Control of a Spider Crane

The 'Spider Crane' is a crane structure that has been developed at the department for automatic control at 'Ecole Polytechnique Fédérale de Lausanne'. This crane structure does not have a moving mechanical structure, which enables it to move the load much faster than a conventional crane. In a previous thesis project a control algorithm for the crane behavior has been developed. This control algorithm is based on flatness conversion of the reference trajectory of the load to reference signal for the crane motors to follow. This master thesis project proposes a new control algorithm that separates the overall control of the crane behavior, from the control of the crane motors. Two different control approaches for the control of the motors are examined. One is based on tracking a ramp reference for the position of the motor. The second one, which has been implemented on the real system uses a cascade position controller for tracking the position reference and a feed forward controller to compensate for the disturbance the crane causes the motor. This control algorithm is tested on a reduced model of the real system. The experimental results suggest that with this control approach it is possible to separate the overall control of the crane from the control of the crane motors