Patent Description:
There is a so-called steer-by-wire steering device in which power transmission between a steering wheel and turning wheels is separated (refer to, for example, <CIT> (<CIT>)). This steering device includes a reaction force mechanism having a reaction force motor that is a source of generating steering reaction force applied to a steering shaft, and a turning mechanism having a turning motor that is a source of generating turning force for turning the turning wheels. When a vehicle travels, a control device of the steering device generates the steering reaction force through electric power supply control to the reaction force motor, and turns the turning wheels through electric power supply control to the turning motor. A steering control device having the features of the preamble of claim <NUM> is known from <CIT>.

The vehicle is requested to have higher crime prevention performance. The steering device mounted on the vehicle is also requested to have higher crime prevention performance. These requests are achieved by the subject-matter of claim <NUM>. Advantageous embodiments are laid out in the dependent claims.

A steering control device according to an aspect of the present invention includes a control circuit configured to control driving of a reaction force motor that generates steering reaction force applied to a steering wheel in which power transmission with turning wheels of a vehicle is separated. When a vehicle power source is turned on, the control circuit requests a vehicle control device that controls traveling of the vehicle to stop the traveling of the vehicle when information is exchanged with the vehicle control device in a manner that does not follow a predetermined pattern.

There is a concern that information exchanged between the steering control device and the vehicle control device may be falsified due to some fraudulent act. In this respect, with the above configuration, it is possible to suppress the traveling of the vehicle when the information is exchanged between the control circuit and the vehicle control device in a manner that does not follow the predetermined pattern. Therefore, crime prevention performance is enhanced.

In the above aspect, when execution of preparatory processing executed with the turn-on of the vehicle power source as a trigger is completed, the control circuit may permit the vehicle control device to cause the vehicle to transition to a travelable state and transition to a normal control state where reaction force control of causing the reaction force motor to generate the steering reaction force is executed when recognition is made via the vehicle control device that the vehicle is in the travelable state.

With the above configuration, when the preparatory processing for the reaction force control is completed, the steering control device permits the vehicle control device to cause the vehicle to transition to the travelable state. That is, the vehicle control device waits until the steering control device permits the vehicle to transition to the travelable state and then causes the vehicle to transition to the travelable state. For this reason, the vehicle can solely travel after the preparatory processing of the steering control device is completed. Therefore, it is possible for the driver to start the traveling of the vehicle in a safer state.

In the above configuration, when the recognition is made via the vehicle control device that the vehicle is in the travelable state even though the vehicle control device is not permitted to cause the vehicle to transition to the travelable state, the control circuit may request the vehicle control device to stop the traveling of the vehicle.

When the recognition is made that the vehicle is in the travelable state even though the steering control device does not permit the vehicle control device to transition the vehicle to the travelable state, the permission to the vehicle control device may be falsified due to a fraudulent act such as impersonation. In this respect, with the above configuration, when the permission to the vehicle control device may be falsified, the vehicle control device is requested to stop the traveling of the vehicle. With the stop of the traveling of the vehicle by the vehicle control device in response to the request from the steering control device, the crime prevention performance is enhanced.

In the above configuration, the preparatory processing may include, on a premise that a steering range of the steering wheel is restricted to less than <NUM>°, midpoint learning processing of operating the steering wheel to a first operation end and then reversely operating the steering wheel to a second operation end for learning of a steering neutral position of the steering wheel and rudder angle synchronization processing of correcting a rotational position of the steering wheel such that the rotational position of the steering wheel is a rotational position corresponding to a turning position of the turning wheels.

For example, when the vehicle starts to travel even though the steering control device is in the middle of executing the midpoint learning processing or the rudder angle synchronization processing, a driver may have difficulty in steering the steering wheel in an intended steering direction. This is because the steering wheel is in an automatically rotating state during the execution of the midpoint learning processing or during the execution of the rudder angle synchronization processing. In this respect, with the above configuration, when the preparatory processing for the reaction force control is completed, the steering control device permits the vehicle control device to cause the vehicle to transition to the travelable state. For this reason, the vehicle can solely travel after the preparatory processing of the steering control device is completed. Therefore, it is possible for the driver to start the traveling of the vehicle in a safer state. There is no sense of discomfort for the driver.

In the above aspect, the vehicle control device may control a start of a powertrain including a drive source for traveling of the vehicle. With the above configuration, with the control of the start of the powertrain of the vehicle through the vehicle control device, it is possible to cause the vehicle to transition to the travelable state.

With the steering control device of the aspect described above, the crime prevention performance can be further enhanced.

