Python Programming for this1 MA1008 Introduction to Computational Thinking Mini Project: A Cam...

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Python Programming for this1    MA1008 Introduction to Computational Thinking  Mini Project: A Cam Design System  Semester 1, AY 2021/2022, Week 10 – Week 13    1. Introduction  The objective of the mini project is for you to produce a program of a moderate size and depth that  will require you to utilise what you have learned in this course, and more, to do something  interesting. Through this, you would learn to design, manage and execute a sizable program.    2. The Project  Disc cam is a common mechanism used in many machines, including car engines. It converts the  rotational motion of the cam to a translational motion in the follower. This website shows some  examples:   https://www.creativemechanisms.com/blog/common-mechanisms-explained-with-animation.-part-1.    This project requires you to write a program in Python for designing disc cams.    A cam system has two main components: the cam  and the roller follower, with the follower always in  contact with the circumference of the cam. Its shape  (also called profile) is a smooth closed curve  determined by the motion of the follower. This  motion is periodic, repeated over a revolution of the  cam, with three basic parts: rise, dwell and return,  which you can observe in the animation in the above  website. Rise is where the follower goes up, dwell is  where it remains stationery and return is where it  falls. The follower motion is defined in a  displacement graph, as shown in Figure 1.    The dwell is a horizontal straight line in the displacement  graph, the rise and return curves are smooth mathematical  curves that connect tangentially with the dwell line at their  end points. For different dynamic behaviours, the rise and  fall curves may take different forms. The mathematical  formulae of the curves are given in Appendix 1.    Figure 2 shows a cam with its constituting elements. There  is always a base circle whose circumference provides the  lowest position for the follower. The pitch circle is the  circle on which the centre of the follower lies at this lowest  position. As the cam rotates, this follower centre traces  out the pitch curve, which is basically the displacement  curve wrapped around the pitch circle. The cam profile is  formed by offsetting the pitch curve by the radius of the  follower in the direction perpendicular to the pitch curve  towards the centre of the cam. Therefore, this profile is  dependent on three things: the radius of the base circle, the  displacement curve and the radius of the follower. The  mathematical formulae for the cam profile are given in  Appendix 2.    Figure 2: A cam with its elements.  The pitch curve is the curve traced  by the centre of the follower whose  displacement is the desired  displacement.   Figure 1: Displacement graph; α, β, γ are the  angles at which one motion changes to another  https://www.creativemechanisms.com/blog/common-mechanisms-explained-with-animation.-part-1 2    The Program  You are to write a program for designing disc cams. Your program should do the following:   i. Obtain inputs from the user for defining the displacement curve over one revolution of the cam.  This requires the number of motion segments, the angular range for each segment, and the  type of motion for each segment. Note that the number of segments is variable.  ii. Display the displacement graph.  iii. Obtain inputs from the user for the radius of the base circle and the radius of the follower.  iv. Generate the cam profile, display it together with the base circle and the follower. Your display  only needs to be in 2D.  v. (Optional) Create an animation showing the cam in rotation with the follower moving  accordingly. To create the animation, you also need the speed of rotation of the cam.  vi. For testing purposes, you need to provide a data file that contains the input data required for  the definition of a cam system. When the data is read in by your program, the displacement  curve and the cam system are displayed.  vii. Provide at least four sets of test data in your file. Make sure that upon the execution with one  set of data, your program pauses for the user to examine the output. Only upon a user  command that the program moves on to the next set of data.    Here are some points you should note:  i. The size of a cam depends on the radius of the base circle and the maximum follower  displacement. They can be any size. But as a rough guide, the maximum displacement should be  no more than the diameter of the base circle.   ii. The number of motion segments is variable, but typically no more than six.  iii. Your screen size is fixed, but your cam size is variable. Therefore, you should scale your display  such that the graph and the cam fit nicely in the display window.  iv. You may choose to have the displacement graph and the cam displayed side by side in the same  window or in separate windows.  v. Your display should be properly annotated, especially the graph. The axes should have tick  marks marking the values in incremental steps and correctly labelled.     3. Resources  The main extra resource that you will need for this project is for the graphical display, for which you  need the graphics library provided with Python, called Turtle. Turtle capabilities and functions are  described fully in Section 24.1 of the Python documentation, which you can access via the IDLE  interactive shell by clicking Help > Python Docs and then search for “Turtle”. Appendix 3 provides  some guidance on the use of Turtle.    4. Prohibitions  Apart from the graphics library, everything you need for this project can be done through what you  have learnt in this course.  To allow you to exercise what you have learned and to prevent you from  veering wildly beyond the scope of this project, your program should:  i. Not use the class construct to define objects you require in your program  ii. Only use the Turtle library for graphics. You cannot use tkinter or matplotlib.  iii. Not use the library numpy.    You may use the standard Python libraries like math.    5. Submission  You need to submit the following:  i. A working Python program that gets the relevant inputs from the user or from a file and  displays the displacement graph and the resulting cam.   ii. A data file containing the required data for four different cams which your program can read.  iii. A report in a Word file, providing   • A guide on how to run your program  3    • Pictures of your graphics window, with displays of the displacement curve and the resulting  cam, together with the input data for generating the cam. You should provide pictures for at  least two different cams.  • Highlights of the key strengths and limitations of the program.    The deadline for project submission is 23:59 hours, Friday 12 November. Please submit all your files  through the course site using the same link to the project file.    6. Grading Rubrics  Here are what the graders will be looking for when grading:  i. The quality and correctness of the outputs, especially the graphics display.  ii. The ease in interacting with the program, which includes specifying the input data and working  with the input files.  iii. The quality and correctness of your program, which includes:  • How easy it is to read and understand your program. This means your program should be  adequately commented with good choice of variable and function names.  • Modularisation of the program including appropriate use of functions.  • The design of the functions which include the appropriateness of parameters in the functions.    7.  Epilogue  You should start working on the program immediately. Do not wait till the last week. What you  produce depends on the time you spend on the project and your ability in creating good algorithms  and writing good code.    This is an individual project. You may consult the tutors and discuss with your classmates, but  everyone must write their own program. Any programs deemed to have been copies of each other  will be penalised heavily, regardless of who is doing the copying.    If in doubt or in difficulty, always ask. And ask early!    There is a great deal more to the science and engineering of cams than what you are required to do  in this project. We have trimmed the project requirements so that it is doable for a first-year  engineering computing project. For more information on cams, you may refer to books on  engineering mechanisms, such as Mechanisms and Mechanical Devices Sourcebook by Sclater and  Chironis.       4    Appendix 1: Displacement curves    The follower displacement, y, is a function of the angle of rotation of the cam, θ. Hence,     y = f(θ), 0 ≤ θ

