Adaptive control for backward quadrupedal walking. IV. Hindlimb kinetics during stance and swing.
Adaptive control for backward quadrupedal walking. IV. Hindlimb kinetics during stance and swing.
复制标题
向后四足行走的自适应控制。
DOI：
10.1152/jn.1993.70.6.2226
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发表时间：
1993
影响因子：
2.5
通讯作者：
Smith,JL
中科院分区：
文献类型：
--
作者：
Perell,KL;Gregor,RJ;Buford,JA;Smith,JL
1.研究了成年猫后肢前向行走(FWD)和后退行走(BWD)的步态循环动力学。后肢被建模为一个连接的刚体系统，并使用逆动力学技术计算髋关节、膝关节和踝关节的动力学。对于摆动，每个关节的净扭矩被分为三个分量：重力扭矩、运动相关扭矩和广义肌肉扭矩。对于站姿，在爪子上的一点(压力中心)施加的地面反作用力的垂直和水平分量被添加到扭矩计算中。肌肉扭矩曲线与从后肢肌肉记录的肌电(EMG)相匹配。2.BWD摆动的扭矩曲线与FWD摆动扭矩曲线的时间反转大致相同。在每个关节，摆动过程中的净扭矩很小，因为平均运动相关扭矩和肌肉扭矩成分相互抵消。在髋部，屈肌扭矩持续存在，除了在FWD摆动后期和BWD摆动开始时有短暂的伸肌扭矩。膝关节的肌肉扭矩相对较小，除了屈肌扭矩峰值在FWD摆动后期和BWD摆动早期。在脚踝，在FWD挥杆过程中，有一个从屈肌到伸肌扭矩的挥杆中期转变，而BWD挥杆的情况正好相反。3.FWD站立时，前肢的垂直地面反作用力大于后肢，BWD站立时的垂直地面反作用力大于后肢。因此，在BWD站立时，后肢承担的体重比例(66%)大于前肢，而在FWD站立时，前肢承担的比例更大(59%)。对于大多数FWD姿势，后肢施加的推进地面反作用力很小，但对于BWD姿势，后肢首先施加制动力，然后是推进力，这一转变发生在站立中间之后(59%的站位)。4.在髋部，在FWD站立时，地面反作用力向量先朝前，然后向后朝向估计的关节中心，并进行站立中间转换。肌肉扭矩和关节功率模式显示出相似的转变，分别从伸肌和动力产生转变为屈肌和能量吸收。在大多数BWD站姿中，地面反作用力向量位于关节中心的前方，并被较大的伸肌扭矩抵消；然而，由于髋关节弯曲，能量被吸收。
1. Hindlimb step-cycle kinetics of forward (FWD) and backward (BWD) walking in adult cats were assessed. The hindlimb was modeled as a linked system of rigid bodies and inverse-dynamics techniques were used to calculate hip, knee, and ankle joint kinetics. For swing, net torque at each joint was divided into three components: gravitational, motion dependent, and a generalized muscle torque. For stance, vertical and horizontal components of the ground-reaction force applied at a point on the paw (center of pressure) were added to the torque calculations. Muscle torque profiles were matched to electromyograms (EMGs) recorded from hindlimb muscles. 2. Torque profiles for BWD swing were the approximate time reversal of those for FWD swing. At each joint, the net torque during swing was small because the mean motion-dependent and muscle torque components counteracted each other. At the hip a flexor muscle torque persisted except for a brief extensor muscle torque late in FWD swing and at the onset of BWD swing. At the knee the muscle torque was relatively negligible except for a peak flexor muscle torque late in FWD swing and early in BWD swing. At the ankle there was a midswing transition from a flexor to an extensor muscle torque during FWD swing and the reverse was true for BWD swing. 3. The vertical ground-reaction force was greater for the forelimbs than the hindlimbs during FWD stance; the reverse was true for BWD stance. Thus the hindlimbs bore a greater percentage (66%) of body weight than the forelimbs during BWD stance, and the forelimbs bore a greater percentage (59%) during FWD stance. For most of FWD stance, the hindlimb exerted a small propulsive ground-reaction force, but for BWD stance the hindlimb first exerted a braking force and then a propulsive force, with the transition occurring after midstance (59% of stance). 4. At the hip the ground-reaction force vector was oriented anteriorly and then posteriorly to the estimated joint center with a midstance transition during FWD stance. The muscle torque and joint power patterns showed similar transitions, changing from extensor and power generation to flexor and power absorption, respectively. For most of BWD stance the ground-reaction force vector was oriented anteriorly to the joint center and was counter-balanced by a large extensor muscle torque; nonetheless, power was absorbed because the hip flexed.(ABSTRACT TRUNCATED AT 400 WORDS)