Active suspension system

Active suspension system
An active suspension is a type of automotive suspension on a vehicle. It uses an onboard system to control the vertical movement of the vehicle's wheels relative to the chassis or vehicle body rather than the passive suspension provided by large springs where the movement is determined entirely by the road surface. So-called active suspensions are divided into two classes: real active suspensions, and adaptive or semi-active suspensions. While adaptive suspensions only very shock absorber firmness to match changing road or dynamic conditions, active suspensions use some type of actuator to raise and lower the chassis independently at each wheel.

1. SUBJECT : MECHATRONICS SYSTEM

GROUP NO. 13

NAME ROLL NO.
GAURAV WADIBHASME [29]
SANGEET KHULE [60]
VAIBHAV PANDEY [74]

SHRI RAMDEOBABA COLLEGE OF ENGINEERING AND
MANAGEMENT



ACTIVE SUSPENSION SYSTEM
GROUP 13 1

2. •An active suspension is a type of automotive suspension on a vehicle.
•It uses an onboard system to control the vertical movement of the vehicle's
wheels relative to the chassis.
•An active suspension system has the capability to adjust itself continuously
to changing road conditions.
•Active suspension offers superior handling, road feel, responsiveness and
safety.
GROUP 13 2
INTRODUCTION
TYPES OF ACTIVE SUSPENSION SYSTEM WORKING
Semi-active Varies shock absorber firmness
Hydraulic actuated Hydraulic servomechanism
Electromagnetic recuperative Linear electromagnetic motors

3. GROUP 13 3
FIGURES

4. GROUP 13 4
BLOCK DIAGRAM
Mode
Ride Height
Forces
Speed
Stereo
camera
ECU
Actuator
(Semi-Active/
Hydraulic
Actuated/ Ele-
ctromagnetic
Recuperative)
Quick up
and down
of suspen-
sion on
each
wheel
Position
CONTROL
UNIT
Lateral G
Forces
Longitudinal
G Forces
Pitch Rate
Roll rate
INPUT ACTUATOR PROCESS OUTPUT

5. RIDE HEIGHT
LATERAL G-FORCE
LONGITUDINAL G-FORCE
ROLL RATE
PITCH RATE
SPEED
STEREO CAMERA DATA
GROUP 13 5
THE LIST OF VARIABLES TO BE
MONITORED

6. SENSORS


GROUP 13 6
VARIABLES SENSORS
•Stereo camera Data •Stereo Video Camera
•Ride Height •Laser Position Sensor
•Speed •Wheel Speed Sensor
•Lateral G-force
•Longitudinal G-force
•Roll Rate
•Pitch Rate
•Inertial Sensor

7. Bosch Stereo video camera
Consists of two CMOS color imagers
 These sensors convert the brightness and color information into
electrical image signals.
The camera is capable of determining the size, speed and
distance of all objects, including vehicles, pedestrians, cyclists
and motorcyclists, as well as obstacles on or near the road.



GROUP 13 7
STEREO VIDEO CAMERA

8. GROUP 13 8
SENSOR CHARACTERISTICS BOSCH
Imager size 1280 x 960 pixels
Field of view
Horizontal
Vertical

50° (nominal)
28° (nominal)
Resolution 25 pixels/°
Frame rate 30 images/second
3-D measurement range ~55 m
Exposure dynamic 110 dB
Wavelength 400...750 nm
Current consumption <5.8 W (0.4 A at 14 V)
Operating temperature -40 to +85°C (+105°C for CAN
communication)
Dimensions (L x W x H) 160 x 60 x 32 mm

9. Acuity AR500
Non-contact displacement
sensor
Consists laser diodes and CCD
receiver
Uses laser
triangulation principle
CCD element receives laser
beam reflected from objects

GROUP 13 9
LASER POSITION SENSOR

10. Measurement ranges 1000 mm
Maximum sampling rate 9,400 Hz
Resolution 200 µm
Linearity 1500 µm
Operating temperature range -10 to 60°C
Analog output 4-20mA or 0-10V
Power 9 - 36 Volts DC, 250 mA max. Voltage tolerance -5%
to +10%
Laser class 3R
Laser spot size 500 µm
Weight no cable 100 grams
Laser type STANDARD 650 nm, ≤4.8 nm visible RED/405 nm,≤0.95mw, visible
BLUE
Environmental NEMA – 4X, IP67
GROUP 13 10
SENSOR CHARACTERISTICS AR500

