Patent Description:
For example, <CIT> describes a system in which an auxiliary power source is connected to an EPS-ECU that is a control device that executes control of applying an assistive torque to turning wheels. In this system, the auxiliary power source is controlled by a power source control ECU. Further, in this system, the power source control ECU and the EPS-ECU can communicate with each other. A power supply device having the features of the preamble of claim <NUM> is known from <CIT>.

In the case where a result of communication with the EPS-ECU is added to conditions for the power source control ECU to turn the auxiliary power source off, a correct communication result may fail to be obtained, for example, immediately after start-up of the EPS-ECU.

In the following, measures that can solve this problem and their effects and advantages will be described. The problem is solved by the subject-matter of claim <NUM>. Advantageous developments are laid out in the dependent claims. A power supply device according to an aspect of the present invention includes a driving control device and an auxiliary control device that are installed in a vehicle. The driving control device includes a steering control device and a turning control device. The vehicle includes a main power source, an auxiliary power source, and a supply path. The auxiliary power source is a power source that stores electricity supplied from the main power source. The supply path is a path that supplies electricity from the main power source to electronic equipment inside the vehicle and configured to be opened and closed according to a state of a start switch of the vehicle. The driving control device is a device that controls a state of equipment installed in the vehicle while using either the main power source or the auxiliary power source as a power source. The auxiliary control device is a device that controls a state of the auxiliary power source. The driving control device is configured to execute a storage process, a permission signal transmission process, and an initial value process. The storage process is a process of storing, in a storage device, a state of the start switch determined based on a signal from the outside of the driving control device. The permission signal transmission process is a process of transmitting a permission signal when the state of the start switch stored in the storage device is an off state. The initial value process is a process of, at start-up of the driving control device, setting an initial value of the state of the start switch stored in the storage device to a value indicating an on state. The auxiliary control device is configured to execute a permission signal reception process and a stop process. The permission signal reception process is a process of receiving the permission signal. The stop process is a process of putting control of supply of electricity from the auxiliary power source to the driving control device into an off state when the permission signal is received.

At start-up of the driving control device, the value stored in the storage device is normally initialized. When a value indicating an off state is thereby set as the state of the start switch, a permission signal may be transmitted from the driving control device to the auxiliary control device. In this case, the control of supply of electricity from the auxiliary power source to the driving control device may be put into an off state. If the main power source is cut off under these circumstances, electricity of the auxiliary power source may fail to be supplied to the driving control device when it should be supplied.

In the above-described configuration, therefore, at start-up of the driving control device, the initial value of the state of the start switch stored in the storage device is set to a value indicating an on state by the initial value process. This helps prevent a permission signal from being accidentally transmitted from the driving control device to the auxiliary control device. This in turn helps prevent the situation where electricity of the auxiliary power source fails to be supplied to the driving control device when it should be supplied.

In the power supply device according to the above-described aspect, the power supply device may be configured to start the storage process when communication between the driving control device and the outside becomes possible. In this configuration, the storage process is started when communication between the driving control device and the outside becomes possible. Thus, the state of the start switch stored in the storage device can be updated.

In the power supply device according to the above-described aspect, the auxiliary control device may be configured to execute a voltage transmission process, the driving control device may be configured to execute a voltage reception process and an off determination process, the voltage transmission process may be a process of transmitting a detected value of a voltage of the main power source, the voltage reception process may be a process of receiving the detected value, the off determination process may be a process of determining that the start switch is in an off state based on the detected value being equal to or smaller than a threshold value, and the storage process may be a process of storing a determination result of the off determination process. In this configuration, the driving control device can determine whether the start switch is in the off state according to the detected value of the voltage of the main power source.

