1. Active Suspension System
Students: Caleb Dell, Leslie Garcia, Alex Jaeger
Advisors: Prof. Jing Wang, Prof. S. D. Gutschlag
Who talks when
Leslie 1-10
Caleb
Alex

2. Outline Project Summary Previous Work System Block-Diagram
Component Descriptions
Functional Descriptions
Work Completed
Future Work
References
Questions

3. Project Summary
Goal
Design a system to minimize vertical disturbance of a suspended body
Application
Provide a gentle ride to passengers by removing disturbances imparted to a vehicle due to uneven terrain
Apparatus Description:
Lower Platform
Linear Actuator
H-bridge
Microcontroller
Upper Platform
Position Sensor
** More professional wording - break to two slides, increase size of font
Lower Platform: used to apply disturbance to the actuator and the upper platform
Upper platform: used to support applied load
Linear Actuator: Extends and retracts to reduce disturbance
Position sensor: upper platform sensor

4. Previous Work 1990-1991 Team 2006-2007 Team Constructed apparatus
Replaced pneumatic cylinder with an electric linear actuator

5. Previous Work Team
2006 -Aside from replacing the pneumatic cylinder with a linear actuator they were able to create a simulink model which represents how the linear actuator functions.
Later on we will talk about our own simulink, but we used 2006s simulink as a base for ours
How the linear actuator functions

6. Previous Work: team
Organized H-bridge and associated electronics in an enclosure
Heat Dissipation
Added cooling fans
Emergency control
Limit switches
Emergency stop

7. System Block Diagram Active Suspension System Block Diagram
Inputs into the Active Suspension system:
Emergency stop, On/Off, User Input
After it goes into the active suspension system, a disturbance is added and then its feedback to be able to go through the system again, then we would get the actuator position

8. Hardware Components Upper & Lower Platform
Position Sensor (Potentiometer)
Safety Relays
4 pole, double throw
Position Limit Switches
Linear Actuator
Motor Type: 160 volt brushed DC
Maximum Load Capacity: 3600 N (810 [lbs])
Rotating Camshaft driven by a 3-phase induction motor controlled by a VFD
Upper and lower Platform: The system will ensure that the upper platforms vertical motion will be maintained at the desired position specified by user. The lower platform will oscillate in the vertical direction and it will be controlled by the 3-phase AC induction motor connected to the camshaft.
Potentiometer:One is connected to the upper platform to measure instantaneous position and provide feedback to the controller.
Safety Relays: two 4 pole relays that are used for emergency system shut-down. In the default position the AC induction motor is open, so the camshaft will not rotate. Once a 24 volt DC signal is applied then the relay coil is active and the switches will close to disables the brake and connect the 3-phase VFD to the AC induction motor. Both the limit switches or emergency stop can switch the relay to the safety position.
Limit Switches: There are two limit switches connected to the system to guarantee an upper and lower bound of motion in the event of a controller malfunction. When one of the switches is activated then both safety relays will switch to their open positions and the system will stop working.
Linear Actuator: It will be driven by the H-bridge, which is also controlled by the Atmega128 board. The actuator is mounted to both the upper and lower platform. The actuator shaft will extend and retract to compensate for the lower platform movements based on the output of the potentiometer.
Rotating Camshaft: The rotating camshaft will rotate at all times during system operations unless the operator turns off the VFD controlling the 3-phase AC induction motor, or the emergency stop is activated.

9. Critical Electrical Hardware Components
LM317 Voltage Regulators (12[V]/1[A]) - Power for cooling fans
LM7815 Voltage Regulators (15[V]) - Vcc for H-bridge
LM7805 Voltage Regulator (5[V]) - Output side of the 6N137 optical isolator
MY2N-D2 Power Relays - Used as safety relays
The white control box mounted to the top of the active suspension system contains the connections to all subsystems on the apparatus.
This includes an LM317 voltage regulator set to provide 12[V] for the cooling fans, one LM7815 voltage regulator used to provide 15[V] to the VCC pin for the MSK H-bridge, and one LM7805 voltage regulator used to provide 5[V] to the 6N137 optical isolators.
There are two OMRON MY2N-D2 safety relays connected to the emergency stop button which can be used to deactivate the linear actuator motor and the AC induction motor in an emergency.

10. Critical Electrical Hardware Components Cont.
6N137 Optical Isolator
MSK 4227 H-Bridge
Maximum Current Rating 20 [A] at a case temperature of 25°C
Maximum Voltage Rating 200 [V]
Atmega128A Board (Embedded C)
Operating Voltages: [V]
Speed Grades: 0-16MHz
Optical Isolator is where the inputs of the microcontroller are going. Used so it destroy pins of the microcontroller. If something fails (diode) - the inductor will keep current going-> destroy microcontroller
Isolate voltage from load
An optically-coupled MSK 4227 H-bridge connected to an Atmega128A microcontroller is used to control the direction, forward and backward, and speed of the linear actuator motor as required to maintain the desired upper platform position.
if asked: 20a at 25C
Thermal computations later on

11. Testing the Microcontroller Subsystem
Microcontroller tasks:
Generate PWM signals at varying duty cycles
Convert analog voltage signal from sensor potentiometer
Compute position based on converted analog signal
Alternate PWM signals for desired motor direction to maintain desired upper platform position

12. Microcontroller - Pins Used
Output pins PB4 (OC0) and PB7 (OC2/OC1C) for generating two PWM signals to control the high-side transistors
Input pin PF0 (ADC0) for ADC input
Separately controlled output pins PC0 and PC1 to control the low-side transistors on the H-bridge
PortA connected to LEDs to indicate position is within desired deadband