11. GROUP 13 11
WHEEL SPEED SENSOR
Bosch PG-3.9
Hall effect sensor and multi
pole ring
Multi pole ring consists of
magnets with alternating
polarity
Magnetic flux changes as
ring rotates
Output voltage generates
according to change in
magnetic flux

12. GROUP 13 12
SENSOR CHARACTERISTICS BOSCH PG-3-9
Minimum trigger-wheel speed 0 min.-1
Maximum trigger-wheel speed 8000 min.-1
Maximum working air gap 1.5 mm
Minimum working air gap 0.3 mm
Rated supply voltage 5 V
Supply voltage range 4.5 …18V
Supply current Typically 6.7
Output current 0 … 20 mA
Output saturation voltage ≤ 0,5 V
Switching time ≤ 1,3 µs
Switching time ≤ 20 µs
Steady-state temperature in sensor and transition zone
-40°C…+150°C

Steady-state temperature in connector zone
-40°C…+130°C

13. Bosch MM5.10 (5 dimensional
sensor)
Principle- Cariolis vibratory
gyroscope
High-frequency electrostatic
forces generate an oscillation
of two seismic masses
controlled by a closed loop
drive system.
When rotating around the axis,
the Coriolis forces acting on the
oscillators can be measured by
capacity changes in
the detection system.



GROUP 13 13
INERTIAL SENSOR

14. It consists of movable comb-
like seismic masses suspended from
silicon spring bars and fixed
counter electrodes.
 As a result of external forces acting
on the sensor, deflections of the
seismic masses along the sensitive
axis generate changes in the
capacity of the system.
GROUP 13 14

15. Sensing axes (Ωz), min/max values L Longitudinal acceleration
sensor (ax, ay, az.)
Measuring range ± 163 °/s ± 4.2 g
Resolution ± 0.1 °/s
Digital resolution 200 LSB/°/s
Sensitivity errors ≤ ±4 % (typically ±2.5 %) ≤ ±3 % (typically ±2.0 %)
Offset ≤ ±3 °/s (typically ±1.5 °/s) ≤ ±0.1 g (typically ±0.05 °/s)
Non-linearity ≤ ±1 °/s (typically ±0.5 °/s) ≤ ±0.072 g (typically ±0.036
g)
Operating temperature range -40°C … +85°C
Supply voltage range 7 to 16 V
Current consumption at 12 V 65 mA
CAN Interface in acc. With ISO 11898
GROUP 13 15
SENSOR CHARACTERISTICS BOSCH MM5.10

16. GROUP 13 16
POWER CALCULATION FOR
NORMAL WORKING OF THE
MECHANICAL SYSTEM

17. SYMBOL DESCRIPTION VALUE
m1 Car Weight (Chassis and
Body)
300 kg
m2 Wheel Weight 60 kg
k1 Spring Between Car body
and Wheel
16000 N/m
k2 Spring Between Road and
Wheel
b1 Damper Between Car body
and Wheel
19000 N/m
f(t) Actuator Force
z1 Displacement of the Car
Weight
z2 Displacement of Car Wheel
GROUP 13 17
QUARTER MODEL

18. GROUP 13 18
OBJECTIVES
Study the operation of active suspension car models.
Establish mathematical model for the active suspension system
of a quarter (one wheel) car model.
Analyze the mathematical model for the system in order to
improve its performance.
Variables: Force, Spring Constant

