BALANCING OF AN INVERTED PENDULUM WITH A SCARA ROBOT

The balancing act of an inverted pendulum with a robotic manipulator i s a classical benchmark for testing modern control strategies in conju nction with fast sensor-guided movements. From the control design pers pective, it presents a challenging and difficult problem, as the syste m is open-loop instable and includes nonlinear effects in the actuator s, such as friction, backlash, and elasticity. In addition, the necess ity of a sensor system that can measure the inclination angles of the pendulum contributes to the complexity of the balancing problem. The p endulum is projected onto the xz and yz planes of the inertial coordin ate system, These projections are treated independently from each othe r and are controlled individually by a state-space controller in the x and y axes, respectively, The nonlinearities of the robot are compens ated by using inverse dynamics and inverse kinematics, A specially dev eloped sensor system allows the contactless measurement of the inclina tion angles of the pendulum, This system consists of a small magnet, p laced at the bottom of the pendulum, and Hall-effect sensors placed in side the end effector.