Andrew E. Jackson

A Control Strategy for Upper Limb Robotic Rehabilitation With a Dual Robot System

This paper describes the development and use of the cooperative control scheme used by the intelligent pneumatic arm movement (iPAM) system to deliver safe, therapeutic treatment of the upper limb during voluntary reaching exercises. A set of clinical and engineering requirements for the control scheme are identified and detailed, which entail controlled, coordinated movement of a dual robot system with respect to the human upper limb. This is achieved by using a 6-DOF model of the upper limb that forms the controllers coordinate system. An admittance control scheme is developed by using this coordinate system such that robotic assistance can be varied as appropriate. Key controller components are derived, including kinematic and force transformations between the upper limb model and the dual robot task space. The controller is tested using a computational simulation and with a stroke subject in the iPAM system. The results demonstrate that the control scheme can reliably coordinate the dual robots to assist upper limb movements. A discussion considers the ramifications of using the system in practice, including the effects of measurement errors and controller limitations. In conclusion, the iPAM system has been shown to be effective at delivering variable levels of assistance to the upper limb joints during therapeutic movements in a clinically appropriate manner.

A novel robotic system for quantifying arm kinematics and kinetics: description and evaluation in therapist-assisted passive arm movements post-stroke.

We developed a system for quantitatively measuring arm movement. Our approach provides a method to simultaneously capture upper limb kinetic and kinematic data during assisted passive arm movements. Data are analysed with respect to Cartesian and upper limb coordinate systems to obtain upper limb joint angles and torques. We undertook an evaluation of the system in participants with stroke to show the feasibility of this approach. During rehabilitation after stroke, one aspect of treatment includes the physiotherapist applying assistive forces to move the impaired arm of the patient who remains passive. There is a dearth of published data on the relationship between upper limb kinematics and the underlying forces (kinetics) in this mode of physiotherapy treatment. Such quantitative data are crucial in facilitating research into therapy practice, for example by measuring variation in practice and determining dosage. An experienced therapist prescribed passive movements tailored to the needs of 16 participants with stroke (41-81 years) with a range of anthropometric sizes and motor impairments. Our novel measurement tool recorded kinematic and kinetic data at 100 Hz for 6-11 movements per participant. The kinetic data show that the majority of movements fall within upper limits of 36.7 N in shoulder elevation, 22.4N in shoulder protraction, 4.6 Nm in shoulder abduction, 12.8 Nm in shoulder flexion, 2.4 Nm in shoulder rotation and 5.5 Nm in elbow flexion. These data show the potential of this system to better understand arm movement, in particular to objectively evaluate physical therapy treatments and support development of robotic devices to facilitate upper limb rehabilitation.

Developing a user interface for the iPAM stroke rehabilitation system

The increasing population of older people is leading to growing healthcare demands. Stroke is the commonest cause of severe disability in developed countries leaving one third of patients with long term disability. Rehabilitation is the cornerstone of recovery. Lack of rehabilitation manpower resources can limit recovery of limb function. However, technology can assist rehabilitation staff to deliver greater intensity of treatment. Robotic systems such as the iPAM robot can provide semi-automated arm exercises for people with complex impairments leading to loss of functional arm movement. Feedback to the patient about their performance, usability of the exercise “workspace” and motivating exercises are key aspects of the successful deployment of robotic systems within routine clinical use. We describe the development of the patient interface for the iPAM robotic system. Central to this development is user involvement (with rehabilitation professionals and people with stroke). Using user centred design methods which included use of questionnaires and one to one discussions, the user interface was changed from a simple screen showing a stick figure of the arm to a 3D scene with simplified indicators and feedback screens, providing feedback about performance and feedback about the quality of the movement. Patients were positive about the changes to the user interface, confirming that the feedback screens were clear, useful and motivating. The user interface can further be improved by adding more feedback about the quality of the movement.

