Caterpillar Locomotion
For this lab we will make a bot that imitates the locomotion of an organism found in nature. We chose to study the movement of caterpillars in particular. Using our basic understanding of locomotion, we will develop a mechanism that mimics the inch-ing movement of a caterpillar.
Completed caterpillar prototype
Materials
3.5 cm x 18 cm cardboard
10 cm string/yarn (or lax wire)
1 microbit
1 robotbit board
2 servo motors
Ideation
Initially, we drafted a bot that used a dragging mechanism to create linear motion. However, this design overall was clunky and impractical for the short time frame.
In our second round of research we were directed towards this inchworm design. Using this as our basis we started creating our caterpillar.
Prototyping
First, we cut the cardboard in half. Then, folded each piece in half so that each side of the fold is around 4.5 cm long. This created the units that make up the caterpillar’s body. Using adhesive we attached the robotbit board (microbit attached) on the side of one piece of cardboard (upside). On the same side as the board we attached the servo so that the blade sat on the edge of the cardboard close to the fold. Here we threaded the string through the blade so, it could contract and expand. This is the procedure to construct one unit. After one was complete we worked to incorporate another unit. Depending on the weight distribution, we added counterweights on the opposite end in order to have it maintain linear motion.
Using the 3D printed fencing we tested whether the bot (1 unit) could drag a weighted object behind. The test was successful so, we moved on to creating a second unit and attaching it behind.
Here we are threading the string through the servo blade so that the caterpillar can contract and expand.
Reflection
Given more time I would like to create more units to have our caterpillar look more like a genuine caterpillar. Additionally, I would be interested to see if adding more units would actually make the bot move faster or would the extra weight simply make it stall.
It would also be interesting to experiment with different types of motors so that we could see if more forward motion could be generated.
Resources:
https://www.youtube.com/watch?v=BiZLjugXMbM
https://www.kitronik.co.uk/blog/using-bbc-microbit-control-servo/