DE112017005108T5 - steering system - Google Patents

Abstract

Embodiments of the invention provide steering systems for vehicles in which the wheels on the front and rear axles are controlled by electric actuators, controlled by control devices. A watchdog controller is provided to detect fault conditions on the actuators and / or on the controllers and the system is arranged to provide steering by the wheels on only one of the axles when one fault condition in the one with the wheels of the other Axis linked control unit or actuators is detected.

Description

TECHNICAL AREA

The present disclosure relates to a steering system, and more particularly, but not exclusively, to a steering control system for a vehicle having a steer-by-wire (wired remote control) system. Aspects of the invention relate to a steering control system, a steering system, a method, a non-transient computer-readable medium, a computer program product, a processor, and a vehicle.

STATE OF THE ART

In conventional vehicles, the steering is usually effected by a mechanical connection between a steering wheel, which receives steering pulses from the operator of the vehicle, and a rack, which controls the steering position of the wheels. Power assistance is often provided by electrically or hydraulically powered actuators that generally provide assist power depending on the force provided by the driver. Typically, only the two front wheels are steered, but it is known that only the rear wheels or a combination of front and rear wheels can be steered.

Steer-by-wire systems have recently been developed which do not contain a permanent mechanical connection between rack and steering wheel. These systems have the potential to provide significant weight and cost savings compared to conventional systems, and can also provide improved crash performance and design flexibility in terms of steering wheel size and position. This may also provide increased design flexibility with respect to the location of other components, such as the engine and transmission, since they may be located at a location previously required for mechanical steering components. However, the design of steer-by-wire systems for road vehicles must be redundant, since it is unacceptable for a single failure to have the potential to cause a complete loss of steering. This has resulted in steer-by-wire systems having dual controllers to compute the required input to the steering actuators, as well as mechanical replacement systems for use in the event of a failure of the steering actuators. These additional components may offset some or all of the potential benefits otherwise associated with steer-by-wire systems.

It is an object of embodiments of the invention to at least mitigate one or more problems of the prior art.

BRIEF SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide: a steering control system, a steering system, a controller, a method, a computer program product, a non-transient computer-readable medium, a processor, and a vehicle as claimed in the appended claims.

• ein erstes Steuermittel, funktionsfähig, um das erste Betätigungsmittel zu steuern;
• ein zweites Steuermittel, funktionsfähig, um das zweite Betätigungsmittel zu steuern; und
• ein Watchdog-Steuermittel, funktionsfähig, um die Steuerung des ersten Betätigungsmittels durch das erste Steuermittel bei Erfassen eines Fehlerzustands in dem ersten Steuermittel und/oder in dem ersten Betätigungsmittel zu verhindern. Das Watchdog-Steuermittel kann konfiguriert sein, um die Steuerung des zweiten Betätigungsmittels durch das zweite Steuermittel bei Erfassen eines Fehlerzustands in dem zweiten Steuermittel und/oder in dem zweiten Betätigungsmittel zu verhindern. Dieses System ist in der Lage, eine Lenkung an zwei separaten Achsen eines Fahrzeugs bereitzustellen, wobei die Lenkungskomponenten an jeder Achse Redundanz bereitstellen, sodass ein Lenken des Fahrzeugs in dem Falle eines Ausfalls der Lenkungskomponenten an der anderen Achse beibehalten werden kann. Dies kann das Bereitstellen eines Steer-by-Wire-Systems ermöglichen, in dem eine mechanische Verbindung zwischen dem Lenkrad und den Zahnstangen nicht erforderlich ist.

According to a first aspect of the present invention, there is provided a steering control system for a vehicle having a steer-by-wire system comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels and a second electrically controlled steering actuator; operable to direct a second group of one or more wheels, the steering control system comprising:

• a first control means operable to control the first actuating means;
• second control means operable to control the second actuating means; and
• a watchdog control means operable to prevent control of the first actuating means by the first control means upon detection of an error condition in the first control means and / or in the first actuating means. The watchdog control means may be configured to prevent control of the second actuating means by the second control means upon detection of a fault condition in the second control means and / or in the second actuating means. This system is capable of providing steering on two separate axles of a vehicle, with the steering components providing redundancy on each axle so that steering of the vehicle can be maintained in the event of failure of the steering components on the other axle. This may allow the provision of a steer-by-wire system in which a mechanical connection between the steering wheel and the racks is not required.

In one embodiment, the first group of wheels is a group of rear wheels and the second group of wheels is a group of front wheels. Optionally, the second control system is operable to communicate with user input means and with the first control means,
wherein the second control means is operable to generate a first control signal indicative of steering assistance to be provided by the first group of wheels and to generate a second control signal indicative of a current to be sent to the second actuating means .
wherein the first control means is operable to generate a third signal indicative of a current to be sent to the first actuating means in response to the first signal. Advantageously, this system may have improved modularity, as the second control means may be operated as part of a system for a vehicle having only one group of steered wheels.

• das erste Niedrigpegel-Steuermittel konfiguriert ist, um das dritte Signal zu empfangen und abhängig vom dritten Signal einen Antriebsstrom an das erste Betätigungsmittel bereitzustellen; und
• das zweite Niedrigpegel-Steuermittel konfiguriert ist, um das zweite Signal zu empfangen und abhängig vom zweiten Signal einen Antriebsstrom an das zweite Betätigungsmittel bereitzustellen.

Optionally, the system further comprises a first low level control means and a second low level control means,
in which:

• the first low level control means is configured to receive the third signal and to provide drive current to the first actuating means in response to the third signal; and
• the second low level control means is configured to receive the second signal and to provide drive current to the second actuating means in response to the second signal.

In one embodiment, the second control means is operable to receive a second signal indicating that an error condition has been detected in the first control means and / or the first actuating means, the second control means being operable to operate in response to receiving the second signal to set at least one control parameter used in controlling the second actuating means. Advantageously, this allows the second control means to control the second actuator and the second group of wheels to compensate for the loss of steering of the first group of wheels.

In one embodiment, the first control means is operable to receive a first signal indicating that an error condition has been detected in the second control means and / or the second actuating means, the first control means being operable, at least in response to receiving the first signal to set a control parameter used in controlling the first actuating means. Advantageously, this allows the first control means to control the first actuator and the first group of wheels to compensate for the loss of steering of the second group of wheels.

Optionally, the watchdog control means comprises input means configured to receive a first input indicative of a driver steering input and a second input indicative of an output of the first actuating means, the watchdog control means operable to determine the error condition in the first control means and / or the first actuating means in response to the first and second inputs. The watchdog control means may comprise input means configured to receive a third input indicative of an output of the second actuating means, the watchdog control means operable to determine the error condition in the second control means and / or the second actuating means in dependence on the first and the third input. The watchdog control means may calculate an expected range of outputs for the first and second control means based on the driver steering input, and may determine that an error condition has occurred if the output of the first or the second controller does not fall within the expected range.

In one embodiment, the watchdog control means is configured to perform a forced reset of the first control means in response to detecting a fault condition in the first control means and / or the first actuating means. Optionally, the watchdog control means is configured to enable control of the first actuating means by the first control means in response to determining that the fault condition has been remedied by the forced reset. This may allow the system to resume normal operation if simple reset fixes the error condition.

In one embodiment, the watchdog control means is configured to perform a forced reset of the second control means in response to detecting a fault condition in the second control means and / or the second actuating means. Optionally, the watchdog control means is configured to enable control of the second actuation means by the second control means in response to determining that the fault condition has been remedied by the forced reset. This may allow the system to resume normal operation if simple reset fixes the error condition.

Optionally, the watchdog control means is operable to cause a warning to be issued to a driver of the vehicle upon detecting an error condition in the first control means and / or the first actuating means. This can ensure that the driver is aware that the capabilities of the vehicle are limited. The warning can be the driver instruct to drive the vehicle to a safe location and then stop.

Optionally, the watchdog control means is operable to cause a warning to be issued to a driver of the vehicle upon detecting an error condition in the second control means and / or the second actuating means. This can ensure that the driver is aware that the capabilities of the vehicle are limited. The warning may instruct the driver to drive the vehicle to a safe location and then stop.

Optionally, the watchdog control means is operable to restrict power of the vehicle upon detecting a fault condition in the first control means and / or the first actuating means. For example, the speed of the vehicle can be limited. This may increase the likelihood that the driver will drive the vehicle to a safe location and then stop driving the vehicle when an error condition is detected.

Optionally, the watchdog control means is operable to restrict power of the vehicle upon detecting a fault condition in the second control means and / or the second actuating means. For example, the speed of the vehicle can be limited. This may increase the likelihood that the driver will drive the vehicle to a safe location and then stop driving the vehicle when an error condition is detected.

In one embodiment, the watchdog control means is operable to issue an externally visible warning upon detection of an error condition in the first control means and / or the first actuating means. This may inform other road users that the vehicle has limited functions.

