Quarter car modelling

UNIVERSITYOF HERTFORDSHIRE, SCHOOL OF ENGINEERING AND COMPUTER SCIENCES

Page 1 of 5

COURSEWORK ASSIGNMENT

Module Title: Automotive dynamics and safety

Module Code: 7AAD0054

Assignment Title: Quarter car modelling

Individual Assignment

Tutor: Mahmoud Chizari

Internal Moderator: Gbanaibolou Jombo

Student ID Number ONLY:

Year Code:

Marks Awarded %: This assignment is worth 15% of the overall assessment for the coursework.

Marks Awarded after Lateness Penalty applied %:

Please see “Penalties for Late Submissions”

Penalties for Late Submissions

• Late submission of any item of coursework will be capped at a minimum pass mark if received up to one week late. Any submission received more than one week late will be awarded a mark of zero.

• Late submission of referred coursework will automatically be awarded a mark of zero.

• Note: The School operates a strict policy on late submission. StudyNet marks all work submitted late, even by one second, as Late, in which case the above late penalties will be applied. Where genuine serious adverse circumstances apply, you may apply for an extension to the hand-in date, provided the extension is requested a reasonable period in advance of the deadline. However, you are warned that lateness due to network congestion (either at the University or on your local network), difficulty with filenames, poor time management and similar issues will not be considered as admissible circumstances. For this reason, you are advised to submit at least one hour before the deadline.

Please refer to your student handbook for details about the grading schemes used by the School when assessing your work. Guidance on assessment will also be given in the Module Guide.

Guidance on avoiding academic assessment offences such as plagiarism and collusion is given at this URL: http://www.studynet.herts.ac.uk/ptl/common/LIS.nsf/lis/citing_menu

If the assignment is laboratory based (though not computer-based), or involves offsite activity, please attach the risk assessment form for the Internal Moderator to see.

UNIVERSITYOF HERTFORDSHIRE, SCHOOL OF ENGINEERING AND COMPUTER SCIENCES

Page 2 of 5

ASSIGNMENT BRIEF

Students, you should delete this section before submitting your work.

This Assignment assesses the following module Learning Outcomes (Take these from the module

DMD):

This assignment aims to enhance students’ knowledge on applied computer simulation and practical

methods to analyse vehicles dynamics and vibration.

The successful student will be able to:

➢ Apply analysis techniques to load an active suspension example

➢ Use commercial packages to model quarter car model with an aim to understand:

• A method of characterizing the Newton laws for modelling oscillating behaviour

• A theoretical approach to establish calculation of a 2 degree of freedom system

• The impact of the modelling choices to the accuracy of results under different loading conditions

• Understands subtle different approaches to model a vibrating system

• How these findings can be used to improve the actual suspension system

➢ The assignment will reinforce a student to:

• Analyse an oscillating structural event such as frequencies and shape modes.

• Understand the fundamental differences to structural behaviour under different modal assumptions

(boundary conditions, load combinations)

• Understand how loads can develop through an assembly. The chosen vehicle part should belong to

this simple assembly

• Compare theoretical outputs to the computer models

• Appreciate how a fundamental approach to simulation can be used to derive structural

performance.

Assignment Brief:

For the purposes of this assignment you have been tasked with simulating a simplified model of a

quarter car active suspension. You are encouraged to consider the identified loading scenarios and

complete the tasks of this assignment. You may develop your own assumptions under your identified

loading/displacement scenarios and provide a clear evaluation on the oscillating system when

experiencing road conditions. Your defined assumptions should be based on a clear loading and

boundary condition you may use to assess these solutions. These should lead you to develop your

own Simulink model and compare the theoretical and Simulink models. In final stage a comparison

should be made on those found from modelling/simulation.

Please provide a report with your assumptions, calculations, solutions and observations as follows:

• Your assumptions in terms of design, requirements and measurables

• State clearly your requirements and their limits

• Justify your model choices and calculate their influence on its performance

• Compare the methods for differences and similarities

• Highlight design recommendations which can improve the function of the design.

Important notes:

All students must submit their individual report through Canvas.

The mark will be awarded to individual within the Canvas.

Submission Requirements:

➢ Students must follow the requested tasks and report findings.

