Project: Application of Mechanical Control
Project Details
Your project is to develop a drive line control for the quad bike from Project 2. To reduce accidents and produce a reliable stunt, it is desired to have an automated control of a wheel stand sequence. Power is applied rapidly to just the rear axle until the front wheels lifts off the ground and the bike attains an angle of 75 degrees. The control system must hold the angle for 5 seconds then let the bike drop in a controlled way to the ground. The control must be robust and work with your stated road corrugations and during a jump initiated by the ramp profile in Project 1.
Develop the controller and test it with the 2 DOF rotational and translational model of Project 1. If you had errors in your Project 1 model you will need to correct these. Your model should accurately represent the quad bike's gear ratio, engine torque and engine power limitations.
Your report will include:
- Evaluation and specifications of suitable controllers, suspension parameters and payload distributions. Your conclusions should be based on initial research and should also be informed by an iterative process based on your analysis.
- Your analysis and work used to develop and test your controllers.
- Addressing of all the Reflection and Discussion points
- Also see the assessment criteria at the end of this document to check you have included everything you need in the report
NOTE: your report should be consistent in the use of labels, terminology and positive directions of motion chosen and assumptions throughout the different parts.
PART A: Problem Investigation, Scope, Assumptions and Limitations
Further investigate the quad bike from Project 1. State and justify the assumptions you make of the Quad bike's engine and drivetrain performance. (i.e. maximum torque, power, gear ratios)
Revisit your Project 1 results and state the starting suspension properties, payload details and variations you will consider for the project (i.e. stiffness and damping values, rider mass, payload mass, location, mass variations, and road variations). Use these variations in each of the following analysis where appropriate.
State any limitations and analysis your report does not cover but could have been done if a larger analysis was required and more time and information was available. You may need to check and add to this section at the end of the project.
[Accuracy is less important than your approach, however, ensure any of your estimates are within a sensible range.]
PART B: Horizontal Speed and Position Model
For this part your analysis is to be limited to creating and testing a single degree of freedom, horizontal speed and position Simulink model. You will need to later incorporate this model with the other parts of the project. This will help with the overall project aim.
Your analysis will include the points below. Explain your working and models so an engineer could understand your process, results and findings of each point. Use each analysis point to help in the main aim described in Section 2.0.
Draw a mathematical model schematic of the quad bike with traction provided by the engine.
Simplify the system to a single degree of freedom system (horizontal motion only).
Draw the horizontal 1 DOF free body diagram and write the modelling equation. Also add in wind drag and other frictional forces to make your model more realistic. State any external references to justify your assumptions.
Model the system in Simulink to determine the acceleration/speed/position vs time of the quad bike at various throttle positions.
Compare the Simulink results with some theoretical calculations to check your model.
In a conclusion to Part B, discuss how your simplified model may differ from the real system (i.e. wheel-road friction limits, tire stiffness, engine power and torque curves etc.). Discuss how you might improve the accuracy of your horizontal model further.
Part C: Two Degree of Freedom Model with Controller (Vertical and Pitch)
Part C is to add and test a number of throttle controllers (P, PI, PID etc.) to your final 2DOF non- linear Simulink model (vertical and pitch) from Project 1. If your model in Project 1 did not behave as expected over the jump you should revise your non-linear elements. The points below will help with the task, but should not been seen as a complete and sequential instructions; use the tutorials and your lecturer to help.
In addition to the information you have from Project 1 and earlier parts you will need to estimate the centre of gravity location as best you can for your rider and payload variations stated in Part A. Check centre of gravity is a realistic value, as it will greatly affect your following analysis.
Draw the simplified model schematic and the 2DOF FBD and write the modelling equations.
Create a suitable 2DOF Simulink Model. Note that the centre of gravity height will change, so ensure this is modelled correctly. Demonstrate your model operates as expected just under the force of gravity and simply applied traction force.
Add a feedback loop PID controller to your model to achieve a wheel-stand on level ground. With this test and explore the effect of different controller variations (i.e. P, PI, PID).
Determine the engine/drivetrain forces and wheel-road friction levels required for the different controllers and compare these to the assumed maximum capacities of the engine and wheel- road surface. Draw some conclusions about how realistic are your initial controllers and model.
Part D: Further Model Improvements
In this part improve your model and controller to be more realistic by adding limitations of engine power/torque and wheel-road interface. Also combining the Part B horizontal model will also give insights into your controller's performance and improve your model accuracy. Using your improved model you will then analyse and evaluate your controller for the other possible variations you determined in Part A.
Add limitations of engine power/torque and the wheel-road interface to your model. Show and update the operation of the controller from
Part C. Recommend how to better achieve the wheel-stand event and implement these changes if required.
Combine the Part B horizontal model to give position and speed data. Present these results and discuss.
Use your new model and controller to analyse the operation of your controller for the variations you stated in Part A. Assume travelling over road corrugations, defects, the ramp of Project 1 and variations in payload/rider mass and positioning.
Re-assess the quad bike's spring and damper values chosen for the suspension based by the displacement and impact forces on the suspension elements during the previous simulations.
Analyse the stability of your final model and controller.
In a conclusion to Part D summarise your key findings and observations.
Part E: Discussion and Conclusion
Complete the following points in regards to the whole project:
Discuss how you would model the quad bike as a four degree of freedom system by modelling the mass of the wheels. Also show the schematic and FBD's you would use.
Also discuss what benefits this may provide in relation to both dynamic analysis and accuracy of the controller.
State your final design for the quad bike suspension stiffness, damper values and recommendations for a controller.
Comment on if your controller was a success and what changes you recommend to the controller to improve it if you had more time.
Discuss the steps you would take to implement the controller on a real quad bike.
Summarise your key findings and observations from the whole project.
Attachment:- Project.rar