In one embodiment, the watchdog control means is operable to issue an externally visible warning upon detection of an error condition in the second control means and / or the second actuating means. This may inform other road users that the vehicle has limited functions.

Optionally, preventing control of the first actuating means by the first control means includes interrupting power to the first control means. Advantageously, this ensures that the control of the first actuating means by the first control means is impossible once an error condition has been detected by the watchdog control means.

Optionally, preventing the second actuating means from being controlled by the second control means comprises interrupting a supply of the second control means with power. Advantageously, this ensures that the control of the second actuating means by the second control means is impossible once an error condition has been detected by the watchdog control means.

According to another aspect of the invention to be protected, there is provided a watchdog controller for a steering control system for a vehicle having a steer-by-wire system, the watchdog controller being operable to detect the control of a first actuating means by the first control means prevent a fault condition in the first control means and / or in the first actuating means, and to prevent the control of a second actuating means by a second control means upon detection of a fault condition in the second control means and / or the second actuating means.

According to yet another aspect of the invention, there is provided a steer-by-wire system and a steer-by-wire system vehicle including a watchdog controller for a steering control system operable to control a first actuating means prevent first control means upon detection of a fault in the first control means and / or in the first actuating means, and a redundant control means comprising two or more control units for calculating the required input to a second actuating means. Optionally, the first actuator directs the rear wheels of the vehicle and the second actuator directs the front wheels of the vehicle.

Redundant control of a steer-by-wire system is known and may be appropriate for the front wheels of a four-steering-wheel vehicle, which normally provide a greater steering angle than the rear wheels. In the event of a failure in one of the redundant systems, the remaining systems would allow the front wheels to steer normally. In contrast, the rear wheels are steered at a smaller angle and a failure of the rear steering is less critical. Accordingly, it is appropriate that the rear-wheel steering be monitored by a watchdog that prevents control of the rear-wheel steering in the event of a control system failure. In the event of rear wheel steering failure, the front wheel steering can adjust its response to compensation, for example by increasing the front wheel steering angle for a particular steering wheel input.

• ein erstes elektrisch gesteuertes Lenkungsbetätigungsmittel, funktionsfähig, um eine erste Gruppe von einem oder mehreren Rädern zu lenken;
• ein zweites elektrisch gesteuertes Lenkungsbetätigungsmittel, funktionsfähig, um eine zweite Gruppe von einem oder mehreren Rädern zu lenken; und
• ein Lenkungssteuersystem, wie zuvor beschrieben.

According to another aspect of the invention to be protected is a steer-by-wire system for a Vehicle provided, the system comprising:

• a first electrically controlled steering actuator operable to direct a first group of one or more wheels;
• a second electrically controlled steering actuator operable to direct a second group of one or more wheels; and
• a steering control system as described above.

Optionally, the steer-by-wire system includes first biasing means operable to move the first group of wheels to a predetermined position in response to detecting a fault condition in the first control means and / or the first actuating means. The predetermined position may correspond to the position of the wheels when the vehicle is traveling straight ahead. Advantageously, this may facilitate steering with the second set of wheels when steering with the first set of wheels is suppressed.

Optionally, the steer-by-wire system includes second biasing means operable to move the second group of wheels to a predetermined position in response to detecting a fault condition in the second control means and / or the second actuating means. The predetermined position may correspond to the position of the wheels when the vehicle is traveling straight ahead. Advantageously, this may facilitate steering with the first group of wheels when steering with the second group of wheels is suppressed.

In an embodiment, the first group of wheels comprises a plurality of wheels, and the first actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels. Optionally, the second group of wheels comprises a plurality of wheels and the second actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels. Advantageously, this allows the individual control of all wheels in a steer-by-wire system.

According to another aspect of the invention, for which protection is sought, there is provided a vehicle comprising a steer-by-wire system as described above.

Optionally, the first group of one or more wheels comprises at least two front wheels and the second group of wheels comprises at least two rear wheels.

• Erfassen eines Fehlerzustands in dem ersten Steuermittel und/oder dem ersten Betätigungsmittel und, als Reaktion auf das Erfassen;
• Verhindern des Steuerns des ersten Betätigungsmittels durch das erste Steuermittel; und optional
• Einstellen wenigstens eines Steuerparameters, der von dem zweiten Steuermittel beim Steuern des zweiten Betätigungsmittels verwendet wird.

According to another aspect of the invention to be protected, there is provided a method of controlling a vehicle with a steer-by-wire system, comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels and a second one electrically controlled steering actuator operable to direct a second group of one or more wheels, the first actuating means being controlled by a first control means and the second actuating means controlled by a second control means, the method comprising:

• Detecting an error condition in the first control means and / or the first actuating means and, in response to the detection;
• Preventing the first actuating means from being controlled by the first control means; and optional
• Adjusting at least one control parameter used by the second control means in controlling the second actuating means.

• Empfangen eines Fehlersignals, das einen Fehlerzustand angibt, in dem ersten Steuermittel und/oder dem ersten Betätigungsmittel und, als Reaktion auf das Fehlersignal;
• Verhindern des Steuerns des ersten Betätigungsmittels durch das erste Steuermittel; und
• Einstellen wenigstens eines Steuerparameters, der von dem zweiten Steuermittel beim Steuern des zweiten Betätigungsmittels verwendet wird.

According to a further aspect of the invention to be protected, a method is provided for controlling a vehicle with a steer-by-wire system, comprising a first electrically controlled steering actuating means ( 202A . 202B ), functional to a first group of one or more wheels ( 204A . 204B ) and a second electrically controlled steering actuator ( 202C . 202D ), functional to a second group of one or more wheels ( 204C . 204D ), wherein the first actuating means is controlled by a first control means ( 208 ) and the second actuating means are controlled by a second control means ( 210 ), the method comprising:

• Receiving an error signal indicative of an error condition in the first control means and / or the first actuating means and, in response to the error signal;
• Preventing the first actuating means from being controlled by the first control means; and
• Adjusting at least one control parameter used by the second control means in controlling the second actuating means.

Optionally, the method includes receiving a first input indicative of a driver steering input and a second input indicating an output of the first actuating means, wherein detecting an error condition in the first control means and / or in the first actuating means depends on the first and second operating means second input is executed.

In one embodiment, the method includes performing a forced reset of the first control means in response to detecting an error condition in the first control means and / or the first actuating means.

In one embodiment, the method comprises enabling the first actuating means to be controlled by the first control means in response to determining that the error condition has been remedied by the forced reset.

Optionally, the method includes issuing a warning to a driver of the vehicle in response to detecting a fault condition in the first control means and / or the first actuating means.

Optionally, the method includes limiting the power of the vehicle in response to detecting a fault condition in the first control means and / or the first actuating means.

In one embodiment, the method includes outputting an outwardly-visible alert in response to detecting a fault condition in the first control means and / or the first actuating means.

Optionally, preventing control of the first actuating means by the first control means includes interrupting power to the first control means.

According to another aspect of the invention to be protected, there is provided a computer program product executable on a processor to implement a method as described above.

In another aspect of the invention to be protected, there is provided a non-transient computer-readable medium containing computer-readable code that, when executed by a computer, causes a vehicle to perform the method as described above.

According to another aspect of the invention to be protected, there is provided a processor arranged to implement the method or the computer program product as described above.

• ein erstes Steuermittel, funktionsfähig, um das erste Betätigungsmittel zu steuern;
• ein zweites Steuermittel, funktionsfähig, um das zweite Betätigungsmittel zu steuern, wobei das zweite Steuermittel ein redundantes Steuermittel umfasst, welches zwei oder mehr Steuergeräte umfasst, um die erforderliche Eingabe in ein zweites Betätigungsmittel zu berechnen; und
• ein Watchdog-Steuermittel, funktionsfähig, um die Steuerung des ersten Betätigungsmittels durch das erste Steuermittel bei Erfassen eines Fehlerzustands in dem ersten Steuermittel und/oder in dem ersten Betätigungsmittel zu verhindern.

According to one aspect of the invention, there is provided a steering control system for a vehicle having a steer-by-wire system comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels and a second electrically controlled steering actuator operable to direct a second group of one or more wheels, the steering control system comprising:

• a first control means operable to control the first actuating means;
• second control means operable to control the second actuating means, the second control means comprising redundant control means comprising two or more controllers for calculating the required input to a second actuating means; and
• a watchdog control means operable to prevent control of the first actuating means by the first control means upon detection of an error condition in the first control means and / or in the first actuating means.

Optionally, the second control means is operable to receive a signal indicating that an error condition has been detected in the first control means and / or the first actuating means, the second control means being operable depending on receiving the first signal at least one in control set the control parameter used the second actuating means.

