Answer Happy

Questions for Part 2 You are required by the vehicle manufacturer to perform some optimisation of the driving strategy to determine the optimal setup for the use case set out in the brief. For each question, some parts have to be submitted via MATLAB Grader and some parts have to be submitted as part of your workings document. Question 2.1 To optimise the vehicle's ability to coast, the resistance forces are the most important factors. The main variables are: • Aerodynamic: Coefficient of aerodynamic drag (Cd) • Rolling resistance: Coefficient of rolling resistance (rr) Assume the following values for other parameters: At 1.4 m? vlow 2 m/s mveh 75 kg vhigh 6 m/s Tm 3 Nm GR 6 Using MATLAB (in the MATLAB Grader environment), produce code that determines the value of percentage time on for a) cd values between 0.08 and 0.3 in steps of 0.01 Set Crn to be 0.002. Show the results by plotting a graph of percentage time on against coefficient of drag (ie, pattime as they axis, and cd as the x-axis). The y-axis should have the label 'Percentage Time On (%) and the x-axis should have the label 'Coefficient of drag [3 marks]
b) Crr values between 0.001 and 0.004 in steps of 0.0001. Set Cd to be 0.1. Show the results by plotting a graph of percentage time on against coefficient of rolling resistance (ie. pcttime as the y-axis, and Crr as the x-axis). The y-axis should have the label 'Percentage Time On (%) and the x-axis should have the label Coefficient of rolling resistance'. [3 marks) Based upon the results from a) and b); c) Explain the shapes of the graphs. [3 marks) d) Which variable out of cd and Crr has the most significant impact (based upon the range of values used) on percentage of time on? [2 marks] e) Suggest optimal values for both cd and crr based upon the range of values used. [2 marks]