Hybrid parallel compliant actuation for lower limb rehabilitation

瘫痪是指骨骼肌的一块或多块肌肉失去功能。与瘫痪的原因相对应，各种治疗方法都是可能的。一方面，康复训练可以通过自动化运动疗法来实现，另一方面，运动功能缺失的补偿可以由电动执行器来代替。在本研究项目中，将对一类新的外骨骼和主动矫形器的驱动器及其控制进行基础性研究，这种驱动器特别适用于残存功能的患者(偏瘫患者、中风幸存者)。对截瘫患者的适宜性将在该项目的后期阶段进行检查。作为其核心部件，本项目致力于设计一种新型的用于下肢运动支撑的变平行弹性驱动器(VPEA)。为了能够完全控制进入平行弹簧的能量流动，执行器配备了一个制动器和一个离合器。这种方法旨在最大限度地减少必要的执行器功率消耗，并使具有残余运动功能的患者在治疗期间更密集地参与运动。在设计执行器的同时，还需要研究一个非线性动力学模型，该模型除了包含混合机电模型外，还包括整个系统的生理和动态子模型。执行器复杂性的增加要求进行多目标控制设计。除了级联力和阻抗控制器(按需辅助原则)外，还必须控制流入平行弹性元件的能量。此外，控制综合必须针对具有多个驱动关节的过驱动系统进行设计。此外，控制器必须确保与佩戴者可能的残余肌肉功能相关的交互稳定性。为了能够达到这些目标，研究了一种级联控制结构，该结构可能结合了切换系统的鲁棒控制、迭代学习控制或模型预测控制，目的是创建一个可用于两组患者的经过验证的康复系统。在将致动器集成到现有的外骨骼结构和运动测试后，还结合VPEA检查了商业FES系统。为此，将开发一种协同生理控制器，它使用患者的肌肉和VPEA一起进行运动。这一工作包的总体目标是将外骨骼的适用性扩展到截瘫患者组。执行器，包括单个关节的底层控制系统，陆续投入运行和测试。最后，整个外骨骼支持系统在北京大学中国运动实验室的跑步机研究中得到了验证，患者来自一家合作的中国医院。

Paralysis is a functional loss of a single or multiple muscles of the skeletal musculature. Corresponding to the cause of the paralysis various therapy approaches are possible. On the one hand, a rehabilitative training can be realised with automated motion therapy and, on the other hand, the compensation of missing motor function can be substituted by powered actuators. In this research project, a new class of actuators and control of exoskeletons and active orthosis are to be fundamentally researched, which are especially suitable for patients with residual function (hemiplegics, stroke survivors). The suitability for paraplegic patients is to be examined in a later phase of the project. As a core component, the project focuses on the design of novel variable-parallel-elastic actuators (VPEA) for the movement support of the lower limbs. In order to be able to fully control the energy flow into the parallel spring, the actuator is equipped with a brake and a clutch. This approach is intended to minimise the necessary actuator power consumption and to involve the patient with a residual movement function more intensively in the motion during therapy due. In parallel to the design of the actuator, a nonlinear dynamical model is to be researched, which also contains physiological and dynamic submodels of the overall system, in addition to the hybrid electromechanical model. The increased complexity of the actuator demands for a multiobjective control design. In addition to cascaded force and impedance controllers (assist as needed principle), the energy flow into the parallel elastic element has to be controlled. Moreover, the control synthesis has to be designed with respect to an overactuated system with multiple actuated joints. Furthermore, the controller has to guarantee interaction stability with respect to possible residual muscle function of its wearer. To be able to achieve these objectives, a cascaded control structure with possible combinations of robust control for switched systems, iterative learning control or model-predictive control are investigated.The goal is to create a proven rehabilitation system that can be used for both patient groups. After integration of the actuator into an existing exoskeleton structure and motion tests, a commercial FES system is also examined in combination with VPEA. For this purpose, a synergistic physiological controller is to be developed which uses the patient muscles and VPEA together for the movement. The overall goal of this work package is the extension of the exoskeleton applicability to the group of paraplegic patients.The actuators, including the underlying control system for the individual joints, are successively put into operation and tested. Finally the whole exoskeletal support system is validated in a treadmill study in a Chinese motion lab of the Tsinghua University of Peking with cross-parlayed patients recruited from a cooperating Chinese hospital.