In modern industrial engineering such as space robots, assembly systems and transportation vehicles, a Gear Bearing Drive (GBD) transmission, with the potential to produce up to 5000:1 torque ratio in a compact size, can be of great interest.However, in a practical actuation system consisting of actuator, GBD and workload, ever-present nonlinearities such as disturbances and perturbations can increase the complexity of the modeling process as well as difficulty of the control design.To reduce such complexities, a simplified model of the actuation plant is developed by linearizing all nonlinearities and numerically estimating the disturbances and perturbations inside the plant. For this, a robust-adaptive control platform, especially designed to deal with system uncertainties and unmodeled dynamics, is selected, analyzed and implemented in real-time. In addition, due to the initially unknown parameters, the adaptive part of the controller must adapt to the system parameters variations and changes. Finally, to guarantee asymptotic convergence, a projection operator is developed and combined with the adaptation law. Furthermore, an optimal combination of proportional-integral-derivative (PID) and robust-adaptive sliding mode control (RASMC) is selected and a novel controller is developed and experimentally implemented and verified.The experimental results of system response are compared to the simulation results to assess control performance and response characteristics. This research suggests that RASMC can ensure its effectiveness in a nonlinear plant with uncertain parameters and unmodeled dynamics and produce a satisfactory experimental performance with minimum settling time and overshoot. Future work is required to explain unpredictable piecewise behavior of the open-loop speed response and other ignored modeling aspects and nonlinearities.iii is taken into consideration.To solve the effect of unknown perturbations, SMC combined with perturbation estimation (SMCPE), which handles with the structured parameter without upper bound knowledge of the disturbance [6,7], is developed to enhance the tracking performance.
Previous Work on GBD
Previous Work by Elias BrassitosElias Brassitos was a Ph.D. student working in the Piezoactive System Laboratory until 2016. He invented GBD transmission in the earlier 2016. By using the prototype of Epicyclic Gearing System (EGS) combined with the level principle in the designing process, GBD transmission could produce high torque ratio in the practical operation within a compact size. The efficiency improves with higher torques output and reaches a maximum of 83% [2, pp. 102].In the practical system, because of the pervasive nonlinearities existing in the system such as gear tooth friction, stiffness, kinematic error and nonlinear damping, precise model of the actuation plant is difficult to generate. In the modeling process made by Brassitos, kinematic error and stiffness have been considered and the simplified model of the GBD transmission was given out.
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