Night Scrawler is my vision of self-sustaining urban hardware. It is deployed on any metal street pole that sees direct sunlight for the majority of the day. During the day, it will recharge the battery using a solar panel. At night, it will display scrolling messages on an LED matrix.
Based on this testing, it looks like the wheg (wheel + leg) concept is a viable path forward for the Night Scrawler. I was pleased with how well it was able to climb without any motor control. For this prototype, I just wired the motors directly to the battery. Speed control of the motors along with feedback from encoders and an accelerometer are planned for the final design.
I chose to evaluate the wheg solution for this prototype for two reasons: 1) I suspected that the flexible legs would do a good job of conforming to the irregular geometry of the climbing surface, and 2) very few magnets are per wheel means slightly lower cost. Overall, I think this iteration of the flexible legs conformed as well as could be expected on the the door. I already have several modifications in mind that will improve the performance of the whegs.
The first proof-of-concept prototype will attempt to evaluate whether the selected magnetic wheel solution is capable of climbing and traversing a ferromagnetic pole. It will be loaded with estimated payload mass and mass distribution of the final design. This prototype will not include the solar panel or the LED matrix -> these will be added later after the magnetic wheel pole climbing concept has been proven.