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William Enns Bray, Mitch Sharpe, Mike Kryski, Andrew Mattson, Nicole Marshall, Ashton Johnson Sponsor: Dr. Bertram Design Review 1. Human Locomotion Research. Millennium Bridge in London. Design Goal. To design a wearable device that shifts the centre of mass of a subject.
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William Enns Bray, Mitch Sharpe, Mike Kryski, • Andrew Mattson, Nicole Marshall, Ashton Johnson • Sponsor: Dr. Bertram • Design Review 1
Human Locomotion Research Millennium Bridge in London
Design Goal • To design a wearable device that shifts the centre of mass of a subject. • The device will involve a mass of 2 kg oscillating at a frequency of up to 4 Hz with a full cycle amplitude of 8 cm. • Normal motion should not be affected when device is worn and not turned on.
Functional Objectives • Oscillate a 2 kg mass • Amplitude of 8 cm • Frequency of 4 Hz • Adjust mass so that it sits on test subjects centre of gravity • Adjustable device to fit most body types
Double Slider Mechanism • Rotating arms to raise and lower mass • Duel motor or single motor configurations • Motors reverse direction to create oscillation • Vertical guide to keep masscentered / level • Controlled by monitoring arm angle.
Double Slider Mechanism • Direction change 8 times per second • Approx. dimensions: 30 cm W x 18 cm H • Depth to be determined by motor requirements. • Torque requirement : 400 Nm on each side • 89° rotation to achieve 8 cm vertical amplitude • 3.1 rad/s (30RPM) to achieve 4Hz
Crank-Slider Mechanism • Modification of classic 4-bar mechanism • Converts angular motion to linear motion
Crank-Slider Mechanism • Torque requirement: 800 Nm • Crank length: 4 cm • Minimum rod length: 8 cm • Approx. dimensions: 8 cm W x 20 cm H • (excluding mass dimensions)
Cam Profile • Force-closed or Form-closed Design • Different cam profiles can be cut to achieve different types of motion • i.e (Harmonic, Cycloidal etc.) • Mass attached to roller follower • Follower slides vertically with respect to mounting bracket
Cam Profile • Crossover Shock(For form-closed cam) • Possibility of “Follower Jump”(For force-closed cam) • Torque Requirement Cam Profile(Simple Harmonic)
Rack & Pinion Mechanism • 3 major components: Rack, Pinion, Motor • Mobile Motor vs. Fixed Motor • Modular vs. Integrated design
Rack & Pinion Mechanism • Torque Requirements • Normal Force: Clip vs. Spring • Angular velocity control