User Local Coordinate-Based Accompanying Robot for Human Natural Movement of Daily Life.

Considering the trend of aging societies, accompanying technology can help frail, elderly individuals participate in daily activities. The ideal accompanying robot should accompany the user in a proper position according to the activity scenarios and context; the prerequisite is that the accompanying robot should quickly move to a designated position and closely maintain it regardless of the direction in which the user moves. This paper proposes a user local coordinate-based strategy to satisfy this need. As a proof of concept, a novel "string-pot" approach was utilized to measure the position difference between the robot and the target. We implemented the control strategy and assessed its performance in our gait lab. The results showed that the robot can follow the user in the designated position while the user performs forward, backward, and lateral movements, turning, and walking along a curve.

Development of an Objective Portable Measurement Device for Spinal Joint Accessory Motion Testing.

Joint accessory motion testing (JAMT) is a standard procedure used by manual therapists to assess and treat musculoskeletal disorders. Joint accessory motion (JAM) is movement that occurs between joint surfaces, and can be induced by applying force. The motion amount, end feel, symptoms, and resistance perceived by therapists during test procedures are recorded as evidence for the diagnosis, prognosis, treatment decision making, and intervention outcome. However, previous studies have shown that accessory motion tests have insufficient reliability. Recently, many instruments have been developed to increase test reliability, but these instruments quantify the test results with a single probe and utilize the external environment as a reference. Therefore, the measured displacement amount may be affected by other spinal segments. This study proposes an objective portable measurement device with two indenter probes for spinal JAMT, wherein the JAM was quantified by displacement and force measurements between two bones. The instrument was verified with a homemade spinal simulator and computer simulation. The results showed that the force-displacement curves measured by the JAMT device (JAMTD) and those simulated by the computer model exhibited similar characteristics. Moreover, a two-probe measurement could distinguish the differences in stiffness better than a one-probe measurement.

Estimating the tendency of motor unit recruitment during steady-hold and rapid contractions using surface EMG and Turns-amplitude analysis.

PURPOSE: The purpose of this study was to investigate changes in the interference pattern in surface electromyography (EMG), and its relationship with the tendency of motor unit (MU) recruitment during steady-hold and rapid muscle contractions. METHODS: Fifteen healthy adults (eight females and seven males, 22.6 ± 1.5 years old) performed steady-hold and rapid isometric contractions of the bicep brachii, adductor pollicis, and tibialis anterior muscles at various force levels. Surface EMG recordings were analyzed using Turns-Amplitude Analysis (TAA). RESULTS: During steady-hold contractions, the number of turns per second (T/s) increased exponentially with force during submaximal contractions, and plateaued after force levels of 66, 70 and 57 % MVC for the tibialis anterior, bicep brachii and adductor pollicis muscles, respectively. These force levels were proximate to the maximal recruitment threshold (MaxRT) reported previously. The slopes of the T/s-force relationships before the MaxRT were significantly greater than the slopes after the MaxRT for all three muscles tested. During rapid contraction, the slopes of the T/s-force relationships were significantly lower than the slopes of the steady-hold contraction at 20-40 % MVC in all three muscles, and for 40-60 % MVC in TA muscles. CONCLUSIONS: Our results suggested that the changes in the number of turns in surface EMG with respect to muscle force can be used to estimate the force levels at which the majority of the MUs to be recruited, and completion of MU recruitment was observed at lower force levels during rapid muscle contraction.

Development of a modularized seating system to actively manage interface pressure.

Pressure ulcers can be a fatal complication. Many immobile wheelchair users face this threat. Current passive and active cushions do reduce the incidence of pressure ulcers and they have different merits. We proposed an active approach to combine their advantages which is based on the concept that the interface pressure can be changed with different supporting shapes. The purpose of this paper is to verify the proposed approach. With practical applications in mind, we have developed a modular system whose support surface is composed by height-adjustable support elements. Each four-element module was self-contained and composed of force sensors, position sensors, linear actuators, signal conditioners, driving circuits, and signal processors. The modules could be chained and assembled together easily to form different-sized support surfaces. Each support element took up a 3 cm × 3 cm supporting area. The displacement resolution was less than 0.1 mm and the force sensor error was less than 1% in the 2000 g range. Each support element of the system could provide 49 N pushing force (408 mmHg over the 3 cm × 3 cm area) at a speed of 2.36 mm/s. Several verification tests were performed to assess the whole system's feasibility. Further improvements and clinical applications were discussed. In conclusion, this modularized system is capable of actively managing interface pressure in real time.

