Design and Kinematics

Design

Final Design:

• self locking mechanism that can be opened when desired

• Neutral position slightly below toggle position

• springs used to keep everything at neutral position

• Cam cleats used because already so widely used

• Emergency opening implemented, because wind can suddenly pick up and create tension that overcomes the user’s maximum strength

• Designed to be easy to place/hold on hand as user has minimal dexterity of fingers to put on a normal glove 

Figure 3: Linkage geometry used in MatLab calculations.

Figure 4: Vector Loop of Linkage design.

Kinematic Differentiation/Analysis

MATLAB was used to determine the kinematics of the linkage over various ranges of motion. One program was created to analytically solve for the geometric positions and angles of all the links at a given position (GripperGeometry.m). A second program runs this first file over a range of positions, differentiates between positions to find link velocities, and returns a matrix containing all the link positions and velocities at each input position. 

This second program was used to analyze the behavior of the output cam links given the input position. The opening motion at the output was found, as was the mechanical advantage between lateral force at the output and the vertical spring force at the round slider opposing vertical movement. Both graphs are pictured to the left.

The two MATLAB files used are included as attachments to this page. 

Figure 5: Graph of the slider position versus the output cam opening distance. Vertical line is position to which input rod displaces slider, and point represents toggle position. 

Figure 6: Mechanical Advantage vs. Lateral Deflection in Cams. Vertical line is position to which input rod displaces slider, and point represents toggle position.