Anderson F C, Pandy M G
Department of Biomedical Engineering, The University of Texas at Austin, 78712, USA.
J Biomech Eng. 2001 Oct;123(5):381-90. doi: 10.1115/1.1392310.
A three-dimensional, neuromusculoskeletal model of the body was combined with dynamic optimization theory to simulate normal walking on level ground. The body was modeled as a 23 degree-of-freedom mechanical linkage, actuated by 54 muscles. The dynamic optimization problem was to calculate the muscle excitation histories, muscle forces, and limb motions subject to minimum metabolic energy expenditure per unit distance traveled. Muscle metabolic energy was calculated by slimming five terms: the basal or resting heat, activation heat, maintenance heat, shortening heat, and the mechanical work done by all the muscles in the model. The gait cycle was assumed to be symmetric; that is, the muscle excitations for the right and left legs and the initial and terminal states in the model were assumed to be equal. Importantly, a tracking problem was not solved. Rather only a set of terminal constraints was placed on the states of the model to enforce repeatability of the gait cycle. Quantitative comparisons of the model predictions with patterns of body-segmental displacements, ground-reaction forces, and muscle activations obtained from experiment show that the simulation reproduces the salient features of normal gait. The simulation results suggest that minimum metabolic energy per unit distance traveled is a valid measure of walking performance.
人体的三维神经肌肉骨骼模型与动态优化理论相结合，以模拟在平地上的正常行走。人体被建模为一个具有23个自由度的机械连杆机构，由54块肌肉驱动。动态优化问题是计算肌肉兴奋历程、肌肉力和肢体运动，同时使单位行进距离的代谢能量消耗最小化。肌肉代谢能量通过简化五个项来计算：基础或静息热量、激活热量、维持热量、缩短热量以及模型中所有肌肉所做的机械功。步态周期被假定为对称的；也就是说，假定模型中左右腿的肌肉兴奋以及初始和终末状态是相等的。重要的是，未解决跟踪问题。相反，仅对模型状态施加了一组终端约束，以确保步态周期的可重复性。将模型预测与从实验中获得的身体节段位移、地面反作用力和肌肉激活模式进行的定量比较表明，该模拟再现了正常步态的显著特征。模拟结果表明，单位行进距离的最小代谢能量是行走性能的有效度量。