A novel instrumented walker for individualized visual cue setting for gait training in patients with Parkinson's disease.

Patients with Parkinson's disease suffer from gait disturbances, such as a shuffling and festinating gait, which reduces their quality of life. To circumvent this problem, external visual cues may be applied in gait training to maintain the integrity of motor function. However, conventional training methods, such as transverse lines stuck on the ground, are difficult to adjust and adapt to personalized gait ability. This study proposes a convenient instrumented wheel walker that provides gap adjustable visual cues and selectable projection modes onto the ground with and without motion relative to the user. Ten subjects with Parkinson's disease were recruited, and the efficacy of the proposed device for their gait training was assessed. We demonstrated the applicability of our device to address personalized demands in gait guidance. With a personalized setting for patients with Parkinson's disease, a significantly lengthened stride length may be achieved.

Development of a Computerized Device for Evaluating Vestibular Function in Locomotion: A New Evaluation Tool of Vestibular Hypofunction.

To evaluate vestibular function in the clinic, current assessments are applied under static conditions, such as with the subject in a sitting or supine position. Considering the complexities of daily activities, the combination of dynamic activities, dynamic visual acuity (DVA) and postural control could produce an evaluation that better reflects vestibular function in daily activities. Objective: To develop a novel sensor-based system to investigate DVA, walking trajectory, head and trunk movements and the chest-pelvis rotation ratio during forward and backward overground walking in both healthy individuals and patients with vestibular hypofunction. Methods: Fifteen healthy subjects and 7 patients with bilateral vestibular hypofunction (BVH) were recruited for this study. Inertial measurement units were placed on each subject's head and torso. Each subject walked forward and backward for 5 m twice with 2 Hz head yaw. Our experiment comprised 2 stages. In stage 1, we measured forward (FW), backward (BW), and medial-lateral (MLW) walking trajectories; head and trunk movements; and the chest-pelvis rotation ratio. In stage 2, we measured standing and locomotion DVA (loDVA). Using Mann-Whitney U-test, we compared the abovementioned parameters between the 2 groups. Results: Patients exhibited an in-phase chest/pelvis reciprocal rotation ratio only in FW. The walking trajectory deviation, calculated by normalizing the summation of medial-lateral swaying with 1/2 body height (%), was significantly larger (FW mean ± standard deviation: 20.4 ± 7.1% (median (M)/interquartile range (IQR): 19.3/14.4-25.2)in healthy vs. 43.9 ± 27. 3% (M/IQR: 36.9/21.3-56.9) in patients, p = 0.020)/(BW mean ± standard deviation: 19.2 ± 11.5% (M/IQR: 13.6/10.4-25.3) in healthy vs. 29.3 ± 6.4% (M/IQR: 27.7/26.5-34.4) in patients, p = 0.026), and the walking DVA was also significantly higher (LogMAR score in the patient group [FW LogMAR: rightDVA: mean ± standard deviation:0.127 ± 0.081 (M/IQR: 0.127/0.036-0.159) in healthy vs. 0.243 ± 0.101 (M/IQR: 0.247/0.143-0.337) in patients (p = 0.013) and leftDVA: 0.136 ± 0.096 (M/IQR: 0.127/0.036-0.176) in healthy vs. 0.258 ± 0.092 (M/IQR: 0.247/0.176-0.301) in patients (p = 0.016); BW LogMAR: rightDVA: mean ± standard deviation: 0.162 ± 0.097 (M/IQR: 0.159/0.097-0.273) in healthy vs. 0.281 ± 0.130 (M/IQR: 0.273/0.176-0.418) in patients(p = 0.047) and leftDVA: 0.156 ± 0.101 (M/IQR: 0.159/0.097-0.198) in healthy vs. 0.298 ± 0.153 (M/IQR: 0.2730/0.159-0.484) in patients (p = 0.038)]. Conclusions: Our sensor-based vestibular evaluation system provided a more functionally relevant assessment for the identification of BVH patients.

