Introduction
Basics of electronics robotics and kinematics are much easier to understand with concrete projects and devices moving in front of you than theoretical courses showing static examples or videos. Based on this assumption, this project has been imagined as a way to explain to students the fundamentals of motion and transmission using simple mechanics. The goal was to create kits that users could build on their own with no more than glue and tape and obtain a satisfying motion.
Kit Number 1: Walking Mechanism
This first kit is created to be a walking device. Here is the requirement for this kit :
- Walking mechanism with at least 2 legs
- Use a few motors as possible
- Being easy to build and intuitive
To create this kit, I have reviewed online different walking mechanisms by seeing youtube videos or websites documenting these types of motion. Here are presented a few examples of such devices.
The one I have chosen to implement is based on the following website :
I initially chose this design because it only requires 4 different pieces, giving me a lot of freedom to implement the rest of the robot. I wanted to have two legs based on this, and two wheels at the back to provide adequate stability.
First iteration
I then started designing all the components in Fusion 360, first doing only one leg to see if the mechanism worked. I used the simulation tool in the software to see how it behaves. I realized that in the simulation, the dimensions of the components were not perfect, as the gait amplitude could be more optimized and I had some serious doubt that this would work in reality. That’s why I started adjusting experimentally the size of each until I found a design that I was confident in it. Here is a picture of the first iteration.
I then laser cut all the components on plywood and mounted everything using sticks and super glue. It turned out that some of the interactions between components were miscalculated and encountered contact with each other. Some things needed to change in the design
I have then adjusted all the different components to optimize the gait as well as ensure the security and repeatability of the motion. I also notices that the components from the two triangles on the bottom and top were fixed in relation to each other. Based on this, I have replaced directly the components with adequate triangles.
Seeing this design working better in simulation, I have decided to laser cut it. I glued all the parts together and it turn out to work well
Constructing the mechanism
I then added two wheels at the back and mount everything together. I also added a 9v battery and a switch to control the device. Here is a picture of the result
Unfortunately, this mechanism wasn’t able to walk properly. Indeed, too much weight was placed on top of the legs, due to the motor, which was turning too fast without producing enough torque. A video is still provided to show the device standing in the air