYExternal forces affect the dynamics of load‐carrying robot devices. The knowledge of such disturbances is generally needed for control purposes. However, direct disturbance measurement using force sensors is not always possible. This paper introduces a force estimator for force‐sensor‐less robotic manipulators. The algorithm is based on the knowledge of the dynamics of the robotic device, whereas mass of the load is typically unknown. Using this algorithm, low‐frequency external forces can be estimated robustly even for quasi‐statically time‐varying and uncertain loads. Experiments validate the proposed strategy in practice. Moreover, the applicability of the estimation algorithm is further illustrated by using it in a human–robot comanipulation setup in which the robot is providing additional coordinated forcing to alleviate human effort needed to manipulate the robot. Copyright © 2013 John Wiley & Sons, Ltd.

Robust Observer Based Disturbance Rejection Control for Euler-Lagrange Systems

“…where ( ) is a low-pass filter to be optimized. According to (14) and (15), it can be obtained that̂= − ( )V + ( )̇2 = ( ) ( ); that is, the observer satisfies the disturbance rejection paradigm in (12). In practical applications, ( ) and ( ) can be realized in state-space.…”

“…For the given second-order mechanical system in (5), the external disturbances and equivalent internal uncertainties satisfy Assumptions 2 and 3. By adopting the observer in (15) and controller in (21), the control error of system states and estimation error of observer are locally uniformly ultimately bounded (UUB).…”

“…The effectiveness of disturbance observer (DOB) has been shown in many applications, such as humanoid robot control [14,15], manipulator control [16][17][18], aircraft control [19,20], optical disk control [21,22], motor control [23,24], and vibration control [25,26]. Traditional DOB methodology, which is proposed based on linear system, cannot be used directly in nonlinear systems [27].…”

Sensorless force estimation of end-effect upper limb rehabilitation robot system with friction compensation

“…Liu et al 24 proposed a method for the real-time estimation of contact location and contact force along a planar joint robot manipulator without using external sensory systems. Lichiardopol et al 25 introduced a force estimator which is based on the knowledge of the dynamics of the robotic device, whereas mass of the load is typically unknown. Using this algorithm, low-frequency external forces can be estimated robustly even for quasi-statically time-varying and uncertain loads.…”

Optimal Trajectory Planning and Compliant Spacecraft Capture Using a Space Robot

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