A first embodiment in which a steering control device is embodied as a steer-by-wire steering device will be described below. As shown in <FIG>, a steering device <NUM> of a vehicle has a steering shaft <NUM> connected to a steering wheel <NUM>. The steering device <NUM> also has a turning shaft <NUM> extending along a vehicle width direction (right and left direction in <FIG>). Both ends of the turning shaft <NUM> are respectively connected to turning wheels <NUM> via tie rods <NUM>. With linear movement of the turning shaft <NUM>, a turning angle θw of the turning wheels <NUM> is changed. The steering shaft <NUM> and the turning shaft <NUM> constitute a steering mechanism of the vehicle. <FIG> illustrates solely the turning wheels <NUM> on one side.

The steering device <NUM> has a reaction force motor <NUM> and a speed reduction mechanism <NUM>. The reaction force motor <NUM> is a source of generating steering reaction force. The steering reaction force is force that acts in a direction opposite to a direction in which the steering wheel <NUM> is operated by a driver. A rotation shaft of the reaction force motor <NUM> is connected to the steering shaft <NUM> via the speed reduction mechanism <NUM>. A torque of the reaction force motor <NUM> is applied to the steering shaft <NUM> as the steering reaction force. With the steering reaction force applied to the steering wheel <NUM>, an appropriate feeling of response can be given to the driver.

The reaction force motor <NUM> is, for example, a three-phase brushless motor. The reaction force motor <NUM> has a winding group N11 of a first system and a winding group N12 of a second system. The winding group N11 of the first system and the winding group N12 of the second system are wound around a common stator (not shown). Electrical characteristics of the winding group N11 of the first system and the winding group N12 of the second system are the same.

The steering device <NUM> has a turning motor <NUM> and a speed reduction mechanism <NUM>. The turning motor <NUM> is a source of generating turning force. The turning force is power for turning the turning wheels <NUM>. A rotation shaft of the turning motor <NUM> is connected to a pinion shaft <NUM> via the speed reduction mechanism <NUM>. Pinion teeth 33a of the pinion shaft <NUM> are engaged with rack teeth of the turning shaft <NUM>. A torque of the turning motor <NUM> is applied to the turning shaft <NUM> via the pinion shaft <NUM> as the turning force. As the turning motor <NUM> rotates, the turning shaft <NUM> moves along the vehicle width direction.

The turning motor <NUM> is, for example, a three-phase brushless motor. The turning motor <NUM> has a winding group N21 of a first system and a winding group N22 of a second system. The winding group N21 of the first system and the winding group N22 of the second system are wound around a common stator (not shown). Electrical characteristics of the winding group N21 of the first system and the winding group N22 of the second system are the same.

The steering device <NUM> has a reaction force control device <NUM>. The reaction force control device <NUM> controls driving of the reaction force motor <NUM>, which is a control target. The reaction force control device <NUM> executes reaction force control to cause the reaction force motor <NUM> to generate the steering reaction force according to a steering torque Th. The reaction force control device <NUM> calculates a target steering reaction force based on the steering torque Th detected by a torque sensor <NUM>. The torque sensor <NUM> is provided on the steering shaft <NUM>. The reaction force control device <NUM> controls electric power supply to the reaction force motor <NUM> to match actual steering reaction force applied to the steering shaft <NUM> with the target steering reaction force. The reaction force control device <NUM> independently controls the electric power supply to the winding groups of the two systems in the reaction force motor <NUM> for each system.

The reaction force control device <NUM> has a first system circuit <NUM> and a second system circuit <NUM>. The first system circuit <NUM> controls the electric power supply to the winding group N11 of the first system in the reaction force motor <NUM> according to the steering torque Th detected by the torque sensor <NUM>. The second system circuit <NUM> controls the electric power supply to the winding group N12 of the second system in the reaction force motor <NUM> according to the steering torque Th detected by the torque sensor <NUM>.

The reaction force control device <NUM> and the in-vehicle vehicle control device <NUM> are interconnected via an in-vehicle network <NUM>. The in-vehicle network <NUM> is, for example, a controller area network (CAN). The reaction force control device <NUM> and the in-vehicle vehicle control device <NUM> exchange information with each other via the in-vehicle network <NUM>. The vehicle control device <NUM> controls traveling of the vehicle. Specifically, the vehicle control device <NUM> controls, for example, a powertrain of the vehicle. The powertrain includes a drive source for traveling of the vehicle and a power transmission mechanism. The drive source for traveling includes, for example, an engine or a motor. The power transmission mechanism is a mechanism that transmits the power generated by the drive source for traveling to drive wheels. The reaction force control device <NUM> controls the driving of the reaction force motor <NUM> based on the information exchanged with the vehicle control device <NUM>.

