Movement Assist System

• Concept Validation and Feasibility• Analysis of chosen design• Integration with Other Systems• Results and Conclusion

Concept Validation and Feasibility

• 4 Main Concepts• Feasibility of

Crank mechanism

• Mechanical Advantage versus difficulty of integration

• Chosen Concept

1 2

3 4

Comparison and Analysis of Designs

• Evaluation of straight line crank mechanism– Showed that the device can provide a mechanical advantage due to crank arm – Main concerns and issues are due to actual construction binding and sticking

in joints of links and moving the crank around two end points of arc– Risk of trying to construct this crank versus the benefit resulted in going with

regular crank arm• Gear Sets

– Large mechanical advantage– Risks in cost and disengagement– Couldn’t find standard made planetary gear sets with the required footprint

too thick/large

• Regular Crank directly coupled to shaft provides lowest risk and best design due to ease of integration and has the benefits of a good mechanical advantage

Analysis of Chosen Design• FBD of Model and EOM• Minimum Torque Required to move

system uphill• Key Assumptions

– Rolling without slip– Frictionless bearings– Lumped Masses– Torque input from user is constant through

Φ– Required Torque to turn generator is lumped

into 1 term, Tmotor, and is constant– Starts from Rest

Results With 1.5m Crank

Results with Hand on Wheel Rim

Conclusion of Movement Assist

• Crank Design is feasible by itself and should be able to be achieved

• Difficulty is in the user activation/disengagement and integration with other systems– Freewheel– Shaft attachment– Integration with braking and ratchet

• Based on CR (component of lowest priority) we are putting this system on hold to focus on more critical systems = Hill holder, Gradual Aid, and Energy Recovery