Establishment of vestibular function multimodality platform.

BACKGROUND: The technology of using inertial measurement units (IMUs) to detect motions in different body segments has drawn enormous attention to research and industry. In our previous research, we have applied IMUs in evaluating and treating patients with vestibular hypofunction. Furthermore, according to the research, when a person's head rotates over 60° on either side in the horizontal plane, and desires to focus vision on any targets, then the function of gaze shift comes in to operation. Herein, we aimed to use IMUs to build up a system to evaluate vestibular ocular reflex (VOR) during gaze shifting maneuver. METHODS: In this study, we developed a platform, which combines the features of gaze shift and computerized dynamic visual acuity (cDVA), called the gaze shift DVA (gsDVA) platform. The gsDVA platform measures the orientations of the subject's head by IMU, and executed the evaluation according to the algorithm that was developed by us. Finally, we used the VICON system to validate the performance of gsDVA platform. RESULTS: The performance of the accuracy was 2.41° ± 1.08°, the maximal sensor error was within 4.25°, and highly correlated between our platform and VICON (p < 0.05, R = 0.99). The intraclass correlation coefficient (ICC) of between-day and within-day was 0.984 and 0.999, respectively. Furthermore, the platform not only executed the evaluation automatically but also recorded other information besides the head orientation, such as rotation speed, rotation time, reaction time, and visual acuity. CONCLUSION: In this study, we demonstrated the utility of vestibular evaluation, and this platform can help to clarify the relationship between gaze shift and VOR. This methodology is useful and can be applied efficiently to different disease groups for interactive evaluation and rehabilitation programs.

Finite element analysis of the lumbar spine with a new cage using a topology optimization method.

In recent years, degenerative spinal instability has been effectively treated with a cage. However, little attention is focused on the design concept of the cage. The purpose of this study was to develop a new cage and evaluate its biomechanical function using a finite element method (FEM). This study employed topology optimization to design a new cage and analyze stress distribution of the lumbar spine from L1 to L3 with a new cage by using the commercial software ANSYS 6.0. A total of three finite element models, namely the intact lumbar spine, the spine with double RF cages, and with double new cages, were established. The loading conditions were that 10Nm flexion, extension, lateral bending, and torsion, respectively, were imposed on the superior surface of the L1 vertebral body. The bottom of the L3 vertebral body was constrained completely. The FEM estimated that the new cage not only could be reduced to 36% of the volume of the present RF cage but was also similar in biomechanical performance such as range of motion, stress of adjacent disc, and lower subsidence to the RF cage. The advantage of the new cage was that the increased space allowed more bone graft to be placed and the cage saved material. The disadvantage was that stress of the new cage was greater than that of the RF cage.

An interactive wireless communication system for visually impaired people using city bus transport.

Visually impaired people have difficulty accessing information about public transportation systems. Several systems have been developed for assisting visually impaired and blind people to use the city bus. Most systems provide only one-way communication and require high-cost and complex equipment. The purpose of this study is to reduce the difficulties faced by visually impaired people when taking city buses, using an interactive wireless communication system. The system comprised a user module and a bus module to establish a direct one-to-one connection. When the user inputs 4-digit numbers, the user module immediately sends out the information. If the bus module receives the matched bus number, it buzzes and the warning LED flashes to notify the bus driver that someone is waiting to board on the bus. User tests were conducted by two visually impaired people in a simulated vehicle and a city bus. The success rate of interactive wireless communication, recognizing the arrival of the bus and boarding the correct bus reached 100% in all of the tests. The interactive wireless communication aid system is a valid and low-cost device for assisting visually impaired people to use city buses.

A 3D mathematical model to predict spinal joint and hip joint force for trans-tibial amputees with different SACH foot pylon adjustments.