19. SOLUTION:
Assuming Compression
For m1 :

GROUP 13 19

20. For m 2 :

GROUP 13 20

21. For m :




Therefore Replacing Z3(S) by Z₂(S)
GROUP 13 21

22. Replacing equation 10 into equation #1

GROUP 13 22

23. Using Mathematica (wolfram alpha) to simplify equation #10

GROUP 13 23

24. After using the Wolfram Alpha website to simplify the equation,
MATLAB was used to plot the transfer function.

GROUP 13 24

25. Active suspension system, the system was analyzed for the
quarter car model.
The equation of motion was developed and then simplified.
The equations of motion were then used to obtain the transfer
function. The transfer function obtained was for the deflection
of the total mass to the force of the actuator Z1(S)/F(S), where
Z1(S) is the deflection of the car body and F(S) is force of the
actuator.
This transfer function was simplified using Mathematical
"Wolfram alpha website". The simplified equation was used in
mat lab to develop the output response graphically.
GROUP 13 25
CONCLUSION

26. GROUP 13 26
SELECTION OF THE ACTUATOR

27. There are generally two types of actuators for the application of
active suspension system
Hydraulic servomechanism
Linear electromagnetic motors

As the advantages of Linear electromagnetic motors are more
than advantages of Hydraulic servomechanism.
The actuator selected is linear electromagnetic motors.
A linear electromagnetic motor is installed at each wheel



GROUP 13 27
SELECTION OF THE ACTUATOR

28. An electromagnetic suspension system could
counter the disadvantages of a hydraulic system due to the
relatively high bandwidth (tens of hertz), and there is no need for
continuous power, ease of control, and absence of fluids.
It is also used for regeneration of energy
The linear electromagnetic motor responds quickly enough
to counter the effects of bumps and potholes
ADVANTAGES
•Increased efficiency
•Improved dynamic behavior
•Stability improvement
•Accurate force control
•Dual operation of the actuator




GROUP 13 28

29. GROUP 13 29
DESCRIPTION OF THE
ACTUATORS SELECTED

30. A high bandwidth linear electromagnetic motor is installed at
each wheel of the vehicle with active suspension system. Inside
the LEM, magnets and coils of wire are installed.
When electrical power is applied to the coils, the motor retracts
and extends, creating motion between the wheel and the car
body.
Thus, electrical energy is converted into linear mechanical force
and motion. The LEM can counteract the body motion of a car
while accelerating, braking, and cornering, thus ensuring
vehicle control.
It also responds quickly enough to counter the effects of bump
sand potholes, thus ensuring passenger comfort.
GROUP 13 30
LINEAR ELECTROMAGNETIC MOTOR

31. The motor is strong enough to put out enough force to prevent
car from rolling and pitching during aggressive driving
maneuvers.
In addition to the motor, the wheel dampers inside each wheel
hub further smooth out road imperfections. Torsion bars take
care of supporting the vehicle, thus optimizing handling and
ride dynamics.
Linear motor is essentially a multi-phase alternating current
(AC) electric motor that has had its stator "unrolled" so that
instead of producing a torque (rotation) it produces a linear
force along its length.

GROUP 13 31

32. The most common mode of operation is as a Lorentz-type
actuator, in which the applied force is linearly proportional to
the current and the magnetic field (F = qv × B)
Inside the linear electromagnetic motor are magnets and coils
of wire. When electrical power is applied to the coils, the
motor retracts and extends, creating motion between the
wheel and chassis.
For example, when the suspension encounters a pothole,
power is used to extend the motor and isolate the vehicle’s
occupants from the disturbance. On the far side of the pothole,
the motor operates as a generator and returns the power back
through
GROUP 13 32

33. A linear motor consists of two mechanical
assemblies: coil and magnet
Current flowing in a winding
in a magnetic flux field produces a force.
The copper windings conduct current (I),
and the assembly generates magnetic flux
density (B). When the current and flux
density interact, a force (F)
is generated in the direction show where

F = I * B
GROUP 13 33
OPERATING PRINCIPLE

34. The electromagnetic linear motor includes a magnetic structure
that has concentric inner and outer magnetic circuits which
move relative to one another in a rectilinear path with a
reciprocating motion based on the principle of generating a
linear force by the interaction of two magnetic fields to cause
relative movement between magnetic members
The inner magnetic circuit includes an elongated cylindrical core
which has a diametrically enlarged portion at one end and is
supported at its other end by a bottom plate.
An outer, concentric shell forms an air gap with the enlarged
portion and the shell is supported at one end by the bottom
plate.


