Impedance-based control of the MIT-Skywalker (original) (raw)
Related papers
MIT-Skywalker: A Novel Gait Neurorehabilitation Robot for Stroke and Cerebral Palsy
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2016
The MIT-Skywalker is a novel robotic device developed for the rehabilitation or habilitation of gait and balance after a neurological injury. It represents an embodiment of the concept exhibited by passive walkers for rehabilitation training. Its novelty extends beyond the passive walker quintessence to the unparalleled versatility among lower extremity devices. For example, it affords the potential to implement a novel training approach built upon our working model of movement primitives based on submovements, oscillations, and mechanical impedances. This translates into three distinct training modes: discrete, rhythmic, and balance. The system offers freedom of motion that forces self-directed movement for each of the three modes. This paper will present the technical details of the robotic system as well as a feasibility study done with one adult with stroke and two adults with cerebral palsy. Results of the one-month feasibility study demonstrated that the device is safe and suggested the potential advantages of the three modular training modes that can be added or subtracted to tailor therapy to a particular patient's need. Each participant demonstrated improvement in common clinical and kinematic measurements that must be confirmed in larger randomized control clinical trials.
Impedance Control of a Robotic Walking Aid
IFAC Proceedings Volumes, 1996
The paper presents a robotic walking aid device called walker, which incorporates external power source and impedance based learning control scheme which enhances walking capabilities of the disabled, complements his remaining abilities and compensates for partial degradation of function of persons suffering from locomotor deficiency. The control concept is based on the so called direct interactive (symbiotic) man machine system. In this paper we present the control scheme of the robotic walker and some experimental results of a similar man machine system consisting of a man riding a training bicycle whose pedals are also actuated by a motor scheme.
Novel method to form adaptive internal impedance profiles in walkers
This paper proposes a novel approach to improve walking in prosthetics, orthotics and robotics without closed loop controllers. The approach requires impedance profiles to be formed in a walker and uses state feedback to update the profiles in real-time via a simple policy. This approach is open loop and inherently copes with the challenge of uncertain environment. In application it could be used either online for a walker to adjust its impedance profiles in realtime to compensate for environmental changes, or offline to learn suitable profiles for specific environments. So far we have conducted simulations and experiments to investigate the transient and steady state gaits obtained using two simple update policies to form damping profiles in a passive dynamic walker known as the rimless wheel (RW). The damping profiles are formed in the motor that moves the RW vertically along a rail, analogous to a knee joint, and the two update equations were designed to a) control the angular velocity profile and b) minimise peak collision forces. Simulation results show that the velocity update equation works within limits and can cope with varying ground conditions. Experiment results show the angular velocity average reaching the target as well as the peak force update equation reducing peak collision forces in realtime.
On the potential field-based control of the MIT-Skywalker
Robotics and Automation (ICRA), 2011
Walking impairments are a common sequela of neurological injury, severely affecting the quality of life of both adults and children. Gait therapy is the traditional approach to ameliorate the problem by re-training the nervous system and there have been some attempts to mechanize such approach. We have recently presented the MIT-Skywalker; a novel device to deliver gait therapy, which, in contrast to previous approaches, takes advantage of the concept of passive walkers and the natural dynamics of the lower extremity in order to deliver more "ecological" therapy. In this paper we present a control scheme for the MIT-Skywalker, which is based on an artificial potential field applied at the foot workspace. It is used to improve sensory feedback to the patient, as well as to increase to normal the range of motion of the paretic leg. Simulation results prove the efficiency of the proposed controller.
Adaptive Impedance Control of a Robotic Orthosis for Gait Rehabilitation
IEEE transactions on cybernetics, 2013
Intervention of robotic devices in the field of physical gait therapy can help in providing repetitive, systematic, and economically viable training sessions. Interactive or assist-as-needed (AAN) gait training encourages patient voluntary participation in the robotic gait training process which may aid in rapid motor function recovery. In this paper, a lightweight robotic gait training orthosis with two actuated and four passive degrees of freedom (DOFs) is proposed. The actuated DOFs were powered by pneumatic muscle actuators. An AAN gait training paradigm based on adaptive impedance control was developed to provide interactive robotic gait training. The proposed adaptive impedance control scheme adapts the robotic assistance according to the disability level and voluntary participation of human subjects. The robotic orthosis was operated in two gait training modes, namely, inactive mode and active mode, to evaluate the performance of the proposed control scheme. The adaptive impedance control scheme was evaluated on ten neurologically intact subjects. The experimental results demonstrate that an increase in voluntary participation of human subjects resulted in a decrease of the robotic assistance and vice versa. Further clinical evaluations with neurologically impaired subjects are required to establish the therapeutic efficacy of the adaptive-impedance-control-based AAN gait training strategy.