Optionally, the watchdog control means comprises input means configured to receive a first input indicative of a driver steering input and a second input indicative of an output of the first actuating means, the watchdog control means operable to determine the error condition in the first control means and / or the first actuating means in response to the first and second inputs.

Optionally, the watchdog control means is configured to perform a forced reset of the first control means in response to detecting an error condition in the first control means and / or the first actuating means.

Optionally, the watchdog control means is configured to enable control of the first actuating means by the first control means in response to determining that the fault condition has been remedied by the forced reset.

Optionally, the watchdog control means is operable to cause, upon detection of a Error condition in the first control means and / or the first actuating means a warning to a driver of the vehicle is issued.

Optionally, the watchdog control means is operable to restrict power of the vehicle upon detecting a fault condition in the first control means and / or the first actuating means.

Optionally, the watchdog control means is operative to issue an externally visible warning upon detecting an error condition in the first control means and / or the first actuating means.

Optionally, preventing control of the first actuating means by the first control means includes interrupting power to the first control means.

According to a further aspect of the invention, there is provided a watchdog controller for a steering control system for a vehicle having a steer-by-wire system, the watchdog controller operative to control a first actuating means by the first control means upon detection of an error condition in prevent the first control means and / or in the first actuating means.

• ein erstes elektrisch gesteuertes Lenkungsbetätigungsmittel, funktionsfähig, um eine erste Gruppe von einem oder mehreren Rädern zu lenken;
• ein zweites elektrisch gesteuertes Lenkungsbetätigungsmittel, funktionsfähig, um eine zweite Gruppe von einem oder mehreren Rädern zu lenken; und
• ein Lenkungssteuersystem und/oder eine Watchdog-Steuerung nach einem der vorhergehenden Ansprüche.

According to another aspect of the invention, there is provided a steer-by-wire system for a vehicle, the system comprising:

• a first electrically controlled steering actuator operable to direct a first group of one or more wheels;
• a second electrically controlled steering actuator operable to direct a second group of one or more wheels; and
• a steering control system and / or a watchdog control according to one of the preceding claims.

Optionally, the steer-by-wire system includes first biasing means operable to move the first group of wheels to a predetermined position in response to detecting a fault condition in the first control means and / or the first actuating means.

Optionally, the first group of wheels comprises a plurality of wheels, and the first actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels.

According to one aspect of the invention, a vehicle is provided that includes a steer-by-wire system.

Optionally, the first group of one or more wheels includes at least two rear wheels, and the second group of wheels includes at least two front wheels.

• Erfassen eines Fehlerzustands oder Empfangen eines Fehlersignals, das einen Fehlerzustand angibt, in dem ersten Steuermittel und/oder dem ersten Betätigungsmittel und, als Reaktion auf das Erfassen oder auf das Fehlersignal;
• Verhindern des Steuerns des ersten Betätigungsmittels durch das erste Steuermittel; und
• Einstellen wenigstens eines Steuerparameters, der von dem zweiten Steuermittel beim Steuern des zweiten Betätigungsmittels verwendet wird.

According to one aspect of the invention, there is provided a method of controlling a vehicle with a steer-by-wire system, comprising a first electrically controlled steering actuator (10). 202A . 202B ), functional to a first group of one or more wheels ( 204A . 204B ) and a second electrically controlled steering actuator ( 202C . 202D ), functional to a second group of one or more wheels ( 204C . 204D ), wherein the first actuating means is controlled by a first control means ( 208 ) and the second actuating means are controlled by a second control means ( 210 ), the method comprising:

• Detecting an error condition or receiving an error signal indicative of an error condition in the first control means and / or the first actuating means and, in response to the detection or to the error signal;
• Preventing the first actuating means from being controlled by the first control means; and
• Adjusting at least one control parameter used by the second control means in controlling the second actuating means.

Optionally, the method includes receiving a first input indicating a driver steering input and a second input indicating an output of the first actuating means, wherein receiving an error signal or detecting an error condition in the first control means and / or in the first actuating means from the first and second inputs.

Optionally, the method comprises performing a forced reset of the first control means in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means.

Optionally, the method comprises allowing the first control means to control the first actuating means in response to determining that the error condition has been remedied by the forced reset.

Optionally, the method includes issuing a warning to a driver of the vehicle in response to receiving an error signal or detecting an error condition in the vehicle first control means and / or the first actuating means.

Optionally, the method includes limiting the power of the vehicle in response to detecting a fault condition in the first control means and / or the first actuating means.

Optionally, the method comprises outputting an externally visible warning in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means.

Optionally, preventing control of the first actuating means by the first control means includes interrupting power to the first control means.

It should be noted that the first control means, the second control means and the watchdog control means each comprise a control unit. These controllers may include a processor having access to electronic memory, for example, a non-transient computer-readable medium. As used herein, the terms "first control means", "second control means" and "watchdog control means" each include a single control means or controller as well as a plurality of control means or collectors which are collectively operated to perform the executed control functionality for a first control means provide second control means or a watchdog controller.

It is expressly intended, within the scope of this application, that the various aspects, embodiments, examples and alternatives presented in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular, their individual features, be independent of each other or in any combination. This means that all embodiments and / or features of any embodiment can be combined in any manner and / or combination, provided that these features are not incompatible. The Applicant reserves the right to change any claim originally filed or to submit any new claim, including the right to alter any originally filed claim, in order to depend on and / or disregard any feature of any other claim although it was previously unclaimed in this way.

list of figures

• 1 ein schematisches Diagramm eines Lenksystems eines Fahrzeugs mit einem Steer-by-Wire-System (STAND DER TECHNIK);
• 2 ein schematisches Diagramm eines Lenksystems eines Fahrzeugs mit einem Steer-by-Wire-System in einer erfindungsgemäßen Ausführungsform;
• 3 ein Flussdiagramm, das den Betrieb eines Watchdog-Steuergeräts in einer erfindungsgemäßen Ausführungsform darstellt;
• 4 ein Fahrzeug mit einem System in einer erfindungsgemäßen Ausführungsform;
• 5 ein schematisches Diagramm eines Lenksystems eines Fahrzeugs mit einem Steer-by-Wire-System in einer zweiten erfindungsgemäßen Ausführungsform; und
• 6 ein schematisches Diagramm eines Lenksystems eines Fahrzeugs mit einem Steer-by-Wire-System in einer weiteren erfindungsgemäßen Ausführungsform.

One or more embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

• 1 a schematic diagram of a steering system of a vehicle with a steer-by-wire system (STATE OF THE ART);
• 2 a schematic diagram of a steering system of a vehicle with a steer-by-wire system in an embodiment according to the invention;
• 3 a flowchart illustrating the operation of a watchdog controller in an embodiment according to the invention;
• 4 a vehicle with a system in an embodiment according to the invention;
• 5 a schematic diagram of a steering system of a vehicle with a steer-by-wire system in a second embodiment according to the invention; and
• 6 a schematic diagram of a steering system of a vehicle with a steer-by-wire system in another embodiment of the invention.

DETAILED DESCRIPTION

1 shows a steer-by-wire system 100 in which steering inputs via a steering wheel 102 through sensor 104 converted into electrical signals and to three separate steering control units 106A . 106B . 106C be transmitted. Each of the three steering controllers provides a steering input to the engines 108A . 108B ready what the position of the rack 110 and thus the wheels 114A . 114B control. Three separate control units 106A . 106B . 106C are provided such that if one of the controllers fails or generates an incorrect output, the outputs of the remaining two controllers may be used and the output of the different controller may be discarded. In this way, a loss of steering due to a failure of a single controller is prevented. It is noted that a majority gate may be provided to ensure that a controller output that is different from the outputs of the remaining two controllers is ignored by the actuators.

If more than one of the control units 106A . 106B . 106C , the sensor 104 and one of the engines 108A . 108B fails or detects an error, becomes a clutch 112 indented, causing the steering wheel 102 over the steering shaft 116 which the rack 110 via a pinion (not shown) controls when the clutch 112 is engaged with the rack 110 is connected.

This in 1 The system shown provides sufficient redundancy to ensure that no single failure can lead to a complete loss of steering. However, providing mechanical replacements and separate controllers increases the cost and weight of the system and may negate some of the potential benefits of steer-by-wire systems. This in 1 shown system is for a vehicle with only a pair of steerable wheels. Would that be in 1 used steering system in a vehicle with steering in front and rear axle, then additional control devices and mechanical replacement components would be required, which would increase the cost and weight of the system even further.

2 shows a schematic diagram of a steering system 200 which is functional to each of the wheels 204A-D via corresponding electric steering actuators 202A-D to steer individually and 4 shows a wheeled vehicle 500 that is a steering system 200 as in 2 can contain shown. The vehicle 500 may be driven by a driving force such as an internal combustion engine or an electric machine. In some embodiments, the vehicle may be a hybrid vehicle powered by a combination of an internal combustion engine and an electric machine.

