For this week’s project we had to create a locomotive robot out of common craft materials, servo motors, and an Arduino. My source of inspiration was a video that I saw earlier this week of a bearded dragon trying to run on a hardwood floor, which made me think about the ways that animals move and how it could be simulated. After doing some research, I came across an article about the bio-mechanics of different animals, including common reptiles.The motion of their legs can be simplified as two sets of feet connected on a bar basically that pivot back and forth opposite of each other.
I realized that this could be replicate pretty simply by using two servos, one for each set of feet, mounted at a slight angle so that as the feet pivot, only two feet are on the ground at a time. For my material of choice in making this I decided to go with plastic straws, because of their really high strength-to-weight ratio and how easy it is to glue them together.
I started by by mounting the servos by sandwiching them both between two straws that eventually formed the main body of the robot, with a small support piece in the middle to prevent the whole thing from buckling too much. The angle I chose for the motors was arbitrary and I thought I might have had to tweak it later on, but luckily it turned out to be perfect.
For the legs, I again used straws but it took some experimenting to get right. I first tried bending them into shape and then taping them to hold it in place, but after some testing I realized it was way too flimsy for the robot to stand on. I then tried using a high temperature hot glue gun to both soften the plastic and hold it in place, which turned out be extremely strong and stable, and I also used the hot glue to create little feet that could grip flat surfaces more reliably. To attach them to the servo mounts, I just ran a bead of hot glue along the straw and held it in place while it cooled.
For my second bot iteration, I decided to try to integrate a bit of intelligence by incorporating a sensor into the robot. Since I’ve used the ultrasonic sensors before I settled on trying to get the bot to avoid running into obstacles. While I was able to get the sensor calibrated and able to detect when the robot was going to run into a object, I haven’t yet figured out a way to reliably control the two motor system to steer the bot in a way other than going in a straight line. If I had more time I think I would experiment more with different motion patterns to see if it is actually possible.