Control of a ball and beam like mechanism

Underactuated mechanisms have attracted a lot of attention because they represent a rich class of control systems from a control standpoint and because they offer robot price reduction due to robot link mass reduction and lower number of robot actuators. Our ball and beam like mechanism is an example of underactuated mechanism. The ball and beam system does not possess a nontriangular structure which allows standard integrator backstepping or forwarding methods therefore approximations of nonlinear control were up to date proposed for the control of such systems. In contrast to Hauser (1992) we proposed a cascaded computed torque controller which is in fact another approximate nonlinear controller. A desirable feature of the cascaded computed torque controller is strong resemblance with standard computed torque method in the case of design and implementation effort. In the case of cascaded computed torque controller the angle of the beam could be constrained. Simulation results for the cascaded computed torque controller were compared with the simulation results obtained for the control approach of Hauser. Experimental results for the cascaded computed torque controller are presented.