ABSTRACT
Objective To investigate the effect from helmet mass and deviation of mass center on neck muscle activity in military pilots. Methods Based on AnyBody software platform, a musculoskeletal model of head neck complex was established including C0, C1-C7, T1 and 136 muscles. Concentrated loads were applied to simulate the role of helmet. Strength from seven main muscle groups under different helmet mass, mass center and +Gz acceleration loads were simulated and calculated.Results When mass center of the helmet and the head coincided with each other, the muscle groups (such as semispinalis, levator scapulae, splenius capitis and cervicis) which took charge of extension were activated. Muscle strength increased with helmet mass linearly and +Gz acceleration loads would make this increase multiplied. Flexion muscle began to work when mass center of the helmet moved backward, so did the lateral bending muscles when mass center of helmet moved in the right-and-left direction. Conclusions Helmet mass and its center have an obvious influence on neck muscle activity in military pilots. The musculoskeletal model established in this paper can be used to calculate the change in muscle strength under different situations and conduct a quantitative analysis for helmet design and validation.
ABSTRACT
Objective To analyze the neck muscle activity during head flexion and explore the cause of muscle fatigue in human head and neck. Methods A musculoskeletal model of head neck complex was established based on AnyBody software platform, and the muscle strengths during head flexion were simulated according to the input data measured by Vicon motion capture system, which were validated with the literature data. Results The neck muscles played a major role during head flexion. The force assignment mode among muscles was different during 45% and 75% flexion process. The integral of muscle strengths on flexion angle WM could reflect the muscle fatigue to some extent. Since the largest WM was found in the semispinalis cervicis and multifidus muscles during head flexion, it may indicate that those muscles have the easy tendency to be fatigue. Conclusions The musculoskeletal model established in this paper can provide a technical support for the exploration of neck fatigue mechanism.
ABSTRACT
@#ObjectiveTo investigate the necessary of letting the intelligent knee joint be adaptive to the road terrain and the key technology of knee moment control method. MethodsBased on data from gait analysis and the dynamic model of lower limb,the knee moments while people walking on the path of different terrain were obtained. Terrain identification method was based on the features of electromyography(EMG) signals of the thigh,and the EMG of some muscles was detected. The methods were applied to an intelligent trans-femoral prosthesis developed for tests in the laboratory.ResultsConsiderable variation of the knee moments appeared when people walking on the path of different terrain,as well as that of the features of EMG of some muscles.ConclusionIt is necessary to make the intelligent knee joint be adaptive to the road terrain,and it is possible to be achieved with satisfied motion of the leg and the trajectory of ankle joint by the intelligent transfemoral prosthesis being studied which can identify the features of EMG signals.