Obstacle Course Hexapod Robot

This is the final project for my Advanced Robotics class in collaboration with Owen Gervais, Dylan Wagman, and Jiajian Zong. Each group was asked to develop a robot that overcomes 3 different obstacles (show below). In short, the robot needs to fit within a size limit (tunnel), climb a wall higher than itself, and march through a debris field.

Project prompt

We ended up building a 18-DOF special hexapod robot with long and thin legs. The robot was able to navigate through the tunnel and demonstrated its potential to overcome the other two obstacles.

Project summary video

Details

We originally designed the robot to only have 4 legs. After building the first version and running some tests, we quickly realized that given the length of the legs and the small size of the feet. stablizing the robot with only 4 legs is becoming very challenging. After some consideration, we switched to a 6-legged design while keeping most of the robot design unchanged.

4 legs vs. 6 legs

To reduce the width of the connection between the leg segments, I adopted my previous hexapod designs and put the plastic part in between the servo and the servo horn. I also made a profile in the 3D printed part for the servo horn, reducing the number of fasteners needed from 2 to 1.

The robot body is designed to be made of 3D printed PLA and carbon fiber rods, in an effort to reduce the weight of the legs while retaining their rigidity. There are a total of 19 micro servos on the robot. 18 of them are distributed across 6 legs, and one slightly smaller servo controls the sweeping motion of a time of flight distance sensor pointing towards the front of the robot. As shown by some of the images, we replaced the robot body with lasercut structure in the end to further reduce its width to go through the tunnel obstacle.

The end of the robot legs were modified by adding round furniture bumps. This was done to improve the friction of contact between the legs and the ground. The rounded surfaces also enable the legs to hold their position on an inclined surface.

We encountered several issues with the design. On the one hand, the backlashes of the servo motors got multiplied because of the overly long legs. The huge lever arm also brings excessive stress to the actuators, making them overheat and prone to permanent damage. Although the robot was not able to complete the entire obstacle course by the end of the project, it was a fun, challenging, and rewarding experience. We had a better understanding in the workflow of developing a complex robot, further practiced our prototyping skills, and had more practice implementing robotics concepts we learned in class.