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.
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INTRODUCTION
TYPES OF ACTIVE SUSPENSION SYSTEM WORKING
Semi-active Varies shock absorber firmness
Hydraulic actuated Hydraulic servomechanism
Electromagnetic recuperative Linear electromagnetic motors
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
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THE LIST OF VARIABLES TO BE
MONITORED
6. SENSORS
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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.
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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
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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
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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.
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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.
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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
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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
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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
24. After using the Wolfram Alpha website to simplify the equation,
MATLAB was used to plot the transfer function.
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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.
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CONCLUSION
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
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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
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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.
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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.
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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
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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
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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.
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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.
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
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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
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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.
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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.
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42. The actuator Lorenz force produced by a pair of windings and a
permanent magnet
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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
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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
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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.
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CONCLUSIONS
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
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PID CONTROLLER
50. TYPE OF CONTROLLER DESCRIPTION EQUATION
PROPORTIONAL Plant input is changed in
direct proportion to the
error
𝒌𝒑. 𝒆(𝒕)
INTEGRAL The controller controls the
output by integrating the
error signal 𝑲𝑰 ⅇ 𝒕 ⅆ𝒕
𝒕
𝟎
DERIVATIVE Derivative controller
controls the plant by
providing the control signal
which is the derivative of
the error signal
𝒌𝑫𝑻𝑫
ⅆ 𝒆 𝒕
ⅆ𝒕
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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
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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.
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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:
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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:
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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 𝐾𝑝, 𝐾𝑖, 𝐾𝑑 and 𝐾𝑁 are the PID controller gains
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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 𝑧𝑓 is filter output for Active Suspension with adapted reference
For the constant reference, 𝑧𝑓 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 :
• 𝐺 = 15 000
• 𝐾𝑝= 4.9751
• 𝐾𝑖 = 4.9489
• 𝐾𝑑 = 0.3614
• 𝐾𝑁 = 414.1968
GROUP 13 61
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 (𝒛𝒔) 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
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
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