The steering device <NUM> has a turning control device <NUM>. The turning control device <NUM> controls driving of the turning motor <NUM>, which is a control target. The turning control device <NUM> executes turning control to cause the turning motor <NUM> to generate the turning force for turning the turning wheels <NUM> according to a steering state. The turning control device <NUM> takes in a steering angle θs detected by a steering angle sensor <NUM> and a stroke Xw of the turning shaft <NUM> detected by a stroke sensor <NUM>. The stroke Xw is a displacement amount of the turning shaft <NUM> with a neutral position as a reference and is a state variable that reflects the turning angle θw. The steering angle sensor <NUM> is provided between the torque sensor <NUM> of the steering shaft <NUM> and the speed reduction mechanism <NUM>. The stroke sensor <NUM> is provided near the turning shaft <NUM>.

The turning control device <NUM> calculates a target turning angle of the turning wheels <NUM> based on the steering angle θs detected by the steering angle sensor <NUM>. The turning control device <NUM> calculates the turning angle θw based on the stroke Xw of the turning shaft <NUM> detected by the stroke sensor <NUM>. The turning control device <NUM> controls the electric power supply to the turning motor <NUM> to match the turning angle θw calculated based on the stroke Xw with the target turning angle. The turning control device <NUM> independently controls the electric power supply to the winding groups of the two systems in the turning motor <NUM> for each system.

The turning control device <NUM> has a first system circuit <NUM> and a second system circuit <NUM>. The first system circuit <NUM> controls the electric power supply to the winding group N21 of the first system in the turning motor <NUM> based on the steering angle θs detected by the steering angle sensor <NUM> and the stroke Xw of the turning shaft <NUM> detected by the stroke sensor <NUM>. The second system circuit <NUM> controls the electric power supply to the winding group N22 of the second system in the turning motor <NUM> based on the steering angle θs detected by the steering angle sensor <NUM> and the stroke Xw of the turning shaft <NUM> detected by the stroke sensor <NUM>.

With integral provision of the reaction force control device <NUM> and the reaction force motor <NUM>, a so-called electromechanical integrated reaction force actuator may be configured. Further, with integral provision of the turning control device <NUM> and the turning motor <NUM>, a so-called electromechanically integrated turning actuator may be configured. The reaction force control device <NUM> and the turning control device <NUM> constitute a steering control device.

Next, a configuration of the reaction force control device will be described in detail. As shown in <FIG>, the reaction force control device <NUM> has the first system circuit <NUM> and the second system circuit <NUM>. The first system circuit <NUM> has a first reaction force control circuit 41A and a motor drive circuit 41B. The second system circuit <NUM> has a second reaction force control circuit 42A and a motor drive circuit 42B.

The first reaction force control circuit 41A is configured of a processing circuit including <NUM>. one or more processors that operate in accordance with a computer program (software), <NUM>. one or more dedicated hardware circuits, such as an application-specific integrated circuit (ASIC), that execute at least some of various types of processing, and <NUM>. a combination thereof. The processor includes a central processing unit (CPU). The processor also includes memories, such as a random-access memory (RAM) and a read-only memory (ROM). The memory stores a program code or a command configured to cause the CPU to execute the processing. The memory, that is, non-transitory computer-readable medium includes any available medium that can be accessed by a general-purpose or dedicated computer.

The first reaction force control circuit 41A calculates the target steering reaction force to be generated in the reaction force motor <NUM> based on the steering torque Th detected by the torque sensor <NUM>, and calculates a first current command value for the winding group N11 of the first system according to a value of the calculated target steering reaction force. However, the first current command value is set to a value of half (<NUM>%) of a current amount (<NUM>%) requested to cause the reaction force motor <NUM> to generate the target steering reaction force. The first reaction force control circuit 41A executes current feedback control in which a value of an actual current supplied to the winding group N11 of the first system follows the first current command value to generate a drive signal (PWM signal) for the motor drive circuit 41B.

The motor drive circuit 41B is a PWM inverter in which three legs respectively corresponding to three phases (U,V,W), with switching elements such as two field effect transistors (FETs) connected in series as a leg that is a basic unit, are connected in parallel. The motor drive circuit 41B switches the switching elements of each phase based on the drive signal generated by the first reaction force control circuit 41A to convert direct-current electric power supplied from a battery into three-phase alternating-current electric power. The three-phase alternating-current electric power generated by the motor drive circuit 41B is supplied to the winding group N11 of the first system of the reaction force motor <NUM> via an electric power supply path for each phase, such as a bus bar or a cable. Accordingly, the winding group N11 of the first system generates a torque according to the first current command value.

