scholarly journals Variable Impedance Control for Bipedal Robot Standing Balance Based on Artificial Muscle Activation Model

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Kaiyang Yin ◽  
Yaxu Xue ◽  
Yadong Yu ◽  
Shuangxi Xie
Keyword(s):  
Muscle Activation ◽  
Control Method ◽  
Balance Control ◽  
Impedance Control ◽  
Artificial Muscle ◽  
Standing Balance ◽  
Activation Model ◽  
Bipedal Robot ◽  
Impedance Model ◽  
Impedance Parameters

The bipedal robot should be able to maintain standing balance even in the presence of disturbing forces. The control schemes of bipedal robot are conventionally developed based on system models or fixed torque-ankle states, which often lack robustness. In this paper, a variable impedance control based on artificial muscle activation is investigated for bipedal robotic standing balance to address this limitation. The robustness was improved by applying the artificial muscle activation model to adjust the impedance parameters. In particular, an ankle variable impedance model was used to obtain the antidisturbance torque which combined with the ankle dynamic torque to estimate the desired ankle torque for robotic standing balance. The simulation and prototype experimentation results demonstrate that the control method improves the robustness of bipedal robotic standing balance control.

scholarly journals Adaptive Variable Parameter Impedance Control for Apple Harvesting Robot Compliant Picking

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Ji Wei ◽  
Ding Yi ◽  
Xu Bo ◽  
Chen Guangyu ◽  
Zhao Dean
Keyword(s):  
Control System ◽  
Contact Force ◽  
Control Method ◽  
Impedance Control ◽  
Viscoelastic Model ◽  
Variable Parameter ◽  
Response Speed ◽  
Self Tuning ◽  
Impedance Parameters ◽  
Harvesting Robot

In order to reduce the damage of apple harvesting robot to fruits and achieve compliant picking, an adaptive variable parameter impedance control method for apple harvesting robot compliant picking is proposed in this paper. Firstly, the Burgers viscoelastic model is used to characterize the rheological properties of apples and study the variation of mechanical properties of apple grasping at different speeds. Then, a force-based impedance control system is designed. On this basis, aiming at the influence of impedance controller parameters on contact force, three impedance parameters self-tuning functions are constructed to complete the design of an improved force-based impedance control system based on the hyperbolic secant function. The simulation and experimental results show that the proposed control makes the desired force smoother, and its overshoot is about 2.3%. The response speed is faster, and the adjustment time of contact force is shorter of about 0.48 s. The contact force overshoot is about 2%, which is 37.5% less than that of the traditional force-based impedance control. This research improves the control performance for apple harvesting robot compliant picking.

Research on the Space Manipulator Control in Capturing Object Based on Noncontact Impedance Control

2012 ◽  
Vol 546-547 ◽  
pp. 1014-1019 ◽  
Author(s):  
Zhi Gang Chen ◽  
Cui Ru Wu ◽  
Guang Yu Zhang
Keyword(s):  
Control Method ◽  
Impedance Control ◽  
Joint Space ◽  
Space Manipulator ◽  
Object Based ◽  
Space Manipulators ◽  
Impedance Parameters ◽  
The Impact ◽  
Virtual Impedance ◽  
Manipulator Control

This paper discusses the control of free flying space manipulators in the impact process which happens in the capturing operation. To solve the intense coupling of the kinematics and dynamics between the space manipulator and the base, this paper builds the noncontact impedance control model of the 6-joint space manipulator system, which can control the space manipulator before impacting with the objects. Computer simulations are performed to verify that the noncontact impedance control method can make the end-effector of the space manipulator keep desired dynamic characteristics and the adjustment of virtual impedance parameters can control the impact force value efficiently.

Patient-Robot-Therapist Collaboration Using Resistive Impedance Controlled Tele-Robotic Systems Subjected to Time Delays

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Mojtaba Sharifi ◽  
Hassan Salarieh ◽  
Saeed Behzadipour ◽  
Mahdi Tavakoli
Keyword(s):  
Time Delays ◽  
Control Method ◽  
Impedance Control ◽  
Robotic Systems ◽  
Virtual Mass ◽  
Healthy Human ◽  
Impedance Model ◽  
Modeling Uncertainties ◽  
Mass Damper ◽  
Spring System

In this paper, an approach to physical collaboration between a patient and a therapist is proposed using a bilateral impedance control strategy developed for delayed tele-robotic systems. The patient performs a tele-rehabilitation task in a resistive virtual environment with the help of online assistive forces from the therapist being provided through teleoperation. Using this strategy, the patient's involuntary hand tremors can be filtered out and the effort of severely impaired patients can be amplified in order to facilitate their early engagement in physical tasks. The response of the first desired impedance model is tracked by the master robot (interacting with the patient), and the master trajectory plus a deviation as the response of the second impedance model is tracked by the slave robot (interacting with the therapist). Note that the first impedance model is a virtual mass-damper-spring system that has a response trajectory to the combination of patient and therapist forces. Similarly, the second impedance model is a virtual mass-damper-spring system that generates the desired slave–master deviation trajectory as its response to the therapist force. Transmitted signals through the communication channels are subjected to time delays, which exist in home-based rehabilitation (i.e., tele-rehabilitation). Tracking of the impedance models responses in the presence of modeling uncertainties is achieved by employing a nonlinear bilateral adaptive controller and proven using a Lyapunov analysis. The stability of delayed teleoperation system is also proven using the absolute stability criterion. The proposed control method is experimentally evaluated for patient–therapist collaboration in resistive/assistive tasks. In these experiments, a healthy human operator simulates a poststroke patient behavior during the interaction with the master robot.