➢ The report must be submitted using provided template.

Please see brief below in this document for upload information.

UNIVERSITYOF HERTFORDSHIRE, SCHOOL OF ENGINEERING AND COMPUTER SCIENCES

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This assignment is worth 15% of the overall assessment for this module.

Marks awarded for:

The assignment contains modelling and simulation tasks must be reported by all students.

Report must be completed by following the instruction of the provided template.

The marking scheme has been specified on the template of the report.

Please see blow document for detail of the tasks.

A note to the Students:

1. For undergraduate modules, a score above 40% represent a pass performance at honours level.

2. For postgraduate modules, a score of 50% or above represents a pass mark.

3. Modules may have several components of assessment and may require a pass in all elements.

For further details, please consult the relevant Module Guide or ask the Module Leader.

Typical (hours) required by the student(s) to complete the assignment: hours

Date Work handed out:

Week 32

Please check your timetable for

your time slot.

Date Work to be handed in:

Week 36

Please check your timetable for

your time slot.

Target Date for the return of

the marked assignment:

4 weeks after the deadline

Type of Feedback to be given for this assignment:

Comments will be given on marked report through Canvas.

Generic feedback will be given in lab/classroom.

UNIVERSITYOF HERTFORDSHIRE, SCHOOL OF ENGINEERING AND COMPUTER SCIENCES

Page 4 of 5

7AAD0054 - Automotive dynamics and safety | Quarter car modelling | Assignment Brief

To improve the quality of the lab sheet please report any errors.

Please report all calculation modelling and computer simulations within the provided template.

Active Suspension System

For road vehicle users, comfort is an important issue. To move from one place to another, road

vehicles usually encounter various vibrations and shocks from ground, for instance, in traveling on

a bumpy surface, or crossing over an obstacle. Prolonged exposures to vibrations cause some

problems, such as pain and fatigue, for the passengers. To alleviate these problems, momentary

loads from ground should be absorbed and damped out. Automotive suspension systems are

intended to absorb and decrease the shocks and vibrations transferred from the ground to the

passengers as well as the vehicle body. Passive suspension systems which consist of spring and

damper components have been traditionally utilized on different types of vehicles, such as

motorcycles, passenger cars, trucks and even bikes. Active suspension systems with separate

actuators to apply controlled forces provide better ride.

Quarter Car Modelling

A quarter-car model of a passenger sedan with active comfort and improved handling. The

suspension system shown below represents the vehicle system at each wheel. It consists of a spring,

ks, a damper, Cs and a hydraulic actuator, Fa. The tire stiffness and damping properties are also

shown by kt and Ct, respectively. The effective vehicle body mass is shown by Ms (sprung mass), and

Mu (unsprung mass) represents the effective mass for the wheel and axle. The vertical

displacements from the static equilibrium for Mu and Ms are shown by xu and xs, respectively. The

road profile is represented by xr. The suspension travel xs - xu is measured and compared to the set

point (r = 0). The required actuator force is determined by the controller to eliminate the error, and

thus, to reduce the vehicle oscillations.

Elements Parameter Value

Effective mass for vehicle body Ms [kg] See your class list

Effective mass for wheel system Mu [kg] See your class list

Spring; vehicle suspension ks [N/m] See your class list

Spring; wheel system kt [N/m] See your class list

Damper; vehicle suspension Cs [Ns/m] See your class list

Damper; wheel system Ct [Ns/m] See your class list

Body vertical displacement Xs [m] See your class list

Wheel vertical displacement Xu [m] See your class list

Road profile xr [m] See your class list

Figure 1. Schematic of a simplified quarter car passive suspension and its specifications

Tasks

Please consider a passive suspension system with elements shown in Figure 1 and complete

following tasks. Report must be completed within the provided template.

Task 1: Theoretical modelling

• Perform free body diagram (FBD) for the system to satisfy the Newton’s 2nd low. Please

develop your own assumptions to address the applied forces onto the identified mases.

• Find the equation of motions and response of the system to oscillations. You may use your

own assumptions as used in the FBD of the system. Please make sure to address loading

scenarios applied to masses, springs and damping elements.

