Abstract
To study amputee-prosthesis (AP) interaction, a novel reconfigurable biped robot was designed and fabricated. In homogeneous configuration, two identical artificial legs (ALs) were used to simulate the symmetrical lower limbs of a healthy person. Linear inverted pendulum model combining with ZMP stability criterion was used to generate the gait trajectories of ALs. To acquire interjoint coordination for healthy gait, rate gyroscopes were mounted on CoGs of thigh and shank of both legs. By employing principal component analysis, the measured angular velocities were processed and the motion synergy was obtained in the final. Then, one of two ALs was replaced by a bionic leg (BL), and the biped robot was changed into heterogeneous configuration to simulate the AP coupling system. To realize symmetrical stable walking, master/slave coordinated control strategy is proposed. According to information acquired by gyroscopes, BL recognized the motion intention of AL and reconstructed its kinematic variables based on interjoint coordination. By employing iterative learning control, gait tracking of BL to AL was archived. Real environment robot walking experiments validated the correctness and effectiveness of the proposed scheme.
Highlights
Lower limb prosthesis is used to compensate the locomotion function for amputees in the field of biomedical rehabilitation
The solid line represents reference knee joint angle estimated by method introduced in Section 5, while the dashed line represents the real output of Iterative learning control (ILC) controller
The results shows that P-type open/close-loop ILC control scheme is effective and can insure the bionic leg (BL) tracking gait of artificial legs (ALs) to realize stable walking of the whole system
Summary
Lower limb prosthesis is used to compensate the locomotion function for amputees in the field of biomedical rehabilitation. To solve problems mentioned above, a novel reconfigurable test-bed for prosthetic leg development is designed and fabricated by the Robotics Group at Northeastern University, China [2], which has two kinds of form called homogeneous configuration and heterogeneous configuration separately The former is mainly used to study the symmetrical locomotion as many common biped robot systems [3, 4]. The heterogeneous configuration of testbed is used to validate the master/slave dual-leg coordination strategy of the AP coupling system, motion intention recognition, and gait tracking based on iterative learning control In this architecture, the master is the sound leg of amputee, corresponds to AL in the test-bed. It perceives the motion intention of the master, and controls itself making gait tracking to realize the coordination to the master
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