| Two wheeled self-balancing mobile, just like an inverted pendulum, is one of the systems characterized with inherently unstable, multi-variables, nonlinear and strongly coupled. Complicated as it is, it's easy to implement not only for the simple structure, but also for its low cost. So it's been an ideal experiment platform for testing many control algorithms. And in this paper, to get the wide-range angle stabilization controller of the two wheeled mobile which is based on linear design, it begins with an improvement linearization model, and then uses two kinds of control algorithms, pole placement and LQR, to stable the mobile. By changing different poles,Q and R, it studies those factors' effect on this nonlinear system quality. With these studies it can provide targeted suggestions on wide-angel range stabilization control design of the two wheeled mobile by linear controller.Detailed contents are as follows: Firstly, based on dynamic analysis, the mobile is modeled, with motor voltage as its input. Secondly, two linearization models are got respectively. One is by Taylor series expansion approximation and the other by feedback linearization approach. A comparison is made and shows that the feedback linearization model is much closer to that of the original model in angel output. So the feedback linearization model is preferred as the one linearization controller based on. Thirdly, by analyzing the changes in angle output and control voltage, it studies different poles'effect on system quality such as transient performances, stability, and controllable angle range. Fourth, by analyzing the changes in angle and control voltage outputs with different values of Q,R, combined with sensitivity analysis, it obtains the effect on LQR system quality such as transient performance, stability, robustness and controllable angle range. Finally, the LQR system is chosen to be simulated and verified that it is robust to a certain disturbances and perturbations. |
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