• Please consider either free or forced vibration and complete the results. The assumption made

in previous step can be used here. However, your defined assumptions should be based on

Cs

Ct

UNIVERSITYOF HERTFORDSHIRE, SCHOOL OF ENGINEERING AND COMPUTER SCIENCES

Page 5 of 5

clear and specific metrics which you may use to assess these solutions. The vibration

characters, e.g. frequency of oscillation and response of the system, need to be appropriately

calculated based on your individual data.

Task 2: MATLAB simulation

• Please simulate the system using a MATLAB program. You can consider the assumption made

in previous tasks. These should lead you to develop your own individual Simulink model with

a potential design choice which can be assessed against the model derived in previous task.

• Please used the model created in Task1 to simulate the suspension model. You are

encouraged to evaluate the function of the suspension on specified road profile. Key

calculations and assumptions need to be explained and justified adequately.

• Please plot the displacement and acceleration of the car/suspension. You can assume that

possible forces are applied uniformly.

Useful references:

1. Control Tutorials for MATLAB and Simulink,

http://ctms.engin.umich.edu/CTMS/index.php?example=Introduction&section=SimulinkModeli

ng, (last seen 11/02/2020)

2. Duc Chung Tran, Quarter Car Modelling,

https://uk.mathworks.com/matlabcentral/fileexchange/46316-quarter-car-modelling-zip, (last

seen 11/02/2020)

3. Jonathan Sprinkle, Quarter car suspension model, published on 30 Aug 2013,

https://www.youtube.com/watch?v=TKbChGz4-mw, (last seen 11/02/2020)

4. James Allison, Simulation and Animation of a Quarter-Car Automotive Suspension Model,

https://uk.mathworks.com/matlabcentral/fileexchange/35478-simulation-and-animation-of-aquarter-

car-automotive-suspension-model, (last seen 11/02/2020)

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Neutral Network Control of a Mobile Robot

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 1 of 5

COURSEWORK ASSIGNMENT

Module Title: Artificial Intelligence

Module Code: 7ENT1116

Assignment Title: Neutral Network Control of a Mobile Robot

Individual Assignment

Tutor: Lily Meng

Internal Moderator: Salvatore Livatino

Student ID Number ONLY:

Year Code:

Marks Awarded %:

Marks Awarded after Lateness Penalty applied %:

Penalties for Late Submissions

 Late submission of any item of coursework for each day or part thereof (or for hard copy submission only, working day or part thereof) for up to five days after the published deadline, coursework relating to modules at Levels 0, 4, 5, 6 submitted late (including deferred coursework, but with the exception of referred coursework), will have the numeric grade reduced by 10 grade points until or unless the numeric grade reaches or is 40. Where the numeric grade awarded for the assessment is less than 40, no lateness penalty will be applied.

 Late submission of referred coursework will automatically be awarded a grade of zero (0).

 Coursework (including deferred coursework) submitted later than five days (five working days in the case of hard copy submission) after the published deadline will be awarded a grade of zero (0).

 Where genuine serious adverse circumstances apply, you may apply for an extension to the hand-in date, provided the extension is requested a reasonable period in advance of the deadline.

Please refer to your student handbook for details about the grading schemes used by the School when assessing your work. Guidance on assessment will also be given in the Module Guide.

Guidance on avoiding academic assessment offences such as plagiarism and collusion is given at this URL: http://www.studynet.herts.ac.uk/ptl/common/LIS.nsf/lis/citing_menu

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 2 of 5

ASSIGNMENT BRIEF

Students, you should delete this section before submitting your work.

This Assignment assesses the following module Learning Outcomes:

 understand the fundamental principles underlying an artificial intelligent system;

 critically evaluate the suitability of hybrid neural/fuzzy/traditional control systems for specific applications;

 design and simulate effective neural network systems for specific applications.

Assignment Brief:

Using the KiKS robot simulator software and the Matlab Deep Learning Toolbox, design, implement and test a neural network which will enable a Khepera mobile robot to wander about its environment, following a wall on its left side whilst avoiding collisions with obstacles.

