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The condition of active assistance is the basic design criteria of target assistance torque profile. Based on the human-exoskeleton interaction model, the condition of active assistance was derived first. And then, some biomechanical simulation experiments based on OpenSim were carried out to demonstrate the the condition of active assistance. The condition of active assistance for exoskeleton robot is that the target assistance torque and the human joint muscle torque should be in a same direction and the assistance ratio should be greater than 0 and less than 1.

Nowadays, exoskeletons are widely used as assistive tools during gait rehabilitation, implementing strategies such as gravity compensation and metabolic cost reduction. However, these devices often require the use of motors and controllers. Our research is driven by the need for a simple, inexpensive and customizable device, a passive exotendon able to provide a desired torque profile to multiple joints. In a simulation model study, we asked whether it was possible to use diagonal tension elements, which act mathematically as basis functions, in order to reproduce the torque field generated by a healthy person during walking. This would allow us to create a wearable exotendon system made of passive elastic elements able to deliver this torque field to the lower extremity of the patient during gait rehabilitation. Our results showed that it is indeed possible to create a passive torque field from elastic elements that approximates the muscular torque demand for the walking cycle. This represents a starting point for the design of a passive exotendon capable of providing assistive torques to patients with motor deficits, thus reducing the metabolic cost of walking.

The aims of this study were to determine sequential pattern of the movement and to investigate the relationship between the muscle and interactive torques in straight punch of Wing Tsun Kung-Fu. Seven male right-handed athletes participated in the experiment. They performed the straight punch when standing in front of a wall mounted target and their upper limb kinematics was recorded using a 2D high-speed camera (300 Hz). Net joint torques was calculated by inverse dynamic approach while athletes' upper limb was modeled with a two-link planar system. Time to peak of segment angular velocities was occurred simultaneously that was in contrast with the proximal-to-distal segment sequencing which is mainly reported for the combat techniques. Moreover, in the total time of the movement, the interactive torques counteracted muscle torques for both shoulder and elbow joints.

This paper presents the development of Quadriceps muscle model by using Artificial Neural Network (ANN) and Adaptive Neuro Fuzzy Inference System (ANFIS) based on Functional Electrical Stimulation (FES). The impacts of the output torque with different stimulation parameters (frequency, pulse width and sampling time) are investigated. These parameters will be used to develop the paraplegic muscle models. Muscle models developed are validated with the clinical data to evaluate the accuracy of the output torque predicted compare to the actual paraplegic muscle torque. From the study, ANN is found to be the most accurate model compare to ANFIS with the value of mean squared error of 0.3758. Both developed models in this study can be used in a various control strategies to control FES parameters during rehabilitation proses using FES.

Interactions between lower limb segments in rugby place kick were studied through segment interaction analysis. In this study we collected motion data during maximal speed rugby kicking from skilled rugby kickers and developed a three-dimensional (3D) anatomical based biomechanical model to quantify lower limb joint kinematics and kinetics using an inverse dynamics approach. A proximal-to-distal movement sequence was observed for rugby place kick motions and knee flexion/extension was found to contribute the most to the kicking speed. Muscle torque (MT) counteracts with interaction torque (IT) for the hip joint and knee joint. The magnitude of MT is greater than IT and the rotation is driven by MT with the assistance of torque from gravity. Before ball contact, both IT and MT for the distal joint (knee) rapidly change their directions and achieved a maximal value. Further analysis of the results indicates that the counteracting relationship might have the advantage of generating maximal kicking speed and stabilizing the knee joint during ball impact.

Muscle fatigue is an exercise-induced reduction in the maximal capacity of muscle to produce force or power output. The continuous changes of brachialis pennation angles during the fatiguing isometric contraction was investigated in this study. The muscle torque, surface electromyography (SEMG) and ultrasound image of brachialis were continuously recorded during the process of isometric contraction. The mean brachialis pennation angles of four subjects increased from 19.75 ±± 2.57° of pre-fatigue to 23.10 ±± 2.85° of post-fatigue. The results demonstrated that the muscle fatigue would result in the dramatic increase of pennation angle during the submaximal sustained isometric contraction.

In this paper the method of practical verification of set up parameters of the hydraulic head and her characteristics has been described. The examination has been carried out on special stand equipped with on-line controlled hydraulic system that can generate resistance torques with different characteristics. The values of loads have been chosen to get full extensions during examination process. While each examination an angle of joint and muscle torque have been measured.

METHODS The purpose of this research was to study fatigue during electrical stimulation and to investigate potential physiological indicators of fatigue. A combined FES stimulator and EMG processor was designed and built to minimize the stimulus artifact, and software was written to control the stimulator during experiments, collect the data, and analyze results. Two parameters of the electromyographic (EMG) signal, EMG median frequency (MF) and EMG root mean square (RMS) amplitude, were measured and compared to knee torque for stimulation fatigue experiments on 20 ablebodied subjects and one spinal cord injured subject. The results for the able-bodied subjects had a wide variance which made identification of any relation between EMG parameters and torque difficult. However, in the experiments on the SCI subject, both parameters tracked muscle torque during FES. Thus, both EMG parameters may have the potential to be used as indicators of muscle fatigue during FES.

Biomechanical properties about the abduction-adduction axis of the human knee joint were studied in vivo, using a newly developed joint driving device. Abduction-adduction torque-angle relationship reflecting knee abduction-adduction laxity and stiffness was determined quasi-statically at full extension for both relaxed knee and for knees actively producing abduction-adduction moment. Knee joint stiffness, viscosity and limb inertia about the abduction-adduction axis were estimated through a dynamic experiment for both passive and actively contracting knees. It was found that human knees have significant abduction-adduction strength, which can be used to reduce abduction-adduction laxity and increase stiffness and is potentially significant in maintaining joint stability and control joint motion. The knee joint showed much higher stiffness and viscosity in abduction-adduction than in flexion-extension for the same level of background muscle torque.