National Yunlin University of Science & Technology

Department  of  Mechanical  Engineering 

EM330陳明辰

Rocker-type W-shaped Track Robot

China university of Mining and TechnologyMechanical and Electrical Engineering

LI Yun-wang, GE Shi-rong, ZHU Hua, FANG Hai-feng

Keywords

• rocker-type track robot• suspension configurations• W-shaped track suspension• obstacles-surmounting

• good passive adaptability to rough unstructured terrain environments

• strong obstacles-surmounting capabilities• applied to the planet surface exploration rovers

successfully

• This type of mobile system is suitable for the natural undulating terrain, but it is difficult to overcome the artificial structured terrain, such as steps, successive stairs and ditches.

• If the barrier was blocked between two landing legs of the rocker suspension, the robot could not move.

• The ditches width which the robot could cross was restricted by the diameter of the wheels.

• The performance of stair-climbing was not well.

• Mechanism R0 was the schematic diagram of a typical rocker-type suspension which was used in the mobile platform

• The mechanisms R1 and R2 not only retained the good adaptability of mechanism R0 to adapt to the uneven terrain, but also avoided the situation that the landing legs in mechanism R0 would be blocked by obstacles, and improved the obstacles-surmounting capabilities, such as steps-climbing and ditches-crossing. Especially the mechanism R2 could be variable to conquer multiform obstacles, if the angle could be changed, but it required more power and complex structure.

• The mechanisms R3 and R4 would be the fixed W type tracks, if the angle was a constant.Each W-shaped track suspension only required one DC motor to drive the tracks and could be implemented easily. The mechanisms R3 and R4 had good performance of the regular landform

climbing. The mechanism R3 and R4 composed of two independent triangle tracks. And the transmission device was set to ensure the two tracks running synchronously. The rear main track ofthe mechanism R4 was longer than the front one, which was useful to climb up the steps.

• The rocker type W-shaped track robot mobile platform was shown in Fig. 4. The platform was comprised of two R4 W-shaped track suspensions, a differential mechanism and a main body

Rough terrain-crossing• When the robot driving on the rough terrain,

the W-shaped track suspensions on both sides of the main body swung to adapt to the terrain and the differential mechanism kept the main body at an average angle between the two track suspensions.

Step-climbing • The step-climbing process of the robot mobile

platform was shown in Fig. 6. This process included two stages: the front tracks climbing over the nosing of the step and the rear tracks climbing over the nosing .

Successive stairs-climbing.• Compared with the step-climbing process, the

main difference was that the front and rear tracks maybe climbed two nosings simultaneously. The robot could climb up the stairs, the riser height of which was 150mm and the going of which was 280mm

Step-climbing down• If the ditch was deep enough, the robot’s travel mechanism wouldn’t contact with the bottom

of the ditch , during the ditch-crossing. The process of ditch-crossing is shown in Fig. 11. The maximum theoretical width of the ditch was l determined by the geometric dimension of the robot’s suspension.

Summary

• The capabilities analysis and prototype test results indicated that the rocker-type W-shaped track mobile platform had excellent passive adaptability to unstructured terrain environments and strong obstacles-surmounting capabilities.