In the in 2 Shown embodiment, the electric steering control actuators 202A-D Electric motors with pinions that are functional to the corresponding racks 206A-D to move and thus the angle of the wheels 204A-D to change. However, it should be understood that other electric steering actuators would be suitable, such as electrically controlled hydraulic steering actuators.

Solid lines representing the components in 2 Connect, show connections for transmitting electrical current and dashed lines connecting components show connections for transmitting control signals. It should be noted that direct electrical connections are not required to transmit control signals since the required communication can also be achieved through wireless connections. It should also be understood that, although for clarity, direct connections between components are shown, in practice the communication of control signals may be achieved by connecting the components to a common network through which the components can transmit and receive signals. A controller area network (CAN) may provide a suitable network over which control signals can be received, and some or all of the ones in FIG 2 Sensors, actuators and ECUs shown can be connected to a CAN bus instead of each other. It is noted that other electrical buses are provided to convey the control signals, such as IP-based buses, such as Ethernet. In this way, all components, such as the sensors, actuators and controllers, can represent a network node in the bus.

Steering the front wheels 204A . 204B in the in 2 shown embodiment is by the front steering control unit 208 generated by an energy storage device 212 , such as a battery, is powered by controlled actuators 202A . 202B executed. In the illustrated embodiment, the battery is a low voltage battery (eg 12V) of the vehicle. Similarly, steering the rear wheels 204C . 204D through from the rear steering control unit 210 , which also by battery 212 is powered, controlled actuators 202C . 202D executed. The front and rear steering control unit 208 . 210 Both are via appropriate switches 218 . 220 with the battery 212 connected, wherein the switches are watchdog controllers 214 . 216 is. The front and rear steering control unit 208 . 210 each may include a processor having access to an electronic memory. Instructions for controlling the actuators in response to one or more inputs may be stored in electronic memories.

In normal operation of the steering system 200 receives the front steering control unit 208 an input indicating the position of the steering wheel 102 and may further receive inputs indicative of the one or more other vehicle operating parameters including, but not limited to, a currently selected off-road mode, a vehicle speed, a current position of the racks 206A . 206B , one or more wheel slip parameters and a vehicle yaw rate. The front steering control unit 208 is configured to be a required to the steering actuators 202A . 202B to calculate the amount of current to be sent in order to calculate the required steering effect requested by the driver, wherein the calculation may be performed using a predetermined function, such as a control map. It should be noted that the calculation of the required amperage depends on the current values of the inputs to the controller 208 can be updated continuously. Under certain circumstances, that can be sent to the control unit 202A provided Amperage from the to the actuator 202B differentiated.

In normal operation of the system 200 receives the rear steering control unit 210 also an input showing the position of the steering wheel 102 and optionally other vehicle operating parameters including, but not limited to, a currently selected off-road mode, a vehicle speed, a current position of the racks 206A . 206B , one or more wheel slip parameters and a vehicle yaw rate. A function, such as a control map, that uses inputs similar to those used by the function used to drive the front actuators 202A . 202B The calculated amount of current provided can be used on the rear steering control unit, that of the rear steering actuators 202C . 202D required to calculate amperage. It is noted, however, that the required to the rear actuators 202C . 202D Amperage provided may differ significantly from that under the same circumstances for the front actuators 202A . 202B is required. The features that are used to set the required amperage for each of the actuators 202A-D based on the input conditions is typically determined empirically to provide an appropriate balance of vehicle stability and steering response.

In some embodiments, the controllers are 208 . 210 functional to receive inputs indicating the positions of the racks 206A-D and required positions of the racks, depending on the rest of the control units 208 . 210 received inputs, to calculate. The controllers can provide feedback control by the steering actuators 202A-D Implement the supplied current to ensure that the current position of the racks is as close as possible to the required positions. Furthermore, the control units 208 . 210 regulate the voltage of the supply of actuators instead of the current provided to the actuators.

It should be noted that the functions that are used to connect to the steering actuators 202A-D To calculate the required amperage to be provided, a relatively large number of inputs may require and can be relatively complicated. Thus, it is necessary to ensure that the outputs provided by the functions are not the result of a bug in the functions or malfunction of the one or more of the processors that implement the functions.

The watchdog controllers 214 . 216 are configured to make sure that the system 200 operates normally and to instruct an appropriate corrective action when an error condition is detected. The front and rear watchdog controllers 214 . 216 each may include a processor having access to an electronic memory.

The watchdog controller 214 is configured to receive an input indicating the position of the steering wheel 102 indicates and inputs from the front steering actuators 202A . 202B to receive the positions of the front racks 206A . 206B specify. 3 FIG. 12 is a flow chart illustrating the control process performed by the watchdog controllers. FIG 208 . 210 is performed. The control process begins with step 302 in which the vehicle is started, and it immediately goes to step 304 in which the watchdog controller receives the inputs P _R1 , P _R2 indicating the positions of the racks which are associated with the controller whose operation the watchdog is configured to test. In the in 2 illustrated embodiment receives the watchdog controller 214 , which is configured to control the operation of the steering control unit 208 to check inputs from steering actuators 202A . 202B showing the positions of racks 206A . 206B specify. Similarly, the watchdog controller receives 216 , which is configured to control the operation of the steering control unit 210 to check inputs from steering actuators 202C . 202D showing the positions of racks 206C . 206D specify.

Once the inputs indicating the positions of the racks have been received, the method continues with step 306 in which the controller receives an input Pw indicating the current position of the steering wheel. Then, the controller calculates an expected range for steering wheel positions P _{R_MIN} -P _{R_MAX} based on the steering wheel position P _W in step 308 , The control process moves to step 310 in which the control unit determines whether the received rack positions P _R1 , P _{R2 are} within the expected range P _{R_MIN} -P _{R_MAX} . If the received rack positions are in the expected range, then the control process returns to step 304 and the process is repeated until at least one of the rack positions is outside the expected range.

When the controller in step 310 determines that at least one of the rack positions is outside the expected range, then the method moves to step 312 in which it is determined that a fault is present either in the steering control unit whose operation the watchdog control unit checks or in one of the steering actuators is present. To prevent this error from producing a wrong steering output, the watchdog controller interrupts the flow of electrical current to the controller whose operation it is testing by opening a switch between the controller and the battery. In the in 2 illustrated embodiment is the watchdog controller 214 functional, to switch 218 to open if a fault in control unit 208 or in one of the front steering actuators 202A . 202B is detected, and the watchdog controller 216 is functional to the switch 220 to open if a fault in control unit 210 or in one of the rear steering actuators 202C . 202D is detected.

Each of the racks 206A-D is provided with biasing means which causes it to return to a neutral position when powering the actuator 202A-D which is associated with the corresponding rack is interrupted, for example, because an error condition has been detected by the watchdog controller. The neutral position may correspond to a straight-ahead position of the wheels. The biasing means may comprise one or more springs arranged to bias the rack into the neutral position. Alternatively or additionally, a magnetic switch may be provided to bias the rack back to the neutral position, wherein the magnetic switch may be actuated to no longer bias the rack into the neutral position when electrical power is supplied to the rack-associated controller , This magnetic switch may be operative to lock the rack in the neutral position once the rack reaches its neutral position, for example by directly engaging a recess of the rack by a component fixed with respect to the vehicle body.

As in 2 shown is the controller 208 functional to receive a signal indicating the position of the switch 220 indicating that selectively the flow of electrical power to the controller 210 can interrupt. Similarly, the controller is 210 functional to receive a signal indicating the position of the switch 218 indicating that selectively the flow of electrical power to the controller 208 can interrupt. In normal operation, both are switches 218 . 220 closed, and therefore all the wheels can 204A-D through control units 208 . 210 be steered. But if one of the watchdog controllers 214 . 216 detects an error condition, then becomes one of the switches 218 . 220 open, reducing the flow of electrical power to one of the control units 208 . 210 is interrupted. If one of the switches 218 . 220 is opened, then the controller, which continues to receive electric power, receives a signal indicating that the switch controlling the flow of electric power has been opened and, accordingly, the wheels associated with the other controller move to their neutral Position and can no longer be steered. Accordingly, the remaining controller adjusts at least one control parameter used to calculate the required amperage for the actuators associated with the controller to account for the fact that the wheels associated with the other controller are no longer controllable.

If, for example, the switch 220 as a result of detecting a fault in the rear steering control unit 210 through the watchdog controller 216 is opened, then the front steering control unit 208 increase the amount of current flowing to the front steering actuators 202A . 202B is sent, especially in cases where during normal operation of the vehicle a crucial steering input from the rear steering actuators 202C . 202D would be expected. Similarly, if the switch 218 as a result of detecting a fault in the front steering control unit 208 through the watchdog controller 214 is opened, the rear steering control unit 210 Change the function used to calculate the amount of amperage sent to the rear steering actuators to ensure that an adequate steering response is provided by the rear steering actuators 202C . 202D is provided alone when the front steering actuators 202A . 202B are inactive. In this way, each of the steering control units 208 . 210 Redundancy in case of failure of the other steering control unit ready. Further, the action of the watchdog controller 214 . 216 sure that if one of the steering control units 208 . 210 outputs a defective output, identifies the erroneous output as such, and disables the error-generating controller. This ensures that no single failure alone can result in a loss of steering or faulty steering output.

