Underwater Robot

Amphibious Wall Climbing Robot for NDT Inspection

A three wheeled triangular robot was developed to investigate sliding suction cups adhering to the wall with vacuum created hydraulically. The sliding suction cups are constructed with a canvas material and a nylon rim to give low sliding friction but a high adhesion force. Suction in the cups is created by using underwater pumps.

The design uses 3 standard DC motors for motion control of the climbing robot, these are sealed in watertight containers that are air pressurised for safety. There are no shaft encoders or position/velocity sensors mounted on the motors; also they are controlled by PWM Servo drives and placed out of the cell. The robot mass in air is 5 kg and it can carry an additional payload of 3 kg in water. Power and control signals are transmitted to the robot via a lightweight umbilical cable.

Equal distributions of weight to the wheel axels ensure that each wheel must overcome the same amount of minimal friction as the others. Another advantage of a triangular base is the structural rigidity gained from the geometry of a triangle; the triangles vertices are fixed, maintaining three 60 degree angles, and therefore creates a rigid structure. Using omni-wheels in the corners of an equilateral triangular where these are able to roll smoothly in any direction, the robot is free to move with three degrees of freedom.

Country & Year

England - 2007

Authors

Hernando Leon-Rodriguez
Tariq Sattar