The second reaction force control circuit 42A basically has the same configuration as the first reaction force control circuit 41A. The second reaction force control circuit 42A calculates the target steering reaction force to be generated in the reaction force motor <NUM> based on the steering torque Th detected by the torque sensor <NUM>, and calculates a second current command value for the winding group N12 of the second system according to the value of the calculated target steering reaction force. However, the second current command value is set to the value of half (<NUM>%) of the current amount requested to cause the reaction force motor <NUM> to generate the target steering reaction force. The second reaction force control circuit 42A executes current feedback control in which a value of an actual current supplied to the winding group N12 of the second system follows the second current command value to generate a drive signal for the motor drive circuit 42B.

The motor drive circuit 42B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 42B converts the direct-current electric power supplied from the battery into the three-phase alternating-current electric power based on the drive signal generated by the second reaction force control circuit 42A. The three-phase alternating-current electric power generated by the motor drive circuit 42B is supplied to the winding group N12 of the second system of the reaction force motor <NUM> via the electric power supply path for each phase, such as a bus bar or a cable. Accordingly, the winding group N12 of the second system generates a torque according to the second current command value. The reaction force motor <NUM> generates a total torque of the torque generated by the winding group N11 of the first system and the torque generated by the winding group N12 of the second system.

Depending on product specifications, there may be a master-slave relationship between the first system circuit <NUM> and the second system circuit <NUM> of the reaction force control device <NUM>. In this case, for example, the first system circuit <NUM> may function as a master, and the second system circuit <NUM> may function as a slave. Further, depending on product specifications, the first system circuit <NUM> and the second system circuit <NUM> may have an equal relationship.

Next, a configuration of the turning control device <NUM> will be described in detail. As shown in <FIG>, the turning control device <NUM> has the first system circuit <NUM> and the second system circuit <NUM>. The first system circuit <NUM> has a first turning control circuit 51A and a motor drive circuit 51B. The second system circuit <NUM> has a second turning control circuit 52A and a motor drive circuit 52B.

The first turning control circuit 51A basically has the same configuration as the first reaction force control circuit 41A. The first turning control circuit 51A calculates the target turning angle of the turning wheels <NUM> based on the steering angle θs detected by the steering angle sensor <NUM>. The turning control device <NUM> calculates the turning angle θw based on the stroke Xw of the turning shaft <NUM> detected by the stroke sensor <NUM>. The first turning control circuit 51A calculates a target turning force to be generated in the turning motor <NUM> through execution of angle feedback control in which the turning angle θw calculated based on the stroke Xw follows a target turning angle, and calculates a third current command value for the winding group N21 of the first system of the turning motor <NUM> according to a value of the calculated target turning force. However, the third current command value is set to a value of half (<NUM>%) of a current amount requested to cause the turning motor <NUM> to generate the target turning force. The first turning control circuit 51A executes current feedback control in which a value of an actual current supplied to the winding group N21 of the first system follows the third current command value to generate a drive signal for the motor drive circuit 51B.

The motor drive circuit 51B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 51B converts the direct-current electric power supplied from the battery into the three-phase alternating-current electric power based on the drive signal generated by the first turning control circuit 51A. The three-phase alternating-current electric power generated by the motor drive circuit 51B is supplied to the winding group N21 of the first system of the turning motor <NUM> via the electric power supply path for each phase, such as a bus bar or a cable. Accordingly, the winding group N21 of the first system generates a torque according to the third current command value.

The second turning control circuit 52A basically has the same configuration as the first reaction force control circuit 41A. The second turning control circuit 52A calculates the target turning angle of the turning wheels <NUM> based on the steering angle θs detected by the steering angle sensor <NUM>. The turning control device <NUM> calculates the turning angle θw based on the stroke Xw of the turning shaft <NUM> detected by the stroke sensor <NUM>. The second turning control circuit 52A calculates the target turning force to be generated in the turning motor <NUM> through the execution of angle feedback control in which the turning angle θw calculated based on the stroke Xw follows a target turning angle, and calculates a fourth current command value for the winding group N22 of the second system of the turning motor <NUM> according to a value of the calculated target turning force. However, the fourth current command value is set to the value of half (<NUM>%) of the current amount requested to cause the turning motor <NUM> to generate the target turning force. The second turning control circuit 52A executes current feedback control in which a value of an actual current supplied to the winding group N22 of the second system follows the fourth current command value to generate a drive signal for the motor drive circuit 52B.

The motor drive circuit 52B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 52B converts the direct-current electric power supplied from the battery into the three-phase alternating-current electric power based on the drive signal generated by the second turning control circuit 52A. The three-phase alternating-current electric power generated by the motor drive circuit 52B is supplied to the winding group N22 of the second system of the turning motor <NUM> via the electric power supply path for each phase, such as a bus bar or a cable. Accordingly, the winding group N22 of the second system generates a torque according to the fourth current command value. The turning motor <NUM> generates a total torque of the torque generated by the winding group N21 of the first system and the torque generated by the winding group N22 of the second system.

