Search

The results from experiments with a screen‐printed piezoelectric sensor, mounted on an artificial finger‐tip and including a cosmetic covering, are shown to detect surface information from regular texture patterns. For the automatic control of an artificial hand and to feedback information to the amputee, an algorithm has been developed based on the standard deviation (SD) of signal data from the sensor. The SD analysis for texture detection is novel as it uses a combination of arithmetic processes. It windows the data sequentially and calculates the SD of the data in the windows and then averages the SDs. The output from the algorithm is the frequency spectrum of a signal. Plots, from the output of the algorithm, show events that correspond to the cyclic waveforms produced from the regularity of object surface patterns. The results from the algorithm are confirmed with an analysis of the signals using fast Fourier transforms. [ABSTRACT FROM AUTHOR]

The Southampton Hand Assessment Procedure (SHAP) was devised to assess quantitatively the functional range of injured and healthy adult hands. It was designed to be a practical tool for use in a busy clinical setting; thus, it was made simple to use and easy to interpret. This paper describes four examples of its use: before and after a surgical procedure, to observe the impact of an injury, use with prostheses, and during recovery following a fracture. The cases show that the SHAP is capable of monitoring progress and recovery, identifying functional abilities in prosthetic hands and comparing the capabilities of different groups of injuries. [ABSTRACT FROM AUTHOR]

Abstract: The surgeon Ambroise Paré designed an anthropomorphic hand for wounded soldiers in the 16th century. Since that time, there have been advances in technology through the use of computer-aided design, modern materials, electronic controllers and sensors to realise artificial hands which have good functionality and reliability. Data from touch, object slip, finger position and temperature sensors, mounted in the fingers and on the palm, can be used in feedback loops to automatically hold objects. A study of the natural neuromuscular systems reveals a complexity which can only in part be realised today with technology. Highlights of the parallels and differences between natural and artificial hands are discussed with reference to the Southampton Hand. The anatomical structure of parts of the natural systems can be made artificially such as the antagonist muscles using tendons. Theses solutions look promising as they are based on the natural form but in practice lack the desired physical specification. However, concepts of the lower spinal loops can be mimicked in principle. Some future devices will require greater skills from the surgeon to create the interface between the natural system and an artificial device. Such developments may offer a more natural control with ease of use for the limb deficient person. [Copyright &y& Elsevier]

This work represents an ongoing investigation of dexterous and natural control of upper extremity prostheses using the myoelectric signal. The scheme described within uses pattern recognition to process four channels of myoelectric signal, with the task of discriminating six classes of limb movement. The method does not require segmentation of the myoelectric signal data, allowing a continuous stream of class decisions to be delivered to a prosthetic device. Due to the fact that the classifier learns the muscle activation patterns for each desired class for each individual, a natural control actuation results. The continuous decision stream allows complex sequences of manipulation involving multiple joints to be performed without interruption. The continuous classifier is optimized with respect to the feature set and classifier used, and post-processing of the decisions to eliminate spurious errors. [ABSTRACT FROM AUTHOR]

This study implemented consumer-level, Internet-based video conferencing for remote configuration of the Otto Bock C-Leg prosthesis. After connecting the C-Leg to a computer, running the SLIDERS control software, and making an IP connection over NetMeeting, a prosthetist at the host site configured a client's C-Leg at the remote site. This protocol was repeated at various connect speeds. Successful C-Leg configurations were completed at all laboratory bandwidths; however, the 33 Kbps rate made the configuration process more difficult. Tests over the public Internet provided unacceptable results at 28~Kbps. Slow data transmission rates limited the "application shared" SLIDERS program from refreshing at a sufficient rate to keep up with the leg dynamics. Similar tests between Canada and China produced successful application sharing results over a broadband connection. [ABSTRACT FROM AUTHOR]

A myokinemetric transducer has been developed whose output changes with the change in cross-sectional area of the finger flexor muscles associated with the collective movement of the anatomical fingers, about their metacarpo-phalangeal joints. This transducer, in association with a specially developed control program, can synchronise the grasp angle of a prosthetic hand with the anatomical hand during several grasping cycles. Experimental results from this study imply that the accuracy of replication of the anatomical grasp angle by the prosthetic prehensor is sufficient to consider using a similar method for proportional control of artificial prehension. [ABSTRACT FROM AUTHOR]

Editorial. Introduces a series of articles on the improvement in technology regarding the control of prosthetic arms including the use of electromyography signals from the muscles in a residual limb.