The watchdog controllers 216 . 214 may be functional to perform other verification routines in addition to the previously described routines. So can the controllers 208 . 210 For example, in normal operation, at predetermined time intervals, send signals to the watchdog controllers (or to a CAN bus from which the watchdog controllers can receive signals). The watchdog controllers 214 . 216 may be configured to monitor these signals and identify a fault condition and disable the controller they are testing if the signal is not updated by the controller within a predetermined time interval. An unexpected absence of the periodically updated Signals may indicate that a controller is stuck in an endless loop that consumes a large portion of its processing power, thereby preventing normal operation of the controller.

It should be noted that when the power supply to one of the steering control units 208 . 210 is interrupted, the steering performance of the vehicle may be worse than if both steering controllers are powered and work properly. Further, if the system is operated with only one of the steering controllers, there is no redundancy in the steering system and failure of the remaining controller could cause loss of steering. Accordingly, it is undesirable for the vehicle to be run with one of the control units turned off for a long period of time.

The system 200 may be configured to issue a warning message to a driver of the vehicle when one of the steering control devices is turned off. The warning message may inform the driver on which axle the steering has been lost and may advise the driver to drive the vehicle to a safe location and then seek help. Further, the system may be configured to issue a warning message to the outside of the vehicle to warn other road users that the vehicle is not operating normally. For example, the hazard warning lights can be switched on automatically if there is a fault in one of the steering control units 208 . 210 is detected.

In some embodiments, the function of the vehicle may be limited when one of the steering control devices 208 . 210 is off. For example, the speed of the vehicle may be limited to a value below a predetermined value. If the speed of the vehicle is above the predetermined value, if an error is detected by one of the watchdog controllers 214 . 216 is detected, then a warning message may be issued informing the driver that the steering on one of the axles has been lost and instructing him to reduce the speed. If the driver does not reduce the speed within a predetermined period of time from the issuance of the warning message, the speed of the vehicle may be automatically reduced to the predetermined value with a gentle deceleration rate.

In the embodiments described above, the watchdog controllers 214 . 216 functional, to switch 218 . 220 when detecting an error condition. In some embodiments, if one of the watchdog controllers 214 . 216 an error in the corresponding control unit 208 . 210 however, the watchdog controller is configured to prevent the controller from which the fault is detected from controlling the actuators by disconnecting the controller from the actuators while maintaining power to the controller. This can be done by opening one or more switches between the controller and the actuators. In other embodiments, the watchdog controller may be configured to issue a cancellation command to the actuators, which cancellation command instructs the actuators to ignore the output of the controller and, optionally, further causes the actuators to move the racks to a preferred position, such as For example, in the position that corresponds to "straight ahead". If a cancellation command that causes the actuators to move the racks to the "straight ahead" position is issued, it may not be necessary to provide separate biasing means to move the racks into the "straight ahead" condition after an error condition has been detected ,

If it has been prevented that a controller that has detected an error controls the actuators, the watchdog controller that has detected the error may be configured to reset the controller. Under certain circumstances, this can correct the error condition. If the watchdog controller determines that the controller reset has remedied the fault condition, it may allow the controller to re-control the actuators, for example, by closing a switch between the controller and the actuators or by stopping the issue of the cancel signal the actors.

It should be understood that embodiments of the invention may be embodied in the form of hardware, software, or a combination of hardware and software. Such software may be in the form of non-volatile storage such. B. a storage device such as a ROM, whether erasable or overwritable or not, or in the form of storage such. As memory chips, devices or integrated circuits or on an optically or magnetically readable medium, such. As a CD, DVD, magnetic disk or a magnetic tape can be stored. It is noted that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the invention. Accordingly, embodiments provide a program that provides code for implementing a system or method as claimed in any one of the preceding claims machine-readable memory that stores such a program ready. Furthermore, embodiments of the invention may be transmitted electronically via a data carrier, such as via a communication signal transmitted via a wired connection or a wireless connection, and embodiments may include the same.

In the in 2 shown embodiment, each of the wheels 204A-D with an individual rack 206A-D provided by a corresponding actuator 202A-D is controlled.

This makes it possible to individually control the steering input to each of the wheels. In some embodiments, the front wheels 204A . 204B but be connected to the same rack. In these embodiments, only one actuator may be needed to control the rack of the front wheels. Similarly, the rear wheels 204C . 204D also be connected to the same rack and a single actuator can be used to control the rear rack.

5 shows a schematic diagram of a steering system 501 which is functional to each of the wheels 504A-D via corresponding electric steering actuators 502A-D to steer individually and the wheeled vehicle 500 out 4 Alternatively, the steering system 501 as in 5 shown included. The vehicle 500 may be driven by a driving force such as an internal combustion engine or an electric machine. In some embodiments, the vehicle may be a hybrid vehicle powered by a combination of an internal combustion engine and an electric machine.

In the in 5 Shown embodiment, the electric steering control actuators 502A-D Electric motors with pinions that are functional to the corresponding racks 506A-D to move and thus the angle of the wheels 504A-D to change. However, it should be understood that other electric steering actuators would be suitable, such as electrically controlled hydraulic steering actuators. Similarly, a single actuator may be provided to steer both front wheels or both rear wheels using conventional racks and steering linkage.

Solid lines representing the components in 5 Connections show connections for transmitting electrical current, and dashed lines connecting components show connections for transmitting control signals. It should be noted that direct electrical connections are not required to transmit control signals since the required communication can also be achieved through wireless connections. It should also be understood that, although for clarity, direct connections between components are shown, in practice the communication of control signals may be achieved by connecting the components to a common network through which the components can transmit and receive signals. A controller area network (CAN) may provide a suitable network over which control signals may be received and some or all of the in 5 Sensors, actuators and ECUs shown can be connected to a CAN bus instead of each other. It is noted that other electrical buses are provided to convey the control signals, such as IP-based buses, such as Ethernet. In this way, each component, such as the sensors, actuators, and controllers, can represent a hub in the bus.

Steering the front wheels 504A . 504B in the in 5 shown embodiment is by the front steering control units 508A-C generated by an energy storage device 512 , such as a battery, are powered by controlled actuators 502A . 502B executed. In the illustrated embodiment, the battery is a low voltage battery (eg 12V) of the vehicle. Steering the rear wheels 504C . 504D gets through from the rear steering controller 510 , which also by battery 512 is powered, controlled actuators 502C . 502D executed. The rear steering control unit 510 is via a corresponding switch 520 that has watchdog controllers 516 is controlled with the battery 512 connected. The front and rear steering control unit 208A-C . 210 each may include a processor having access to an electronic memory. Instructions for controlling the actuators in response to one or more inputs may be stored in electronic memories.

In normal operation of the steering system 500 receive the front steering control units 508A-C an input indicating the position of the steering wheel 502 and further may receive inputs indicative of the one or more other vehicle operating parameters including, but not limited to, a currently selected off-road mode, a vehicle speed, a current position of the racks 506A . 506B , one or more wheel slip parameters and a vehicle yaw rate. The front steering control units 508A-C are configured to be a required to the steering actuators 502A . 502B to calculate the current to be sent to the required by the driver requested To calculate steering effect, wherein the calculation can be performed using a predetermined function, such as a control map. It should be noted that the calculation of the required amperage depends on the current values of the inputs to the control units 508A-C can be updated continuously. Under certain circumstances, that can be sent to the control unit 502A provided current strength from that to the actuator 502B differentiated.

In normal operation of the system 501 receives the rear steering control unit 510 also an input showing the position of the steering wheel 502 and optionally other vehicle operating parameters including, but not limited to, a currently selected off-road mode, a vehicle speed, a current position of the racks 506A . 506B , one or more wheel slip parameters and a vehicle yaw rate. A function, such as a control map, that uses inputs similar to those used by the function that is applied to the front actuators 502A . 502B The calculated amount of current provided can be used on the rear steering control unit, that of the rear steering actuators 502C . 502D required to calculate amperage. It is noted, however, that the required to the rear actuators 502C . 502D Amperage provided may differ significantly from that under the same circumstances for the front actuators 502A . 502B is required. The features that are used to set the required amperage for each of the actuators 502A-D based on the input conditions is typically determined empirically to provide an appropriate balance of vehicle stability and steering response.

