Problem Statement

We seek to enable motor-impaired students in Julie Cimino’s art class to engage in projects by creating an accessible sketching mechanism.

Concept

The function model to the right outlines the context of the mechanism's use. As shown on the right, motion detected by the accelerometer is used to actuate a motor that drives our sketching mechanism. This method allows the user to feel engaged in the process as their motion, detected by the accelerometer, causes the mechanism to operate.

The red box denotes the kinematics challenge we are attempting to solve.

The initial mechanism design concept is shown to the left. The outer and inner radii of the cam map to the desired x and y positions of the output joint, respectively. The motion of the output joint is then magnified using a pantograph mechanism shown at the top of the sketch. A pencil or pen is at the mechanism's end effector in order to draw the output path.

The cam will be rotated with constant angular velocity, ω, to avoid introducing jerky motion. To implement this, a proportional controller will be used in the control system to maintain velocity even with changing torque loads on the motor.

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