In the power supply device according to the above-described aspect, the driving control device may be configured to execute a voltage detection process, the voltage detection process may be a process in which the driving control device detects a power source voltage of the driving control device, and the off determination process may be a process of determining that the start switch is in an off state based on a logical sum of the following conditions being true: that the power source voltage detected by the voltage detection process is equal to or lower than a predetermined value; and that the detected value is equal to or smaller than the threshold value. In this configuration, the state of the start switch can be determined with the power source voltage detected by the driving control device taken into account.

In the power supply device according to the above-described aspect, the power source voltage may be a voltage of the main power source or a voltage of the auxiliary power source, whichever is higher.

In this configuration, the driving control device detects a higher one of the voltages. Thus, even when the main power source is experiencing an abnormality, the abnormality of the main power source may fail to be detected by the detected voltage. Therefore, it is particularly advantageous to use the detected value of the voltage of the main power source transmitted from the auxiliary control device in the off determination process.

In the power supply device according to the above-described aspect, the off determination process may be a process of determining that the start switch is off based on a further condition that a command signal for putting the start switch into an off state is received, and the command signal may be not transmitted to a communication line leading to the auxiliary control device.

In this configuration, it is determined that the start switch is in the off state with the command signal taken into account, which can increase the reliability of the start switch being in the off state compared with when the command signal is not taken into account. Since the auxiliary control device cannot receive the command signal in this configuration, it is particularly advantageous that the driving control device executes the off determination process.

In the power supply device according to the above-described aspect, the vehicle may include a reaction force actuator that applies a reaction force to a steering wheel, and a turning actuator that turns turning wheels, the driving control device includes the steering control device and the turning control device, the steering control device may be a device that controls a state of the steering wheel by operating a driving circuit of the reaction force actuator, the turning control device may be a device that controls a state of the turning wheels by operating a driving circuit of the turning actuator, the off determination process may include a steering-side determination process and a turning-side determination process, the steering-side determination process being a process, executed by the steering control device, of determining whether the detected value is equal to or smaller than the threshold value, the turning-side determination process being a process, executed by the turning control device, of determining whether a logical sum of the following conditions is true: that the power source voltage detected by the voltage detection process is equal to or lower than the predetermined value; and that the detected value is determined to be equal to or smaller than the threshold value by the steering-side determination process, the steering control device may be configured to execute, in addition to the permission signal transmission process, a steering-side determination result transmission process and a turning-side determination result reception process, the turning control device may be configured to execute, in addition to the storage process, the initial value process, and the voltage detection process, a steering-side determination result reception process and a turning-side determination result transmission process, the steering-side determination result transmission process may be a process of transmitting a determination result of the steering-side determination process, the steering-side determination result reception process may be a process of receiving the determination result of the steering-side determination process, the storage process may be a process of storing a determination result of the turning-side determination process, the turning-side determination result transmission process may be a process of transmitting a determination result of the state of the start switch stored in the storage device, and the turning-side determination result reception process may be a process of receiving the determination result of the state of the start switch stored in the storage device.

In this configuration, in the case where the initial value process is not executed, a delay in either execution of the voltage transmission process by the auxiliary control device or execution of the steering-side determination result transmission process by the steering control device may lead to the following situation. Information that the state of the start switch stored in the storage device is the off state is transmitted to the steering control device by the turning-side determination result transmission process. As a result, a permission signal is transmitted from the steering control device to the auxiliary control device.

As a countermeasure, executing the initial value process helps prevent the occurrence of this series of events.

An embodiment will be described below with reference to the drawings.

<FIG> shows the configuration of a steering control system of a vehicle according to the embodiment. This embodiment assumes, as a steering system, a so-called steer-by-wire system in which a power transmission path between a steering wheel and turning wheels is cut off.

A battery <NUM> is a supply source of electricity to electronic equipment of the vehicle. The battery <NUM> can supply electricity through a main power source line Lb as well as can supply electricity through a start switch <NUM> and a start line Lig. The start switch <NUM> is a switch that allows the vehicle to travel. The start switch <NUM> is switched from one to the other of an on state and an off state by operation of a user of the vehicle. When the vehicle includes an internal combustion engine, the start switch <NUM> may be an ignition switch. When the vehicle includes a motor-generator, the start switch <NUM> may be a switch that operates in conjunction with turning on and off of a system main relay between an inverter connected to the motor-generator and a high-voltage battery.

