During the time when interest in robotics was continuosly growing in our campus, and there was established the first ever robotics club, we and two other friends of mine, decided to come up with a prototype of a wall climbing robot. Having read about solar cells before, I was aware of how wall climbing robots can help a lot in cleaning the surface of solar cells, which are installed at such heights or places that are not easily reachable for humans. Thus, we were naturally interested in wall clmbers.
Our natural world has numerous expert climbers that use a variety of mechanisms; for example the use of negatve pressure in suckers, or the use of millions of fine hair in geckos, the use of wet adhesion in tree frogs, etc. We studied a few bio-mimitc designs and found a few to be highly inspiring, for example the gecko inspired robot from MIT and the static-electric wall climbing robot from SRI.
Having read about many existing designs, we decided to go along with the "flipping style" of robot, following the motion of hydra. We had the aims of keeping the hardware simple, of achieving the basic functionality of linear motion and turning movement, and of keeping the financial requirements as low as possible. The flipping style robot requires a suction mechanism for holding on to the wall, for which we planned to use cylinders fitted with a piston connected to a DC motor. Two otehr DC motors, would be used in synchronous fashion to bring about the locomotion.
Steps of Locomotion : The locomotion can be explained in four steps, with respect to the gievn diagram of the robot. Let X and Y represent the motors responsible for the piston movement and R and S be the motors responsible for the movement of the arm.
Rotating Mechanism : The design of the setup used for roating was inspired by Leonardo Da Vinci's design of a turning platform using cage gears and ball bearings. The main features of the arrangement can be explained in the following manner.
Problems faced : We faced a steep task when we reached the stage of manufacturing the prototype. Finding the correct off-the-shelf motors were a challenge in itself. Even after buying the motors, and setting up the motor driver circuitry, we still needed gears. To make matters worse these gears needed to be custom made using a Computer Numerical Control (CNC) machine to suit our purposes and to fit our dimensions. Inspite of all our efforts to gather the required parts, we could not proceed to build the complete prototype, considering our monetary constraints as well. However we still plan to test out our design in the future.