Sathishkumar · Accepted Answer

Solution/disp_set1.py
import math
def displacement1():
        beta1=int(input('Enter rise angle'))
        dwell1=int(input('Enter dwell angle'))
        beta2=int(input('Enter return angle'))
        dwell2=int(input('Enter dwell angle'))
        if (dwell1+beta1+beta2)>360:
            print('Angle exceeds 360!')
        else:
            h=int(input("Enter h value:"))
            target_motion=int(input('''Enter the type of angular motion:
                        1-> Constant Acceleration,
                        2-> Simple harmonic Motion,
                        3-> Cycloidal Motion: '''))
            pi2=360 
            pi=math.pi

            b1=int(beta1/2)
            b2=int(beta2/2)
            y=[]
            x=[]
            if target_motion==1:

                for i in range(0,b1):
                    y_e=2*h*((i/beta1)**2)
                    y.append(y_e)
                    x.append(i)
            
                for i in range(b1,beta1):
                    y_e=h*(1-2*(1-i/beta1)**2)
                    y.append(y_e)
                    x.append(i)
            
                for i in range(beta1,beta1+dwell1):
                    y_e=h
                    y.append(y_e)
                    x.append(i)

                for i in range(0,b2):
                    y_e=h*(1-2*(i/beta2)**2)
                    y.append(y_e)
                    x.append(i+beta1+dwell1)

                for i in range(b2,beta2):
                    y_e=2*h*((1-i/beta2)**2)
                    y.append(y_e)
                    x.append(i+(beta1+dwell1))
                    l=i+(beta1+dwell1)
            
                if i!=pi:
                    for i in range(l,pi2):
                        y_e=0
                        y.append(y_e)
                        x.append(i)
                    
            if target_motion==2:

                for i in range(0,beta1):
                    y_e=(h*(1-math.cos((pi*i)/beta1)))/2
                    y.append(y_e)
                    x.append(i)
                for i in range(beta1,beta1+dwell1):
                    y_e=h
                    y.append(y_e)
                    x.append(i)
            
                for i in range(0,beta2):
                    y_e=(h*(1+math.cos((pi*i)/beta2)))/2
                    y.append(y_e)
                    x.append(i+beta1+dwell1)
                    l=i+(beta1+dwell1)
                if i!=pi:
                    for i in range(l,pi2):
                        y_e=0
                        y.append(y_e)
                        x.append(i)
            if target_motion==3:

                for i in range(0,beta1):

1 MA1008 Introduction to Computational Thinking Mini Project: A Cam Design System Semester 1, AY 2021/2022, Week 10 – Week 13 1. Introduction The objective of the mini project is for you to produce a...

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