Medical engineering & physics, 2014
A large number of gait rehabilitation robots, together with a variety of control strategies, have been developed and evaluated during the last decade. Initially, control strategies applied to rehabilitation robots were adapted from those applied to traditional industrial robots. However, these strategies cannot optimise effectiveness of gait rehabilitation. As a result, researchers have been investigating control strategies tailored for the needs of rehabilitation. Among these control strategies, assisted-as-needed (AAN) control is one of the most popular research topics in this field. AAN training strategies have gained the theoretical and practical evidence based backup from motor learning principles and clinical studies. Various approaches to AAN training have been proposed and investigated by research groups all around the world. This article presents a review on control algorithms of gait rehabilitation robots to summarise related knowledge and investigate potential trends of development.
Impedance Control for Legged Robots: An Insight Into the Concepts Involved
IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews), 2012
The application of impedance control strategies to modern legged locomotion is analyzed, paying special attention to the concepts behind its implementation which is not straightforward. In order to implement a functional impedance controller for a walking mechanism, the concepts of contact, impact, friction, and impedance have to be merged together. A literature review and a comprehensive analysis are presented compiling all these concepts along with a discussion on position-based versus forcebased impedance control approaches, and a theoretical model of a robotic leg in contact with its environment is introduced. A theoretical control scheme for the legs of a general legged robot is also introduced, and some simulations results are presented.
Robust Impedance Control for Rehabilitation Robot
2015
Original Research Paper Received 31 May 2015 Accepted 19 June 2015 Available Online 13 July 2015 In this study, novel robust impedance control for lower-limb rehabilitation robotic system using voltage control strategy is used. Most existing control approaches are based on control torque strategy, which requires knowledge of robot dynamics as well as dynamics of patients. This obliges the controller to overcome complex problems such as uncertainty and nonlinearity involved in the dynamics of the system, robot and patients. Conversely, the voltage-based control approaches are free from the system dynamics. In addition, it considers the actuator dynamics. The performance of voltage-based approaches is demonstrated by experimental result in robotic applications. Compared with torque control scheme, it is simpler, less computational and more efficient. Nevertheless, uncertainty of actuator dynamics results in challenges for the voltage control strategy applications. The present paper pr...
Improved Design of a Gait Rehabilitation Robot
New Trends in Medical and Service Robots
Gait therapy is important to a person's recovery following spinal cord or brain injury, stroke, lower extremity surgery, as well as with many chronic conditions (e.g., Parkinson's disease or multiple sclerosis). Although some affordable equipment for adult gait rehabilitation exists, such equipment for adaptive gait rehabilitation across the spectrum of pediatric sizes is not commercially available. This paper presents design improvements for a new pediatric gait rehabilitation machine intended to address this technology gap. The design is in the style of elliptical machines but is synthesized to emulate the normal kinematic demands of walking. It includes a 7-bar linkage for each foot, a chain/sprocket coupling for left/right synchronization, and motorized speed control.
Bioinspired Legged Robot Design via Blended Physical and Virtual Impedance Control
Journal of Intelligent & Robotic Systems
In order to approach the performance of biological locomotion in legged robots, better integration between body design and control is required. In that respect, understanding the mechanics and control of human locomotion will help us build legged robots with comparable efficient performance. From another perspective, developing bioinspired robots can also improve our understanding of human locomotion. In this work, we create a bioinspired robot with a blended physical and virtual impedance control to configure the robot’s mechatronic setup. We consider human neural control and musculoskeletal system a blueprint for a hopping robot. The hybrid electric-pneumatic actuator (EPA) presents an artificial copy of this biological system to implement the blended control. By defining efficacy as a metric that encompasses both performance and efficiency, we demonstrate that incorporating a simple force-based control besides constant pressure pneumatic artificial muscles (PAM) alone can increas...