Design Constraints

Workspace

This is the theoretical workspace of a two link manipulator whose second link can slide over and under the first link. The workspace for your robot will be different. See below

Dimensions and Angles

This nifty picture shows you where to measure the various dimensions and angles for this arm.

Variables

Theta 1 = zero when first link is horizontal to the right of the origin.
Shoulder axis of rotation is defined to be the origin.

Theta 2 = zero when shoulder axis, elbow axis, and pen are all colinear.

In other words, the reference configuration is when the arm is entirely horizontal.

Theta 1's range of motion is 0 deg to +180 deg
Theta 2's range of motion, centered about zero, is -90 deg to +90 deg. Rotation counterclockwise from the reference position is positive, clockwise from reference is negative.

Points can be in the first or second quadrant with the shoulder axis being the origin, positive x extending to the right, and positive y extending upwards.

Parameters

L1 = 3 3/4"
L2 = 2 1/2"

L1= straight line distance from shoulder axis to elbow axis (see image above).
L2= straight line distance from elbow axis to pen axis (see image above).

Be very careful that you measure these distances carefully; if you have any questions, talk to one of the TAs, and we can check it for you. If these distances are incorrect, you will not reach the appropriate point given a pair of joint angles. This would be a Very Bad Thing.

The arm must be mounted on the board such that all points in the target quadrant are on the board. The boards that you will mount your robot on is a flat lego board, mounting should be very straightforward.