Modeling of human neuromuscular system in due consideration of nonlinearities in muscle contraction process

研究脊椎动物的运动控制系统（神经肌肉系统）的建模，以了解其肌肉骨骼系统的动力学行为和/或将模型应用于医学和工程用途。本研究提出的骨骼肌运动模型是一个与跨桥循环系统配合工作的流变模型。电机模型由两个麦克斯韦和一个沃伊特元件组成，它们彼此并联连接。权重函数用于改变电机的粘弹性常数，与所产生的力成比例。对电机的等压缩短和慢拉伸/释放实验进行了数值模拟，并计算了能量释放。电机的力-速度关系呈双曲曲线，具有与肌纤维一样的节能功能。拉伸引起的力增强和缩短引起的骨骼肌的力抑制可以很好地表示为……更多的假设是力产生能力的增加/减少与电机在缓慢拉伸/释放过程中所遭受的机械脉冲的量相对应。然后，我们提出了一个肌肉收缩过程模型，该模型除了具有上述运动模型的缩短特征外，还具有肌浆网Ca^<++>释放功能。Ca^<++>释放的函数由脉冲响应的卷积积分表示。过程模型的输入是动作电位，输出是力。首先以一排单正弦脉冲（对应动作电位）作为输入进行数值模拟，计算力的时间过程。骨骼肌的典型力产生行为，抽搐和破伤风，分别根据在肌肉纤维中观察到的输入信号的频率发生。最后对人体肱二头肌进行了五种发力模式的肌电图测量。将肌电信号数据输入肌肉收缩过程模型，模拟力的时间过程。仿真结果与力生成实验结果吻合较好。结果表明，本文提出的模型对于分析和理解人体肌肉骨骼系统的动态行为是非常有用的。少

Modeling of the motion control system (neuromuscular system) of vertebrates is studied to understand the kinetic behavior of their musculoskeletal systems and/or to apply the model to medical and engineering uses. The motor model of the skeletal muscle proposed in this study is a rheological model that works in corporation with the cross-bridge cycling system. The motor model consists of two Maxwell- and one Voigt elements connected in parallel with each other. Weight functions are used to change the visco-elastic constants of the motor in proportion to the force generated. The numerical simulations of the isotonic shortening and the slow stretch/release experiments of the motor are carried out and the energy liberation is calculated. The force-velocity relation of the motor shows a hyperbolic curve and the energy saving function is possessed as in the muscle fibers. The stretch-induced force enhancement and shortening-induced force depression of skeletal muscle are well represented wi … More th an assumption that the force generation ability is increased/decreased corresponding to the amount of the mechanical impulse that the motor is suffered during the slow stretch/release. Then we propose a muscle contraction process model with the function of the Ca^<++> release from the sarcoplasmic reticulum in addition to the aforementioned shortening characteristics of the motor model. The function of the Ca^<++> release is represented by a convolutional integral of the impulse response. The input into the process model is the action potential and the output is the force. The numerical simulations are first carried out with the input of a row of single sinusoidal pulses (corresponding to action potentials) and the time course of force is calculated. The typical force generation behavior of the skeletal muscle, twitch and tetanus, take place according to the frequency of the input signal as observed in muscle fibers, respectively. Finally the measurements of the electromyogram (EMG) signals are made in the force generation experiments of human biceps brachii muscle with five kinds of force generation patterns. The EMG signal data are input into the muscle contraction process model and the time course of force is simulated. The simulation results for all of the force generation patterns coincide well with the experimental results obtained in the force generation experiments. It is confirmed that the model proposed here is quite useful for analyzing and understanding the dynamic behavior of human masculoskeletal systems. Less