Depending on product specifications, there may be a master-slave relationship between the first system circuit <NUM> and the second system circuit <NUM> of the turning control device <NUM>. In this case, for example, the first system circuit <NUM> may function as a master and the second system circuit <NUM> may function as a slave. Further, depending on product specifications, the first system circuit <NUM> and the second system circuit <NUM> may have an equal relationship.

Next, communication paths inside the reaction force control device <NUM> and the turning control device <NUM> and communication paths between the reaction force control device <NUM> and the turning control device <NUM> will be described.

As shown in <FIG>, the first reaction force control circuit 41A and the second reaction force control circuit 42A exchange information with each other via a communication line L1. The information includes abnormality information of the first reaction force control circuit 41A and the second reaction force control circuit 42A or the motor drive circuits 41B, 42B. The information also includes flag values indicating various states. The first reaction force control circuit 41A and the second reaction force control circuit 42A cooperate to control the driving of the reaction force motor <NUM> based on the information exchanged with each other.

The first turning control circuit 51A and the second turning control circuit 52A exchange information with each other via a communication line L2. The information includes abnormality information of the first turning control circuit 51A and the second turning control circuit 52A or the motor drive circuits 51B, 52B. The information also includes flag values indicating various states. The first turning control circuit 51A and the second turning control circuit 52A cooperate to control the driving of the turning motor <NUM> based on the information exchanged with each other.

The first reaction force control circuit 41A and the first turning control circuit 51A exchange information with each other via a communication line L3. The information includes abnormality information of the first reaction force control circuit 41A, the first turning control circuit 51A, and the motor drive circuits 41B, 51B. The information also includes flag values indicating various states. The first reaction force control circuit 41A and the first turning control circuit 51A operate in cooperation based on the information exchanged with each other.

The second reaction force control circuit 42A and the second turning control circuit 52A exchange information with each other via a communication line L4. The information includes abnormality information of the second reaction force control circuit 42A and the second turning control circuit 52A or the motor drive circuits 42B, 52B. The information also includes flag values indicating various states. The second reaction force control circuit 42A and the second turning control circuit 52A operate in cooperation based on the information exchanged with each other.

Next, a comparative example of activation sequences of the reaction force control device <NUM> and the vehicle control device <NUM> will be described. The activation sequence is a series of pieces of processing executed with turn-on of a vehicle power source as a trigger. During a period when the vehicle power source is turned off, the reaction force control device <NUM> and the vehicle control device <NUM> are maintained in an inoperative state. The turn-on or turn-off of the vehicle power source also means turn-on or turn-off of an activation switch provided in the driver's seat, for example. The activation switch is operated when the drive source for traveling of the vehicle is started or stopped, and is, for example, an ignition switch or a power switch.

First, the comparative example of the activation sequence of the vehicle control device <NUM> will be described. As shown in a time chart of <FIG>, when the vehicle power source is turned on (time point T1), the vehicle control device <NUM> starts execution of predetermined activation preparation. The activation preparation includes an initial check by the vehicle control device <NUM> and processing requested to start the powertrain of the vehicle. The vehicle control device <NUM> starts the powertrain (mainly drive source for traveling) after the activation preparation is completed. The vehicle control device <NUM> turns on a preparation completion signal S1 when the execution of the powertrain start processing is completed (time point T2). The vehicle control device <NUM> turns on the preparation completion signal S1 regardless of the state of the reaction force control device <NUM>.

The preparation completion signal S1 is information indicating whether or not preparation for the traveling of the vehicle is completed, including the completion of execution of the powertrain start processing, and the vehicle is in a travelable state. The fact that the preparation completion signal S1 is turned on indicates that the vehicle is in the travelable state. The fact that the preparation completion signal S1 is turned off indicates that the vehicle is not in the travelable state. The preparation completion signal S1 is transmitted to the reaction force control device <NUM> as an electric signal.

Next, a comparative example of the activation sequence of the reaction force control device <NUM> will be described. As shown in the time chart of <FIG>, when the vehicle power source is turned on (time point T1), the reaction force control device <NUM> is activated, sequentially executes the initial check, midpoint learning processing, and rudder angle synchronization processing, and then transitions to an assist start waiting state. The initial check, the midpoint learning processing, and the rudder angle synchronization processing are a series of pieces of preparatory processing requested to start the execution of the reaction force control that causes the reaction force motor <NUM> to generate the steering reaction force.

The initial check is an initial inspection that is executed with the turn-on of the vehicle power source as a trigger, and includes, for example, a hardware check, central processing unit (CPU) initialization, and initialization of a variable or a flag.

