Active Suspension System Test Platform Bradley University Department

Active Suspension System Test Platform Bradley University Department of Electrical & Computer Engineering By: Craig Chan & Olusegun Michael Abidoye Advisor: Steven Gutschlag 27 April 2005

Outline n n n n Project Summary Division of Labor Functional Description Block Diagrams Subsystems Test Results Parts List Questions?

Project Summary n Providing a test platform for active/passive suspension system n Testing vehicle suspension system n Actuator driven and micro-controller based n Common feedback control applications CNC fabrication machines n Aviation control n

Division of Labor n Craig n Design and build power electronics to drive a 115 Volt DC motor n Microcontroller isolation circuitry n H-Bridge design Control algorithm n Testing and debugging n n Mike n Microcontroller based feedback control system n Control Algorithm n A/D converter n PWM (Timer 2) n Testing and debugging

Functional Description n Microcontroller feedback system ensures proper output independent of load. n The mode of operation will be determined by the user via a keypad on the micro-controller. n n Sinusoidal Step Triangular Flexibility in selecting desired speed and travel distance of the platform

Overall Control Block Diagram Pe Pi Pa Perror = Pinput – Pactuator Output (Platform Position)

System Block Diagram Analog Position Input Keypad Input (Desired Platform Motion) A/D Converter EMAC Micropac 535 Micro-Controller Interface POSITION FEEDBACK Display ( user input) Power Electronics Test Platform Output (Platform Motion)

Hardware Subsystem

Hardware Configuration Power MOSFETS

4 N 25 Phototransistor Optocouplers Infrared emitting diode driving a phototransistor n Provides voltage isolation between the microcontroller and the IR 2213 n

IR 640 N Power MOSFET’s Drain to Source Voltage Max = 200 Volts n Continuous Drain Current Max = 18 A n

IR 2213 High & Low Side Driver Configuration Load supply voltage up to +1200 volts n N-Channel MOSFETs (Faster & Cheaper) n

IR 2213 High & Low Side Driver Decoupling Capacitors Charge Pump Bootstrap Circuit Decoupling Capacitor

H-Bridge IR 2213 Vcc (Signal to MOSFETs) A (Signal to MOSFETs) B ON ON C Gnd D

Software Subsystem

Setup Module n Initializes the microcontroller n Setups interrupt vector tables n Setups necessary peripherals n Configures interrupt priority n Jumps to main module

Main Module n Welcomes the user n Prompts the user platform parameters n Amplitude and frequency n Waveform (single or continuous)

Keypad Module n EX 1 interrupt handler Fetches keys pressed via kpad subroutine n Translates keys to ASCII equivalent n Performs necessary task for each key n n Key A = Single Step input n Key B = Backspace n Key C = Continuous waveform input n Key D = Stop suspension n Key E = Start suspension

Lcd Module n Displays prompts n Displays user’s entries

Timer 2 Module n Configuration Auto reload , mode 0 n Compare mode 1 (16 bits) n n Subroutines PWM Subroutine n Timer 2 interrupt handler n EX 4 interrupt handler (when T 2 register = CC 1) n EX 5 interrupt handler (when T 2 register = CC 2) n

PWM Subroutine Generates two PWM signals at P 4. 1 and P 4. 2 n Decides which one to turn on, via direction flag n Generates three interrupts n T 2 interrupt (overflow) n CC 1 = T 2 EX 4 interrupt n CC 2 = T 2 EX 5 interrupt n

PWM Subroutine • Checking direction flag • Forward Pwm • Reverse Pwm

n Timer 2 interrupt handler

n EX 4 interrupt handler n Forward PWM

n EX 5 interrupt handler n Reverse PWM

A/D Module n Determines status of direction flag n A/D_pi n n Fetches input signal from AN 0 A/D_pa n Fetches position feedback from AN 2

Control Block Diagram Input Voltage Signal Representing the Desired Platform Motion (Provided by the Waveform Generator) Gain Old Duty Cycle Output (Platform Motion)

Suspension Module n DC_new = DC_old + K * Pe n n Pe = Pi – Pa PWM) (Pi > Pa, clr dir flag, forward DC_new = DC_old – K *Pe n Pe = Pa – Pi PWM) (Pa > Pi, setb dir flag, reverse

Test Platform Subsystem

Rated DC Motor Specifications RPM Max 1725 n Horse Power 1/3 n Volts 115 n Amps 3. 4 n

Screw Jack Specifications (Nook Industries) 18 Inches of Stroke Length n Gear Ratio 5: 1 n Turns of worm per inch travel = 10 n Max Horse Power 1/3 n Max load = 1000 Lbs n Max worm speed at rated load = 868 RPM n Max load at 1750 RPM = 496 lbs n Assembled with a top plate n

Inch Ball Screw Jack n Without Top Plate n With Top Plate

Preliminary Experimental Results Electrak mini actuator Pi = Input signal Pa = Actuator Position

Sinusoidal Input Pi = Input signal Pa = Actuator Position

Triangular Input Pi = Input signal Pa = Actuator Position

Parts List Micro Pac 535 (EMAC Kit # 5) n High and Low Side Driver (IR 2213) n Phototransistor (4 N 25) n N-channel Power MOSFETS (IR 640) n Electrak mini actuator n Screw Jack (0. 5 HL-BSJU) n DC Motor (437698 -AW) n

QUESTIONS ?