Ankle Rehabilitation Robot Research Articles

The Statics Analysis and Verification of 3-DOF Parallel Mechanism Based on Two Methods

Statics of the 3-RSS/S parallel ankle-rehabilitation robot is analyzed in this paper using two methods, i.e. the component vector method and the principle of virtual work. Static equilibrium equations based on component vector theory were established on a moving platform, and cranks of 3-RSS/S parallel Ankle-rehabilitation Robot, using this method, to obtain mathematical relationships between the external torque of moving platform and the output torque of three cranks. The velocity Jacobian matrix of the robot is calculated firstly using the principle of virtual work method, then the force Jacobian matrix is obtained based on the relationship between velocity Jacobian matrix and force Jacobian matrix. The results of the two methods are verified and found to be consistent by calculation, and the force Jacobian matrix of the robot is the basis of the force feedback control for the Ankle-rehabilitation Robot.

Design of a spherical parallel kinematic machine for ankle rehabilitation

Existing ankle rehabilitation robots have the limitations of insufficient motion ranges and coupled translations. An improved spherical robot has been proposed to overcome these limitations. The forward and inverse kinematic problems of this new machine are formulated and solved; the dexterity of the workspace is evaluated and the workspace has been optimized with the consideration of the motion ranges of passive joints. The operation of machine has been simulated; it will be further expanded as a control program to run the rehabilitation robot.

Design and Analysis of a Mechanism of Ankle Rehabilitation Robot

This paper puts forward a new type of wearable parallel mechanism on the basis of the analysis of the human ankle motion mechanism, damage analysis and methods of rehabilitation. The mechanism can realize three DOFs rotation of ankle. And the axes of the three rotations intersect at a point. Did the position and velocity analysis using the screw theory of mechanism analysis. The singularity and dexterity of this mechanism are also analyzed. According to the simulation result, this parallel mechanism has no singular configuration or uncertainty configuration in human lower limb workspace, has good maneuverability.

Effectiveness of robot-assisted therapy on ankle rehabilitation--a systematic review.

ObjectiveThe aim of this study was to provide a systematic review of studies that investigated the effectiveness of robot-assisted therapy on ankle motor and function recovery from musculoskeletal or neurologic ankle injuries.MethodsThirteen electronic databases of articles published from January, 1980 to June, 2012 were searched using keywords ‘ankle*’, ‘robot*’, ‘rehabilitat*’ or ‘treat*’ and a free search in Google Scholar based on effects of ankle rehabilitation robots was also conducted. References listed in relevant publications were further screened. Eventually, twenty-nine articles were selected for review and they focused on effects of robot-assisted ankle rehabilitation.ResultsTwenty-nine studies met the inclusion criteria and a total of 164 patients and 24 healthy subjects participated in these trials. Ankle performance and gait function were the main outcome measures used to assess the therapeutic effects of robot-assisted ankle rehabilitation. The protocols and therapy treatments were varied, which made comparison among different studies difficult or impossible. Few comparative trials were conducted among different devices or control strategies. Moreover, the majority of study designs met levels of evidence that were no higher than American Academy for Cerebral Palsy (CP) and Developmental Medicine (AACPDM) level IV. Only one study used a Randomized Control Trial (RCT) approach with the evidence level being II.ConclusionAll the selected studies showed improvements in terms of ankle performance or gait function after a period of robot-assisted ankle rehabilitation training. The most effective robot-assisted intervention cannot be determined due to the lack of universal evaluation criteria for various devices and control strategies. Future research into the effects of robot-assisted ankle rehabilitation should be carried out based on universal evaluation criteria, which could determine the most effective method of intervention. It is also essential to conduct trials to analyse the differences among different devices or control strategies.

Online Estimation Algorithm for a Biaxial Ankle Kinematic Model With Configuration Dependent Joint Axes

The kinematics of the human ankle is commonly modeled as a biaxial hinge joint model. However, significant variations in axis orientations have been found between different individuals and also between different foot configurations. For ankle rehabilitation robots, information regarding the ankle kinematic parameters can be used to estimate the ankle and subtalar joint displacements. This can in turn be used as auxiliary variables in adaptive control schemes to allow modification of the robot stiffness and damping parameters to reduce the forces applied at stiffer foot configurations. Due to the large variations observed in the ankle kinematic parameters, an online identification algorithm is required to provide estimates of the model parameters. An online parameter estimation routine based on the recursive least-squares (RLS) algorithm was therefore developed in this research. An extension of the conventional biaxial ankle kinematic model, which allows variation in axis orientations with different foot configurations had also been developed and utilized in the estimation algorithm. Simulation results showed that use of the extended model in the online algorithm is effective in capturing the foot orientation of a biaxial ankle model with variable joint axis orientations. Experimental results had also shown that a modified RLS algorithm that penalizes a deviation of model parameters from their nominal values can be used to obtain more realistic parameter estimates while maintaining a level of estimation accuracy comparable to that of the conventional RLS routine.

