| Lower extremity exoskeletons are wearable devices that can augment and rebuild the wearers’ motion capability. So they can be applied in rehabilitation engineering, military field and emergency situations. A distributed control system for the PRMI lower extremity exoskeleton is built in the thesis which aims at carrying load application. The implementation of hybrid control algorithm is realized in the system.A distributed 3-layer control system frame for PRMI exoskeleton has been realized in the thesis. The frame consists of a master controller, several node controllers and sensors & actuators. The nodes controllers and sensors & actuators modules are distributed in the exoskeleton to accelerate the control speed and ease the master controller’s work. This frame improves the efficiency and stability of the control system and provides a verification platform for hybrid control algorithm.For a better control, the multi-joint inverse dynamics analysis of exoskeleton is carried out in this thesis. According to the motion sensor information and Lagrange Equation, the joint torque can be calculated. Depending on two stages human gait classification, this thesis describes the exoskeleton’s stand leg by using the top-fixed 2-joint model and swing leg by using bottom-fixed 3-joint model.Finally, a hybrid control algorithm for carrying load application according to the multi-joint inverse dynamics is proposed. This hybrid control algorithm consists of a dynamic-model-based fuzzy-PD master-slave control algorithm and torque-amplify control algorithm based on the dynamic model. The foot pressure sensors are used for the switch of the two control algorithm. By the built dynamic model above, the stand leg is applied with the master-slave control algorithm and the swing leg is applied with the torque-amplify control algorithm. The feasibility of the hybrid control algorithm has been proved more stable and faster than other algorithm by experiments. |
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