Prototype 2

Changes were made to the overall design of the first prototype to focus the viewer’s attention on the kinematics of Sisyphus’ limbs.

CAD Design

Materials

All wood and acrylic pieces were cut to precision using a laser cutter. The prototype fits into an 18’’x18’’ frame. The once rotating world is now a fixed incline within the frame. Mountains were added to the background to make the prototype more aesthetically pleasing.

Mounting Frame

The mounting frame was designed to accommodate space for the Arduino, motor, and electronic speed controller in the bottom left hand corner.

Sisyphus

Sisyphus has increased significantly in size. The model now has an elbow joint. The addition of a 4-bar linkage allows the arms to move in a path that follows the boulder, which simulates a pushing motion.

Sisyphus' Limbs

A router was used to cut out half of Sisyphus’ limbs at the joints. The limbs now fall flush with each other. As a result, Sisyphus is thinner, and the depth of the prototype could be reduced.

Front View

Profile View

Axle

The axle driving Sisyphus’ legs has been given a new shape to allow for smoother movement.

Linkages

The linkages connected to the axle were constructed out of clear acrylic in hopes to reduce their visibility. The picture below displays the shapes of the linkages. Here, they have paper to protect their transparent surfaces while cutting.

Below, the linkages are stripped of their paper covers and are connected to the ankles of Sisyphus.

Pulley System

A pulley system was designed to transmit the torque of the motor and synchronize the rotary motion of the boulder and Sisyphus’ limbs. The MLX timing belts and pulleys were purchased from McMaster-Carr.

Top view

Profile view

Attached to the motor are two nylon 90 degree bevel gears. This allowed a reduction in depth of the prototype to about 3''.

Prototype 2 Internal Structure

Improvements for Final Design:

Depending on the performance of Sisyphus’ limb motion, we may need to develop a better method for bending the driver axle. Additionally, we will laser cut another frame and mountains. An error occurred when using the laser cutter resulting in the left side of the frame being very thin. The mountains will be remodeled to make them stand taller and fill up more of the blank space in the frame.