Submission Requirements:

Submit on StudyNet by 23:59 Sunday 19th April 2020,

 your report;

 your trained neural network saved as a Matlab data file in the format of .mat

 your modified NN_navigate.m

This assignment is worth 20 % of the overall assessment for this module.

Marks Awarded for:

Please see attached assignment description and the marking schemes published on StudyNet.

A note to the Students:

1. For undergraduate modules, a score above 40% represent a pass performance at honours level.

2. For postgraduate modules, a score of 50% or above represents a pass mark.

3. Modules may have several components of assessment and may require a pass in all elements. For further details, please consult the relevant Module Guide or ask the Module Leader.

Typical (hours) required by the student(s) to complete the assignment: 20 hours

Date Work handed out:

24/03/2020

Date Work to be handed in:

See Submission Requirements above

Target Date for the return of the marked assignment:

Four weeks after the submission deadline

Type of Feedback to be given for this assignment:

A general feedback will be given at the end of each project demo session. An individual written

feedback will be published on StudyNet along with the marks awarded for each assessment

element.

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 3 of 5

7ENT1116 Artificial Intelligence

Coursework Assignment 2 – Neural Network Control of a Mobile Robot

Use the Matlab Deep Learning Toolbox to create and train a neural network that can be used to control a simulated mobile robot so that it will be able to wander about its environment, following a wall on its left side whist avoiding collisions with obstacles. You should aim to make your trained neural network able to match the performance of the given Fuzzy Inference System.

You have been given a working Fuzzy Inference System which performs the same task and can therefore be used to generate training data for the neural network.

The trained neural network will be tested using the KiKs simulator in the same test environments as in Coursework Assignment 1.

Report Requirements

You must submit a report that describes and evaluates the work you have done to meet all the requirements of this assignment. The report should contain (at least) the following:

 a description of the data that you used to train your neural network, explaining how the data was generated; (20%)

 a full description of your final neural network architecture; (10%)

 a description of the training process, including the training algorithm and the method that you used to avoid overfitting; (20%)

 explanations of any problems that you encountered and the design decisions that you made to overcome these problems; (20%)

 a brief discussion of the control performance of the trained network in comparison to the given FIS and the suitability of a neural network for this control application; (20%)

 a printout from the KiKS simulator to show the path travelled by the robot during a successful trial; (5%)

 a listing of the final Matlab code for your control system. (5%).

The percentages above are intended to give an approximate guide to the weighting that will be given to each component during assessment of the report. Marks will be awarded for:

 a clear, complete description of the software that you have developed;

 a logical discussion the design decisions that you made;

 a well-designed neural network;

 a well-presented original report.

Your report should be approximately 2000 words in length and cover about six sides of A4, not including appendices, cover abstract and contents page. Use 11 point Times New Roman font for the main body of text. You may use illustrations and/or diagrams that help you describe your work but any pictorial content must not amount to more than

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

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20% of your report. If you wish to include more illustrations, then these must go in an appendix. The structure and preparation of your report is important.

You must submit an individual piece of work. You may, of course, ask colleagues for help and advice, but the finished system must be your own, unique solution to the problem. Standard University procedures will be applied if there is evidence of plagiarism or collusion.

Overview of the Task

The file left_wall_follower.fis contains a Fuzzy Inference System (FIS) that can be used as a controller to guide the simulated robot successfully around the test environment. This file and a version of FIS_navigate.m that uses it as a controller can be downloaded from Studynet. This FIS can be used to generate training data for a neural network. Your main task is to design, train and test a neural network that can generate appropriate actuator outputs when being presented with sensor inputs. This trained network can then be used as a controller and demonstrated in the KiKs simulator.

Questions to Consider in Your Experiments

During this investigation, you should consider and investigate (at least) the following questions:

 What is the best way to generate the training data?

 What type of neural network should you use?

 How many layers should you use?

 What transfer functions should you use for each layer?

 Does the training data have to be “normalised” to give input and output values that are in appropriate ranges for the neural network?

 How many neurons should you include in each layer (particularly any hidden layers)?

 What training algorithms should you use?

 Does the network show any signs of overfitting, with the corresponding poor generalisation?

 How well does the trained neural network work as a controller for the robot?

