Design of Stewart Platform for Wave Compensation

Student thesis: Master thesis (including HD thesis)

  • Anders Lolk Lohmann Madsen
  • Søren Giessing Kristensen
4. term, Electro-Mechanical System Design, Master (Master Programme)
Ship mounted cranes has a limited workability on the seas due to wave exited pendulation of the hoisted load. This poses a problem as crane operations are aborted and time is lost. The motion of ships and the pendulation of the hoisted load can be counteracted by a Stewart platform due to its 6 DOF motion capacity.
The Stewart platform is a complex parallel manipulator which kinematics is difficult to design by hand. The design procedure involves selecting the type of Stewart platform, creating a design capable of generating forces and velocities in all direction, ensure the prescribed workspace can be reached, and many physical constraints on the design. To solve these problems a thorough theoretical review of kinematics and kinematic performance indices are included in this thesis. Mathematical optimization using Sequential Quadratic Programming (SQP) is used to create the best design for wave compensation. Methods of ensuring feasible actuator relations and avoidance of leg collision are developed and are incorporated into the optimization of kinematic performance indices. All methods described can equally be used for other applications than wave compensation. Two types of Stewart platforms are selected and optimized to find that the traditional type is inferior to a slightly more complex type. The more complex type is smaller and has 13.5 % better dexterity. The demands for a hydraulic actuation system are determined using optimization methods, and finally a complete simulation model of the hydraulic and mechanical system is derived.

Publication date1 Jun 2012
Number of pages82
ID: 63502225