Control Of Upper Limb Prostheses Research Articles

Prediction of Distal Arm Posture in 3-D Space From Shoulder Movements for Control of Upper Limb Prostheses

C5/C6 tetraplegic patients and transhumeral amputees may be able to use voluntary shoulder motion as command signals for a functional electrical stimulation (FES) system or a transhumeral prosthesis. Such prostheses require, at the most basic level, the control of endpoint position in three dimensions, hand orientation, and grasp. Spatiotemporal synergies exist between the proximal and distal arm joints for goal-oriented reaching movements as performed by able-bodied subjects. To fit these synergies, we utilized three-layer artificial neural networks. These networks could be used as a means for obtaining user intent information during reaching movements. We conducted reaching experiments in which subjects reached to and grasped a handle in a three-dimensional gantry. In our previous work, the three rotational angles at the shoulder were used to predict elbow flexion/extension angle during reaches on a two-dimensional plane. In this paper, we extend this model to include the two translational movements at the shoulder as inputs and an additional output of forearm pronation/supination. Counterintuitively, as the complexity of the task and the complexity of the neural network architecture increased, the performance also improved.

Identifying the role of proprioception in upper-limb prosthesis control

Proprioception plays a crucial role in enabling humans to move purposively and interact with their physical surroundings. Current technology in upper-limb prostheses, while beginning to incorporate some haptic feedback, does not provide amputees with proprioceptive information about the state of the limb. Thus, the wearer must visually monitor the limb, which is often inconvenient or even impossible for some tasks. This work seeks to quantify the potential benefits of incorporating proprioceptive motion feedback into upper-limb prosthesis designs. We apply a noninvasive method for controlling the availability of proprioceptive motion feedback in unimpaired individuals in a human subject study to compare the benefits of visual and proprioceptive motion feedback in targeted motion tasks. Combined results of the current study and our previous study using a different task indicate that the addition of proprioceptive motion feedback improves targeting accuracy under nonsighted conditions and, for some tasks, under sighted conditions as well. This work motivates the development of methods for providing artificial proprioceptive feedback to a prosthesis wearer.

PROSTHETIC PROTOCOL DEFINITION REALIZING AN APPLICATIVE PROFILE BASED UPON PC STANDARD

The paper will present the definition of a Prosthetic Bus, specifing an application profile based on PC standard. Aim of this definition is to realize an upper limb prosthesis control oriented bus, wich grants an efficient sensors and actuators management, with the possibility both of centralized and distributed control, trought the transmissione and reception of high level command and data. The enlarge possibility and reconfigurability of the system will be necessary aspects on following discussion.

Upper limb prosthesis control system using the relationship between motions of the both arms

Upper limb prosthesis control system using the relationship between motions of the both arms

The use of targeted muscle reinnervation for improved myoelectric prosthesis control in a bilateral shoulder disarticulation amputee

A novel method for the control of a myoelectric upper limb prosthesis was achieved in a patient with bilateral amputations at the shoulder disarticulation level. Four independently controlled nerve-muscle units were created by surgically anastomosing residual brachial plexus nerves to dissected and divided aspects of the pectoralis major and minor muscles. The musculocutaneous nerve was anastomosed to the upper pectoralis major; the median nerve was transferred to the middle pectoralis major region; the radial nerve was anastomosed to the lower pectoralis major region; and the ulnar nerve was transferred to the pectoralis minor muscle which was moved out to the lateral chest wall. After five months, three nerve-muscle units were successful (the musculocutaneous, median and radial nerves) in that a contraction could be seen, felt and a surface electromyogram (EMG) could be recorded. Sensory reinnervation also occurred on the chest in an area where the subcutaneous fat was removed. The patient was fitted with a new myoelectric prosthesis using the targeted muscle reinnervation. The patient could simultaneously control two degrees-of-freedom with the experimental prosthesis, the elbow and either the terminal device or wrist. Objective testing showed a doubling of blocks moved with a box and blocks test and a 26% increase in speed with a clothes pin moving test. Subjectively the patient clearly preferred the new prosthesis. He reported that it was easier and faster to use, and felt more natural.

A two degree-of-freedom microprocessor based extended physiological proprioception (EPP) controller for upper limb prostheses

A two degree-of-freedom microprocessor based controller that uses the principle of Extended Physiological Proprio- ception (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.

Dimensional change in muscle as a control signal for powered upper limb prostheses: a pilot study

The vast majority of externally powered prostheses are controlled from the myoelectric signal, measured at the skin surface using socket-located electrodes. This signal has been well researched and sophisticated signal processing methods developed. Nevertheless, the inherent properties of the signal, such as its broad bandwidth and low voltage amplitude, make its use less than straightforward in the control of low frequency activity such as powered prosthetic hand movement. This paper reports on a pilot study of an alternative, a signal derived from dimensional change in muscle. A new socket-located sensor was designed to measure dimensional change in muscle, the linearised output of which is termed the myokinemetric (MK) signal. This was used in a series of tasks aimed at investigating the potential for its use in upper-limb prosthesis control. Six amputee subjects were tested, of whom one was a regular user of the myoelectric hand, one had some experience, and four had little or no previous experience of controlling devices using their residual limb. Data is presented on the problems of shift in signal range with time and socket donning and doffing and on the ability of subjects to control the amplitude of the signal. The results show that subjects were able to control the magnitude of the MK signal to a significant degree, with typical errors averaging 0.1–0.3 mm, around 10% of the signal range. The principal problem encountered was the shift in signal with time and socket donning and doffing.

Control accuracy and response time in multiple-state myoelectric control of upper-limb prostheses. Initial results in nondisabled volunteers.

In myoelectrically operated prosthetic systems control performance decreases with an increasing number of possible movements. A test has been designed that allows quantification of two related qualities of performance. A predefined amount of training was given to 40 nondisabled volunteers without previous prosthetic experience. After training they attempted the test. The two parameters measured were the response time and the control accuracy corresponding to the different movements. It is concluded that even with a very limited amount of training fairly complex control systems can be operated with acceptable performance.

A microprocessor system for multifunctional control of upper limb prostheses via EMG signal identification

A microprocessor system for multifunctional control of upper limb prostheses via EMG signal identification