A solid-ankle cushioned heel (SACH) foot is a non-joint foot without natural ankle function. Trans-tibial amputees may occur toe scuffing in the late swing phase due to a lack of active dorsiflexion. To address this problem, clinical guidelines suggests shortening the pylon to produce a smooth gait. However, this causes a leg length discrepancy, induces asymmetry in the hip joint, and causes an overload of L5/S1 joint force. Therefore, this study aimed to investigate the influence of different prosthesis pylons on the hip joint and L5/S1 joint forces. Ten subjects were recruited using leg length for normalisation. Four different pylon reductions (0%, 1%, 2%, and 3%) were used for gait analysis. A Vicon system and force plates were used to collect kinematic data and ground reaction force, respectively. The software package MATLAB was used to create a mathematical model for evaluating the symmetry and force of the hip joint and the low back force of the L5/S1 joint. The model was validated by the correlation coefficient (CC=0.947) and root mean square (RMS=0.028 BW). The model estimated that the 1% group had a symmetrical hip joint force and a lower L5/S1 joint force in the vertical direction. This study indicates that a 1% pylon shortening on a SACH prosthesis is appropriate for a trans-tibial amputee.

Ankle-foot simulator development for testing ankle-foot orthoses.

The fatigue failure of thermoplastic ankle-foot orthoses (AFOs) was observed in clinics. However, there was no standard evaluation for the AFOs to enhance the understanding of how AFOs become more readily acceptable to patients. Therefore, this study aimed to develop an ankle-foot simulator (AFS) as a testing apparatus for AFOs, and performed a pilot test to investigate the failure mechanism of anterior ankle-foot orthosis (AAFO). The accuracy and repeatability of the AFS during cyclic walking, cyclic stepping and cyclic stepping with the AAFO in sagittal plane were measured. The root mean square errors (RMSEs) of cyclic walking of AFS compared to a target gait data were less than 80.52N and 2.55 degrees in the vertical ground reaction force and in the kinematics, respectively. The RMSE of ankle plantarflexion and dorsiflexion of AFS in the cyclic stepping tests were less than 1.25 degrees. The repeatability was assessed by standard deviation, which were less than 9.46N and 0.72 degrees in all testing conditions. A typical failure progression of five AAFOs was observed and graded for four phases under cyclic stepping test. Failure always initiated at the junction of anterior tarsal bar and lateral (or medial) bar of the AAFOs, from which the rest failures were extended. It is suggested that this junction must be reinforced or prevented the stress concentration to elongate the endurance of AAFO.

Comparing the shoulder impingement kinematics between circular and pumping strokes in manual wheelchair propulsion.

PURPOSE: The study aimed to investigate the glenohumeral kinematic difference between the circular and pumping strokes in manual wheelchair users. METHOD: This is a repeated measures design with randomised testing conditions. We recruited 10 manual wheelchair users and asked them to perform both the pumping and circular strokes on a stationary roller system. We used the Zebris motion analysis system to collect the 3-dimension glenohumeral motion data. RESULTS: The pumping and the circular strokes were similar in the starting and ending positions in the sagittal plane. However, the pumping stroke started at a significantly larger abduction and internal rotation and ended with a significantly larger abduction and even larger internal rotation, it also traveled more ranges in all three planes and stayed longer in the combined positions of rotation/flexion and rotation/abduction as compared to the circular stroke. CONCLUSIONS: The circular stroke appeared more advantageous than the pumping technique in the injury prevention prospect because the latter involved more flexion, abduction and internal rotation of the shoulder, which could add more impingement stresses to the joint. Clinicians may need to prescribe proper wheelchair propulsion techniques for their clients to avoid accumulating impingement stresses in the shoulder joints.

Using an optimization approach to design an insole for lowering plantar fascia stress--a finite element study.

Plantar heel pain is a commonly encountered orthopedic problem and is most often caused by plantar fasciitis. In recent years, different shapes of insole have been used to treat plantar fasciitis. However, little research has been focused on the junction stress between the plantar fascia and the calcaneus when wearing different shapes of insole. Therefore, this study aimed to employ a finite element (FE) method to investigate the relationship between different shapes of insole and the junction stress, and accordingly design an optimal insole to lower fascia stress.A detailed 3D foot FE model was created using ANSYS 9.0 software. The FE model calculation was compared to the Pedar device measurements to validate the FE model. After the FE model validation, this study conducted parametric analysis of six different insoles and used optimization analysis to determine the optimal insole which minimized the junction stress between plantar fascia and calcaneus. This FE analysis found that the plantar fascia stress and peak pressure when using the optimal insole were lower by 14% and 38.9%, respectively, than those when using the flat insole. In addition, the stress variation in plantar fascia was associated with the different shapes of insole.