A steering main control device <NUM> is a device that controls the state of the steering wheel by operating a reaction force actuator. The reaction force actuator is an actuator that applies a reaction force that is a force resisting operation of the steering wheel. The reaction force actuator includes a reaction force motor, and a reaction force is generated by a torque of the reaction force motor.

The steering main control device <NUM> includes an inverter <NUM> and a steering main microcomputer <NUM>. The inverter <NUM> applies an alternating-current voltage to terminals of a motor included in the reaction force actuator. The steering main microcomputer <NUM> operates the inverter <NUM> so as to control the steering wheel as a control target.

A steering sub control device <NUM> is a device that controls the state of the steering wheel by operating the reaction force actuator. The reaction force actuator is an actuator that applies a reaction force that is a force resisting operation of the steering wheel. The steering sub control device <NUM> includes an inverter <NUM> and a steering sub microcomputer <NUM>. The inverter <NUM> applies an alternating-current voltage to terminals of a motor included in the reaction force actuator. A configuration may be adopted in which the inverter <NUM> and the inverter <NUM> apply an alternating-current voltage to different stator coils of the reaction force motor that share a rotor. The steering sub microcomputer <NUM> operates the inverter <NUM> so as to control the steering wheel as a control target. A voltage in the start line Lig is applied to the steering sub microcomputer <NUM> through a diode <NUM>. The diode <NUM> has an anode side on the side of the battery <NUM> and a cathode side on the side of the steering sub microcomputer <NUM>. A terminal voltage of the battery <NUM> is applied to the steering sub microcomputer <NUM> through a diode <NUM>, without the start switch <NUM> being interposed. The diode <NUM> has an anode side on the side of the battery <NUM> and a cathode side on the side of the steering sub microcomputer <NUM>.

A turning main control device <NUM> is a device that controls the state of turning wheels by operating a turning actuator. The turning actuator is an actuator that turns the turning wheels. The turning actuator includes a turning motor and turns the turning wheels by a torque of the turning motor.

The turning main control device <NUM> includes an inverter <NUM> and a turning main microcomputer <NUM>. The inverter <NUM> applies an alternating-current voltage to terminals of a motor included in the turning actuator. The turning main microcomputer <NUM> operates the inverter <NUM> so as to control the turning wheels as a control target.

A turning sub control device <NUM> is a device that controls the state of the turning wheels by operating the turning actuator. The turning sub control device <NUM> includes an inverter <NUM> and a turning sub microcomputer <NUM>. The inverter <NUM> applies an alternating-current voltage to terminals of a motor included in the turning actuator. A configuration may be adopted in which the inverter <NUM> and the inverter <NUM> apply an alternating-current voltage to different stator coils of the turning motor that share a rotor. The turning sub microcomputer <NUM> operates the inverter <NUM> so as to control the turning wheels as a control target. A voltage in the start line Lig is applied to the turning sub microcomputer <NUM> through a diode <NUM>. The diode <NUM> has an anode side on the side of the battery <NUM> and a cathode side on the side of the turning sub microcomputer <NUM>. A terminal voltage of the battery <NUM> is applied to the turning sub microcomputer <NUM> through a diode <NUM>, without the start switch <NUM> being interposed. The diode <NUM> has an anode side on the side of the battery <NUM> and a cathode side on the side of the turning sub microcomputer <NUM>.

An auxiliary control device <NUM> is a device that controls the state of an auxiliary power source <NUM> as a control target. The auxiliary power source <NUM> is an electricity storage device that stores electric charge from the battery <NUM>. The auxiliary power source <NUM> may be, for example, a capacitor. The auxiliary control device <NUM> may use the main power source as a power source.