13. Microcontroller - PWM Signal
Fast PWM mode
Pre-scalar = 64
Frequency = 976 [Hz]
OCR0 and OCR2 control duty cycle
figure - indicate where it is from,
Fix upper text boxes - bigger font
Where did 1Khz come from?
To be more efficient

14. Microcontroller - ADC Pin PF0 (ADC0) is used for ADC input 10-bit ADC
0-5 [V] range
5 [V] = 6 [in] (full length of actuator stroke)
ADC input is used to compute current position

15. Proposed Bang-Bang Controller Flow Diagram

16. Work Completed Updated schematic diagram
Three-phase motor safety relay connections corrected
Built and tested discrete component H-bridge
Used to verify software functionality
Designed and conducted experiments to determine motor friction constants Tc and b
Simulink models for the linear actuator
Completed parts list

17. Schematic Diagram

18. Three-Phase Motor Safety Relay
Team
Three-phase was not functional
Used updated schematic diagram to determine the wiring error
Three-phase induction motor was initially connected to the normally closed pins instead of the normally open pins

19. Discrete Component H-Bridge
Used to test the linear actuator control software
Duty cycle must be less than 93% to ensure bootstrap capacitors recharge between cycles
Bootstrap capacitors provide a floating voltage for the high-side transistors to use
Discrete component 93%
MSK 97%

20. Discrete Component H-bridge
Reverse

21. Forward Motion Simulation
Signal 1: Duty cycle generated by the waveform generator
Signal 2: Voltage of the HINA gate
Signal 3: Voltage across the Pittmann motor

22. Modeling Friction Constants
Coulombic friction (Tc) and viscous damping coefficient (b) are not listed in actuator datasheet
Experimental procedure to determine Tc and b
Generated software to drive the linear actuator at a specific shaft speed for a specified time
Measured average current flow to the actuator motor to compute generated torque
Computed steady-state linear velocity
Solved system of equations for Tc and b using ω and ω2
Not complex equations - simple

23. Simulink Diagram Block diagram with omega (ω) 45 volts and 5lbs
*ADD PLOTS*
Get experimental plots
get simulink plots for position vs time - velocity

24. Linear Velocity: Model vs. Experiment
Linear Velocity (Model): in/sec
45[V] applied to motor at 60% duty cycle with 5[lb] load
Linear Velocity (Experiment): ~4.8 in/sec
45[V] applied to motor at 60% duty cycle with no-load
This is what we are getting at the moment - W^2 should be more accurate

25. Simulink Diagram Block Diagram with ω2
Conducted simulations with 45 [V] input and a 5 [lb] mass on actuator

26. Linear Velocity: Model vs. Experiment
Linear Velocity (Model): in/sec
45[V] applied to motor at 60% duty cycle with 5[lb] load
Linear Velocity (Experiment): ~4.8 in/sec
45[V] applied to motor at 60% duty cycle with 5[lb] load
Could be off 5% for the experimental data - ability to read experimental data is limited.
Difference between w and W^2 at low voltages should be virtually identical

27. Parts List point out the equipment that we would need:
Voltage regulator
Extra limit switches

28. Future Work Scheduled controller designs Bang Bang Controller
Proportional Controller
Percent overshoot
Rise time
Settling time
Gain and phase margins
Damping ratio
Natural frequency

29. Future Work Cont. If time permits Proportional- Integrator (PI)
Proportional-Integrator-Derivative (PID)
Feedback component from position to acceleration

30. Future Division of Labor
Caleb: Programming control theories in embedded C
Leslie: Simulink and research
Alex: Hardware and circuit design

31. Tentative Schedule Fall Semester
11/08/ /28/18: Work on bang-bang control system
11/28/18-12/4/18: Website and proposal
Spring semester
1/22/ /20/2019: Finish with bang-bang and work on proportional system
4/16/ /30/2029: If time allows, work on proportional-integral system and proportional-integral-derivative.
4/30/ /10/2019: Work on final presentation, poster, and deliverables

32. References
[1]   A. Serreurier, J. Rose, C. Ramseyer, R. Vassey (2017): 
[2] A. Tantos, “H-Bridges - The Basics.” Modular Circuits, [Online]. Available: secrets/h-bridges-the-basics/. [Accessed: Oct. 20, 2018]
[3]   Atmel, “8’bit Atmel Microcontroller with 128Kbytes In-System Programmable Flash,” ATmega128/L Datasheet, 2011
[4]  Avago, “2.5 Amp Output Current IGBT Gate Drive Optocoupler,” HCPL-3120/J312 datasheet, March 21, 2016
[5]   G. Franklin, D. Powell, and A. Emami-Naeini, Feedback Control of Dynamic Systems, Seventh. Pearson, 2015.
[6]   Industrial Devices Corp., “Electric Cylinder Overview,” EC2-H Series Datasheet
[7]   Maurey, “Linear Motion Potentiometers,” P1613 Datasheet
[8]   M. S. Kennedy Corp., “200 Volt 20 Amp MOSFET H-Bridge With Gate Drive,” MSK 4227 Datasheet, November  2004
[9]   Omron, “Miniature Power Relays,” MY4N-D2 Datasheet
[10] STMicrocontrollers, “N-Channel 250V – 22A Power MOSFET,” STP22NS25Z Datasheet
[11] Texas Instruments, “LM317 3-Terminal Adjustable Regulator,” LM317 Datasheet

33. Questions include back up slide for equations
bootstrap capacitor - explain it

34. Equations