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ME 50400 / ECE 59500Automotive Control

Lecture Notes: 1

InstructorSohel Anwar, Ph.D., P.E.

Dept. of Mechanical EngineeringIUPUI

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Background on Automotive Control

Future Automobiles: Are expected to be equipped with advanced electronically controlled subsystems such as brake-by-wire, steer-by-wire, active suspension, fuel-cell and battery powered cars, etc.

Early automobiles: Had mechanically controlled engines with manual throttle, manual transmission, and mechanical steering and brakes.

Todays Automobiles: Have numerous electronically control systems, such as electronic fuel injection, ignition timing control, anti-knock control, throttle-by-wire, automatic transmission, anti-lock brakes, traction control, yaw stability control, on-demand all-wheel drive systems, hybrid-electric propulsion, to name a few.

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High gasoline prices fueling the production of hybrid-electric-vehicles (HEVs). Advanced controls can make todays internal combustion (IC) engines more fuel efficient and less polluting to the environment. Advanced chassis controls systems can make todays vehicles safer with active and intelligent sensing, detection, and prevention of accidents. Advanced control initiatives (such as drive-by-wire) are aimed at integrating various functionalities of vehicles for improved performance with respect to fuel efficiency, safety, ergonomics, durability, diagnostics, and various other factors.

Need for Automotive control

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Superior fuel efficiency leading to lower fuel consumption. Government regulations mandating lower vehicle emissions to protect environment. Superior occupant safety in various driving conditions and drivers demands. Customizable performance features for different drivers based on ride and handling requirements. Superior diagnostic capability to identify system fault and inform driver of the situation. Superior drivability via proper driveline torque management. Modular automotive systems for easy assembly. More features on the car at a lower cost.

Leading Factors for Advanced Automotive Control Systems

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Drive By Wire Systems: Advanced Automotive Control

Typical by-wire systems comprise of redundant sensors, actuators, microprocessors, and communication channels for fault tolerance.

No mechanical or hydraulic connection between the drivers input interface (e.g. throttle, brake, steering) and the vehicle system (e.g. engine/traction motor, brake/steering actuators).

An automotive system that interprets drivers input and executes the command to produce desired vehicle behavior, typically via a microprocessor based control system.

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Examples of Advanced Automotive Control

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Brake-By-Wire: Mercedes SL 500

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Hybrid Electric Vehicle with Drive-By-Wire (Concept)

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Solar Powered Vehicle

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Benefits of Drive-By-Wire Systems

Easily configurable for added features and/or tunable features

Enhanced vehicle performance Improved fuel economy via better engine / motor /

powertrain control Enhanced safety at no cost (stability control added in

the software No hardware change required) Further improvement in fuel efficiency via

regenerative braking Better ergonomics

- Adjustable feel at Drivers Interface- Optional joystick activation

Better fault detection and warning

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Design Challenges for Fuel Cell Hybrid Electric Vehicle (FCHEV)

Investigate methods of operating the motor at its peak efficiency level most of the time despite the variation in drivers power requests, road conditions, and state of charge in the fuel cell.

Investigate the development of novel algorithms for Fuel Cell / Battery power management systems for maximum motor efficiency.

Investigate the development of accurate models of the fuel-cell based powertrain systems. A number of modeling tools (e.g. neural network, fuzzy logic) can be utilized.

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Design Challenges in Fault Tolerant Control of Drive-By-Wire Vehicles

Investigate minimization of redundancy in the hardware components (sensors/actuators) via the use of robust model-based fault detection, isolation, and management algorithms for Drive-By-Wire systems.

Physics-based mathematical model as well as models based on system identification methods and/or Artificial Neural Network (ANN) models can be investigated for drive-by-wire sub-systems modeling.

For fault identification and management, intelligent rule-based algorithms as well as fuzzy-logic based algorithms for the DBW system can be investigated.

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Electro-hydraulic Brake-By-Wire System

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BBW Pedal Modeling & Control

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Brake Pedal Feel

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Yaw Stability Control: Vehicle Active Safety

Yaw instability can be defined as the vehicles inability to follow drivers request for a directional change.

Two distinct situations may arise: - Understeer: when the vehicle yaw rate falls short of expected yaw rate (front slip angle > rear slip angle)

- Oversteer: when the vehicle yaw rate exceeds the expected value (front slip angle < rear slip angle.

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Benefits of Yaw Stability Control

Improved performance in various lane change and steering maneuvers via correction of understeer and oversteer conditions

Improved safety in lane change, turning, and other steering actions on a low friction coefficient surface at various vehicle speeds

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ABS Performance in a Lane Change Maneuver

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Stability Control Performance

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Stability Control Performance

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Yaw Stability Control System

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Adaptive Cruise Control System

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Adaptive Lane Keeping System

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Basic Subsystems of an Automobile that have Control Functionality

Propulsion System: Normally comprised of engine / electric motor that produces power to drive the vehicle. Cruise control maintains vehicle speed by controlling the throttle opening.

Transmission: It controls the engine torque output to the drive wheels via gear shifts to accommodate for different torque demands at difference vehicle speeds.

Driveline System: It selectively controls the torque to the part-time drive axle for an all-wheel drive system.

Chassis Systems: It includes steering, brakes, throttle, suspension, driveline, axles.

Body Electronics: It is responsible for various body control functions such as door lock, instrument cluster, windows, mirrors, lights, wipers, etc.

Climate Control: It controls the inside temperature of the vehicle and aids in keeping windshield screens clear.

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Questions?