In some embodiments, the controllers are 508A-C . 510 functional to receive inputs indicating the positions of the racks 506A-D specify and required positions of the racks depending on the rest through the control units 508 . 510 to receive received inputs. The controllers can provide feedback control by the steering actuators 502A-D Implement power levels provided to ensure that the current positions of the racks are as close as possible to the required positions. Furthermore, the control units 508 . 510 regulate the voltage of the supply of actuators instead of the current provided to the actuators.

It should be noted that the functions that are used to connect to the steering actuators 502A-D To calculate the required amperage to be provided, a relatively large number of inputs may require and can be relatively complicated. Thus, it is necessary to ensure that the outputs provided by the functions are not the result of a programming error in the functions or malfunction of the one or more of the processors that implement the functions.

A watchdog controller 516 is configured to ensure that the system 501 works normally and instructs an appropriate corrective action when an error condition is detected. The watchdog controller 216 may include a processor having access to electronic memory.

The watchdog controller 516 is configured to receive an input indicating the position of the steering wheel 102 indicates and inputs from the rear steering actuators 502C . 502D to receive the positions of the front racks 506C . 506D specify. 3 FIG. 12 is a flow chart illustrating the control process performed by the watchdog controller. FIG 510 is performed. The control process begins with step 302 in which the vehicle is started, and it immediately goes to step 304 in which the watchdog controller receives the inputs P _R1 , P _R2 indicating the positions of the racks which are associated with the controller whose operation the watchdog is configured to test. In the in 5 illustrated embodiment receives the watchdog controller 516 , which is configured to control the operation of the steering control unit 510 to check inputs from steering actuators 502C . 502D showing the positions of racks 506C . 506D specify.

Once the inputs indicating the positions of the racks have been received, the method continues with step 306 in which the controller receives an input Pw indicating the current position of the steering wheel. Then, the controller calculates an expected range for steering wheel positions P _{R_MIN} -P _{R_MAX} based on the steering wheel position P _W in step 308 , The control process moves to step 310 in which the control unit determines whether the received rack positions P _R1 , P _{R2 are} within the expected range P _{R_MIN} -P _{R_MAX} . If the received rack positions are in the expected range, then the control process returns to step 304 and the process is repeated until at least one of the rack positions is outside the expected range.

When the controller in step 310 determines that at least one of the rack positions is outside the expected range, then the method moves to step 312 in which it is determined that a fault is present either in the steering control unit whose operation the watchdog control unit is checking, or in one of the steering actuators. To prevent this error from producing a wrong steering output, the watchdog controller interrupts the flow of electrical current to the controller whose operation it is testing by opening a switch between the controller and the battery. In the in 5 illustrated embodiment is the watchdog controller 515 functional, to switch 520 to open if a fault in control unit 510 or in one of the rear steering actuators 502C . 502D is detected.

Each of the racks 506C-D is provided with biasing means which causes it to return to a neutral position when powering the actuator 502C D, which is associated with the corresponding rack, is interrupted, for example, because an error condition has been detected by the watchdog controller. The neutral position may correspond to a straight-ahead position of the wheels. The biasing means may comprise one or more springs arranged to bias the rack into the neutral position. Alternatively or additionally, a magnetic switch may be provided to bias the rack into the neutral position, wherein the magnetic switch may be actuated to stop the rack from being further biased to the neutral position when electrical power is applied to the rack linked control unit is delivered. This magnetic switch may be operative to lock the rack in the neutral position once the rack reaches its neutral position, for example by directly engaging a recess of the rack by a component fixed with respect to the vehicle body.

As in 5 is the watchdog controller 516 functional to receive a signal indicating the position of the switch 520 indicating that selectively the flow of electrical power to the controller 510 can interrupt. In normal operation is the switch 520 closed, and therefore can the rear wheels 504C-D through the control unit 510 be steered. But if the watchdog controller 516 detects an error condition, then the switch 520 open, reducing the flow of electrical power to the control unit 510 is interrupted. When the switch 520 is opened, then receive the front steering control units 508A-C a signal indicating that the switch controlling the flow of electric power to the rear controller has been opened, and thus the wheels associated with this controller move to their neutral position and can no longer be steered. Accordingly, the front steering control devices 508A-C at least one control parameter used to calculate the required amperage for the actuators associated with the controllers to account for the fact that the rear wheels are no longer controllable.

As in 5 As shown, the front steering system provides triple redundancy in this embodiment. Each of the front steering control units 508A-C receives a signal indicating the position of the steering wheel 502 indicates and actuating current to the front steering actuators 502A . 502B provides. The front steering actuators 502A . 502B control the steering angles of the front wheels 504A and 504B , In case of failure or failure of one of the front steering control units 508A-C Other control units lift up an exit of the failed ECU and stop steering of forward wheels. The steering of the front wheels is therefore similar to the prior art, as in 1 although a control parameter associated with the front steering control system may be modified in the event of a rear steering failure.

The rear racks 506C-D are provided with a biasing means which causes them to return to a neutral position when powering the actuator 502C-D which is associated with the corresponding rack is interrupted, for example, because an error condition has been detected by the watchdog controller. The neutral position may correspond to a straight-ahead position of the wheels. The biasing means may comprise one or more springs arranged to bias the rack into the neutral position. Alternatively or additionally, a magnetic switch may be provided to bias the rack into the neutral position, wherein the magnetic switch may be actuated to stop the rack from being further biased to the neutral position when electrical power is applied to the rack linked control unit is delivered. This magnetic switch may be operative to lock the rack in the neutral position once the rack reaches its neutral position, for example by directly engaging a recess of the rack by a component fixed with respect to the vehicle body.

The watchdog controller 516 may be functional to perform other verification routines in addition to the previously described routines. So can the controllers 508A-C . 510 for example, in normal operation at predetermined time intervals, signals (generally referred to as "alive counters") to the watchdog controllers (or to a CAN bus, of which the Watchdog control units can receive signals). The watchdog controller 516 may be configured to monitor these signals and identify a fault condition, and disable the controller that tests it, if the signal is not updated by the controller within a predetermined time interval. An unexpected failure of the periodically updated signals may indicate that a controller is stuck in an endless loop that consumes a large portion of its processing power, thus preventing normal operation of the controller.

It should be noted that when the power supply to the rear control unit 510 interrupted, the steering performance of the vehicle may be worse than if all the steering control units are powered and functioning correctly. The system 501 can be configured to issue a warning message to a driver of the vehicle when the rear steering control unit is turned off. The alert message may inform the driver that the steering at the rear axle has been lost and may suggest the driver to drive the vehicle to a safe location and then seek help. Further, the system may be configured to issue a warning message to the outside of the vehicle to warn other road users that the vehicle is not operating normally. For example, the hazard warning lights can be switched on automatically if there is a fault in one of the steering control units 508A-C . 510 is detected.

In some embodiments, the function of the vehicle may be limited when one of the steering control devices 508A-C . 510 is off. For example, the speed of the vehicle may be limited to a value below a predetermined value. If the speed of the vehicle is above the set value, if there is an error by the watchdog controller 516 is detected, then a warning message can be issued informing the driver that the steering at the rear axles has been lost and instructs him to reduce the speed. If the driver does not reduce the speed within a predetermined period of time from the issuance of the warning message, the speed of the vehicle may be automatically reduced to the predetermined value with a gentle deceleration rate.

In the embodiments described above, the watchdog controller 516 functional, a switch 520 when detecting an error condition. In some embodiments, when the watchdog controller 516 an error in the corresponding control unit 510 however, the watchdog controller is configured to prevent the controller from which the fault is detected from controlling the actuators by disconnecting the controller from the actuators while maintaining power to the controller. This can be done by opening one or more switches between the controller and the actuators. In other embodiments, the watchdog controller may be configured to issue a cancel command to the actuators, this cancel command instructing the actuators to ignore the output of the controller, and optionally optionally further causing the actuators to move the racks to a preferred position, such as in the position that corresponds to "straight ahead". If a cancellation command that causes the actuators to move the racks to the "straight ahead" position is issued, it may not be necessary to provide separate biasing means to move the racks into the "straight ahead" condition after an error condition has been detected ,

If it has been prevented that a controller that has detected an error controls the actuators, the watchdog controller that has detected the error may be configured to reset the controller. Under certain circumstances, this can correct the error condition. If the watchdog controller determines that the controller reset has remedied the fault condition, it may allow the controller to re-control the actuators, for example, by closing a switch between the controller and the actuators or by stopping the issue of the cancel signal the actors.

