Fractional-Order Impedance Control Design for Robot Manipulator

2021 ◽  
Author(s):  
Xiaolian Liu ◽  
Shaohua Wang ◽  
Ying Luo
Keyword(s):  
Fractional Order ◽  
Force Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Design Method ◽  
Control Design ◽  
Performance Comparison ◽  
Positioning Errors ◽  
Impedance Parameters ◽  
Mass Spring

Abstract In order to make robot manipulators work more compliantly when contacting with the environment, it is necessary to reduce the contact force caused by positioning errors. One effective way to solve this problem is impedance control, which makes the robot manipulator a second-order mass-spring-damping system in principle. In this paper, a position-based fractional-order impedance control design method is proposed for the robot manipulator force control. The end-effector/environment contact model is established, and the closed-loop system is analyzed with the reference force as input. A fractional-order impedance parameters design method is proposed for better force-control performance, which calculates and optimizes parameters through frequency-domain specifications (i.e., phase margin and gain crossover frequency) and time-domain specification (i.e., the minimum JITSE). With the Robotics ToolBox for MATLAB (RTB), the performance comparison between integer-order and fractional-order impedance controls is illustrated in simulation. The fractional-order impedance control system has a faster response, smaller overshoot, and better resistance to external disturbances from the environment.

scholarly journals FRACTIONAL-ORDER PASSIVITY-BASED ADAPTIVE CONTROLLER FOR A ROBOT MANIPULATOR TYPE SCARA

Fractals ◽  
2020 ◽  
Vol 28 (08) ◽  
pp. 2040008
Author(s):  
J. E. LAVÍN-DELGADO ◽  
S. CHÁVEZ-VÁZQUEZ ◽  
J. F. GÓMEZ-AGUILAR ◽  
G. DELGADO-REYES ◽  
M. A. RUÍZ-JAIMES
Keyword(s):  
Fractional Order ◽  
Control Strategy ◽  
Control Method ◽  
Robot Manipulator ◽  
Adaptive Controller ◽  
Performance Comparison ◽  
External Disturbances ◽  
Scara Robot ◽  
Comparison Results ◽  
Lagrange Formalism

In this paper, a novel fractional-order control strategy for the SCARA robot is developed. The proposed control is composed of [Formula: see text] and a fractional-order passivity-based adaptive controller, based on the Caputo–Fabrizio and Atangana–Baleanu derivatives, respectively; both controls are robust to external disturbances and change in the desired trajectory and effectively enhance the performance of robot manipulator. The fractional-order dynamic model of the robot manipulator is obtained by using the Euler–Lagrange formalism, as well as the model of the induction motors which are the actuators that drive their joints. Through simulations results, the effectiveness and robustness of the proposed control strategy have been demonstrated. The performance of the fractional-order proposed control method is compared with its integer-order counterpart, composed of the PI controller and the conventional passivity-based adaptive controller, reported in the literature. The performance comparison results demonstrate the superiority and effectiveness of the fractional-order proposed control strategy for a SCARA robot manipulator.

scholarly journals Force control design for a robot manipulator attached to a UAV

2018 ◽  
Vol 51 (30) ◽  
pp. 548-553 ◽  
Author(s):  
Konstantinos Gkountas ◽  
Dimitris Chaikalis ◽  
Anthony Tzes
Keyword(s):  
Force Control ◽  
Robot Manipulator ◽  
Control Design

Development of User-friendly Tuning for Impedance Control Parameters

2001 ◽  
Vol 13 (3) ◽  
pp. 230-237
Author(s):  
Junji shimamura ◽  
◽  
Masaki Arao ◽  
Keyword(s):  
Control System ◽  
Force Control ◽  
Impedance Control ◽  
External Environment ◽  
Parameter Tuning ◽  
Control Parameters ◽  
Trial And Error ◽  
Impedance Parameters ◽  
User Friendly ◽  
Ic Test

Impedance control, a type of indirect force control, is a method for providing a control system with compliance against forces effected by external environment. This method is expected to be applied primarily to industrial purposes, but it has such disadvantages that the process for tuning its parameters is based on a trial-and-error rule and largely depends on the controlling skill of operators. This paper describes a parameter tuning tool capable of readily setting the optimum impedance parameters and then clarifies the effectiveness of the suggested tool according to the results of experiments conducted on IC test inserter. Operators are not necessarily required to acquire the knowledge about impedance control.

