Programmable Stiffness Joint

Team Members

• Amanda Care (Junior in Mechanical Engineering, Northwestern University)
• Eric Nickel (BS in Biomedical Engineering from the Milwaukee School of Engineering, Graduate Student in Biomedical Engineering, Northwestern University)
• James Yeung (Junior in Electrical Engineering, Northwestern University)

Overview

The Programmable Stiffness Joint is a device that takes a user input (turning a simple dial) and adjusts its stiffness to the desired level.

The goal of our project is:

This is how it works:

We will discuss:

Stiffness Theory

The rotational stiffness of a joint is defined as the moment required to cause a given angular rotation.

Fundamental Equations

Based upon the diagram at right, the following variables are defined for these equations:

Give full description of the theory here

MATLAB Simulation

Simulations of the above theory in MATLAB produced the following results.

MATLAB Code

Insert MATLAB code here with appropriate comments.

Mechanical Design

The primary structural components used in this device are:

The sensors/actuators used are:

Electrical Design

The primary components used in this circuit are:

• Controller (PIC)

Code

See full code here

Results

Our resulting design:

Reflections

• Move circuitry to shank
• Reduce weight of foot plate
• Select different motors (or gear up current motors) to increase adjustment speed