Effector force requirements to enable robotic systems to provide assisted exercise in people with upper limb impairment after stroke

iPAM (intelligent Pneumatic Arm Movement) is a dual robotic system that aims to assist in the recovery of upper-limb movement in people with all severities of motor impairment after stroke. This paper presents effector force data gathered during the course of a pilot clinical study. It identifies the forces and workspace required to facilitate reach-retrieve exercises in a range of patients as part of rehabilitation treatments. These findings have been used in further refinements of the iPAM system.

Development of the iPAM MkII system and description of a randomized control trial with acute stroke patients

iPAM (intelligent Pneumatic Arm Movement) is a dual robot system for providing assistive upper-limb exercise to people with arm weakness as a result of stroke. This paper highlights refinements made to the system in the development of iPAM MkII. The rationale of an on-going random control trial using the iPAM MkII is also presented.

Acceptability of robot assisted active arm exercise as part of rehabilitation after stroke

In this paper, a solution is proposed to render both rough and detailed images information using only audio-range sound. The procedure is implemented in consecutive stages with stage-dependent parameters selected by the user. The first stage consists of edge detection and tracking of the boundaries of the objects to obtain the sketch of the image. In the second stage, the user can selectively access the details of the image, such as brightness, texture and spatial position of the objects. Practical methods are proposed and tested which accelerate the training process. As a particular application, an educational module is presented which assists students of a special school for the blind by vocalization and description of geographical maps.

Position tracking of a passive rehabilitation robot

This paper presents a position tracking system for real-time position estimation of a passive rehabilitation robot. The table-top robot shall be used for upper limb rehabilitation by stroke patients. Accurate estimates of the robots position are determined by fusing data from two sensors: a laser optical sensor and a webcam. The laser optical sensor is mounted underneath the robot and tracks the motion of the robot relative to the surface on which the robot is used. The webcam is positioned above the robot and mounted on a stand fixed to the surface. The webcam detects the robots motion relative to a fixed absolute coordinate system and supplies data at a lower frequency than the optical sensor. A data fusion scheme is implemented and validated in experiments where markers are moving along circular and pentagram trajectories. After the fusion is completed, a Kalman filter is implemented to investigate if it can improve the accuracy of the fusion tracking system. The results demonstrate that the developed fusion position tracking system can reliably track the robots position with greater accuracy than would be possible with the webcam or the optical sensor tracking systems on their own.

Enhancing exploratory learning behaviour in people with stroke undertaking iPAM robot assisted upper limb exercises

This paper describes how semiautomated variation in active upper limb exercise is achieved by the iPAM robotic rehabilitation system.

Advances in the Inspection of Unpiggable Pipelines

The field of in-pipe robotics covers a vast and varied number of approaches to the inspection of pipelines with robots specialising in pipes ranging anywhere from 10 mm to 1200 mm in diameter. Many of these developed systems focus on overcoming in-pipe obstacles such as T-sections and elbows, as a result important aspects of exploration are treated as sub-systems, namely shape adaptability. One of the most prevalent methods of hybridised locomotion today is wall-pressing; generating traction using the encompassing pipe walls. A review of wall-pressing systems has been performed, covering the different approaches taken since their introduction. The advantages and disadvantages of these systems is discussed as well as their effectiveness in the inspection of networks with highly varying pipe diameters. When compared to unconventional in-pipe robotic techniques, traditional full-bore wall-pressing robots were found to be at a disadvantage.

Case study of patients participating in a randomised controlled trial of upper-limb robotic rehabilitation in acute stroke services

This paper presents some findings from a randomised controlled trial in patients with upper-limb weakness in acute stroke services within the UKs National Health Service. Three patients were selected from the robot arm of the trial; one who exhibited a large increase in Fugl-Meyer score (change > 30); one who exhibited a moderate change (10 <; change <; 20) and a subject who demonstrated no change between baseline and follow-up. The results from robot assistance level and target achievement over the course of the treatment are presented for the three patients, demonstrating the systems ability to automatically alter the assistance level as patients progress.