Assistive Arm Research Articles

Development of a Human Symbiotic Assist Arm “PAS-Arm” (Experimental System and Creation of Virtual Guiding Surfaces)

We describe a new robotic assist device: the passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator. PASArms are physically passive. The force to manipulate the arm end must be provided by the operator. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces that constrain and guide the motion of the operator. PAS-Arms have three joints and a three dimensional workspace, but possess only two degrees of freedom due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. In this paper, we first discuss the manipulability ellipsoid for the PAS-Arm. The major axis of the ellipsoid is the direction in which the arm end may be easily manipulated, and vice versa. We have developed an experimental system for the PAS-Arm. The CVTs of the experimental system may not adjust the transmission ratio to zero. Second, we describe an algorithm to address that problem. Finally, we present initial experiments that verify the PAS-Arm mechanism. The experimental results successfully produced virtual guiding surfaces.1 1. This paper is the full translation from the transactions of JSME, Series C, Vol.76, No.763, pp. 611-618, 2010.

D.P.26 3D kinematic and EMG study of the arm function in boys with DMD: A pilot study

Duchenne muscle dystrophy (DMD) is a muscular disorder characterized by progressive muscle weakness, resulting in loss of functions. With increasing life expectancy, the preservation of functional abilities becomes increasingly important. Good assistive arm supports however are rare and do not support the full range of arm functional abilities. For designing new functional arm support a good knowledge of the pattern of arm function loss is needed. Therefore a new measurement protocol, using 3D kinematics and surface electromyography (sEMG), was developed. Five boys with DMD (12.03years, sd 2.52, range 8–15, Brooke 1–4) and 6 age matched controls participated in this pilot study. Standardized (StM) and non standardized (NStM) single joint movements and ADL activities were examined by means of 3D-Vicon motion analysis in combination with sEMG. Outcome measures were: normalized EMG amplitude, passive range of motion (pROM), active range of motion (aROM) and the absolute difference between pROM and aROM. Patients used significantly more of their maximal muscle capacity to conduct StM and NStM compared to controls, also seen in compensatory muscles. pROM was significantly lower in patients in 4 out of 10 movements. aROM of StM was significantly lower in patients in 5 out of 10 movements and aROM of NStM was significantly lower in 7 out of 10 movements. The difference between pROM and aROM was larger in patients than controls for all shoulder movements. A strong relation between age of patients and muscle capacity as well as aROM was seen. The protocol was found feasible for measuring arm function in boys with DMD. The tool was able to discriminate between patients and controls and also between different stages of the disease. Patients used relatively more muscle capacity to conduct arm movements and have a decreased pROM and aROM with increasing age.

Development of a Human Symbiotic Assist Arm “PAS-Arm” (Basic Concept and Mechanism)

We describe a new robotic assist device: a passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator, handling a shared payload. PAS-Arms are physically passive. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces, which constrain and guide the motion of the payload within a shared workspace. PAS-Arms have three joints and a three dimensional workspace, but possesses only a two degrees of freedom, due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. The combination of CVTs and differential gears places one mechanical constraint on three angular velocities of the joints. PAS-Arms have no joint actuators and no force sensors. Thus they are potentially well suited to safety and low cost. This paper proposes a basic concept of PAS-Arms and explains a principle and a construction of PAS-Arms. We discuss the relation of PAS-Arms to conventionally actuated robots and another type of assist arms. We also describe range of transmission ratio of CVTs.11. This paper is the full translation from the transactions of JSME, Series C, Vol.73, No.730, 2007.

人間共存型作業補助アームPAS-Armの開発 : 機能検証システムによる案内面生成実験(機械力学,計測,自動制御)

人間共存型作業補助アームPAS-Armの開発 : 機能検証システムによる案内面生成実験(機械力学,計測,自動制御)

Robotic Arm-assisted UKA Improves Tibial Component Alignment: A Pilot Study

The alignment of the components of unicompartmental knee arthroplasty (UKA) reportedly influences outcomes and durability. A novel robotic arm technology has been developed with the expectation that it could improve the accuracy of bone preparation in UKA. During the study period, we compared the postoperative radiographic alignment of the tibial component with the preoperatively planned position in 31 knees in 31 consecutive patients undergoing UKA using robotic arm-assisted bone preparation and in 27 consecutive patients who underwent unilateral UKA using conventional manual instrumentation to determine the error of bone preparation and variance with each technique. Radiographically, the root mean square error of the posterior tibial slope was 3.1 degrees when using manual techniques compared with 1.9 degrees when using robotic arm assistance for bone preparation. In addition, the variance using manual instruments was 2.6 times greater than the robotically guided procedures. In the coronal plane, the average error was 2.7 degrees +/- 2.1 degrees more varus of the tibial component relative to the mechanical axis of the tibia using manual instruments compared with 0.2 degrees +/- 1.8 degrees with robotic technology, and the varus/valgus root mean square error was 3.4 degrees manually compared with 1.8 degrees robotically. Further study will be necessary to determine whether a reduction in alignment errors of these magnitudes will ultimately influence implant function or survival. Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

White Paper

The aim of this White Paper was to review the current recommendations for strength training of older adults, to promote physical therapist best practice and achieve optimal functional outcomes. A secondary intent was to encourage prospective researchers to use published guidelines to establish an adequate strength stimulus for patients in their research, rather than perpetuating "usual or traditional" care.