The auxiliary control device <NUM> includes a switching element <NUM> that opens and closes a path between the main power source line Lb and the inverters <NUM>, <NUM>. The auxiliary control device <NUM> includes a switching element <NUM> that opens and closes a path between the main power source line Lb and the auxiliary power source <NUM> through the switching element <NUM>. The auxiliary control device <NUM> includes a diode <NUM> that connects the auxiliary power source <NUM> on one side and the steering main microcomputer <NUM> and the turning main microcomputer <NUM> on the other side to each other. The diode <NUM> is a rectifier element that has an anode on the side of a positive electrode terminal of the auxiliary power source <NUM> and a cathode on the side of the steering main microcomputer <NUM> and the turning main microcomputer <NUM>. The auxiliary control device <NUM> includes a diode <NUM> that connects the start line Lig on one side and the steering main microcomputer <NUM> and the turning main microcomputer <NUM> on the other side to each other. The diode <NUM> is a rectifier element that has an anode on the side of the battery <NUM> and a cathode on the side of the steering main microcomputer <NUM> and the turning main microcomputer <NUM>. Specifically, the steering main microcomputer <NUM> is connected to the cathode sides of the diodes <NUM>, <NUM> through a diode <NUM>. The diode <NUM> is a rectifier element that has an anode side on the cathode sides of the diodes <NUM>, <NUM> and a cathode side on the side of the steering main microcomputer <NUM>. The turning main microcomputer <NUM> is connected to the cathode sides of the diodes <NUM>, <NUM> through a diode <NUM>. The diode <NUM> is a rectifier element that has an anode side on the cathode sides of the diodes <NUM>, <NUM> and a cathode side on the side of the turning main microcomputer <NUM>. The auxiliary control device <NUM> includes a switching element <NUM> that opens and closes a path between the anode side of the diode <NUM> and the auxiliary power source <NUM>.

The auxiliary control device <NUM> includes an auxiliary microcomputer <NUM>. The auxiliary microcomputer <NUM> detects a voltage and a current of the auxiliary power source <NUM> and monitors the state of the auxiliary power source <NUM>. The auxiliary microcomputer <NUM> controls supply of electricity from the battery <NUM> to the inverters <NUM>, <NUM> by opening and closing the switching element <NUM>. The auxiliary microcomputer <NUM> controls exchange of electricity between the auxiliary power source <NUM> and the battery <NUM> and exchange of electricity between the inverters <NUM>, <NUM> and the auxiliary power source <NUM> by opening and closing the switching element <NUM>. The auxiliary microcomputer <NUM> controls supply of electricity from the auxiliary power source <NUM> to the steering main microcomputer <NUM> and the turning main microcomputer <NUM> by opening and closing the switching element <NUM>. The auxiliary microcomputer <NUM> maintains the switching element <NUM> in a closed state during a period when the auxiliary microcomputer <NUM> is running.

The steering main microcomputer <NUM> and the steering sub microcomputer <NUM> can communicate with each other through a local line <NUM>. The turning main microcomputer <NUM> and the turning sub microcomputer <NUM> can communicate with each other through a local line <NUM>. The steering main microcomputer <NUM> and the turning main microcomputer <NUM> can communicate with each other through an inter-main communication line <NUM>. The steering main microcomputer <NUM> and the steering sub microcomputer <NUM> are connected to a gateway <NUM> through a bus line <NUM>. The turning main microcomputer <NUM> and the turning sub microcomputer <NUM> are connected to the gateway <NUM> through a bus line <NUM>. The auxiliary microcomputer <NUM> and the steering main microcomputer <NUM> can communicate with each other through a local line <NUM>.

<FIG> shows the configurations of the steering main microcomputer <NUM>, the steering sub microcomputer <NUM>, the turning main microcomputer <NUM>, the turning sub microcomputer <NUM>, and the auxiliary microcomputer <NUM>. In <FIG>, variable i is "<NUM> to <NUM>" (i = <NUM> to <NUM>). That is, when the variable i is "<NUM>," "i20" indicates "<NUM>.

