Mechanical Design and Basic Run Experiments with the Tri-StarIII – Horizontal Polyarticular Expandable 3-Wheeled Planetary Rover –

The exploration of planets has attracted intense research efforts in recent years. It is increasingly apparent that rovers are best suited for obtaining detailed information about a planet's surface. In this paper, we designed Tri-StarIII, a horizontal polyarticular expandable planetary rover. Inside the spacecraft, the rover is in a retracted configuration to fit in a smaller envelope. After reaching the surface of its destination planet, the rover expands to increase stability and traversability over rough terrain. Each joint angle of the arms is controlled by the driving wheels. A braking mechanism locks the joints when they are at the desired angles. The arm configuration was decided using an expandable ratio which we defined, the performance of a gripping type joint braking mechanism and a mechanism that preventing wire-twisting in the wheel steering joints are developed and experimentally confirmed. Basic expanding motion and step and slope traversal experiments have been preformed.