An Experimental Study on Cartesian Impedance Control for a Joint Torque-Based Manipulator

2008 ◽  
Vol 22 (11) ◽  
pp. 1155-1180 ◽  
Author(s):  
Hong Liu ◽  
Ye-chao Liu ◽  
Minghe Jin ◽  
K. Sun ◽  
J. B. Huang
Keyword(s):  
Experimental Study ◽  
Impedance Control ◽  
Joint Torque

2P1-C08 Local Impedance Control Based on Joint Torque Sensing Using New Optical Torque Sensors

2006 ◽  
Vol 2006 (0) ◽  
pp. _2P1-C08_1-_2P1-C08_3
Author(s):  
Dzmitry TSETSERUKOU ◽  
Riichiro TADAKUMA ◽  
Hiroyuki KAJIMOTO ◽  
Susumu TACHI
Keyword(s):  
Impedance Control ◽  
Joint Torque ◽  
Optical Torque

scholarly journals Cerebellar ataxia impairs modulation of arm stiffness during postural maintenance

2013 ◽  
Vol 110 (7) ◽  
pp. 1611-1620 ◽  
Author(s):  
Tricia L. Gibo ◽  
Amy J. Bastian ◽  
Allison M. Okamura
Keyword(s):  
Cerebellar Ataxia ◽  
Motor Coordination ◽  
Matched Control ◽  
Impedance Control ◽  
Torque Control ◽  
Joint Torque ◽  
Motor Deficits ◽  
Control Subjects ◽  
Impedance Modulation ◽  
Cerebellar Damage

Impedance control enables humans to effectively interact with their environment during postural and movement tasks, adjusting the mechanical behavior of their limbs to account for instability. Previous work has shown that people are able to selectively modulate the end-point stiffness of their arms, adjusting for varying directions of environmental disturbances. Behavioral studies also suggest that separate controllers are used for impedance modulation versus joint torque coordination. Here we tested whether people with cerebellar damage have deficits in impedance control. It is known that these individuals have poor motor coordination, which has typically been attributed to deficits in joint torque control. Subjects performed a static postural maintenance task with two different types of directional force perturbations. On average, patients with cerebellar ataxia modified stiffness differentially for the two perturbation conditions, although significantly less than age-matched control subjects. Thus cerebellar damage may impair the ability to modulate arm impedance. Surprisingly, the patients' intact ability to generally alter their limb stiffness during the postural task (albeit less than age-matched control subjects) improved their movement performance in a subsequent tracing task. The transfer of stiffness control from the static to the movement task may be a strategy that can be used by patients to compensate for their motor deficits.

Hybrid impedance control of a knee joint orthosis

2019 ◽  
Vol 46 (2) ◽  
pp. 192-201
Author(s):  
Mohamed Amine Alouane ◽  
Hala Rifai ◽  
Kwangtaek Kim ◽  
Yacine Amirat ◽  
Samer Mohammed
Keyword(s):  
Knee Joint ◽  
Impedance Control ◽  
Hybrid Approach ◽  
Joint Torque ◽  
Joint Movement ◽  
Content Type ◽  
Control Approach ◽  
Flexion Extension ◽  
Proportional Derivative Controller ◽  
Linear Disturbance

Purpose This paper aims to deal with the design of new hybrid approach for the assistance of the flexion extension movement of the knee joint. Design/methodology/approach The control approach combines the use of a knee joint orthosis along with functional electrical stimulation (FES) within an assist-as-needed paradigm. An active impedance controller is used to assist the generation of muscular stimulation patterns during the extension sub-phase of the knee joint movement. The generated FES patterns are appropriately tailored to achieve flexion/extension movement of the knee joint, which allows providing the required assistance by the subject through muscular stimulation. The generated torque through stimulation is tracked by a non-linear disturbance observer and fed to the impedance controller to generate the desired trajectory that will be tracked using a standard proportional derivative controller. Findings The approach was tested in experiments with two healthy subjects. Results show satisfactory performances in terms of estimating the knee joint torque, as well as in terms of cooperation between the FES and the orthosis actuator during the execution of the knee joint flexion/extension movements. Originality/value The authors designed a new hybrid approach for the assistance of the flexion extension movement of the knee joint, which has not been studied yet. The control approach combines the use of a knee joint orthosis along with FES within an assist-as-needed paradigm.

