I. Introduction and Background - CZ
My goal with the ME 350R final project was to design and build an iteration of a previous robot that I made during my first year in college. The robot, shown in the picture below consisted of 4 legs and was designed to mimic the walking pattern of a spider. Each leg had 3 servo motors and 3 degrees of freedom which led to a fairly complicated trigonometric model which I was unable to implement properly. That in addition to the relatively weak motors meant that the robot had a very difficult time supporting its own weight and walking.
Figure 1 – “Webby” the spider robot
Despite that project not working as well as I had hoped, I learned a lot from the endeavor and still find the concept of walking robots very interesting. With this project, I wanted to design a robot that fits the ME 350R design goals while also playing to my strengths in mechanical design rather than electronics. In order to simplify the build, I decided to design a robot that can walk utilizing only 2 motors and doesn’t require a trigonometric model. After some research, I found the Klann linkage which converts a rotational input into a walking output using a 5-linkage mechanism with a single degree of freedom.
Figure 2 – Klann Linkage Kinematic Diagram
Mechanism Goals:
For this project, I created a list of goals with which I can evaluate the success of the project:
Robot walks under its own power.
Is stable
Is durable
Is reasonably easy to build
Is reasonably low cost (<$100)
I planned for the robot to have 8 legs (4 per motor) because it is the most stable configuration of the robot as, at any given time, there will always be four legs touching the ground. For the robot body, I planned to lasercut ¼” wood from Texas Inventionworks since it is cheap and easy to work with. While wood isn’t as strong as some other materials, it is lighter which would help the robot walk more smoothly. The joints would be attached with bolts and I planned to add plastic washers between the joints to provide a smoother surface of rotation.
Project Success Metrics:
From the kinematic analysis of the system and my research about the Klann linkage, I expected the leg to move in a simple “walking motion” when a torque is applied. That motion will have a relatively flat bottom motion with a vertical retraction as it moves forward (see figure 2). This project will be successful if it meets all of the mechanism goals that I have set out to reach.
Next → II. Design Process