A novel sliding mode control for series elastic actuator torque tracking with an extended disturbance observer

Wang, Meng; Sun, Lei; Yin, Wei; Dong, Shuai; Liu, Jingtai

doi:10.1109/robio.2015.7419699

Cited by 21 publications

(10 citation statements)

References 24 publications

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“…The advantages of the harmonic gearing mechanism are no backlash, high compactness, lightweight, high gear ratios in a small volume, and coaxial input and output shafts. In the research of Meng ( Wang et al,2015 ; Wang et al, 2017 ), a nonlinear series elastic joint with variable stiffness is presented. There are two motors and a harmonic gearing mechanism in this design.…”

Section: Related Research Workmentioning

confidence: 99%

Modelling and Control of a 2-DOF Robot Arm with Elastic Joints for Safe Human-Robot Interaction

2021

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Collaborative robots (or cobots) are robots that can safely work together or interact with humans in a common space. They gradually become noticeable nowadays. Compliant actuators are very relevant for the design of cobots. This type of actuation scheme mitigates the damage caused by unexpected collision. Therefore, elastic joints are considered to outperform rigid joints when operating in a dynamic environment. However, most of the available elastic robots are relatively costly or difficult to construct. To give researchers a solution that is inexpensive, easily customisable, and fast to fabricate, a newly-designed low-cost, and open-source design of an elastic joint is presented in this work. Based on the newly design elastic joint, a highly-compliant multi-purpose 2-DOF robot arm for safe human-robot interaction is also introduced. The mechanical design of the robot and a position control algorithm are presented. The mechanical prototype is 3D-printed. The control algorithm is a two loops control scheme. In particular, the inner control loop is designed as a model reference adaptive controller (MRAC) to deal with uncertainties in the system parameters, while the outer control loop utilises a fuzzy proportional-integral controller to reduce the effect of external disturbances on the load. The control algorithm is first validated in simulation. Then the effectiveness of the controller is also proven by experiments on the mechanical prototype.

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Section: Related Research Workmentioning

confidence: 99%

Modelling and Control of a 2-DOF Robot Arm with Elastic Joints for Safe Human-Robot Interaction

2021

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“…In view of the above statement, the following points can be noted: The control architecture of the SEA can consist of three nested control loops: an innermost velocity loop, an intermediate torque loop, and the outer impedance control loop that renders virtual impedance for safe and comfortable human-robot interactions: see [ 107 , 126 , 127 , 130 , 134 ]. However, many control schemes do not use the innermost velocity loop [ 139 – 145 ]. In addition, a nested loop using acceleration feedback has been proposed showing excellent results in terms of both performance and stability [ 105 , 146 ] A powerful tool for tuning the gains of cascade control of the SEA and determining the ranges of the virtual impedance target is the passivity theory.…”

Section: Active Impedance Control Of Constant Impedance Flexible Jmentioning

confidence: 99%

Active Impedance Control of Bioinspired Motion Robotic Manipulators: An Overview

Al-Shuka

Leonhardt

Zhu

et al. 2018

Applied Bionics and Biomechanics

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There are two main categories of force control schemes: hybrid position-force control and impedance control. However, the former does not take into account the dynamic interaction between the robot's end effector and the environment. In contrast, impedance control includes regulation and stabilization of robot motion by creating a mathematical relationship between the interaction forces and the reference trajectories. It involves an energetic pair of a flow and an effort, instead of controlling a single position or a force. A mass-spring-damper impedance filter is generally used for safe interaction purposes. Tuning the parameters of the impedance filter is important and, if an unsuitable strategy is used, this can lead to unstable contact. Humans, however, have exceptionally effective control systems with advanced biological actuators. An individual can manipulate muscle stiffness to comply with the interaction forces. Accordingly, the parameters of the impedance filter should be time varying rather than value constant in order to match human behavior during interaction tasks. Therefore, this paper presents an overview of impedance control strategies including standard and extended control schemes. Standard controllers cover impedance and admittance architectures. Extended control schemes include admittance control with force tracking, variable impedance control, and impedance control of flexible joints. The categories of impedance control and their features and limitations are well introduced. Attention is paid to variable impedance control while considering the possible control schemes, the performance, stability, and the integration of constant compliant elements with the host robot.

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“…To suppress the chattering of the SMC force controller, Wang et al proposed a modified SMC controller by using nonlinear DOb and high gain control in ref. [24]. Force control of an SEA was performed by using RRC in ref.…”

Section: Introductionmentioning

confidence: 99%

A Sliding Mode Force and Position Controller Synthesis for Series Elastic Actuators

Sarıyıldız¹,

Mutlu²,

Huang³

2019

Robotica

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SummaryThis paper deals with the robust force and position control problems of series elastic actuators (SEAs). It is shown that an SEA’s force control problem can be described by a second-order dynamic model which suffers from only matched disturbances. However, the position control dynamics of an SEA is of fourth order and includes matched and mismatched disturbances. In other words, an SEA’s position control is more complicated than its force control, particularly when disturbances are considered. A novel robust motion controller is proposed for SEAs by using disturbance observer (DOb) and sliding mode control. When the proposed robust motion controller is implemented, an SEA can precisely track desired trajectories and safely contact with an unknown and dynamic environment. The proposed motion controller does not require precise dynamic models of environments and SEAs. Therefore, it can be applied to many different advanced robotic systems such as compliant humanoids, industrial robots and exoskeletons. The validity of the proposed motion controller is experimentally verified.

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A novel sliding mode control for series elastic actuator torque tracking with an extended disturbance observer

Cited by 21 publications

References 24 publications

Modelling and Control of a 2-DOF Robot Arm with Elastic Joints for Safe Human-Robot Interaction

Modelling and Control of a 2-DOF Robot Arm with Elastic Joints for Safe Human-Robot Interaction

Active Impedance Control of Bioinspired Motion Robotic Manipulators: An Overview

A Sliding Mode Force and Position Controller Synthesis for Series Elastic Actuators

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