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 5 of 5

Programming Tips

 All the Matlab code and files that are necessary for a similar task of obstacle avoidance have been provided on StudyNet as an example for this coursework. These files are available under the Matlab Code folder.

 The Matlab commands meshgrid and reshape may be useful to generate input patterns for the training set. A simple example (meshgrid_demo.m) of the use of these functions is included the navigate_example folder on StudyNet.

 Training data can also be generated by running KiKS simulator with FIS_navigate.m.

 The command evalfis can take a matrix of input values as a parameter and generate many target output values at once.

 You can define, train and test your neural network either by using Matlab commands directly at the command line or by using the graphical interface of nntool.

 You will need to use the Matlab commands load and sim to read the neural network into NN_navigate.m and to calculate the running speed and turn rate.

 If you had to “normalise” your training data, don't forget to "un-normalise" the output of your neural network to get the desired turn rate for testing the controller.

 The inputs and outputs of your neural network must be identical to those of the given FIS. Check the given FIS and the given FIS_navigate.m file to see what they are and how they are generated.

 Remember to choose the best neural network from a solution pool.

 Has negative running speed be avoided in your design?

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Finite Element Analysis of Engineering Components

School of Engineering and Computer Science

Page 1 of 6

COURSEWORK ASSIGNMENT

Module Title: FEA & Applications

Module Code: 7ENT1059

Assignment Title: Finite Element Analysis of Engineering Components

Group Assignment (3 students per group)

Tutor: Opus David-West

Internal Moderator: Mahmoud Chizari

Student ID Number ONLY:

Year Code:

Marks Awarded %:

Marks Awarded after Lateness Penalty applied %:

Penalties for Late Submissions

• Late submission of any item of coursework for each day or part thereof (or for hard copy submission only, working day or part thereof) for up to five days after the published deadline, coursework relating to modules at Levels 0, 4, 5, 6 submitted late (including deferred coursework, but with the exception of referred coursework), will have the numeric grade reduced by 10 grade points until or unless the numeric grade reaches or is 40. Where the numeric grade awarded for the assessment is less than 40, no lateness penalty will be applied.

• Late submission of referred coursework will automatically be awarded a grade of zero (0).

• Coursework (including deferred coursework) submitted later than five days (five working days in the case of hard copy submission) after the published deadline will be awarded a grade of zero (0).

• Where genuine serious adverse circumstances apply, you may apply for an extension to the hand-in date, provided the extension is requested a reasonable period in advance of the deadline.

Please refer to your student handbook for details about the grading schemes used by the School when assessing your work. Guidance on assessment will also be given in the Module Guide.

Guidance on avoiding academic assessment offences such as plagiarism and collusion is given at this URL: http://www.studynet.herts.ac.uk/ptl/common/LIS.nsf/lis/citing_menu

If the assignment is laboratory based (though not computer-based), or involves offsite activity, please attach the risk assessment form for the Internal Moderator to see.

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 2 of 6

ASSIGNMENT BRIEF

Students, you should delete this section before submitting your work.

This Assignment assesses the following module Learning Outcomes (Take these from the module DMD):

1. Explore the underlying physical principles and numerical methods of CAD and FEA Techniques

2. Use appropriate material properties, physical properties and boundary conditions for CAE models.

3. Critically evaluate simulation results from complex problems requiring advanced solution methods using industry standard post processors and analytical techniques

Assignment Brief:

• Complete all tasks in FEA Assignment 1 and FEA Assignment 2

• Write a report in which you should consider the aspects requested in the task sheets.

The page number of your report should not exceed 10 pages. Your report should be submitted as ONE document ONLY through the StudyNet/Canvas by ONE member.

No hard copy is needed.

Submission Requirements:

The page number of your report should not exceed 10 pages. Your group report (3 persons per group) should be submitted as ONE document ONLY through the StudyNet/Canvas by ONE member.

SRN numbers of the group members should be written on the front page.

No hard copy is needed.

This assignment is worth 25 % of the overall assessment for this module.

Marks awarded for:

See marking guide below.

A note to the Students:

1. For undergraduate modules, a score above 40% represent a pass performance at honours level.

2. For postgraduate modules, a score of 50% or above represents a pass mark.

3. Modules may have several components of assessment and may require a pass in all elements. For further details, please consult the relevant Module Guide or ask the Module Leader.

