Posts Tagged impedance control

[Abstract] Variable impedance control of finger exoskeleton for hand rehabilitation following stroke

Abstract

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.

 

via Variable impedance control of finger exoskeleton for hand rehabilitation following stroke | Emerald Insight

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[Abstract] Exoskeleton design and adaptive compliance control for hand rehabilitation

An adaptive robotic system has been developed to be used for hand rehabilitation. Previously developed exoskeletons are either very complex in terms of mechanism, hardware and software, or simple but have limited functionality only for a specific rehabilitation task. Some of these studies use simple position controllers considering only to improve the trajectory tracking performance of the exoskeleton which is inadequate in terms of safety and health of the patient. Some of them focus only on either passive or active rehabilitation, but not both together. Some others use EMG signals to assist the patient, but this time active rehabilitation is impossible unless different designs and control strategies are not developed. The proposed mechanical structure is extremely simple. The middle and the proximal phalanxes are used as a link of consecutively connected two 4-bar mechanisms, respectively. The PIP and MCP joints are actuated by a single electro mechanical cylinder to produce complex flexion and extension movements. It is simpler than similar ones from aspect with the mechanical structure and the biodynamic fit of the hand, making it practicable in terms of production and personal usage. Simple design lets to implement adaptive compliance controller for all active and passive rehabilitation tasks, instead of developing complex and different strategies for different rehabilitation tasks. Furthermore, using the Luenberger observer for unmeasured velocity state variable, an on-line estimation method is used to estimate the dynamic parameters of the system. This makes possible to estimate the force exerted by the patient as well, without a force sensor.

 

via Exoskeleton design and adaptive compliance control for hand rehabilitation – Gazi Akgun, Ahmet Emre Cetin, Erkan Kaplanoglu,

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[Abstract] A novel backstepping adaptive impedance control for an upper limb rehabilitation robot

Abstract

Stroke contributes to hemiplegia, which severely reduces people’s ability to perform activities of daily living. Due to the insufficiency of medical resources, there is an urgent need for home-based rehabilitation robot. In this paper, we design a home-based upper limb rehabilitation robot, based on the principle that three axes intersect at one point. A three-dimensional force sensor is equipped at the end of the manipulator to measure the interaction forces between the affected upper limb and the robot during rehabilitation training. The virtual rehabilitation training environment is designed to improve the enthusiasm of patients. A backstepping adaptive fuzzy based impedance control method is proposed for the home-based upper limb rehabilitation robot to prevent secondary injury of the affected limb. The adaptive law is introduced, and the backstepping adaptive fuzzy based impedance controller is proved in details. Experiments results demonstrate the effectiveness of the proposed control method.

 

via A novel backstepping adaptive impedance control for an upper limb rehabilitation robot – ScienceDirect

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[Abstract] An Adaptive Iterative Learning Based Impedance Control For Robot-Aided Upper-limb Passive Rehabilitation

In this paper, an anthropomorphic arm is introduced and used to the upper-limb passive rehabilitation therapy. The anthropomorphic arm is constructed via pneumatic artificial muscles so that it may assist patients suffering upper-limb diseases to achieve mild therapeutic exercises. Due to the uncertain dynamic environment, external disturbances and model uncertainties, a combined control is proposed to stabilize and to enhance the adaptivity of the system. In the combined control, an iterative learning control is used to realize accurate position tracking. Meanwhile, an adaptive iterative learning based impedance control is proposed to execute the appropriate contact force during the therapy of the upper-limb. The advantage of the combined control is that it doesn’t depend on the accurate model of systems and it may deal with highly nonlinear system which has strong coupling and redundancies. The convergence of the adaptive iterative learning based impedance control is emphasized analyzed. Numerical simulations are performed to verify the proposed control method. In addition, real experiments are executed on the Southwest anthropomorphic arm.

Source :
https://www.frontiersin.org/articles/10.3389/frobt.2019.00041/abstract  

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[Abstract + References] A compact wrist rehabilitation robot with accurate force/stiffness control and misalignment adaptation

Abstract

Robots have been demonstrated to assist the rehabilitation of patients with upper or lower limb disabilities. To make exoskeleton robots more friendly and accessible to patients, they need to be lightweight and compact without major performance tradeoffs. Existing upper-limb exoskeleton robots focus on the assistance of the coarse-motion of the upper arm while the fine-motion rehabilitation of the forearm is often ignored. This paper presents a wrist robot with three degrees-of-freedom. Using a geared bearing, slider crank mechanisms, and a spherical mechanism, this robot can provide the complete motion assistance for the forearm. The optimized robot dimensions allow large torque and rotation output while the motors are placed parallel to the forearm. Thus lightweight, compactness, and better inertia properties can be achieved. Linear and rotary series elastic actuators (SEAs) with high torque-to-weight ratios are proposed to accurately measure and control the interaction force and impedance between the robot and the wrist. The resulting 1.5-kg robot can be used alone or easily in combination with other robots to provide various robot-aided upper limb rehabilitation.

References

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via A compact wrist rehabilitation robot with accurate force/stiffness control and misalignment adaptation | SpringerLink

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[Abstract+References] Impedance Control of a Pneumatic Muscles-Driven Ankle Rehabilitation Robot – Conference paper

Abstract

Pneumatic muscle is a new type of flexible actuator with advantages in terms of light weight, large output power/weight ratio, good security, low price and clean. In this paper, an ankle rehabilitation robot with two degrees of freedom driven by pneumatic muscle is studied. The force control method with an impedance controller in outer loop and a position inner loop is proposed. The demand of rehabilitation torque is ensured through tracking forces of three pneumatic muscle actuators. In the simulation, the constant force and variable force are tracked with error less than 10 N. In the experiment, the force control method also achieved satisfactory results, which provides a good support for the application of the robot in the ankle rehabilitation.

