Robert C. Richardson

Control of ionic polymer metal composites

Robotic devices are traditionally actuated by hydraulic systems or electric motors. However, with the desire to make robotic systems more compact and versatile, new actuator technologies are required. In this paper, the control of ionic polymer metal composite actuators is investigated from a practical perspective. The actuator characteristics are examined through the unblocked maximum displacement and blocked force output. An open-loop position control and closed-loop position proportional-integral-derivative (PID) control are then applied to a strip of actuators. Finally, the performance of the polymer is investigated when implementing an impedance controller (force/position control).

Dual robot system for upper limb rehabilitation after stroke: The design process

Abstract Stroke is the most common cause of severe disability in the UK. Arm impairment is common and recovery is partly dependent on the intensity and frequency of rehabilitation intervention. However, physical therapy resources are often limited, so methods of supplementing traditional physiotherapy are essential. Robot assisted physiotherapy is one way to increase the duration patients spend participating in rehabilitation activities. A single robot system has been developed at the University of Leeds that actively assists patients undertaking therapeutic movements in a three-dimensional workspace. However, using only a single point of contact at the wrist to assist with therapeutic reaching movements does not allow control or support of the more proximal joints of the upper limb. This could lead to discomfort during assisted exercise. In addition, the design suffers from a restrictive workspace, limiting the range of therapeutic exercise that can be undertaken. To address these limitations, the intelligent Pneumatic Arm Movement system has been developed. A major aspect of the development process has been the continual involvement of physiotherapists and stroke patients; the end users of the system. Through inclusion of these stakeholders, a system has been developed that satisfies their requirements for workspace, comfort, safety, and ease of use.

User involvement in developing Rehabilitation Robotic devices: An essential requirement

Treatment from a trained therapist is an important aspect of stroke rehabilitation, but resource limits mean that not all stroke patients receive the treatment that they require. The iPAM (Intelligent Pneumatic Arm Movement) is a robotic system that aims to provide more time-efficient rehabilitation therapy. To make sure this really addresses the needs of therapists and patients, the iPAM development has involved significant input from both parties throughout its development. However, despite the generally accepted importance of user involvement in the development of rehabilitation robotics, there is still a lack of published literature in this area, and most of the reported cases only seek user opinion once a device has been developed. This paper reviews existing literature on user involvement, and discusses the approach adopted in the iPAM project. Feedback from the user tests is presented, along with a discussion of its implications for future development of the system, and the importance of involving users in all stages of the development process.

Humanoid Upper Torso Complexity for Displaying Gestures

Body language is an important part of human-to-human communication; therefore body language in humanoid robots is very important for successful communication and social interaction with humans. The number of degrees of freedom (d.o.f) necessary to achieve realistic body language in robots has been investigated. Using animation, three robots were simulated performing body language gestures; the complex model was given 25 d.o.f, the simplified model 18 d.o.f and the basic model 10 d.o.f. A subjective survey was created online using these animations, to obtain peoples opinions on the realism of the gestures and to see if they could recognise the emotions portrayed. It was concluded that the basic system was the least realistic, complex system the most realistic, and the simplified system was only slightly less realistic than the human. Modular robotic joints were then fabricated so that the gestures could be implemented experimentally. The experimental results demonstrate that through simplification of the ...

A Cooperative Control Scheme for Robotic Rehabilitation of Arm Impairment after Stroke

Recovery of arm movement after stroke partly relates to quantity of functionally relevant practice. Physical therapies involve careful guidance of the paretic arm through therapeutic exercise to allow relearning of joint co-ordinations needed for functional arm movement. A robotic device that helps deliver more rehabilitation treatment would accelerate recovery of arm weakness. This paper describes the development of a cooperative controller for a robotic system (iPAM) that is being developed which provides intelligent, interactive, safe movement treatment to help recovery of arm weakness after stroke

A Novel USAR Digging Mechanism

The uncertain and dynamic terrain within an urban search and rescue (USAR) scenario presents an enormous challenge to the mobility of any robotic platform. To maximise the chance of success the design must be performed with consideration of the likely target environment. Current knowledge on building collapse debris fields suggest that robots must be able to move through and underneath debris utilizing void spaces. Due to the likely chance of void spaces being partially blocked, an USAR robot should have manipulation capability, a very under-explored area of USAR robotics. The moving of debris can be likened to the digging action of some animals such as the European mole. The current work proposes a novel digging mechanism that is simulated using MSC visualNastran 4D and controlled using Matlab Simulink and shown to have distinct efficiency benefits

ORTHO-BOT : A Modular Reconfigurable Space Robot Concept

A new set of challenging tasks are envisaged for future robotic planetary space missions. In contrast to conventional exploration rovers, industrial robotic roles are required for object manipulation and transportation in e.g. habitat construction. This prompts research into more robust failsafe robot designs, having greater mission redundancy for cost-effectiveness, with adjustable structures for multi-tasking. A Modular Reconfigurable design is investigated to meet these requirements using linear actuation over revolute since this alternative approach to modular robotics can form truss type structures providing inherently stable structures appropriate to the given task type. For ease of reconfiguration a connectivity solution is sought that may be simple enough to allow self-reconfiguration thus enabling extremely remote autonomous operation. In effort to meet this challenge the ORTHO-BOT developmental concept is introduced in this paper. Based on the core module developed thus far, a walking design has been successfully demonstrated in simulation to fulfil the key requirement of locomotion. Though the focus for this research is aimed at space-based roles conceptual solutions developed should also find useful application in terrestrial remote or hazardous environments.

Object Shape Characterisation using a Haptic Probe

One of the fundamental challenges in robotics is object detection in unstructured environments where objects’ properties are not known a priori. In these environments sensing is susceptible to error. Conventional sensors, for example sonar sensors, video cameras and infrared sensors, have limitations that make them inadequate for successful completion of outdoor tasks where vision is partially or totally impaired. For instance, in harsh atmospheric conditions, the poor image quality that video cameras suffer and the low spatial resolution sonar sensors exhibit make them unsuitable for object detection. Therefore, we propose an alternative approach for object characterisation in unstructured environments using active touch. A simulated anthropomorphic haptic probe system with 3 DOF and a force sensor was used in this approach. The system measures and analyses forces at contact points, and data useful for object characterisation were realised. Two shapes, a sphere and a cuboid, were modelled and used in the object detection simulation and satisfactory results were obtained.

Self-sensing miniature electromagnetic actuators for a cardiac assist device application

This paper describes the application of self-sensing control to a cardiac assist device. We propose to improve the pumping performance of diseased or weakened hearts by applying direct cardiac compression using artificial muscle. This particular application imposes strict limitations on size, weight and system complexity, therefore employing self-sensing could offer advantages over separate sensors and actuators. Many electromagnetic actuators produce a back-e.m.f. proportional to velocity. Using a simple system model, it is possible to separate this back-e.m.f. from the supply voltage, thus the actuator velocity can be self-sensed. Furthermore, using a more detailed model, it also is possible to self-sense the force being applied. Experimental results are presented for linear moving-coil actuators and miniature d.c. motors. Estimation of position has been performed by numerical integration of self-sensed velocity, and shown to compare favourably to data from displacement sensors. Force estimation has also been shown to closely agree with data from a load cell. Combined force and position control has been implemented, without using sensors. Unfortunately, since self-sensed position is derived by integrating velocity, the estimated position can suffer from drifting. An automatic re-calibration scheme is proposed for the cardiac assist application.