DOMER: A Walking Robot

From concept sketch to creating a detailed CAD, to assembly and programming the robot to walk, I created a four-legged walking robot in 16 weeks. I present to you: DOMER.

Phase 1: Concept Sketch

During the initial conception of the robot, I turned to abstract sculptures and animals for my inspiration. I wanted my design to not just be mechanically sound, but aesthetically pleasing as well. After many brainstorming and sketching sessions, I designed a "geometric crab": a four-legged robot featuring a low-poly effect. Each leg would have two joints actuated by servo motors.

Phase 2: Detailed CAD

In this step, I had to incorporate all the fine details: how to secure the motors, the placement of the electrical components (computer board, DC converter, motor controller, battery), the size of given components, cable management, and more. I also had to consider the constraints from 3D printing and how to limit the total print time.

*CAD files of given components and screws/inserts were taken from GradCAD. Sources cited at the end.

Phase 3: Assemble One Working Leg

After creating the CAD, it was time to assemble the electrical components and 3D print the parts to create a single working leg. This was a crucial step, as it confirmed that the design was sound, but also revealed form and fit issues that had to be fixed before assembling the entire robot.

Phase 4: Manufacture and Assemble Entire Robot

This is where it all came together. All parts were 3D printed and laser cut. Thermoplastic inserts were melted into the prepared holes in the parts. The limbs and the shell were sanded and spray painted with a metallic finish to highlight the low-poly feature. The servo motors were connected in a daisy chain and the electronics were correctly wired. Finally, all the components were bolted together.

Phase 5: Program DOMER to Walk

The robot has a name now: DOMER. Because of the low supply of Raspberry Pi computers, we were given Le Potato computer boards. To start programming DOMER to walk, I first had to install an operating system onto Le Potato and all the required packages to control the servo motors, LewanSoul LX-16A. From there, I was able to start experimenting with different gait patterns in order for DOMER to walk. The movement for the motors follow sinusoidal waves so that there are no sudden changes in position of the motor. It took a lot of time to determine how to offset the movement for different limbs and legs in order to create a gait.

Phase 6: Simulate DOMER in PyBullet

*CADs used

https://grabcad.com/library/aml-s905x-cc-le-potato-1

https://grabcad.com/library/lewansoul-lx-16a-bus-servo-solidworks-fix-1

https://grabcad.com/library/motor-shaft-adapter-for-lx-16a-1

https://grabcad.com/library/talentcell-rechargeable-12v-3000mah-lithium-ion-battery-pack-1

https://grabcad.com/library/lewansoul-lx-16a-servo-bus-linker-1

https://grabcad.com/library/lewansoul-lx-16a-serial-bus-snap-fit-mount-1