Abstract
Background: Interlimb neural coupling implies that arm swing should be included during gait training to improve rehabilitation outcomes. We previously developed several systems for production of walking with arm swing, but the reaction forces on the foot sole during usage of the systems were not satisfactory and there was potential to improve control system performance. This work aimed to design and technically evaluate a novel system for producing walking with synchronised arm and leg movement and with dynamic force loading on the foot soles.Methods: The robotic system included a passive curved treadmill and a trunk frame, upon which the rigs for the upper and lower limbs were mounted. Ten actuators and servocontrollers with EtherCAT communication protocol controlled the bilateral shoulder, elbow, hip, knee and ankle joints. Impedance control algorithms were developed and ran in an industrial PC. Flexible pressure sensors recorded the plantar forces on the foot soles. The criteria of implementation and responsiveness were used to formally evaluate the technical feasibility of the system.Results: Using impedance algorithms, the system produced synchronous walking with arm swing on the curved treadmill, with mean RMS angular tracking error <2° in the 10 joint profiles. The foot trajectories relative to the hip presented similar shapes to those during normal gait, with mean RMS displacement error <1.5 cm. A force pattern that started at the heel and finished at the forefoot was observed during walking using the system, which was similar to the pattern from overground walking.Conclusion: The robotic system produced walking-like kinematics in the 10 joints and in the foot trajectories. Integrated with the curved treadmill, the system also produced walking-like force patterns on the foot soles. The system is considered feasible as far as implementation and responsiveness are concerned. Future work will focus on improvement of the mechanical system for future clinical application.
Highlights
Arm swing is an integral component of human gait, and should be included during gait training to improve rehabilitation outcomes [1]
Motivated by the theory and clinical results described above, we previously developed three rotational orthoses for walking with arm swing [11,12,13], but the reaction forces on the foot sole during walking in those systems were not satisfactory
The high tracking accuracy of the 10 joint trajectories showed that the robotic system with the low values of impedance controller parameters produced synchronous arm-leg walking
Summary
Arm swing is an integral component of human gait, and should be included during gait training to improve rehabilitation outcomes [1]. The coordinated arm-leg movement during walking is modulated by interlimb neural circuits. Apart from the theory of interlimb neural coupling [6], clinical results support integrating arm movement into gait rehabilitation. After 5 weeks of arm cycling training, chronic stroke patients demonstrated stronger interlimb neural coupling, accompanied with enhanced performance of walking and balance [7]. Compared to traditional walking training with the lower limbs only, inclusion of rhythmic arm swing brought more favourable rehabilitation effects in subacute stroke patients [9], with improved balance, sensation, and motor function. Interlimb neural coupling implies that arm swing should be included during gait training to improve rehabilitation outcomes. We previously developed several systems for production of walking with arm swing, but the reaction forces on the foot sole during usage of the systems were not satisfactory and there was potential to improve control system performance. This work aimed to design and technically evaluate a novel system for producing walking with synchronised arm and leg movement and with dynamic force loading on the foot soles
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