Impedance control of collaborative robots based on joint torque servo with active disturbance rejection

2019 ◽  
Vol 46 (4) ◽  
pp. 518-528 ◽  
Author(s):  
Tianyu Ren ◽  
Yunfei Dong ◽  
Dan Wu ◽  
Ken Chen
Keyword(s):  
Force Control ◽  
Disturbance Rejection ◽  
Impedance Control ◽  
State Observer ◽  
Extended State Observer ◽  
Joint Torque ◽  
Extended State ◽  
Collaborative Robots ◽  
Content Type ◽  
Control Framework

Purpose The purpose of this paper is to present a simple yet effective force control scheme for collaborative robots by addressing the problem of disturbance rejection in joint torque: inherent actuator flexibility and nonlinear friction. Design/methodology/approach In this paper, a joint torque controller with an extended state observer is used to decouple the joint actuators from the multi-rigid-body system of a constrained robot and compensate the motor friction. Moreover, to realize robot force control, the authors embed this controller into the impedance control framework. Findings Results have been given in simulations and experiments in which the proposed joint torque controller with an extended state observer can effectively estimate and compensate the total disturbance. The overall control framework is analytically proved to be stable, and further it is validated in experiments with a robot testbed. Practical implications With the proposed robot force controller, the robot is able to change its stiffness in real time and therefore take variable tasks without any accessories, such as the RCC or 6-DOF F/T sensor. In addition, programing by demonstration can be realized easily within the proposed framework, which makes the robot accessible to unprofessional users. Originality/value The main contribution of the presented work is the design of a model-free robot force controller with the ability to reject torque disturbances from robot-actuator coupling effect and motor friction, applicable for both constrained and unconstrained environments. Simulation and experiment results from a 7-DOF robot are given to show the effectiveness and robustness of the proposed controller.

scholarly journals A Human-Robot Interaction Based Coordination Control Method for Assistive Walking Devices and an Assessment of Its Stability

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Xia Zhang ◽  
Wenliang Ge ◽  
Hao Fu ◽  
Renxiang Chen ◽  
Tianhong Luo ◽  
...  
Keyword(s):  
Knee Joint ◽  
Hip Joint ◽  
Control Method ◽  
Impedance Control ◽  
Lyapunov Stability Theory ◽  
Human Robot Interaction ◽  
Joint Torque ◽  
Coordination Control ◽  
Linkage Mechanism ◽  
Control Laws

A biologically inspired motion control method is introduced to ameliorate the flexibility and multijoint autonomy of assistive walking devices based on human-robot interactions (HRIs). A new HRI-based coordination control system consisting of a hip central pattern generator (CPG) control, a knee hierarchical impedance control, and a hip-knee linkage control is also investigated. Simulations and walking experiments are carried out which demonstrate that (i) the self-oscillation and external communication characteristics of the CPG are capable of realizing ideal master/slave hip joint trajectories. In addition, symmetrical inhibition in the CPG unit is essential for maintaining the antiphase motion of the left and right hip joints. (ii) High and low hierarchical impedance control laws allow appropriate knee joint torque to be calculated to maintain posture during the support and swing phases as walking proceeds. (iii) A hip-knee joint linkage mechanism which incorporates a hip joint CPG control and knee joint impedance control allows natural and relevant hip-knee trajectories to be realized. The stability of the HRI-based coordination control method is also confirmed using Lyapunov stability theory.

scholarly journals Disturbance Observer-Based Robot End Constant Contact Force-Tracking Control

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Tie Zhang ◽  
Xiaohong Liang
Keyword(s):  
Contact Force ◽  
Tracking Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Sliding Mode ◽  
Impedance Control ◽  
Joint Torque ◽  
Estimation Accuracy ◽  
Force Tracking ◽  
High Control

A disturbance observer-based hybrid sliding mode impedance control method is proposed in this paper, which is able to achieve robot end constant contact force-tracking control without force/torque sensors. The method requires only the values of joint torque, joint angle, and joint angular velocity, which are converted by robot servo motor signals, to implement the control. The control scheme consists of two parts: one is a disturbance observer and the other is a hybrid sliding mode impedance controller. The disturbance observer, which takes robot internal signals mentioned above as the inputs to estimate the robot end contact force, is designed based on generalized momentum, thus improving the estimation accuracy. The hybrid sliding mode impedance controller, which uses the values estimated by the disturbance observer and the robot internal signals as the inputs to calculate the corresponding position adjustment, integrates both the impedance control and sliding mode control, thus improving the force-tracking performance and robustness. Experimental results show that the proposed disturbance observer-based hybrid sliding mode impedance control method possesses high control precision.

Sign in / Sign up

Export Citation Format

Share Document