Many prostheses are not being used because of the discrepancy between the expectations of patients with an arm defect and the reality. A patient wants and expects a prosthesis that looks naturally beautiful, that is comfortable to wear and that is easy to use. None of the existing prostheses fulfills all these demands. Based on patient preference and considerations from control theory, a program for the development of voluntary closing hand prostheses is proposed. Advantages are intuitive operation, accurately controllable pinch force, and inherently good quality feedback of force and motion. Several steps have been undertaken already. Scientific and patent literature has been collected, psychophysical measurements are commenced to establish optimal force perception, rolling-link mechanisms have been studied and developed, and statically balanced spring mechanisms have been investigated and implemented. Furthermore, a preliminary prototype has been manufactured. The design is based on optimal force transmission, and features adaptive fingers, rolling joints, glove compensation, and a special operating pattern. It is intended to develop this prototype into a clinical version and conduct an evaluation study. [ABSTRACT FROM AUTHOR]

This paper presents an innovative multi-function myoelectric hand prosthesis, where the key technology is a new hardware paradigm called evolvable hardware (EHW). An EHW chip, which is capable of adapting its own circuit structure to changes in specifications, is used as the action decision circuit of the mechanical hand to classify myoelectric patterns, because myoelectric signals vary both among individuals and over time for the same individual. Beside, because the EHW chip executes myoelectric pattern classification with a simple logic circuit, it is suitable for applications where size is an important consideration, such hand prosthesis. [ABSTRACT FROM AUTHOR]

A two degree-of-freedom microprocessor based controller that uses the principle of Extended Physiological Proprioception (EPP), was designed for the simultaneous multifunctional control of upper-limb prostheses. In an EPP system, the output is related to the input by a mechanically ``unbeatable'' position servomechanism. Use of embedded microprocessor systems in the control of upper-limb prostheses provides a high degree of control algorithm flexibility allowing different control algorithms to be downloaded and executed in the same controller circuit. In addition, control parameters can be easily adjusted and tailored to different user capabilities. In a trans-humeral or shoulder disarticulation prosthesis we envision this controller enabling EPP control of both elbow flexion-extension, and humeral rotation. In a wrist disarticulation or trans-radial prosthesis this controller, in conjunction with other similar controllers, could provide EPP control of individual digits in a multifunctional hand prosthesis. [ABSTRACT FROM AUTHOR]

The recent emergence of microprocessor based prosthetic control for the individual with upper limb deficiency has significantly expanded the spectrum of treatment options and inclusion criteria for this patient population. Microprocessors can accept a wide variety of input devices and ranges enhancing an individual's prosthetic function allowing control options for individuals who were at one time not candidates for such prosthetic management. Additionally, myoelectric control parameters can be adjusted. This paper will provide an overview of input and output devices to acquaint the rehabilitation professional with microprocessor augmentation of current upper limb control modalities. It represents the second paper in a series investigating commercially available microprocessor technology in the field of prosthetics. [ABSTRACT FROM AUTHOR]

A model of the upper extremity is developed in which the forearm is constrained to lie in a horizontal plane and electrical stimulation is applied to the triceps muscle. Identification procedures are described to estimate the unknown parameters using tests that can be performed in a short period of time. Examples of identified parameters obtained experimentally are presented for both stroke patients and unimpaired subjects. A discussion concerning the identification's repeatability, together with results confirming the accuracy of the overall representation, is given. The model has been used during clinical trials in which electrical stimulation is applied to the triceps muscle of a number of stroke patients for the purpose of improving both their performance at reaching tasks and their level of voluntary control over their impaired arm. Its purpose in this context is threefold: Firstly, changes occurring in the levels of stiffness and spasticity in each subject's arm can be monitored by comparing frictional components of models identified at different times during treatment. Secondly, the model is used to calculate the moments applied during tracking tasks that are due to a patient's voluntary effort, and it therefore constitutes a useful tool with which to analyze their performance. Thirdly, the model is used to derive the advanced controllers that govern the level of stimulation applied to subjects over the course of the treatment. Details are provided to show how the model is applied in each case, and sample results are shown. [ABSTRACT FROM AUTHOR]