publication . Bachelor thesis . 2008

Pressure Control of a Pneumatic Actuator Using On/O Solenoid Valves

Jeddi Tehrani, Maisam;
Open Access English
  • Published: 01 Jan 2008
  • Publisher: KTH, Reglerteknik
  • Country: Sweden
Abstract
Nowadays a very important aspect in heavy duty vehicles is the braking system. The braking system can be divided into EBS brakes, exhaust brake and retarder, where the latter is of interest in the present Master's Thesis. This thesis presents an investigation whether it is possible to substitute today's concept, i.e. controlling the air pressure to the retarder using a proportional-valve, with two so-called on/o®-valves and a pressure sensor, which will reduce expenses and contingently hysteresis phenomena seen in the current system. A non-linear model of the Electronic Control Unit (ECU) electrical drives, and the electrical, magnetic, mechanical, and pneumatic...
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2 Retarder 17 2.1 Scania's Retarder . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.1.1 Retarder system today . . . . . . . . . . . . . . . . . . 17 2.1.2 Retarder System Using On/O® Solenoid Valves . . . . 18 2.2 Dead Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.3 Solenoid Valves . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.4 Equipments In Experiments . . . . . . . . . . . . . . . . . . . 21 2.4.1 ECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4.2 Prototypes . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.5 Retarder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.6 Pressure sensor . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.7 Software Program . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.8 Oscilloscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.9 Multimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3 Modelling 25 3.1 System description . . . . . . . . . . . . . . . . . . . . . . . . 26 3.2 ECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.3 Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.3.1 The Electrical Subsystem . . . . . . . . . . . . . . . . 28 3.3.2 The Magnetic Subsystem . . . . . . . . . . . . . . . . . 31 3.3.3 The Mechanical Subsystem . . . . . . . . . . . . . . . 32 3.3.4 The Pneumatic Subsystem . . . . . . . . . . . . . . . . 33 3.4 Regulating valve . . . . . . . . . . . . . . . . . . . . . . . . . 36

5 Model Improvements 55 5.1 Parameter tuning . . . . . . . . . . . . . . . . . . . . . . . . . 55 5.1.1 Discharge coe±cient Cd . . . . . . . . . . . . . . . . . 55 5.1.2 Air gap . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5.2 System identi¯cation of electrical model . . . . . . . . . . . . 59 5.3 Time Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 5.4 Temperature dependent resistance . . . . . . . . . . . . . . . . 61

6 Control Design 63 6.1 Control Objectives and Background . . . . . . . . . . . . . . . 63 6.2 PID Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 6.2.1 Principles of PID Control . . . . . . . . . . . . . . . . 64 6.2.2 Implementation . . . . . . . . . . . . . . . . . . . . . . 65 6.3 Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 6.3.1 Scheme 1-Fill Valve and Ventilation Valve activated separately for ¯lling and ventilation. . . . . . . . . . . 66 6.3.2 Scheme 2-Both Valves activated simultaneously for ¯lling and ventilation. . . . . . . . . . . . . . . . . . . . . 66 6.4 Results-Scheme 2 . . . . . . . . . . . . . . . . . . . . . . . . . 68 6.4.1 Simulations . . . . . . . . . . . . . . . . . . . . . . . . 68 6.4.2 Test on Prototypes . . . . . . . . . . . . . . . . . . . . 69 6.5 Control Improvements . . . . . . . . . . . . . . . . . . . . . . 70 6.5.1 Anti-Windup . . . . . . . . . . . . . . . . . . . . . . . 70 6.5.2 Improved Control using Non-Linear Control . . . . . . 70 6.5.3 Improved Control using Prediction . . . . . . . . . . . 72 6.6 Comparison between the two approaches . . . . . . . . . . . . 73

[1] Scania CV AB, SÄodertaÄlje. 2008. http://www.scania.com

[2] Kleinknecht Automotive GMBH. 2008. http://www.kleinknecht.com/

[3] Lennart Ljung, Torkel Glad, Modellbygge och simulering,2004.

[4] Gunnar Petersson, "Elkretsanalys", Alfvenlaboratoriet, Tekniska HÄogskolan, Stockholm, 2003.

[5] G.Petersson. "Teoretisk Elektroteknik - StationÄara fenomen". 2004.

[7] Christer Nyberg, Mekanik Grundkurs.Liber AB, 336, January 2003.

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