BY-WIRE-STEERED SYSTEM

BY-WIRE-STEERED SYSTEM

By-wire-steered system is integration of electronic devices and mechanical systems in order to improve the performance of the steering system.Recent advances in dependable embedded system technology, as well as continuing demand for improved handling and passive and active safety improvements, have led vehicle manufacturers and suppliers to actively pursue development programs in computer-controlled, by-wire subsystems. These subsystems include steer and brake-by-wire, and are composed of mechanically decoupled sets of actuators and controllers connected through multiplexed, in-vehicle computer networks.A steer-by-wire system replaces the traditional mechanical linkage between the steering wheel and the road wheel actuator (e.g., a rack and pinion steering system) with an electronic connection. This allows flexibility in the packaging and modularity of the design. Since it removes the direct Kinematic relationship between the steering and road wheels, it enables control algorithms to help enhance driver input.There is no mechanical link to the driver.

Steer- and brake-by-wire provide a number of packaging and assembly advantages over conventional subsystems. For instance, electromechanical brake-by-wire subsystems require no hydraulic fluid to store or load at the assembly plant and permit more modular assembly, thus reducing the number of parts to be handled during production. Steer-by-wire systems have no steering column and may also eliminate cross-car steering assemblies such as racks. Arguments for ‘by-Wire’ systems include production costs, packaging and traffic safety . The ‘by-Wire’ technology as in drive, brake and steer is gaining ground and is undoubtedly an automotive solution of the future.

The arguments to support such ‘by-Wire’ systems include reduced production costs and packaging advantages and improved traffic safety. Emerging drive-by- wire technologies offer new possibilities for designing the steering characteristics of road vehicles. When the mechanical link between the steering wheel and the front wheels is replaced by sensors, controllers and actuators, enormous flexibility is achieved in terms of the control device applied and in terms of the transfer function of the steering system. This offers new possibilities for optimizing the steering system for mass-produced vehicles. However, the flexibility is of even greater advantage in the area of car adjustment for drivers with physical disabilities.The transition to purely electrical steering systems will take place step by step via systems with mechanical or hydraulic backup. Development and production of the next generations of electrical steering systems up to purely electrical steering systems create high safety demands on components and systems. Reliable and safe electrical steering systems can be realized by using appropriate safety techniques for these new systems and their components combined with the know-how of safety relevant vehicle systems.

The main limitations of by-wire-steered system are the requirement of a 42 Volts car supply, high output alternator and new generation batteries.The steer-by-wire principle becomes absolutely necessary when Future innovative steering functions, such as vehicle dynamic interventions, collision avoidance, individual wheel steering, tracking assistance, automatic lateral guidance, and finally autonomous driving functions have to be implemented in a system compound of various vehicle systems.

INTRODUCTION

By-wire-steered system is an application of ‘MECHATRONICS’, which is the integration of electronic devices and mechanical systems in order to improve the performance of the system .Recent advances in dependable embedded system technology, as well as continuing demand for improved handling and passive and active safety improvements, have led vehicle manufacturers and suppliers to actively pursue development programs in computer-controlled, by-wire subsystems. These subsystems include steer and brake-by-wire, and are composed of mechanically decoupled sets of actuators and controllers connected through multiplexed, in-vehicle computer networks. There is no mechanical link to the driver.

Steer- and brake-by-wire provide a number of packaging and assembly advantages over conventional subsystems. For instance, electromechanical brake-by-wire subsystems require no hydraulic fluid to store or load at the assembly plant and permit more modular assembly, thus reducing the number of parts to be handled during production. Steer-by-wire systems have no steering column and may also eliminate cross-car steering assemblies such as racks. Arguments for ‘by-Wire’ systems include production costs, packaging and traffic safety.The ‘by-Wire’ technology as in drive, brake and steer is gaining ground and is undoubtedly an automotive solution of the future.

The arguments to support such ‘by-Wire’ systems include reduced production costs and packaging advantages and improved traffic safety (a boon for everybody involved). Emerging drive-by- wire technologies offer new possibilities for designing the steering characteristics of road vehicles. When the mechanical link between the steering wheel and the front wheels is replaced by sensors, controllers and actuators, enormous flexibility is achieved in terms of the control device applied and in terms of the transfer function of the steering system. This offers new possibilities for optimizing the steering system for mass-produced vehicles. However, the flexibility is of even greater advantage in the area of car adjustment for drivers with physical disabilities.

A steer-by-wire system replaces the traditional mechanical linkage between the steering wheel and the road wheel actuator (e.g., a rack and pinion steering system) with an electronic connection. This allows flexibility in the packaging and modularity of the design. Since it removes the directKinematic relationship between the steering and road wheels, it enables control algorithms to help enhance driver input.The transition to purely electrical steering systems will take place step by step via systems with mechanical or hydraulic backup. Development and production of the next generations of electrical steering systems up to purely electrical steering systems create high safety demands on components and systems.

Reliable and safe electrical steering systems can be realized by using appropriate safety techniques for these new systems and their components combined with the know-how of safety relevant vehicle systems.‘Steer-by-Wire’ (SbW) there exists a legislation obstacle as European regulations require a mechanical connection between the steering wheel and the wheels. The column electric power steering (C-EPS) in the Opel Astra is therefore only an electric

hybridization at steering level: the steering torque levels will increase when the car picks up speed. The “Dual drive” system in the Fiat Punto has an EPS with dual settings: the driver can activate the “city” mode and obtain gentler steering when parking. The main limitations of by-wire-steered system are the requirement of a 42 Volts car supply, high output alternator and new generation batteries.The steer-by-wire principle becomes absolutely necessary when Future innovative steering functions, such as vehicle dynamic interventions, collision avoidance, individual wheel steering, tracking assistance, automatic lateral guidance, and finally autonomous driving functions have to be implemented in a system compound of various vehicle systems