GROUP 13 34
CONSTRUCTION

35. GROUP 13 35
A conductor is wound on the core to form a first electrical coil
to produce a first magnetic field across the air gap in response
to a first-applied electric signal.
 The outer magnetic circuit includes a shuttle assembly or
armature which is coaxially arranged between the core and
shell for rectilinear motion through the air gap.
A conductor is wound on the shuttle to form a second electrical
coil to produce a second magnetic field in response to a second-
applied electrical signal.
The shuttle moves with a reciprocating motion through the air
gap in response to the interaction of the first and second
magnetic fields.

36. GROUP 13 36
POWER CALCULATION FOR THE
ACTUATION MOTION

37. The actuator should be able to produce an r.m.s. force value​
of 1050 Newton in the steady state. Its stroke should be 160​
mm, and the peak velocity is about 1.2 m/s. ​

ACTUATOR DESIGN PARAMETERS

GROUP 13 37

38. GROUP 13 38
Actuator configurations: a) radial magnetization
b) axial magnetization
Linear actuator magnetic
circuit configuration.

39. The magnetic flux through the permanent magnet top:​


The magnetic flux density on the ferromagnetic cylinder​
wall: ​
​
​
where Bm is the permanent magnet working magnetic flux​
density medium value​

GROUP 13 39

40. Multiple Finite Elements simulations shown for a NdFeB​
permanent magnets slot less cylindrical linear actuator, that​
the maximum magnetic energy density is achieved when​
the air gap volume under the poles is approximately equal to​
the permanent magnet volume associated to this poles. For​
the analyzed lay-out:​

where Vm is the permanent magnet volume and Vg is the​
associated air gap volume. ​
​

GROUP 13 40

41. Taking a magnetic flux value through the armature equal to the
magnetic flux value through the ferromagnetic cylinder wall

where la is the length of the armature wall and Ba the
armature magnetic flux density.
GROUP 13 41

42. The actuator Lorenz force produced by a pair of windings and a
permanent magnet

GROUP 13 42

43. Where Lcu is the total conductor length of one winding under
the magnetic field, Bg the airgap medium magnetic flux density
and i the windings current, calculated from an allowed current
density value, taking into account the actuator cooling system.
The actuator final dimensions were calculated from


Where FA is the actuator steady state final force and nW the
total number of windings under magnetic field. The coefficient
K was calculated from

GROUP 13 43

44. GROUP 13 44
Flux plot of an actuator pair of
poles, using radially magnetized
NdFeB permanent magnets.
Flux plot of an actuator pair of poles,
using axially magnetized
NdFeB permanent magnets.

45. Presents the parameters used in the
calculations and several values
obtained from the FEA results.



Based on the above analysis and
calculations, a linear actuator was
built using axially magnetized NdFeB
cylindrical permanent magnets. The
experimental actuator parameters
are presented

GROUP 13 45

46. GROUP 13 46
Force produced by the actuator
prototype, versus the current
per phase.
Force produced by the actuator

47. It is possible to build an electromagnetic actuator, suitable for
application in an automobile electromagnetic suspension. It is
shown that the force values produced by the actuator are
suitable for the proposed application. The constructed actuator
is oil-free and does not need any kind of hydraulic system.
Although the dimensions and the weight are suitable, these
values are larger than an equivalent hydraulic actuator.
The utilization of this electrical drive system in the automobile
suspensions allows a relatively easy implementation of an
active control suspension law. Furthermore, the application of
other control laws allowing improvements in the automotive
suspension performance becomes possible.
GROUP 13 47
CONCLUSIONS

48. GROUP 13 48
CONTROLLER SELECTION

49. PID controllers are frequently selected for feedback control in
automated industry. To measure the resulting error, the PID
controller calculates the gap within the measured value of
process and optimal set point value.
PID has the potential of reducing the steady-state error by
regulating the process control inputs.
Building blocks of PID controller includes three special variables
which in result becomes the reason of the name of controller,
i.e., Proportional, Integral and Derivative denoted by kp, ki and
kd . respectively. These variables are tuning gains of this
controller.
PID controller is most used feedback control design

GROUP 13 49
PID CONTROLLER

50. TYPE OF CONTROLLER DESCRIPTION

EQUATION

PROPORTIONAL Plant input is changed in
direct proportion to the
error
??????
??????.&#3627408518;(??????)
INTEGRAL The controller controls the
output by integrating the
error signal
??????
?????? ⅇ??????ⅆ??????
??????
??????

