Safety has always been an important issue for the vehicle manufacturers. Passive safety systems like safety belt are found in nearly every vehicle and airbags can be installed in the front as well as the side of the vehicle.
Traction is necessary for a vehicle to be able to brake, accelerate and turn. When pushing the accelerator pedal too hard during an acceleration, the wheel can loose traction and start spinning, which leads to a worsen vehicle control and also wears out the tyres faster. The traction control system prevents the wheels from spinning and tries to make the tyres maintain maximum traction. The purpose of this master’s thesis is to evaluate different control methods and to investigate possible ways to control the traction. This is a difficult control problem due to its nonlinearity and the fact that the friction is an unknown parameter.For the investigation, a model of the wheel dynamics and a model of the powertrain…
Contents
1 Introduction
1.1 Traction control
1.2 Problem formulation
1.3 Purpose and objective
1.4 Related research
1.5 Limitations
1.6 Outline of the report
2 Wheel dynamics
2.1 A driven wheel
2.2 Adhesive force
2.3 Wheel slip
2.4 Resistance forces
2.5 Model of the wheel dynamics
3 Powertrain
3.1 Introduction to the powertrain
3.2 Powertrain components
3.3 Powertrain model
4 System modelling
4.1 System
4.2 Model simplifications
4.2.1 Stiff components
4.2.2 Internal frictions
4.2.3 Resistance forces
4.2.4 Summary of the model simplifications
4.3 Choice of parameters
4.4 Simulation problems
4.5 Model validation
4.5.1 Real system
4.5.2 Torque and angular velocity propagation
ix5 Control theory
5.1 Observer
5.2 PID control
5.2.1 The PID terms
5.2.2 PID parameter tuning
5.3 Fuzzy control
5.3.1 Fuzzification
5.3.2 Fuzzy rules
5.3.3 Defuzzification
5.4 Sliding mode control
6 Control design
6.1 Choice of controllers
6.2 Observer
6.3 PID controller
6.4 Fuzzy controller
6.5 Fuzzy-PI controller
7 Tests and results
7.1 Testing
7.1.1 µ-slip curves
7.1.2 Test cycles
7.2 Results
7.2.1 Test cycle 1 – Acceleration 0-20 km/h
7.2.2 Test cycle 2 – Acceleration 15-40 km/h
7.2.3 Test cycle 3 – Surface change
8 Conclusions and future work
8.1 Conclusions
8.2 Future work
Bibliography
Author: Zetterqvist, Carin
Source: Linköping University
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