Stable Nonlinear Trilateral Impedance Control for Dual-User Haptic Teleoperation Systems With Communication Delays

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Mojtaba Sharifi ◽  
Hassan Salarieh ◽  
Saeed Behzadipour ◽  
Mahdi Tavakoli
Keyword(s):  
Absolute Stability ◽  
Impedance Control ◽  
Communication Delays ◽  
Haptic System ◽  
Impedance Model ◽  
Human Operators ◽  
Impedance Parameters ◽  
Teleoperation Systems ◽  
Dual User ◽  
Impedance Models

A new nonlinear adaptive impedance-based trilateral controller is proposed to ensure the absolute stability of multi-degrees-of-freedom (DOFs) dual-user haptic teleoperation systems subjected to communication delays. Using this strategy, reference impedance models are realized for the trilateral teleoperation system represented by a three-port network to facilitate cooperation of two human operators in order to perform a remote physical task. For this purpose, an impedance model defines the desired haptic interaction between the two human operators, while another impedance model specifies the desired behavior of the slave robot in terms of tracking the mater robots' trajectories during interaction with the remote environment. It is shown that different performance goals such as position synchronization and force reflection can be achieved via different adjustments to the impedance parameters. The sufficient conditions for the trilateral haptic system's absolute stability are investigated in terms of the impedance models' parameters. Accordingly, guidelines for modification of the impedance parameters are obtained to guarantee the absolute stability of the trilateral haptic system in the presence of communication time delays. A trilateral nonlinear version of the model reference adaptive impedance control (MRAIC) scheme is developed for implementing the proposed reference impedance models on the masters and the slave. The convergence of robots' trajectories to desired responses and the robustness against modeling uncertainties are ensured using the proposed controller as proven by the Lyapunov stability theorem. The proposed impedance-based control strategy is evaluated experimentally by employing a nonlinear multi-DOFs teleoperated trilateral haptic system with and without communication delays.

Variable impedance control of finger exoskeleton for hand rehabilitation following stroke

2019 ◽  
Vol 47 (1) ◽  
pp. 23-32
Author(s):  
Fuhai Zhang ◽  
Legeng Lin ◽  
Lei Yang ◽  
Yili Fu
Keyword(s):  
Control System ◽  
Real Time ◽  
Control Method ◽  
Impedance Control ◽  
Contact Forces ◽  
Hand Rehabilitation ◽  
Content Type ◽  
Flexion Extension ◽  
Output Trajectory ◽  
Impedance Parameters

Purpose The purpose of this paper is to propose a variable impedance control method of finger exoskeleton for hand rehabilitation using the contact forces between the finger and the exoskeleton, making the output trajectory of finger exoskeleton comply with the natural flexion-extension (NFE) trajectory accurately and adaptively. Design/methodology/approach This paper presents a variable impedance control method based on fuzzy neural network (FNN). The impedance control system sets the contact forces and joint angles collected by sensors as input. Then it uses the offline-trained FNN system to acquire the impedance parameters in real time, thus realizing tracking the NFE trajectory. K-means clustering method is applied to construct FNN, which can obtain the number of fuzzy rules automatically. Findings The results of simulations and experiments both show that the finger exoskeleton has an accurate output trajectory and an adaptive performance on three subjects with different physiological parameters. The variable impedance control system can drive the finger exoskeleton to comply with the NFE trajectory accurately and adaptively using the continuously changing contact forces. Originality/value The finger is regarded as a part of the control system to get the contact forces between finger and exoskeleton, and the impedance parameters can be updated in real time to make the output trajectory comply with the NFE trajectory accurately and adaptively during the rehabilitation.

Impedance Control Based Sliding Mode for Lower Limb Rehabilitation Robot

2014 ◽  
Vol 672-674 ◽  
pp. 1770-1773 ◽  
Author(s):  
Fu Cheng Cao ◽  
Li Min Du
Keyword(s):  
Dynamic Response ◽  
Sliding Mode Control ◽  
Lower Limb ◽  
Control Method ◽  
Sliding Mode ◽  
Impedance Control ◽  
Rehabilitation Robot ◽  
Active Rehabilitation ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

Aimed at improving the dynamic response of the lower limb for patients, an impedance control method based on sliding mode was presented to implement an active rehabilitation. Impedance control can achieve a target-reaching training without the help of a therapist and sliding mode control has a robustness to system uncertainty and vary limb strength. Simulations demonstrate the efficacy of the proposed method for lower limb rehabilitation.

Research on a New Type of Lithium Battery String Equalization and Management System

2011 ◽  
Vol 383-390 ◽  
pp. 1470-1476
Author(s):  
Hao Wang ◽  
Ding Guo Shao ◽  
Lu Xu
Keyword(s):  
Lithium Batteries ◽  
Management System ◽  
Lithium Battery ◽  
Large Scale ◽  
Control Method ◽  
Balance Control ◽  
Industrial Applications ◽  
Control Technique ◽  
New Type ◽  
Management Functions

Lithium battery has been employed widely in many industrial applications. Parameter mismatches between lithium batteries along a series string is the critical limits of the large-scale applications in high power situation. Maintaining equalization between batteries is the key technique in lithium batteries application. This paper summarizes normal equalization techniques and proposed a new type of lithium Battery Equalization and Management System (BEMS) employing the isolated DC-DC converter structure. The system is integrated both equalization functions and management functions by using distributed 3-level controlled structure and digital control technique. With this control method the flexibility of the balance control strategy and the compatibility for different battery strings are both improved dramatically. The experimental results show optimizing equalization, efficiency and the battery string life span has been extended.

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