DERIVATIVE Derivative controller
controls the plant by
providing the control signal
which is the derivative of
the error signal
??????
????????????
??????
ⅆ&#3627408518;??????
ⅆ??????

GROUP 13 50

51. f(t) = ??????
??????.&#3627408518;??????+??????
?????? &#3627408518;??????&#3627408517;??????
??????
??????
+ ??????
????????????
??????
&#3627408517;&#3627408518;??????
&#3627408517;??????

Transfer function ??????
????????????= ??????
?????? +
??????
??????
??????
+ ??????
????????????

GROUP 13 51
PID CONTROLLER

52. A proportional controller (Kp) has the effect of reducing the
rise-time but never eliminate the steady-state error.
An integral action (Ki) has the effect of eliminating the steady-
state error, but it may make the transient response worse.
Finally a derivative control (Kd) has the effect of increasing the
stability of the system, reducing the overshoot, and improving
the transient response
GROUP 13 52

53. GROUP 13 53
EFFECTS OF ADDING CONTROLLER

54. GROUP 13 54
PID CONTROLLER OF ACTIVE
SUSPENSION SYSTEM FOR A
QUARTER CAR MODEL

55. GROUP 13 55
PID CONTROLLER

56. GROUP 13 56
TYPES OF ACTIVE SUSPENSION SYSTEM

57. A road bump will be used as a disturbance to the vehicle
system in this work. The bump was assumed as a sinusoidal
form.
GROUP 13 57
DISTURBANCE MODEL

58. For standard passive suspension systems, if the comfort is improved,
then handling stability is deteriorated. This problem is the main
reason why active suspension systems are used. However, most
active suspension systems aim to bring car body into equilibrium
value, which always needs high energy, or in some cases, can cause
damage to the tire and/or suspension system.
Therefore, in this work, the active suspension tries to bring car body
to comfortable situation according to tire movements in such way
that annoying frequencies must be eliminated ,they can be ranged
between 4 and 8 Hz. The filter was chosen in such way to ensure a
comfortable ride and taking into account sudden displacements. The
figure below shows the step response of the proposed filter. For a
step disturbance, the desired displacement must stabilize after about
1 second so the passengers will feel a minor annoyance.
The filter transfer function is as follows:
GROUP 13 58
FILTER MODEL

59. With these parameters and
the given equations, and with
assuming that the initial
values are zero.
The system can be written as
follows:
GROUP 13 59
MODEL PARAMETERS

60. PID controller has been widely used in industry because of its
simplicity and effectiveness. Despite many uses of the PID
controller, its standard structure has constant gain parameters
and is not good to decrease velocity control error (Eski and
Yildirim, 2009). Therefore, exponential function is added to
derivate component of conventional PID controller.
The used PID controller and can be described as follows:



Where ????????????, ????????????, ???????????? and ???????????? are the PID controller gains






GROUP 13 60
PID CONTROLLER DESIGN

61. Random tuning technique has been used to optimize controller
parameters using step response that will be analyzed later. The Fitness
function, that has to be minimized, is defined as follows :




With ???????????? is filter output for Active Suspension with adapted reference
For the constant reference, ???????????? is assumed to be zero. And T is the
simulation period, which in our case equals to 5 seconds. Method of trial
and error is used to determine the parameters of PID controller. After
5000 iterations, the parameters for adapted reference (left), and
constant reference (right) were set to :
•?????? = 15 000
•????????????= 4.9751
•???????????? = 4.9489
•???????????? = 0.3614
•???????????? = 414.1968
GROUP 13 61