Typical (hours) required by the student(s) to complete the assignment: 20 hours

Date Work handed out:

6th March 2020

Date Work to be handed in:

3rd April 2020

Target Date for the return of the marked assignment:

Within 4 weeks

Type of Feedback to be given for this assignment:

Comments on marks document through StudyNet / Canvas.

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 3 of 6

Note: All sources used must be referenced using Vancouver or

Harvard referencing style.

FEA Assignment Task1: (65%)

LINEAR ANALYSIS and MODEL UPDATING

In present day structural dynamics, finite element tools are used to simulate the dynamic behaviour of

structures under several operating conditions and this usually includes some simplification /

assumptions in the development of the analysis; usually the initial numerical result does not match the

dynamic characteristics of the real structure, hence it must be updated to reduce the degree of mismatch.

In this task you are required to:

Create a finite element model of the box shown in Fig. 1 made of steel of which typical elastic properties

are presented in Table 1. The box is hollow at the bottom and in Fig. 2 is a schematic of the structure

with the dimensions shown.

TASK 1A: 45%

Conduct a vibration analysis and update the initial analysis result to predict the experimentally obtained

natural frequencies shown in Table 2 which were extracted from the experimental frequency response

plot. Also presented in Table 3 are the mode shapes from the experiment.

Fig. 1: Photograph of box

Fig. 2: Schematic of box

Table 1: Elastic properties of steel

Modulus 200 G Pa

Poisson’s ratio 0.3

Density 7830 kg/m3

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 4 of 6

Table 2: Experimental natural frequencies

Mode number

Natural frequency (Hz)

1

16.99

2

20.01

3

23.47

Table 3: Experimental mode shapes

Your report should be presented technically to include the following:

o Concept of the dynamic analysis implemented

o Geometric modelling strategy

o Choice of elements

o Discretisation and boundary conditions implementation strategies

o Three mode shapes

o Comparison the numerical and experimental results.

o Initial set of natural frequencies and the updated set of natural frequencies

o Explanation of the model updating strategies

TASK 1B 20%

It is required to change material used in the construction of the box in Fig. 1 to an advanced material with orthotropic properties; highlight the challenges of included the material model to run the finite element analysis?

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

Page 5 of 6

FEA Assignment Task 2: (35%)

Consider a 0.3 m square aluminium plate of thickness 2.5 cm with a centrally located circular hole of 1.3 cm radius as shown in Fig. 3. It is subjected to a pressure on either side of 7 MPa on both ends.

The properties of aluminium are written in Table 4.

TASK:

o Create a nonlinear finite element model of the loaded aluminium plate and run the analysis.

o Obtain the change in length from the numerical model and compare with a simple analytical result.

o Present the discretization and possible stress result (eg stress intensity)

o Explain the result presented, stating possible suggestion for improvement to reduce tendency for early failure.

Fig. 3: Schematic of hollow plate

Table 4: Mechanical properties of aluminium

Modulus

76 GPa

Poisson’s ratio

0.33

Yield stress

275 MPa

Tangent modulus

1.33 GPa

UNIVERSITYOF HERTFORDSHIRE

School of Engineering and Computer Science

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Fig. 4 is a schematic illustration of bilinear material model.

Fig. 4: Bilinear material model

MARKS ASSESSMENT STRATEGY

REPORT STRUCTURE

(5 marks)

INTRODUCTION

✓ Technical explanation of the phenomena plus references and industrial application

✓ Select a citation style and keep consistency throughout your report.

(10 marks)

ANALYTICAL

✓ Understanding of the problem

✓ Justification and engineering understanding of approach used.

(10 marks)

SIMULATION

✓ Geometry and discretisation

✓ Judgement of discretisation.

✓ Interpretation and inclusion of parameters

✓ Loading and analyses

✓ Extraction of results and analysis

(30 marks)

DISCUSSION

✓ Explain the results obtained.

✓ Justification of methods used

✓ Interpret the significance, stating useful suggestions.

(25 marks)

CONCLUDING REMARKS

(15 marks)

REFERENCES

(5 marks)

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