Our team decided on two primary goals to distinguish the robot from existing, servo-based robots: biomimetic spider leg movement and a maximum of three DC motors to control all movement. My primary contribution to this project was the design and prototyping of the six-bar linkage system that comprises the front and back legs of the spider.
Skills & softwares: Onshape, Arduino, Controls Design, Mechanical Design, Gears and Linkages, Rapid Prototyping, 3D Printing
Process Through analysis of video resources and experimentation with linkage systems, I discovered that the motion of the front and back legs of the spider moved synchronously and could therefore be driven with only one motor on each side. The DC motors were then geared down to decrease torque in order to match gait timing and speed. Each DC motor drives one gear train that powers two legs.
Friction in the gear system remained a challenge throughout the prototyping process. Rubbing a bar of soap on the gears prior to assembly (see above right) proved an effective solution.
A spool on top of the robot pulled on opposite tendons (e.g., front right and back left), lifting the corresponding legs while the other two remained in contact with the ground.
The robot was controlled through bluetooth on a cellphone and was able to move forward, backward, and turn 360º clockwise and counter-clockwise.
We presented Arachne at the Jacobs Institute for Design Spring Showcase in May 2025.