What It Does
The objective of this project was to design and build a mechanism powered by a standard servomotor which lifted a cylindrical weight. The mechanism was clamped in a fixed position while the other end lifted a weight that slides along a vertical post. Between the clamping area for the base of the design and the post holding the weight sits an obstacle. The mechanism was required not to touch the obstacle or any other surface besides the base and the sliding weight. Other requirements included: a maximum weight of 20.0 oz, the ability to lift the sliding weight at least 2”, and the material options were limited to only aluminum sheets, bolts, nuts, a U-channel, and a strip of delrin (plastic). (this was adapted from the document describing the project)
How It Does It
Our structure is composed of a base, truss, and lever arm. The base is clamped to the ground and the truss is attached to the base. Then a lever arm, attached to the truss, lifts the weight. The base is designed so that the truss can be directed straight through the wood opening.
An important feature of the structure is its ability to resist bending and torsion. If the structure bends or twists then instead of lifting the weight, the structure will deflect. In order to prevent bending and twisting our structure utilizes a triangular truss. Being a truss, the structure deflects and twists less than a solid beam with the same weight.
A lever arm moves the weight using a servo motor and a counter-weight. The servo motor is placed as close to the weight as possible while the counter-weight is placed far from the weight. Both increase the moment on the arm, causing the weight to lift.