The midpoint learning processing is processing for learning a steering neutral position of the steering wheel <NUM>. The steering device <NUM> has a stopper mechanism that restricts the rotation of the steering wheel <NUM> in order to limit the steering angle of the steering wheel <NUM>. The stopper mechanism restricts a steering range of the steering wheel <NUM> to less than <NUM>°, for example. The reaction force control device <NUM> controls the reaction force motor <NUM> to operate the steering wheel <NUM> to a first operation end and then to reversely operate the steering wheel <NUM> to a second operation end. Thereafter, the reaction force control device <NUM> calculates a midpoint of the steering angle based on rotation angles of the reaction force motor <NUM> at a start point in time and an end point in time of the reverse operation of the steering wheel <NUM>. The midpoint of the steering angle corresponds to a motor midpoint that is a rotational position of the reaction force motor <NUM> when the steering wheel <NUM> is positioned at the steering neutral position. The reaction force control device <NUM> stores the midpoint of the steering angle or the motor midpoint as the steering neutral position of the steering wheel <NUM>.

However, the reaction force control device <NUM> learns the steering neutral position of the steering wheel <NUM> when a new battery is attached and then the vehicle power source is turned on for the first time. This is because information related to the steering neutral position stored in the reaction force control device <NUM> disappears due to the fact that the electric power is not supplied to the reaction force control device <NUM> when the battery is removed from the vehicle for battery replacement work, for example.

The rudder angle synchronization processing is processing of correcting a rotational position of the steering wheel <NUM>. When the rotational position of the steering wheel <NUM> is different from a rotational position corresponding to a turning position of the turning wheels <NUM>, the reaction force control device <NUM> drives the reaction force motor <NUM> such that the rotational position of the steering wheel <NUM> is the rotational position corresponding to the turning position of the turning wheels <NUM>.

The assist start waiting state is a state of waiting for confirmation of the completion of the execution of the powertrain start processing by the vehicle control device <NUM> after the execution of the preparatory processing is completed. The reaction force control device <NUM> determines whether or not transition from the assist start waiting state to the normal control state is possible according to the start state of the powertrain of the vehicle. When the preparation completion signal S1 is not turned on by the vehicle control device <NUM>, the reaction force control device <NUM> determines that the execution of the start processing of the powertrain of the vehicle has not been completed and maintains the assist start waiting state. When the preparation completion signal S1 is turned on by the vehicle control device <NUM>, the reaction force control device <NUM> determines that the execution of the start processing of the powertrain of the vehicle has been completed (time point T3) and transitions from the assist start waiting state to the normal control state. The normal control state is a state where the reaction force control of causing the reaction force motor <NUM> to generate the steering reaction force is executed. The reaction force control device <NUM> controls the driving of the reaction force motor <NUM> according to the steering state of the steering wheel <NUM> in the normal control state.

In the time chart of <FIG>, the vehicle control device <NUM> turns on the preparation completion signal S1 during the execution of the midpoint learning processing, as an example. However, when the vehicle is in the travelable state regardless of the state of the reaction force control device <NUM>, the vehicle can travel even though the reaction force control device <NUM> is in the middle of executing the preparatory processing. In this case, there are concerns about the following.

For example, when the vehicle starts to travel even though the reaction force control device <NUM> is in the middle of executing the midpoint learning processing, the driver may have difficulty in steering the steering wheel <NUM> in an intended steering direction. This is because the steering wheel <NUM> is in an automatically rotating state during the execution of the midpoint learning processing.

When the vehicle starts to travel even though the reaction force control device <NUM> is in the middle of executing the rudder angle synchronization processing, the driver may have difficulty in steering the steering wheel <NUM> in an intended steering direction. This is because the steering wheel <NUM> is in an automatically rotating state during the execution of the rudder angle synchronization processing. This is also because the rotational position of the steering wheel <NUM> is different from an original rotational position corresponding to the turning position of the turning wheels <NUM> during the execution of the rudder angle synchronization processing. Thus, the reaction force control device <NUM> is configured to execute the following processing.

The reaction force control device <NUM> executes start permission determination processing with the turn-on of the vehicle power source as a trigger. The start permission determination processing is processing of determining whether or not to permit the vehicle control device <NUM> to start the powertrain. The start permission determination processing is executed at a predetermined control cycle according to a program stored in the reaction force control device <NUM>.

As shown in a flowchart of <FIG>, the reaction force control device <NUM> determines whether or not the preparatory processing for the reaction force control is completed (step S101). The preparatory processing is processing for preparation requested to start the execution of the reaction force control and includes the initial check, the midpoint learning processing, and the rudder angle synchronization processing.

