Practical Velocity Tracking Control of a Parallel Robot Based on Fuzzy Adaptive Algorithm

Abstract

Due to the advantages of its compact structure and high operation accuracy, the six degrees of freedom (6-DOF) parallel platform has been widely used as a carrier of medical rehabilitation devices. Fuzzy adaptive algorithm does not depend on the mathematical model of controlled object, which possesses good nonlinear characteristics. Those entire features make it an effective method to control such complex and coupling platforms. To facilitate the application of robotics in lower limb rehabilitation fields, a robotic system in practical environment was established based on kinematics modeling of the 6-DOF Stewart-based platform. In order to improve the velocity tracking accuracy, this paper proposed a closed-loop control strategy based on fuzzy adaptive algorithm. The velocity feedback information was utilized to modify the PID parameters adaptively in realtime through fuzzy inference units. Several experiments in practical environment were conducted, and the results demonstrated that the proposed algorithm could effectively reduce the speed jitter, enhance the position and velocity tracking precision of the robot, and the reliability and robustness of the system could also be ensured.

Factors Influencing Usability of Rehabilitation Robotic Devices for Lower Limbs

“…Among the advanced countries, the percentage of physiotherapists for every 100 people in South Korea is 0.54, lower than 0.62 of the US and 0.89 of Europe [6]; this is also a critical impediment for providing equitable healthcare services by service providers. In addition, conventional manual therapy is significantly affected by the experience of therapists, which makes it difficult to fulfil the requirements of high-intensity and repetitive training [7]; therefore, effective treatment cannot be guaranteed [8]. Utilizing robots in rehabilitation medicine is expected not only to release physicians from the heavy burden of training sessions but also to help patients precisely, quantitatively, and scientifically perform training exercises [9].…”

“…Because of the practical needs of society and the healthcare industry, rehabilitation robotics has become an attractive research field that has drawn considerable attention in the last decade [7]; however, research progress in this field remains slow. In the past decade, most studies have focused on demonstrating the therapeutic effectiveness, efficiency, or advantages of robot-assisted therapy rather than conventional labor-intensive training procedures; therefore, research in this field should focus on overcoming these challenges to make robotics more user-friendly [1] and create better interaction between robots and their diverse users [18].…”

Optimal design and control of a Stewart-Gough Platform

“…Cause of parallel robot can be defined as a closed-loop chain mechanism, it has nonlinear behavior and complex control [11][12][13][14][15][16][17]. To make the payload platform moving, we need to synchronize moving of all actuators.…”

“…Therefore, the study of optimization of design and control is important to minimize their noted drawbacks. Examples of design optimization in [3][4][5], determination singularity of parallel manipulators in [6][7][8][9] and tracking motion control for parallel manipulators papers in [11][12][13][14][15][16][17]. But these above articles did not consider optimal design and control problems as the overall system of the parallel mechanism.…”

An EMG-based force prediction and control approach for robot-assisted lower limb rehabilitation

“…The Stewart platform shown in Fig. 5 was designed by the authors' research group for the purpose of investigating lower limb rehabilitation [14]. The radius of the upper platform is 180 mm, and the angle is 28°, likewise, the parameters of the fixed platform are 270 mm and 22°, respectively.…”