Extended Physiological Proprioception Research Articles

Extended physiological proprioception is affected by transhumeral Socket-Suspended prosthesis use

The objective of this study was to define targeted reaching performance without visual information for transhumeral (TH) prosthesis users, establishing baseline information about extended physiological proprioception (EPP) in this population. Subjects completed a seated proprioceptive targeting task under simultaneous motion capture, using their prosthesis and intact limb. Eight male subjects, median age of 58 years (range 29–77 years), were selected from an ongoing screening study to participate. Five subjects had a left-side TH amputation, and three a right-side TH amputation. Median time since amputation was 9 years (range 3–54 years). Four subjects used a body-powered prosthetic hook, three a myoelectric hand, and one a myoelectric hook. The outcome measures were precision and accuracy, motion of the targeting hand, and joint angular displacement. Subjects demonstrated better precision when targeting with their intact limb compared to targeting with their prosthesis, 1.9 cm2 (0.8–3.0) v. 7.1 cm2 (1.3–12.8), respectively, p = 0.008. Subjects achieved a more direct reach path ratio when targeting with the intact limb compared to with the prosthesis, 1.2 (1.1–1.3) v. 1.3 (1.3–1.4), respectively, p = 0.039 The acceleration, deceleration, and corrective phase durations were consistent between conditions. Trunk angular displacement increased in flexion, lateral flexion, and axial rotation while shoulder flexion decreased when subjects targeted with their prosthesis compared to the intact limb. The differences in targeting precision, reach patio ratio, and joint angular displacements while completing the targeting task indicate diminished EPP. These findings establish baseline information about EPP in TH prosthesis users for comparison as novel prosthesis suspension systems become more available to be tested.

Testing Precision and Accuracy of an Upper Extremity Proprioceptive Targeting Task Assessment

ObjectiveTo develop and test an assessment measuring extended physiological proprioception (EPP). EPP is a learned skill that allows one to extend proprioception to an external tool, which is important for controlling prosthetic devices. The current study examines the ability of this assessment to measure EPP in a nonamputee population for translation into the affected population. DesignMeasuring precision and accuracy of an upper extremity (UE) proprioceptive targeting task assessment. Participants completed 2 sessions of a targeting task while seated at a table. The targeting was completed with the dominant and nondominant hand and with eyes open and eyes closed during the task. Participants completed 2 sessions of the clinical test with a 1-week washout period to simulate reasonable time between clinical visits. SettingResearch laboratory. ParticipantsTwenty right-handed participants (N=20) with no neurologic or orthopedic deficits that would interfere with proprioception, median age of 25 years (range, 19-33 years), completed the assessment (10 men, 10 women). InterventionsNot applicable. Main Outcome MeasuresPrecision (consistency in targeting) and accuracy (distance between the intended target and participant result) in UE targeting task using EPP; test-retest repeatability between sessions. ResultsBoth precision and accuracy were significantly decreased in the eyes-closed condition compared with the eyes-open condition regardless of targeting with dominant or nondominant hand (all P<.001). In the eyes-open condition, there was a dominance effect relating to the accuracy; however, in the eyes-closed condition, accuracy between dominant and nondominant hands was statistically equivalent. Based on minimum detectable change with 95% confidence, there was no change in either metric between the first and second sessions. ConclusionsThe results of this study support the feasibility of using this assessment to measure EPP—based on the definition of EPP as a learned skill that indicates control over an external, simple tool—because they demonstrate reliance on proprioception in the eyes-closed condition, symmetry in proprioceptive accuracy between hands for within-participant control, and test-retest reliability for longitudinal measurements. The results also establish normative values for this assessment in young, healthy adults. Further research is required in a clinical population to evaluate the UE proprioceptive targeting task assessment further and collect objective data on EPP.

A biomechatronics-based EPP topology for upper-limb prosthesis control: Modeling & benchtop prototype

This article reintroduces the concept of Extended Physiological Proprioception (EPP) for below the elbow amputations, eliminating the use of a harness, cineplasty, or Bowden cables, and proposing instead a contemporary scheme inspired by teleoperation theory and its applications. A biomechatronics-based master/slave topology is developed to provide EPP-equivalent control using implanted micro servo actuators directly attached to amputee’s residual muscles and wirelessly communicating with the prosthesis. A Position-Force (P-F) control architecture guarantees the dynamic coupling of the actuating muscles with the prosthetic limb, enabling amputee kinesthetic sense. Simulations and Hardware in the Loop (HIL) preliminary experiments with an able-bodied individual are conducted and provide an evaluation of the proposed teleoperation scheme in terms of control transparency and time delay with promising results. An initial feasibility analysis on implants size and power demands based on specific performance criteria, is encouraging, while the materialization potential of the topology is assessed.

A “Biomechatronic EPP” Upper-Limb Prosthesis Control Configuration and its Performance Comparison to Other Control Configurations

Upper-limb prosthetic technology has significantly changed in recent years. The devices available and those under development, have progressed the state of the art considerably. However, most are based on velocity control and fail to activate the proprioception of the amputee, as they do not provide their user with adequate feedback. A novel control configuration called “Biomechatronic EPP” has been developed to overcome these shortcomings, which is based on the concept of the Extended Physiological Proprioception (EPP), an upper-limb prosthesis proven to be functionally superior to velocity control configurations. The performance of the “Biomechatronic EPP” is compared to that of three other control toplogies including: a “Classic EPP” controller, an “Unconnected” controller and an “EMG” controller. Fourteen able-bodied subjects engaged in a 1-D Fitts’ Law style task, designed with the Psychophysics Toolbox, a free set of MATLAB. Performance was evaluated using several measures. Overall, the experimental results show that the performance of “Biomechatronic EPP” is comparable to “Classic EPP” and superior to “Unconnected” and “EMG”. The proposed Biomechatronic EPP control configuration is an alternative to various invasive and non-invasive sensory feedback control integration methods for prosthesis control.