When the preparatory processing is determined to be completed (YES in step S101), the reaction force control device <NUM> turns on a start permission signal S2 (step S102) and ends the processing. When the preparatory processing is determined to be not completed (NO in step S101), the reaction force control device <NUM> turns off the start permission signal S2 (step S103) and ends the processing.

The start permission signal S2 is information indicating whether or not to permit the vehicle control device <NUM> to start the powertrain. The fact that the start permission signal S2 is turned on indicates that the vehicle control device <NUM> is permitted to start the powertrain. The fact that the start permission signal S2 is turned off indicates that the vehicle control device <NUM> is not permitted to start the powertrain. The start permission signal S2 is transmitted to vehicle control device <NUM> as an electric signal.

Next, a first pattern of the activation sequence will be described. As shown in a time chart of <FIG>, when the vehicle power source is turned on (time point T1), the reaction force control device <NUM> is activated to sequentially execute the initial check, the midpoint learning processing, and the rudder angle synchronization processing. When the preparatory processing including the initial check, the midpoint learning processing, and the rudder angle synchronization processing is completed, the reaction force control device <NUM> transitions to the assist start waiting state and turns on the start permission signal S2. The assist start waiting state is a state where the preparation for the reaction force control is ready and transition to the normal control state is possible.

When the vehicle power source is turned on (time point T1), the vehicle control device <NUM> starts the execution of the predetermined activation preparation. The vehicle control device <NUM> transitions to the start permission waiting state after the activation preparation is completed (time point T4). The start permission waiting state is a state of waiting for the reaction force control device <NUM> to permit the powertrain to start, that is, for the turn-on of the start permission signal S2.

When the fact that the start permission signal S2 is turned on in the start permission waiting state is recognized (time point T5), the vehicle control device <NUM> starts the powertrain of the vehicle. When the execution of the powertrain start processing is completed, the vehicle control device <NUM> turns on the preparation completion signal S1.

When the fact that the preparation completion signal S1 is turned on in the assist start waiting state is recognized (time point T6), the reaction force control device <NUM> transitions to the normal control state (time point T8). The reaction force control device <NUM> controls the driving of the reaction force motor <NUM> according to the steering state of the steering wheel <NUM>.

In this manner, even when the activation preparation of the vehicle control device <NUM> is completed, the vehicle control device <NUM> waits until the preparatory processing is completed when the preparatory processing for the reaction force control by the reaction force control device <NUM> is not completed and starts the powertrain of the vehicle. For this reason, the vehicle can solely travel after the reaction force control device <NUM> transitions to the assist start waiting state where the reaction force control is executable. Therefore, the vehicle is avoided to be in the travelable state even though the reaction force control device <NUM> is in the middle of executing the preparatory processing. Further, the vehicle can be started to travel in a safer state for the driver, that is, in a state where the vehicle can be turned in the direction intended by the driver.

In the first pattern of the activation sequence, there are concerns about the following. That is, there is a concern that a third party impersonating the reaction force control device <NUM> or the vehicle control device <NUM> falsifies turn-on of the start permission signal S2 by the reaction force control device <NUM> or turn-on of the preparation completion signal S1 by the vehicle control device <NUM>. In this case, the vehicle may transition to the travelable state before the reaction force control device <NUM> transitions to the assist start waiting state where the reaction force control is executable. Thus, the reaction force control device <NUM> is configured to execute the following processing.

The reaction force control device <NUM> executes stop request determination processing for the vehicle with the turn-on of the vehicle power source as a trigger. The stop request determination processing is processing of determining whether or not there is a need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle. The stop request determination processing is executed at a predetermined control cycle according to a program stored in the reaction force control device <NUM>.

As shown in a flowchart of <FIG>, the reaction force control device <NUM> determines whether or not there is a need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle (step S201).

The reaction force control device <NUM> determines whether or not there is a need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle, based on whether or not a predetermined determination condition is satisfied. The determination condition is a condition for determining whether the turn-on of the start permission signal S2 by the reaction force control device <NUM> or the turn-on of the preparation completion signal S1 by the vehicle control device <NUM> is falsified.

The determination condition includes, for example, the following two conditions A1, A2. When both of the two conditions A1, A2 are satisfied, the reaction force control device <NUM> determines that there is a need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle. Further, when any one of the two conditions A1, A2 is not satisfied, the reaction force control device <NUM> determines that there is no need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle.

The start permission signal S2 is turned off. The preparation completion signal S1 is turned on. The determination conditions are set based on the following viewpoints. That is, for example, when the vehicle control device <NUM> turns on the preparation completion signal S1 even though the reaction force control device <NUM> does not turn on the start permission signal S2, the third party impersonating the reaction force control device <NUM> may falsify the turn-on of the start permission signal S2.