A steering system 601 in another embodiment of the invention is in 6 shown. In the in 6 Shown embodiment, the front steering actuators 602A , B controlled by a redundant control means, the three control units 608A-C includes. Each of the controllers 608A-C is functional to receive a signal indicating the position of a steering wheel 630 and, optionally, a signal indicative of a value of one of the steering wheel motor 632 to the steering wheel 630 indicates applied torque. It should be noted that the steering wheel motor 632 is configured to provide feedback to a user of the vehicle so as to provide a similar "feel" as when a mechanical connection between the steering wheel 630 and the rack 606 is present. The controllers 608A-C may further receive inputs indicating the speed of the vehicle and other vehicle parameters, such as a current driving mode of the vehicle. The controllers 608A-C are arranged to provide a signal indicating the amperage applied to each of the actuators 608A . 608B is given to the appropriate Low-level control devices 608AL . 608BL provide. The low level controllers 608AL . 608BL are arranged by the signal from the control units 608A-C to cause the actors 608A . 608B a required amperage from the battery 612 receive. This causes a movement of the front rack 606F and therefore the steering of the front wheels 604A . 604B ,

It should be noted that the control units 608A-C Provide redundancy in the calculation of the signals that determine what current to each of the actuators 608A B, so if one of the actuators 608A-C fails, there are still two control devices that can safely calculate the signal. Further, the controllers 608A-C arranged to communicate with each other to ensure that, when one of the control units generates a signal that does not correspond to that generated by the other two, only the corresponding signals to the low-level control devices 608AL . 608BL be sent. This may be referred to as "triple redundancy" and thus provides a sufficiently low probability of failure that it may be considered suitable for use in safety-critical systems, such as for steering the front wheels 604A , B.

Typically, the whole of a driver of a vehicle in which the steering system 601 is provided, requested steering by the steering of the front wheels 604A , B are executed. However, the steering system 601 also functional to the rear wheels 604C , D about actuators 602C To steer D, which are the rear wheels 604C D by moving the rear rack 606R to steer. The controllers 608A-C are functional to determine when steering the rear wheels 604C , D is required, and a signal to the rear steering control unit 640 to provide the amount of steering that must be performed by the rear wheels. Upon receipt of the signal indicative of the amount of steering that must be provided by the rear wheels, the rear steering control unit is 640 arranged to calculate a signal indicative of the amperage applied to the rear steering control devices 602C , D is to apply, this signal to the corresponding low-level control devices 602CL . 602DL the rear steering actuators 602C , D is sent. The low level controllers 602CL . 602DL then cause a current that is due to the received signal from the battery 612 requested corresponds to the rear steering actuators 602C , D is created. This causes a movement of the rear rack 606R and therefore the steering of the rear wheels 604C , D by a value that by the control units 608A-C calculated corresponds.

The signal indicative of the amount of steering required to be performed by the rear wheels is also sent to the rear watchdog controller 642 communicates, wherein the controller is arranged to calculate a range of current values based on the steering they need to perform from the rear actuators 602C , D is required. The rear watchdog controller is further configured to receive an input of the current level to each of the rear steering actuators 602C , D is provided. In the case where the actual one of the rear steering actuators 602C , D provided outside the current through the rear watchdog control unit 642 calculated range, the rear watchdog controller is configured to determine that there is an error in the rear watchdog controller 640 or in one of the low level controllers 602CL . 602DL the rear actuators 602C , D occurred. If it is determined that an error has occurred, the rear watchdog controller is arranged to control the rear actuators 602C , D using the rear steering control unit 640 to control. This causes the rear wheels 604C D will return to its "straight-ahead" position and it will cause all the steering required by the front wheels 604A , B is provided. It is acceptable to have a single controller 640 and a watchdog 642 provide a triple redundant controller for steering the rear wheels, if a failure of the rear steering system leads to a safe state, such as if in case of failure of the steering of the rear wheels steering continues through the front wheels 604A , B can be performed without compromising safety.

A special advantage of in 6 The illustrated arrangement is that a modular system is provided, as this can provide adequate redundancy for a rear wheel steering vehicle and without a mechanical connection between the steering wheel and the racks. In this modular system, the components associated with the rear-wheel steering (ie all of the components under line L) can be omitted if they are installed in a vehicle that does not have rear-wheel steering. In the case of a vehicle without rear-wheel steering, the wheels 604C , D replaced by wheels that are not connected to a rack, and thus are fixed in the straight-ahead position. Thus, the system can be used with appropriate modification in a vehicle line in which some but not all vehicles are operable to perform rear wheel steering. Further, providing a rear steering controller allows 640 physically from the main control units 608A-C Separate, greater flexibility in the design of the system and supplying components.

It should also be noted that in 6 Dotted lines represent connections through which control signals can be transmitted, and solid lines represent connections through which electrical power can be transmitted. Further, although connections only between the battery 612 and the low level controllers 602AL . 602BL . 602CL . 602DL are shown, a power connection (either battery 612 or from an alternative power source) also for each of the other controllers and each of the other sensors.

It should be understood that embodiments of the invention may be embodied in the form of hardware, software, or a combination of hardware and software. Such software may be in the form of non-volatile storage such. B. a storage device such as a ROM, whether erasable or overwritable or not, or in the form of memory such. As memory chips, devices or integrated circuits or on an optically or magnetically readable medium, such. As a CD, DVD, magnetic disk or a magnetic tape are stored. It is noted that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the invention. Accordingly, embodiments provide a program that provides code for implementing a system or method as claimed in any one of the preceding claims and a machine-readable memory storing such a program. Furthermore, embodiments of the invention may be transmitted electronically via a data carrier, such as via a communication signal transmitted via a wired connection or a wireless connection, and embodiments may include the same.

In the in 5 shown embodiment, each of the wheels 504A-D with an individual rack 506A-D provided by a corresponding actuator 502A-D is controlled. This makes it possible to individually control the steering input to each of the wheels. In some embodiments, the front wheels 504A . 504B but be connected to the same rack. In these embodiments, only one actuator may be needed to control the rack of the front wheels. Similarly, the rear wheels 504C . 504D also be connected to the same rack and a single actuator can be used to control the rear rack.

All of the features disclosed in this specification (including any appended claims, summaries, and drawings) and / or all of the steps of any such disclosed methods and operations may be combined as desired, except for combinations in which at least some of these features and / or steps are interrelated exclude each other.

Each feature disclosed in this specification (including any appended claims, abstract and drawings) may be replaced by alternative features that serve the same, equivalent or similar purpose unless expressly stated otherwise. Therefore, unless otherwise indicated, each feature disclosed is just one example of a generic series of equivalent or similar features.

The invention is not limited to the details of any of the above embodiments. The invention extends to any single new or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings) or any single new or any novel combination of steps of such disclosed method or process. The claims should not be construed to cover only the above embodiments, but also any embodiments falling within the scope of the claims.

Claims (57)

