Green Joshua T, Hale Rena F, Hausselle Jerome, Gonzalez Roger V
Mem. ASME Department of Metallurgical, Materials and Biomedical Engineering, College of Engineering, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968 e-mail: .
Orthopedic Biomechanics Laboratory, Mayo Clinic, 200 1st Street Southwest, Rochester, MN 55905 e-mail: .
J Biomech Eng. 2017 Dec 1;139(12). doi: 10.1115/1.4037853.
Advancements in computational musculoskeletal biomechanics are constrained by a lack of experimental measurement under real-time physiological loading conditions. This paper presents the design, configuration, capabilities, accuracy, and repeatability of The University of Texas at El Paso Joint Load Simulator (UTJLS) by testing four cadaver knee specimens with 47 real-time tests including heel and toe squat maneuvers with and without musculotendon forces. The UTJLS is a musculoskeletal simulator consisting of two robotic manipulators and eight musculotendon actuators. Sensors include eight tension load cells, two force/torque systems, nine absolute encoders, and eight incremental encoders. A custom control system determines command output for position, force, and hybrid control and collects data at 2000 Hz. Controller configuration performed forward-dynamic control for all knee degrees-of-freedom (DOFs) except knee flexion. Actuator placement and specimen potting techniques uniquely replicate muscle paths. Accuracy and repeatability standard deviations across specimen during squat simulations were equal or less than 8 N and 5 N for musculotendon actuators, 30 N and 13 N for ground reaction forces (GRFs), and 4.4 N·m and 1.9 N·m for ground reaction moments. The UTJLS is the first of its design type. Controller flexibility and physical design support axis constraints to match traditional testing rigs, absolute motion, and synchronous real-time simulation of multiplanar kinematics, GRFs, and musculotendon forces. System DOFs, range of motion, and speed support future testing of faster maneuvers, various joints, and kinetic chains of two connected joints.
计算肌肉骨骼生物力学的进展受到实时生理负荷条件下实验测量不足的限制。本文通过对四个尸体膝关节标本进行47次实时测试，包括有无肌腱力量的足跟和脚趾深蹲动作，展示了德克萨斯大学埃尔帕索分校关节负荷模拟器（UTJLS）的设计、配置、功能、准确性和可重复性。UTJLS是一种肌肉骨骼模拟器，由两个机器人操纵器和八个肌腱驱动装置组成。传感器包括八个拉力传感器、两个力/扭矩系统、九个绝对编码器和八个增量编码器。一个定制的控制系统确定位置、力和混合控制的命令输出，并以2000Hz的频率收集数据。控制器配置对除膝关节屈曲外的所有膝关节自由度（DOF）执行前向动态控制。驱动装置的放置和标本灌封技术独特地复制了肌肉路径。在深蹲模拟过程中，各标本间肌腱驱动装置的精度和可重复性标准偏差分别等于或小于8N和5N，地面反作用力（GRF）为30N和13N，地面反作用力矩为4.4N·m和1.9N·m。UTJLS是其设计类型中的首个产品。控制器的灵活性和物理设计支持轴约束，以匹配传统测试装置、绝对运动以及多平面运动学、GRF和肌腱力的同步实时模拟。系统自由度、运动范围和速度支持未来对更快动作、各种关节以及两个相连关节的动力链进行测试。