When determination is made that there is a need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle (YES in step S201), the reaction force control device <NUM> turns on a vehicle stop request signal S3 (step S202) and ends the processing.

When determination is made that there is no need to request the vehicle control device <NUM> to stop the start of the powertrain of the vehicle (NO in step S201), the reaction force control device <NUM> turns off the vehicle stop request signal S3 (step S203) and ends the processing.

The vehicle stop request signal S3 is information indicating whether or not to request the vehicle control device <NUM> to stop the operation of the powertrain. The fact that the vehicle stop request signal S3 is turned on indicates that the vehicle control device <NUM> is requested to stop the operation of the powertrain. The fact that the vehicle stop request signal S3 is turned off indicates that the vehicle control device <NUM> is not requested to stop the operation of the powertrain. The vehicle stop request signal S3 is transmitted to the vehicle control device <NUM> as an electric signal.

Next, a second pattern of the activation sequence will be described. As an example, a case is examined in which the turn-on of the start permission signal S2 is falsified in the middle of executing the midpoint learning processing, which is one of pieces of the preparatory processing by the reaction force control device <NUM>. Further, the preparation for activating the vehicle control device <NUM> is completed before the midpoint learning processing by the reaction force control device <NUM> is completed.

As shown in a time chart of <FIG>, when the vehicle power source is turned on (time point T1), the reaction force control device <NUM> is activated to start the execution of the initial check. After the initial check is normally completed, the reaction force control device <NUM> starts the execution of the midpoint learning processing. For example, when the turn-on of the start permission signal S2 is falsified in the middle of executing this midpoint learning processing (time point T7), the vehicle control device <NUM> recognizes that the start permission signal S2 has already been turned on, for example, at a timing when the activation preparation is completed. Therefore, after the activation preparation is completed, the vehicle control device <NUM> immediately starts the powertrain of the vehicle without transitioning to the start permission waiting state. When the execution of the powertrain start processing is completed, the vehicle control device <NUM> turns on the preparation completion signal S1 (time point T8).

When recognition is made that the preparation completion signal S1 is turned on even though the midpoint learning processing is being executed, the reaction force control device <NUM> turns on the vehicle stop request signal S3 (time point T9). This is because the turn-on of the start permission signal S2 may be falsified by the third party impersonating the reaction force control device <NUM>.

After the powertrain of the vehicle is started, the vehicle control device <NUM> executes predetermined processing when the turn-on of the vehicle stop request signal S3 is recognized. The predetermined processing is, for example, processing for stopping the operation of the powertrain. Accordingly, the vehicle is in an untravelable state. Further, the vehicle is suppressed to be maintained in the travelable state due to a fraudulent act, such as impersonation, even though the reaction force control device <NUM> is in the middle of executing the preparatory processing.

Therefore, according to the present embodiment, the following effects can be obtained. (<NUM>) When the vehicle power source is turned on, the reaction force control device <NUM> requests the vehicle control device <NUM> to stop the traveling of the vehicle when information is exchanged with the vehicle control device <NUM> in a manner that does not follow a predetermined pattern. The exchange of information includes, for example, the recognition of the turn-on of the start permission signal S2 by the vehicle control device <NUM> and the recognition of the turn-on of the preparation completion signal S1 by the reaction force control device <NUM>. The predetermined pattern includes, for example, the turn-on of the start permission signal S2 by the reaction force control device <NUM> and then the turn-on of the preparation completion signal S1 by the vehicle control device <NUM> in response to the turn-on of the start permission signal S2. When this configuration is employed, there is a concern that the information exchanged between the reaction force control device <NUM> and the vehicle control device <NUM> may be falsified due to some kind of fraudulent act. In this respect, according to the present embodiment, when the information is exchanged between the reaction force control device <NUM> and the vehicle control device <NUM> in a manner that does not follow the predetermined pattern, it is possible to suppress the vehicle to travel. Therefore, crime prevention performance is further enhanced.

The present embodiment may be implemented with the following changes. The preparation completion signal S1, the start permission signal S2, and the vehicle stop request signal S3 may be flags.

Claim 1:
A steering control device comprising a control circuit configured to control driving of a reaction force motor (<NUM>) that generates steering reaction force applied to a steering wheel (<NUM>) in which power transmission with turning wheels (<NUM>) of a vehicle is separated, characterized in that when a vehicle power source is turned on, the control circuit requests a vehicle control device (<NUM>) that controls traveling of the vehicle to stop the traveling of the vehicle when information is exchanged between the control circuit and the vehicle control device (<NUM>) in a manner that does not follow a predetermined pattern.