Educational Force Control Using a Modular 2-DOF Serial Robot Manipulator and Low-Cost 2-DOF Force Sensor

2019 ◽  
Author(s):  
Stephen Mascaro
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Low Cost ◽  
Force Sensor ◽  
Physical Contact ◽  
Dynamic Force ◽  
Control Techniques

Abstract This paper describes a modular 2-DOF serial robotic system and accompanying experiments that have been developed to instruct robotics students in the fundamentals of dynamic force control. In prior work, we used this same robot to showcase and compare the performance of a variety of textbook techniques for dynamic motion control (i.e. fast/accurate trajectory tracking using dynamic model-based and robust control techniques). In this paper we now add a low-cost 3D-printed 2-DOF force sensor to this modular robot and demonstrate a variety of force control techniques for use when the robot is in physical contact with the environment. These include stiffness control, impedance control, admittance control, and hybrid position/force control. Each of these various force control schemes can be first simulated and then experimentally implemented using a MATLAB/Simulink real-time interface. The two-degrees of freedom are just enough to demonstrate how the manipulator Jacobian can be used to implement directional impedances in operational space, and to demonstrate how hybrid control can implement position and force control in different axes. This paper will describe the 2-DOF robot system including the custom force sensor, illustrate the various force control methods that can be implemented, and demonstrate sample results from these experiments.

Position-Based Fractional-Order Impedance Control of a 2 DOF Serial Manipulator

Robotica ◽  
2021 ◽  
pp. 1-15
Author(s):  
Selçuk Kizir ◽  
Ali Elşavi
Keyword(s):  
Fractional Order ◽  
Position Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Torque Control ◽  
Control Scheme ◽  
Absorption Performance ◽  
And Performance ◽  
Comparison Of The Results ◽  
Robotic Tasks

SUMMARY Impedance control is one of the interaction and force control methods that has been widely applied in the research of robotics. In this paper, a new position-based fractional-order impedance control scheme is proposed and applied to a 2 DOF serial manipulator. An RR robot manipulator with full arm dynamics and its environment were designed using Matlab/Simulink. The position control of the manipulator was utilized based on computed torque control to cancel out the nonlinearities existing on the dynamic model of the robot. Parameters of classical impedance controller (CIC) and proposed fractional-order impedance controller (FOIC) were optimized in order to minimize impact forces for comparison of the results in three conditions. In CIC condition: three constant parameters of the impedance controller were optimized: in Frac_λμ condition: Only non-integer parameters of the FOIC were re-optimized after the parameters in CIC had been accepted, and in Frac_all condition: all parameters of the FOIC were re-optimized. In order to show the effectiveness of the proposed method, simulations were conducted for all cases and performance indices were computed for the interaction forces. Results showed that impacts were reduced with an improvement of 26.12% from CIC to Frac_ λμ and an improvement of 47.21% from CIC to Frac_all. The proposed scheme improves the impedance behavior and robustness showing better impact absorption performance, which is needed in many challenging robotic tasks and intelligent mechatronic devices.

Robotic Time-Varying Force Tracking in Position-Based Impedance Control

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Wenkang Xu
Keyword(s):  
Force Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Time Varying ◽  
Closed Loop System ◽  
Impedance Function ◽  
System A ◽  
Control Framework ◽  
Force Tracking

This paper presents a unified control framework for both set-point and time-varying force control of robot manipulator by introducing an improved position-based impedance control (IPBIC). In order to essentially achieve accurate force control, especially time-varying force tracking, a new target impedance function compensated by a force controller is presented. The essence of the improved method in realizing time-varying force tracking, as well as the coupled stability of the manipulator–environment system is investigated. To further improve the force control performance, the Newton-type iterative learning control (ILC) is introduced upon the closed-loop system. A case study on a two-link robot model demonstrates the effectiveness of this method.

scholarly journals Active Impedance Control of Bioinspired Motion Robotic Manipulators: An Overview

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Hayder F. N. Al-Shuka ◽  
Steffen Leonhardt ◽  
Wen-Hong Zhu ◽  
Rui Song ◽  
Chao Ding ◽  
...  
Keyword(s):  
Force Control ◽  
Impedance Control ◽  
Control Strategies ◽  
Muscle Stiffness ◽  
Effective Control ◽  
Interaction Forces ◽  
Control Schemes ◽  
Force Tracking ◽  
Mass Spring ◽  
Active Impedance

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.

Fuzzy Logic Based Impedance Control to Monitor on Torque under Impulsive Loading

2011 ◽  
Vol 110-116 ◽  
pp. 5345-5350
Author(s):  
Mostafa Rahimi Dizaji ◽  
Mohammad Reza Hairi Yazdi ◽  
Moteaal Asadi Shirzi
Keyword(s):  
Fuzzy Logic ◽  
Force Control ◽  
Pid Controller ◽  
Force Feedback ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Impulsive Loading ◽  
Reference Trajectory ◽  
End Effector ◽  
Supervisory System

This paper is devoted to design a control system for robot manipulator to optimize motor torque due to external impulsive loading exerted on the manipulator. Under impulsive loading, overloading may occur in the absence of any monitoring on the torque. To avoid the overloading, impedance control is proposed as a force control strategy. Here impedance control based on force feedback of which has hit the end-effector modifies the reference trajectory. In fact, instead of resisting against impulsive loading up to extreme power of the motor, the proposed design generates small movements in the direction of impact. Therefore, the motor produces less torque in comparison to the absence of impedance control. A supervisory system assisting fuzzy logic has been used to adapt impedance controller parameters with various impact conditions. The simulation result confirms the improvement of the manipulator behavior which yields sensible reduction in motor developed torque in comparison to single PID controller.

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