This studio had two goals; to make something using the new linear actuators and to stress test the linear actuators for the coaches who were developing a new product. Using the linear actuators, we created Hexabot, which is essentially a six-legged spider robot. We used one linear actuator and one servo per leg to control the height and the rotation. We wanted to build a walking robot by the end of the studio.
The robot can easily lift itself and a payload of about 2 kilograms. Each of the legs is attached to the central hexagonal base using loose pin hinges. The servo on each of the legs is linked to the base using a four bar linkage. Since the linkage is in the shape of a parallelogram, the servo horn will always stay parallel to the side of the base. This makes it easier to program and control the rotation of each leg.
Each leg is also made using a four bar linkage in the shape of a parallelogram. This shape is beneficial because the part of the leg that is hitting the ground does not rotate. If it did rotate, the robot would have difficulty balancing. The actuator is attached to the upper point on the side closest to the base and to the lower point on the side furthest away from the base. When the actuator pulls, the leg is lowered, effectively lifting the robot. Likewise, when the actuator is released and goes back to its normal state, the leg is raised, lowering the robot.
While building this robot, we tested, broke, and helped make improvements to the linear actuators brought in by our coaches. This was one of the few studios where breaking what we were given was a “good” thing. With each break, they sought to create a shield from it happening again. Whether it needed a stronger motor, higher torque gears, or redesigning break points, the process of building Hexabot allowed them to create a more complete product. Though it slowed the overall process of building the Hexabot, we were able to give them a proper amount of feedback.
In the end, the Hexabot was built to spec. Six linear actuators, six servos, six legs, and a six-sided base made up our walking spider robot. Improvements can most definitely still be made, but where it stands, or squats rather, we have a fully functioning Hexabot.