Implementation and Testing of a Semi-Active Damping System

The purpose of this thesis is to implement and test a semi-active damping system based on a concept from an earlier thesis. The project includes implementation of mechanical, hydraulic and electronic hardware, as well as controller software. The idea is to measure the movements of the vehicle chassis and based on these measurements set the damping torque using hydraulics. To be able to develop, test and evaluate the system, realistic input data must be available. To acquire such data, driving trials have been conducted on a variety of tracks.The first part of the system is the sensors that measure chassis movements. Both accelerometers and a gyro has been used. To remove drift and high frequency vibrations, the signals are filtered. The suggested controller from the earlier thesis requests damping torque based on the dampers vertical velocity. When accelerometer signals are integrated, measurement and rounding errors causes drift in the velocity. To compensate for this, a floating average is calculated and used.The main hydraulic component is a pressure reduction valve that controls the pressure inside the damper. Higher pressure will give higher damping torque…


1 Introduction
1.1 Background
1.2 Purpose
1.3 Presentation of Problems
1.4 Method
1.5 Outline
1.6 Delimitation
1.7 Goal
1.8 Target Group
2 Semi-Active Damping System
2.1 Tools and Interface
2.1.1 Development and Testing Tools
2.1.2 Programming
2.1.3 Code Transfer
2.1.4 Calibration and Interface
2.1.5 TargetLink, DataDictionary and External Declaration
2.1.6 Driving Trials
2.1.7 Software Simulation
2.2 Systems Overview
2.3 Mechanical and Hydraulic Hardware
2.3.1 Damper modiļ¬cations
2.3.2 Pressure Control Hydraulics
2.3.3 Valve Plate and Hosing
2.4 Electronic Hardware
2.4.1 Accelerometers and Gyro
2.4.2 Control Computer
2.4.3 DSV
2.4.4 Wiring and Connectors
2.5 Damper Control Software
2.5.1 Input Conversion
2.5.2 Signal Filtering
2.5.3 Integration
2.5.4 Floating Average Drift Compensation
ix2.5.5 Anti Saturation
2.5.6 Velocity Recalculation
2.5.7 Aurora Controller
2.5.8 Rate Limiter, Backlash and Requested Pressure
2.5.9 Output Conversion
2.5.10 Interface Code
2.6 Test Equipment
2.6.1 Recreating the Recorded Signals
3 Test Results and Conclusion
3.1 Simulation Results
3.1.1 Drift
3.1.2 Filter Effects on Acceleration
3.1.3 Which is Faster, Accelerometers or Gyro?
3.1.4 Damper Velocities at Exaggerated Bumps Track
3.2 Test Results
3.2.1 Hydraulics Alone
3.2.2 Entire System Including Control Computer
3.2.3 Recorded Tracks
3.3 Conclusions
3.3.1 Sensors
3.3.2 Computer and Control Software
3.3.3 Hydraulics
3.3.4 Other Things
A Recorded Signal
B Figures
C Offset Electronics
D Distorted Signal

Author: Nordin, Peter

Source: Linkoping University

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