Feasibility of a biomechatronic EPP Upper Limb Prosthesis Controller.

In this paper, we examine the feasibility of an implantable topology of a Biomechatronic Extended Physiological Proprioception (EPP) Upper Limb Prosthesis Controller. Initial findings support the hypothesis that the topology is safe and feasible. This novel controller topology can maintain the advantages of EPP, but without its inherent disadvantages i.e. of the existence of unaesthetic cables, or mechanical linkages.

Dexterous motion recognition for myoelectric control of multifunctional transradial prostheses

Attributed to its superior dexterity, the human’s thumb plays a significant role in the activities of daily living (ADLs). In order to promote the operational capability of the prosthetic hand, state-of-the-art designs tend to integrate multiple degrees of freedom (DOFs) in thumb’s trapeziometacarpal (TM) joint for achieving versatile movements. However, without proper control methods, this fine dexterity of multi-DOF prosthetic hand is hard to be demonstrated. This problem becomes more serious when the control signals, electromyography (EMG), are highly limited on the residual stump of the amputee. Through experiments, the paper examines the feasibility of recognizing 4 thumb motions (flexion/extension and abduction/adduction) together with the other 12 finger- and wrist-related motions under a general surface EMG configuration. After surveying the classification accuracy of several selective motion groups (thumb motions, thumb-involved finger motions, thumb-involved wrist motions, etc.), we report here the current limitations of the prevalent pattern recognition-based EMG control schemes. Considering the severely impaired neuromuscular systems of the amputees, controlling those thumb motions for achieving dexterous operations still faces many challenges. We finally discuss several alternative strategies, including switching, extended physiological proprioception (EPP) and postural synergy, for dealing with this problem.

EMG and EPP-Integrated Human–Machine Interface Between the Paralyzed and Rehabilitation Exoskeleton

Although a lower extremity exoskeleton shows great prospect in the rehabilitation of the lower limb, it has not yet been widely applied to the clinical rehabilitation of the paralyzed. This is partly caused by insufficient information interactions between the paralyzed and existing exoskeleton that cannot meet the requirements of harmonious control. In this research, a bidirectional human-machine interface including a neurofuzzy controller and an extended physiological proprioception (EPP) feedback system is developed by imitating the biological closed-loop control system of human body. The neurofuzzy controller is built to decode human motion in advance by the fusion of the fuzzy electromyographic signals reflecting human motion intention and the precise proprioception providing joint angular feedback information. It transmits control information from human to exoskeleton, while the EPP feedback system based on haptic stimuli transmits motion information of the exoskeleton back to the human. Joint angle and torque information are transmitted in the form of air pressure to the human body. The real-time bidirectional human-machine interface can help a patient with lower limb paralysis to control the exoskeleton with his/her healthy side and simultaneously perceive motion on the paralyzed side by EPP. The interface rebuilds a closed-loop motion control system for paralyzed patients and realizes harmonious control of the human-machine system.

The effects of static friction and backlash on extended physiological proprioception control of a powered prosthesis

In general, externally powered prostheses do not provide proprioceptive feedback and thus require the user to rely on cognitively expensive visual feedback to effectively control the prosthesis. Applying the concept of extended physiological proprioception (EPP) to externally powered prostheses provides direct feedback to the user's proprioceptive system regarding the position, velocity, and forces applied to the prosthesis. However, electric elbows with EPP controllers developed at the Northwestern University Prosthetics Research Laboratory have exhibited unexplained "jerky" behavior in both clinical fittings and bench-top operation. In addition, the development of limit cycles, a specific type of constant-amplitude oscillation, had been observed in bench-top use of these elbows. Backlash and static friction within the EPP system were found to be primarily responsible for the development of limit cycles. Reducing static friction and backlash improved the system's performance. These results suggest that to most effectively implement EPP, prosthesis manufacturers should design prosthetic components that minimize static friction and backlash.

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.

Control of functional electrical stimulation with extended physiological proprioception

The use of functional electrical stimulation (FES) of muscle for paraplegic locomotion, or grasp augmentation in tetraplegia, is limited by the variability in muscle response to stimulation as a result of several external and internal factors. Previous approaches to this problem have used position-servo controllers, which have been shown to function satisfactorily in the laboratory. However, such systems will fail should obstacles be encountered or should the stimulation hardware develop a fault. To prevent such potentially dangerous failures some form of sensory feedback is required. This paper describes the first application of a technique known as extended physiological proprioception (EPP) to the control of FES to compensate for muscle response variability and provide proprioceptive feedback via the appropriate sensory pathways. In the experimental system described, a paraplegic subject controlled the extension of his paralysed knee by shoulder protraction. A Bowden cable linked the two joints, and a dynamometer in this cable was used to derive the control signal for a computer-controlled stimulator which delivered surface stimulation to the quadriceps muscle group. Modelling and parameter identification were performed by analysis of the step response, and the controller was designed from consideration of the root locus. The advantages of the system, in terms of improved proprioceptive feedback and reduced limb-positioning error were assessed in a test of joint positioning accuracy with vision occluded. The EPP system showed improvements over both open and closed-loop position-servo controllers.