Coordinated Control of Assistive Robotic Devices for Activities of Daily Living Tasks

Recent research in rehabilitation indicates that tasks that focus on activities of daily living (ADL) are likely to show significant increase in motor recovery after stroke. Most ADL tasks require patients to coordinate their arm and hand movements to complete these tasks. This paper presents a new control approach for robot-assisted rehabilitation of stroke patients that enables them to perform ADL by providing controlled and coordinated assistance to both arm and hand movement. The control architecture is represented in terms of a hybrid system model combining a high-level controller for decision-making and two low-level assistive controllers (arm and hand controllers) for arm and hand motion assistance. The presented controller is implemented on a test-bed and the results of this implementation are presented to demonstrate the feasibility of the proposed control architecture.

Development of a Human Symbiotic Assist Arm "PAS-Arm" (Basic Concept and Mechanism)

We describe a new robotic assist device : a passive assist arm (pas-arm). Pas-arms are intended for direct physical interaction with a human operator, handling a shared payload. Pas-arms are physically passive. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces, which constrain and guide the motion of the payload within a shared workspace. Pas-arms have three joints and a three dimensional workspace, but possesses only a two degrees of freedom, due to the reduction of degrees of freedom created by a combination of continuously variable transmissions (CVTs) and differential gears. The combination of CVTs and differential gears places one mechanical constraint on three angular velocities of the joints. Pas-arms have no joint actuators and no force sensors. Thus they are potentially well suited to safety and low cost. This paper proposes a basic concept of pas-arms and explains a principle and a construction of pas-arms. We discuss the relation of pas-arms to conventionally actuated robots and another type of assist arms. We also describe range of transmission ratio of CVTs.

Effects of Body Weight Squats on Balance and Upright Mobility in Participants with Incomplete SCI

BACKGROUND:Few exercise interventions have been designed to improve the lower body strength of individuals with incomplete spinal cord injury (SCI). Such improvements could improve balance and upright mobility. OBJECTIVE:To determine the effects of a 6-week resistance training program using body weight squats (BWS) on measures of balance and upright mobility in participants with SCI. Design and setting: A test-retest design with one within subjects' factor was utilized. Testing and training occurred in an exercise facility used by participants with SCI. Participants: Three males and one female with incomplete SCI participated in the study. Two of the males and the female were classified as ASIA functional category C and the other male was classified as functional category D. Intervention:Participants trained 3d/wk for 6 weeks using 3 sets of 10 reps of BWS. outcome Measures: The three outcome measures included a modified Timed Up and Go Test (mTUG), the Berg Balance Scale, and the Sit to Stand Test. RESULTS: All participants completed the training, attending a minimum of twice per week, without injury or complaint of pain. Each participant demonstrated marked improvement in all outcome measures. The large inter-participant heterogeneity in functional ability necessitated that the investigators compare the pre- intervention scores to the post- intervention scores for each of the participants individually. Participant 1, who was unable to take a single step in the mTUG test, was able to take several steps with the use of a walker on the post-test. His score on the Berg Balance test improved from 7 to 19 and on the Sit to Stand test he was able to rise from his chair at a much lower starting angle and with much less dependence on the use of his arms. Participant 2 improved his time on the mTUG test by 31 seconds (25% improvement). His score on the Berg Balance test improved from 11 to 14. Participant 3 improved her time on the mTUG test by 12 seconds (14% improvement). On the Berg Balance test her score improved from 12 to 21 on the posttest. On the Sit to Stand test she was able to rise out of her chair relying much less (18% improvement) on the use of her arms. Participant 4 improved his time on mTUG test by 18 seconds (20% improvement). His score on the Berg Balance test improved from 25 to 43. On the Sit to Stand test he improved from initially having to rise from the chair using his arms to rising from his chair without any arm assistance. CONCLUSION:Resistance training using BWS can improve lower body strength in individuals with incomplete SCI which in turn can improve their balance and upright mobility.

Evaluation of hand-held computers compared to pen and paper for documentation on an acute pain service

Summary Purpose: To assess the utility of personal digital assistants for documentation at the bedside on an acute pain service. Methods: This reality-based unblinded randomized trial recruited 35 patients on the personal digital assistant (PDA) arm and 39 patients on the paper arm. The primary outcome measure was assessment time and comprehensiveness between patient visits documented on paper versus the PDA. Secondary objectives were to gather qualitative information about the use of PDAs at the point-of-care. Results: The median time to complete the initial patient assessment was 2.8 min on the PDA arm and 2.7 min on the paper arm. The median total patient encounter time (assessment and recording) was 6.1 and 4.6 min on the PDA and paper arms, respectively ( Z = −2.28, P -value = 0.00). Pain scores were documented on 65% of assessments on the PDA arm and 44% of the assessments on the paper arm. Nausea, pruritis and sedation were collected on 100% of PDA assessments, compared to 13–33% of paper assessments. Conclusions: This study found that patient encounter time was longer but more information was collected on the PDA compared to paper. Non-PDA owners took significantly longer to document on the PDA compared to paper.

Arm rest for the surgical assistant.

The surgical assistant's practice of resting his forearm on the patient's chest has long been a source of contention between him and the anesthetist. It is not denied that he does want some means of support; it is indeed wearying to hold one's hand in a single position without rest for hours, particularly while holding a retractor. On the other hand, the anesthetist's objection is not without justification. The fact that the assistant's task is tiring does not warrant his transferring his burden to the patient, whose chest cannot be looked on as an inert and insensitive object. I have heard more than one patient under spinal anesthesia complain of the weight of the assistant's arm. Surely it requires a considerable effort for a patient, conscious or unconscious, to lift an assistant's forearm with each inspiration. In addition, heavy drapes, numerous instruments, and even the patient's own stomach have been