A steering control system for a vehicle having a steer-by-wire system, comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels, and a second electrically controlled steering actuator operable to engage a second group of one or multiple wheels, the steering control system comprising: first control means operable to control the first actuating means; second control means operable to control the second actuating means, the second control means comprising redundant control means comprising two or more controllers for calculating the required input to a second actuating means; and a watchdog control means operable to control the first actuating means by the first control means upon detection of an error condition in the first control means and / or in the first actuating means. Steering system after Claim 1 wherein the first group of wheels is a group of rear wheels and the second group of wheels is a group of front wheels. Steering control system according to Claim 1 or 2 wherein the second control system is operable to communicate with user input means and with the first control means, the second control means being operable to generate a first control signal indicative of steering assistance to be provided by the first group of wheels. and a second control signal indicative of a current to be sent to the second actuating means, wherein the first control means is operable to generate a third signal indicative of a current to be sent to the first actuating means in response to the first signal , Steering control system according to Claim 3 wherein the system further comprises a low level control means and a second low level control means, wherein: the first low level control means is configured to receive the third signal and to provide drive current to the first actuating means in response to the third signal; and the second low level control means is configured to receive the second signal and to provide drive current to the second actuating means in response to the second signal. A steering control system as claimed in any one of the preceding claims, wherein the second control means is operable to receive a signal indicating that a fault condition has been detected in the first control means and / or the first actuating means, the second control means being operable to operate in response to Receiving the first signal to set at least one control parameter used in controlling the second actuating means. A steering control system according to any one of the preceding claims, wherein the watchdog control means comprises input means configured to receive a first input indicative of a driver steering input and a second input indicative of an output of the first actuating means, the watchdog control means operable is to detect the error state in the first control means and / or the first actuating means depending on the first and the second input. A steering control system according to any one of the preceding claims, wherein the watchdog control means is configured to perform a forced reset of the first control means in response to the detection of an error condition in the first control means and / or the first actuating means. Steering control system according to Claim 7 wherein the watchdog control means is configured to enable control of the first actuating means by the first control means in response to determining that the error condition has been remedied by the forced reset. A steering control system according to any one of the preceding claims, wherein the watchdog control means is operable to cause a warning to be issued to a driver of the vehicle upon detection of an error condition in the first control means and / or the first actuating means. A steering control system according to any one of the preceding claims, wherein the watchdog control means is operable to restrict power of the vehicle upon detecting a fault condition in the first control means and / or the first actuating means. A steering control system as claimed in any one of the preceding claims, wherein the watchdog control means is operative to issue an externally visible warning upon detection of an error condition in the first control means and / or the first actuating means. A steering control system according to any one of the preceding claims, wherein preventing the first actuating means from controlling the first actuating means comprises interrupting power supply of the first control means. Watchdog control for a steering control system for a vehicle with a steer-by-wire system, wherein the watchdog control is operative to control the control of a first actuating means by the first control means upon detection of a fault condition in the first control means and / or in the prevent first actuating means. A steer-by-wire system for a vehicle, the system comprising: a first electrically controlled steering actuator operable to steer a first group of one or more wheels; a second electrically controlled steering actuator operable to direct a second group of one or more wheels; and a steering control system and / or a watchdog control according to one of the preceding claims. Steer-by-wire system after Claim 14 and further comprising first biasing means operable to move the first group of wheels to a predetermined position in response to detecting a fault condition in the first control means and / or the first actuating means. Steer-by-wire system according to one of the Claims 14 - 15 wherein the first group of wheels comprises a plurality of wheels, and the first actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels. A vehicle comprising a steer-by-wire system according to any one of Claims 14 - 16 , Vehicle after Claim 17 wherein the first group of one or more wheels comprises at least two rear wheels and the second group of wheels comprises at least two front wheels. A method of controlling a vehicle with a steer-by-wire system, comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels, and a second electrically controlled steering actuator operable to control a second group of one or more wheels, wherein the first actuating means is controlled by a first control means and the second actuating means is controlled by a second control means, the method comprising: Detecting an error condition or receiving an error signal indicative of an error condition in the first control means and / or the first actuating means and, in response to the detection or to the error signal; Preventing the first actuating means from being controlled by the first control means; and Adjusting at least one control parameter used by the second control means in controlling the second actuating means. Method according to Claim 19 , comprising receiving a first input indicating a driver steering input and a second input indicating an output of the first actuating means, wherein receiving an error signal or detecting an error condition in the first control means and / or in the first actuating means depends on the first and second input is executed. Method according to Claim 19 or 20 comprising performing a forced reset of the first control means in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means. Method according to Claim 21 comprising, by the first control means, enabling the first control means to control the first control means in response to determining that the error condition has been remedied by the forced reset. Method according to one of Claims 19 - 22 comprising issuing a warning to a driver of the vehicle in response to receiving an error signal or detecting a fault condition in the first control means and / or the first actuating means. Method according to one of Claims 19 - 23 comprising limiting the power of the vehicle in response to detecting a fault condition in the first control means and / or the first actuating means. Method according to one of Claims 19 - 24 comprising outputting an externally visible warning in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means. Method according to one of Claims 19 - 25 wherein preventing control of the first actuating means by the first control means comprises interrupting power supply of the first control means. Non-transient computer-readable medium carrying computer-readable code which, when executed by a computer, causes a vehicle to perform the method of any one of Claims 19 - 26 performs. Processor, arranged to follow the procedure of one of Claims 19 - 26 to implement. A steering control system for a vehicle having a steer-by-wire system, comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels, and a second electrically controlled steering actuator operable to engage a second group of one or multiple wheels, the steering control system comprising: first control means operable to control the first actuating means; second control means operable to control the second actuating means; and watchdog control means operable to prevent control of the first actuating means by the first control means upon detection of an error condition in the first control means and / or in the first actuating means and control of the second actuating means by the second control means upon detection of a fault condition prevent the second control means and / or the second actuating means. Steering control system according to Claim 29 wherein the second control means is operable to receive a second signal indicating that a fault condition has been detected in the first control means and / or the first actuating means, the second control means being operable to operate at least one of the second signal to set a control parameter used in controlling the second actuating means. Steering control system according to Claim 29 or 30 wherein the first control means is operable to receive a first signal indicating that a fault condition has been detected in the second control means and / or the second actuating means, the first control means being operable to operate at least one of a plurality of times depending on receiving the first signal to set a control parameter used in controlling the first actuating means. Steering control system according to Claim 29 - 31 wherein the watchdog control means comprises input means configured to receive a first input indicative of a driver steering input and a second input indicative of an output of the first actuating means, the watchdog control means operable to detect the fault condition in the first control means and / or the first actuating means depending on the first and the second input to capture. Steering control system according to Claim 32 wherein the watchdog control means comprises input means configured to receive a third input indicative of an output of the second actuating means, the watchdog control means being operable to depend on the error condition in the second control means and / or the second actuating means from the first and third inputs. Steering control system according to one of Claims 29 - 33 wherein the watchdog control means is configured to perform a forced reset of the first control means in response to detecting an error condition in the first control means and / or the first actuating means. Steering control system according to Claim 34 wherein the watchdog control means is configured to enable control of the first actuating means by the first control means in response to determining that the error condition has been remedied by the forced reset. Steering control system according to Claim 29 - 35 wherein the watchdog control means is operable to cause a warning to be issued to a driver of the vehicle upon detection of an error condition in the first control means and / or the first actuating means. Steering control system according to one of Claims 29 - 36 wherein the watchdog control means is operable to restrict power of the vehicle upon detecting a fault condition in the first control means and / or the first actuating means. Steering control system according to one of Claims 29 - 37 wherein the watchdog control means is operative to issue an externally visible warning upon detecting an error condition in the first control means and / or the first actuating means. Steering control system according to one of Claims 29 - 38 wherein preventing control of the first actuating means by the first control means comprises interrupting power supply of the first control means. Watchdog control for a steering control system for a vehicle with a steer-by-wire system, wherein the watchdog control is operative to control the control of a first actuating means by the first control means upon detection of a fault condition in the first control means and / or in the prevent first actuating means and to prevent the control of a second actuating means by a second control means upon detection of a fault condition in the second control means and / or the second actuating means. Steer-by-wire system for a vehicle, the system comprising: a first electrically controlled steering actuator operable to direct a first group of one or more wheels; a second electrically controlled steering actuator operable to direct a second group of one or more wheels; and a steering control system and / or a watchdog control according to one of the preceding claims. Steer-by-wire system after Claim 41 , further comprising a first biasing means, the is operable to move the first group of wheels to a predetermined position in response to detection of an error condition in the first control means and / or the first actuating means. Steer-by-wire system after Claim 41 or 42 , further comprising second biasing means operable to move the second group of wheels to a predetermined position in response to detection of a fault condition in the second control means and / or the second actuating means. Steer-by-wire system according to one of the Claims 41 - 43 wherein the first group of wheels comprises a plurality of wheels and the first actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels. Steer-by-wire system according to one of the Claims 41 - 44 wherein the second group of wheels comprises a plurality of wheels and the second actuating means comprises a plurality of actuators, each of the actuators being associated with a corresponding one of the plurality of wheels. A vehicle comprising a steer-by-wire system according to any one of Claims 41 - 45 , Vehicle after Claim 46 wherein the first group of one or more wheels comprises at least two front wheels and the second group of wheels comprises at least two rear wheels. A method of controlling a vehicle with a steer-by-wire system, comprising a first electrically controlled steering actuator operable to steer a first group of one or more wheels, and a second electrically controlled steering actuator operable to control a second group of one or more wheels, wherein the first actuating means is controlled by a first control means and the second actuating means is controlled by a second control means, the method comprising: Detecting an error condition or receiving an error signal indicative of an error condition in the first control means and / or the first actuating means and, in response to the detection or to the error signal; Preventing the first actuating means from being controlled by the first control means; and Adjusting at least one control parameter used by the second control means in controlling the second actuating means. Method according to Claim 48 , comprising receiving a first input indicating a driver steering input and a second input indicating an output of the first actuating means, wherein receiving an error signal or detecting an error condition in the first control means and / or in the first actuating means depends on the first and second input is executed. Method according to Claim 48 or 49 comprising performing a forced reset of the first control means in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means. Method according to Claim 50 comprising, by the first control means, enabling the first control means to control the first control means in response to determining that the error condition has been remedied by the forced reset. Method according to one of Claims 48 - 51 comprising issuing a warning to a driver of the vehicle in response to receiving an error signal or detecting a fault condition in the first control means and / or the first actuating means. Method according to one of Claims 48 - 52 comprising limiting the power of the vehicle in response to detecting a fault condition in the first control means and / or the first actuating means. Method according to one of Claims 48 - 53 comprising outputting an externally visible warning in response to receiving an error signal or detecting an error condition in the first control means and / or the first actuating means. Method according to one of Claims 48 - 54 wherein preventing control of the first actuating means by the first control means comprises interrupting power supply of the first control means. Non-transient computer-readable medium carrying computer-readable code which, when executed by a computer, causes a vehicle to perform the method of any one of Claims 48 - 55 performs. Processor, arranged to follow the procedure of one of Claims 48 - 55 to implement.

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