Pid and lqr control of a planar head stabilization platform

Akgül, Emre
During the uniform locomotion of legged robots with compliant legs, the body of the robot exhibits quasi-periodic oscillations that have a disturbing e ect on di erent onboard sensors. Of particular interest is the camera sensor which su ers from image degradation in the form of motion-blur as a result of this camera motion. The e ect of angular disturbances on the camera are pronounced due to the perspective projection property of the camera. The thesis focuses on the particular problem of legged robots exhibiting angular body motions and attempts to analyze and overcome the resulting disturbances on a camera carrying platform (head). Although the full problem is in 3D with three independent axes of rotation, a planar analysis provides signi cant insight into the problem and is the approach taken in the thesis. A carefully modeled planar version of an actual camera platform with realistic mechanical and actuator selections is presented. Passive ( ltering) and active (controller) approaches are discussed to compensate/cancel motion generated disturbances. We consider and comparatively evaluate PID and LQR based active control. Since PID has the limitation of controlling only one output, PID-PID control is considered to iv control two states of the model. Due to its state-space formulation and the capability of controlling an arbitrary number of states, LQR is considered. In addition to standard reference signals, Gyroscope measured disturbance signals are collected from the actual robot platform to analyze the bandwidth and test the performance of the controllers. Inverted pendulum control performance is evaluated both on a Matlab-Simulink as well as a precise electro-mechanical test setup. Since construction of the planar head test setup is in progress, tests are conducted on simulation.