References

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Source: Impedance Control of a Pneumatic Muscles-Driven Ankle Rehabilitation Robot | SpringerLink

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[Abstract+References] Robot assisted rehabilitation of the arm after stroke: prototype design and clinical evaluation

Abstract

Robot assisted rehabilitation training is a promising tool for post-stroke patients’ recovery, and some new challenges are imposed on robot design, control, and clinical evaluation. This paper presents a novel upper limb rehabilitation robot that can provide safe and compliant force feedbacks to the patient for the benefits of its stiff and low-inertia parallel structure, highly backdrivable capstan-cable transmission, and impedance control method in the workspace. The “assist-as-needed” (AAN) clinical training principle is implemented through the “virtual tunnel” force field design, the “assistance threshold” strategy, as well as the virtual environment training games, and preliminary clinical results show its effectiveness for motor relearning for both acute and chronic stroke patients, especially for coordinated movements of shoulder and elbow.

Supplementary material

11432_2017_9076_MOESM1_ESM.pdf (1.7 mb)

Robot assisted rehabilitation of the arm after stroke: prototype design and clinical evaluation
11432_2017_9076_MOESM2_ESM.mp4 (96.2 mb)

Supplementary material, approximately 96.2 MB.
11432_2017_9076_MOESM3_ESM.mp4 (43.6 mb)

Supplementary material, approximately 43.6 MB.

Source: Robot assisted rehabilitation of the arm after stroke: prototype design and clinical evaluation | SpringerLink

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[Book Chapter] Control of the E2REBOT Platform for Upper Limb Rehabilitation in Patients with Neuromotor Impairment – Springer

Abstract

In this paper, the most significant aspects of the new robotic platform E2REBOT, for active assistance in rehabilitation work of the upper limbs for people with neuromotor impairment, are presented. Special emphasis is made on the characteristics of their control architecture, designed based on a three level model, one of which implements a haptic impedance controller, developed according to the “assist as needed” paradigm, looking to dynamically adjust the level of assistance to the current situation of the patient, in order to improve the results of the therapy. The two modes of therapy that supports the platform are described, highlighting the behavior of the control system in each case and describing the criteria used to adapt the behavior of the robot. Finally, we describe the ability of the system for the automatic recording of kinematic and dynamic parameters during the execution of therapies, and the availability of a management environment for exploiting these data, as a tool for supporting the rehabilitation tasks.

Source: Control of the E2REBOT Platform for Upper Limb Rehabilitation in Patients with Neuromotor Impairment – Springer

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[REVIEW] A review of technological and clinical aspects of robot-aided rehabilitation of upper-extremity after stroke – Full Text PDF

Abstract

Cerebrovascular accident (CVA) or stroke is one of the leading causes of disability and loss of motor function. Millions of people around the world are effected by it each year. Stroke results in disabled arm function. Restoration of arm function is essential to regaining activities of daily living (ADL). Along with traditional rehabilitation methods, robot-aided therapy has emerged in recent years. Robot-aided rehabilitation is more intensive, of longer duration and more repetitive. Using robots, repetitive dull exercises can turn into a more challenging and motivating tasks such as games. Besides, robots can provide a quantitative measure of the rehabilitation progress. This article overviews the terms used in robot-aided upper-limb rehabilitation. It continues by investigating the requirements for rehabilitation robots. Then the most outstanding works in robot-aided upper-limb rehabilitation and their control schemes have been investigated. The clinical outcomes of the built robots are also given that demonstrates the usability of these robots in real-life applications and their acceptance. This article summarizes a review done along with a research on the design, simulation and control of a robot for use in upper-limb rehabilitation after stroke.

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[ARTICLE] A review of technological and clinical aspects of robot-aided rehabilitation of upper-extremity after stroke

Abstract

Cerebrovascular accident (CVA) or stroke is one of the leading causes of disability and loss of motor function. Millions of people around the world are effected by it each year. Stroke results in disabled arm function. Restoration of arm function is essential to regaining activities of daily living (ADL).

Along with traditional rehabilitation methods, robot-aided therapy has emerged in recent years. Robot-aided rehabilitation is more intensive, of longer duration and more repetitive. Using robots, repetitive dull exercises can turn into a more challenging and motivating tasks such as games. Besides, robots can provide a quantitative measure of the rehabilitation progress.

This article overviews the terms used in robot-aided upper-limb rehabilitation. It continues by investigating the requirements for rehabilitation robots. Then the most outstanding works in robot-aided upper-limb rehabilitation and their control schemes have been investigated. The clinical outcomes of the built robots are also given that demonstrates the usability of these robots in real-life applications and their acceptance. This article summarizes a review done along with a research on the design, simulation and control of a robot for use in upper-limb rehabilitation after stroke.

Implications for Rehabilitation

  • Reviewing common terms in rehabilitation of upper limb using robots
  • Reviewing rehabilitation robots built up to date
  • Reviewing clinical outcomes of the mentioned rehabilitation robots

via A review of technological and clinical aspects of robot-aided rehabilitation of upper-extremity after stroke, Disability and Rehabilitation: Assistive Technology, Informa Healthcare.

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