62. GROUP 13 62
PASSIVE SUSPENSION SYSTEM

63. Active suspension system requires actuator force to provide
external control, the goal of this actuator to provide a better
ride and handling. The force fa is given by a PID controller that
aims to bring the body position (????????????) to constant value (zero)
GROUP 13 63
ACTIVE SUSPENSION SYSTEM WITH
CONSTANT REFERENCE

64. The following configuration, the actuator tries to bring car
body to a comfortable ride in accordance with wheel
displacements.
GROUP 13 64
ACTIVE SUSPENSION SYSTEM WITH
ADAPTED REFERENCE

65. From results, it can be seen that passive
Suspension System suffers from high
displacement rates (up to 20 cm) for
low speeds. Though, the classical active
suspension system reduced disturbance
to 3 cm, and the proposed system gave
a displacement up to 5 cm. However, if
the car speed is increased, the body
displacement for the three systems are
similar. Moreover, the proposed system
needed less force for small speeds. This
is due to the control system that tries to
reduce disturbance with taking into
account sudden vibrations.
GROUP 13 65
BODY DISPLACEMENT FOR DIFFERENT
CAR SPEEDS

66. GROUP 13 66
ACTUATOR FORCE FOR DIFFERENT CAR
SPEEDS

67. GROUP 13 67

68. GROUP 13 68

69. GROUP 13 69
RANDOM DISTURBANCE

70. GROUP 13 70
STEP INPUT

71. Simulation results shows that the technique performs better
than passive suspension system for different disturbances.
However active suspension system with constant reference
gave better results compared to the proposed technique, this
is due to the controller tending to bring the body displacement
to constant value which is the best comfort option.
This technique tries to bring the car body to a certain comfort
which takes into account sudden road displacement in such
way to assure a certain ride comfort.
GROUP 13 71
CONCLUSION

72. http://www.123seminarsonly.com/ME/Active-Suspension-
System.html
https://en.wikipedia.org/wiki/Active_suspension#:~:text=An%20a
ctive%20suspension%20is%20a,entirely%20by%20the%20road%20su
rface.
https://images.app.goo.gl/vHvF2ixwAMsiWfim8
https://www.evoindia.com/news/decoding-the-mercedes-benz-e-
active-body-control-suspension
https://patents.google.com/patent/US4787823
https://en.wikipedia.org/wiki/Linear_motor


GROUP 13 72


REFERENCES

73. https://www.bosch-mobility-
solutions.com/media/global/products-and-services/passenger-
cars-and-light-commercial-vehicles/driver-assistance-
systems/lane-departure-warning/stereo-video-camera/product-
data-sheet-stereo-video-camera.pdf
https://www.acuitylaser.com/laser-sensors/case-studies/ar500-
laser-position-sensor/laser-ride-height-sensor/
https://www.bosch-
ibusiness.com/media/images/products/sensors/xx_pdfs_1/sensor
s_i-business.pdf
https://www.usna.edu/EE/ee301/supplements/Linear%20Motors%
20Supplement.pdf




GROUP 13 73

74. PAPERS
Bart L. J. Gysen, Johannes J. H. Paulides, Jeroen L. G. Janssen,
and Elena A. Lomonova, IEEE Active Electromagnetic
Suspension System for Improved Vehicle Dynamics
Harish C , Naveen Lara, Design and Analysis of Active
Suspension System
Ismenio Martins, Jorge Esteves, G. D. Marques, Fernando Pina
da Silva, Permanent-Magnets Linear Actuators Applicability in
Automobile Active Suspensions
Bart L.J. Gysen, Jeroen L.G. Janssen, Johannes J.H. Paulides,
Elena A. Lomonova, Design Aspects of an Active
Electromagnetic Suspension System for Automotive
Applications


GROUP 13 74

75. Adel Djellal, Rabah Lakel, Adapted reference input to control
PID based active suspension system, 2018
Yumna Shahid and Minxiang Wei, Comparative Analysis of
Different Model-Based Controllers Using Active Vehicle
Suspension System, 2019
Abd El-Nasser S. Ahmed, Ahmed S. Ali, Nouby M. Ghazaly, G. T.
Abd el- Jaber, Pid controller of active suspension system for a
quarter car model, 2015
GROUP 13 75

76. GROUP 13 76
THANK YOU