An iterative fuzzy controller for pneumatic muscle driven rehabilitation robot

Pneumatic muscle actuators (PMA) show great potential in wearable and compliant rehabilitation devices as they are flexible and lightweight. However, the varying and non-linear behavior of the actuators imposes modeling and control challenges, which are difficult to comprehend. This research proposes a new wearable ankle rehabilitation robot, first of its kind in the world driven by PMAs in a parallel form. The focus of this presented work is to develop an iterative controller to overcome the challenges for PMA driven devices. A fuzzy feedforward controller is proposed to accurately predict the behavior of PMA. A modified Genetic Algorithm (GA) is developed to identify the optimal set of parameters for the fuzzy controller. The iterative controller has been tested on the proposed PMA driven ankle rehabilitation robot, and is found capable of mapping the complex relationship in length, force and pressure of the PMA with high accuracy. Experimental results show excellent trajectory tracking performance of the controller when given various desired trajectories.

Design and control of a parallel robot for ankle rehabilitation

The use of robots in rehabilitation, particularly for physical therapy has the potential to bring about various benefits including reduction of physical workload of physiotherapists and improved repeatability. A three degree of freedom parallel robot is proposed in this paper to accommodate range of motion (ROM) and muscle strengthening exercises for ankle rehabilitation. Singularity analysis of the design revealed that a redundantly actuated robot is required to avoid singularity in the workspace. Kinematic parameters of the robot were selected so that the available workspace could closely match the available ankle ROM. An impedance control scheme has been utilised to allow control of both force and motion to ensure safety of the patient. The redundant actuation degree of freedom is exploited to regulate the vertical reaction force at the ankle.

Kinematic design optimization of a parallel ankle rehabilitation robot using modified genetic algorithm

Rehabilitation robotics is an evolving area of active research and recently novel mechanisms have been proposed to reinstate complex human movements. Parallel robots are of particular interest to researchers since they are rigid and can provide enough load capacity for human joint movements. This paper proposes a soft parallel robot (SPR) for ankle joint rehabilitation. Kinematic workspace analysis is carried out and the singularity criterion of the SPR’s Jacobian matrix is used to define the feasible workspace. A global conditioning number (GCN) is defined using the Jacobian matrix as a performance index for the evaluation of the robot design. An optimization problem is formulated to minimize the GCN using modified genetic algorithm (GA). Results from simple GA and modified GA are compared and discussed. As a result of the optimization, an optimal robot design is obtained which has a near unity GCN with almost uniform distribution in the entire feasible workspace of the robot.

Robot-Aided Neurorehabilitation: A Novel Robot for Ankle Rehabilitation

In this paper, we present the design and characterization of a novel ankle robot developed at the Massachusetts institute of technology (MIT). This robotic module is being tested with stroke patients at Baltimore Veterans administration medical center. The purpose of the on-going study is to train stroke survivors to overcome common foot drop and balance problems in order to improve their ambulatory performance. Its design follows the same guidelines of our upper extremity designs, i.e., it is a low friction, backdriveable device with intrinsically low mechanical impedance. Here, we report on the design and mechanical characteristics of the robot. We also present data to demonstrate the potential of this device as an efficient clinical measurement tool to estimate intrinsic ankle properties. Given the importance of the ankle during locomotion, an accurate estimate of ankle stiffness would be a valuable asset for locomotor rehabilitation. Our initial ankle stiffness estimates compare favorably with previously published work, indicating that our method may serve as an accurate clinical measurement tool.

Development of a Robot for Ankle Rehabilitation of Stroke Patients

This paper presents a unified framework for the design and development of a passive biped robot and of its digital twin. A serial procedure is followed starting from the system's physical description, continuing to the dynamic analysis of independent models, and concluding with an experimental validation. The biped's mechanical model is tailored to preserve passive walker key functionalities without sacrificing design simplicity. The mechanical model gives rise to a mathematical model that describes the biped's gait, and to a multibody dynamics model of the biped. A passive biped robot prototype is developed based on the model. The prototype is equipped with a wireless sensor measuring system to enable data acquisition. The highlight of this work is the high degree of coincidence achieved between the passive response of the numerically simulated mathematical model, the response obtained by a multibody dynamics simulation, and the experimentally obtained response of the physical passive walking robot. This finding verifies the simulation methods used and encourages the use of a carefully designed digital twin in the design iterations involved in the development of walking robots.

Reconfigurable ankle rehabilitation robot for various exercises

AbstractThis paper presents a reconfigurable ankle rehabilitation robot to cover various rehabilitation exercise modes. The designed robot can allow desired ankle and foot motions, including toe and heel raising as well as traditional ankle rotations, since the mechanism can generate relative rotation between the fore and rear platforms as well as pitch and roll motions. In addition, the robotic device can be reconfigured from a range of motion (ROM)/strengthening exercise device to a balance/proprioception exercise device by simply incorporating an additional plate. Further, the action of the device is twofold in the sense that while a patient's foot is fastened firmly to the ROM/strengthening device for task specific training, that person can also stand on the balance/proproception device. To perform each mode of ROM, strengthening, and proproception exercises, a unified position‐based impedance control is systematically developed taking into account the desired position and velocity. © 2005 Wiley Periodicals, Inc.