2. Feedback Control systems 2
Elements of Feedback Control (1/7)
• Plant (Process) -- The plant is the system (process) whose output is to be
controlled, e.g., a DC motor with the rotor speed as output.
• Actuator -- An actuator is a device that can influence the input to the plant, e.g. the
stator current for the motor example.
• Disturbance d(t) -- Disturbances are uncontrollable signals to the plant that tend to
adversely affect the output of the system, e.g., external load torque for the motor
example.
• Sensor (Measurement System) -- The dynamics of the device (system) that
measures the system output, e.g., an encoder.
• Controller -- The controller is the device that generates the controlled input that is
to affect the system output, e.g., electric power system generally managed by a DSP
(Digital signal processor).
4. Feedback Control systems 4
Elements of Feedback Control (3/7)
The objective of the control system is to control the output y by using the input u,
such that the output y follows a set of reference inputs r.
5. Feedback Control systems 5
Elements of Feedback Control (4/7)
Open-Loop Control
The control input u(t) is synthesized based on the a priori knowledge of the system
(plant) and the reference input r(t)
6. Feedback Control systems 6
Elements of Feedback Control (6/7)
Closed-Loop Control
The control input u(t) is synthesized based on the a priori knowledge of the system
(plant), the reference input r(t) and the measurement of the actual output y(t).
How to design a controller?
7. Feedback Control systems 7
Elements of Feedback Control (7/7)
Control design steps:
• Plant model
• System analysis
• Sensors analysis
• Actuators analysis … etc.
• Control design
• goals and design of the control law
• Validation and simulations
• Experimental tests
• hardware in the loop … etc.
10. Feedback Control systems 10
Sensors in the automotive systems (1/3)
Gyroscope:
angular speed mesuremets
Accelerometer
lateral and longitudinal accelerations
Encoder
steering wheel position
Hall effect sensors
tire angular speed measurement
Thermocouple
temperature sensor
Unconventional sensors
11. Feedback Control systems 11
Sensors in the automotive systems (2/3)
Unconventional sensors
Optical sensor used to measure the lateral speed of a vehicle CORREVIT® SFII P.
High cost
12. Feedback Control systems 12
Sensors in the automotive systems (3/3)
Analog to digital converter
Comunication buses
Comunication protocol
Data rate
Noise
Etc …
17. Feedback Control systems 17
A full vehicle model of a standard Carsim small SUV (is used to analyze the
responses of both the uncontrolled and the controlled vehicle and to check
robustness with respect to combined lateral and longitudinal tire forces effects
and to unmodelled dynamics such as pitch and roll.
CARSIM unmodelled dynamics
…
18. Feedback Control systems 18
Three increasing driver steering wheel angles are simulated. The proposed control
counteracts the yaw rate tracking errors so that the oscillations are suppressed and
lateral speed is reduced both during transients and in steady state.
CARSIM sudden direction changes
…
19. Feedback Control systems 19
The results, exported from CarSim for a moose test, are shown following:
CARSIM Moose test
Moose test uncontrolled and controlled vehicle
Carsim - Moose test