As shown in the drawing, the aforementioned five microcomputers include PUs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, respectively. The aforementioned five microcomputers include ROMs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, respectively. The aforementioned five microcomputers include RAMs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, respectively. The PUs <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are software processing devices including at least one processing unit, such as a CPU, GPU, or TPU. The ROMs <NUM>, <NUM>, <NUM>, <NUM>, <NUM> store programs that the PUs <NUM>, <NUM>, <NUM>, <NUM>, <NUM> execute.

<FIG> shows the procedure of processing executed by the PU <NUM> of the steering sub microcomputer <NUM> and the PU <NUM> of the turning sub microcomputer <NUM>. The processing shown in <FIG> is processing that is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle. Further, the processing shown in <FIG> is processing that is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle. In the following, the step number of each process will be represented by a number given an "S" at the beginning. For the convenience of description, the processing executed by the PU <NUM> will be described as an example below. The processing executed by the PU <NUM> is one for which a voltage Vss is read as a voltage Vst in the following description.

In the series of processes shown in <FIG>, the PU <NUM> first detects the voltage Vss (S10). The voltage Vss is a voltage in the start line Lig connected to the steering sub control device <NUM>. That is, the voltage Vss is a voltage on the anode side of the diode <NUM>. On the other hand, the voltage Vst is a voltage in the start line Lig connected to the turning sub control device <NUM>. That is, the voltage Vst is a voltage on the anode side of the diode <NUM>. Next, the PU <NUM> determines whether the logical product of the following Condition (SS1) and Condition (SS2) is true (S12).

Condition (SS1): a condition that a command signal for turning the start switch off has been received. In <FIG>, this is indicated as "IGOFF COMMAND HAS BEEN RECEIVED. " This command signal is input into the steering sub microcomputer <NUM> through the bus line <NUM>. The command signal may be a signal that is generated by, for example, another control device that is not shown in <FIG>.

Condition (SS2): a condition that the voltage Vss is equal to or lower than a threshold value Vth. Here, the threshold value Vth may be set to be smaller than a maximum value of a voltage that the start line Lig can assume when the start switch <NUM> is in an open state.

When the PU <NUM> determines that the above-described logical product is true (S12: YES), the PU <NUM> makes an IG off determination that is a determination that the start switch is off (S14). Then, the PU <NUM> transmits a sub-side off determination that is a determination result that the start switch is off to the steering main microcomputer <NUM> through the local line <NUM> (S16). Then, the PU <NUM> determines whether it is confirmed that the start switch is in the off state (IG off) (S18). Here, the PU <NUM> determines that IG off is confirmed on the condition, for example, that information that the steering main microcomputer <NUM> has determined that the start switch is off is transmitted from the steering main microcomputer <NUM> through the local line <NUM>. When the PU <NUM> determines that the IG off is confirmed (S18: YES), the PU <NUM> executes a process of stopping the steering sub microcomputer <NUM> (S20).

In the case where the PU <NUM> executes the process of S20 and the case where the PU <NUM> determines in the negative in the processes of S12 and S18, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

<FIG> shows the procedure of processing executed by the PU <NUM> of the steering main microcomputer <NUM>. The processing shown in <FIG> is processing that is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle.

In the series of processes shown in <FIG>, the PU <NUM> first detects a voltage Vms on the cathode sides of the diodes <NUM>, <NUM> (S30). The voltage Vms is a voltage on the anode side of the diode <NUM>. Next, the PU <NUM> determines whether the logical product of the following Condition (MS1) and Condition (MS2) is true (S32).

Condition (MS1): a condition that a command signal for turning the start switch off has been received. In <FIG>, this is indicated as "IGOFF COMMAND HAS BEEN RECEIVED. " This command signal is input into the steering main microcomputer <NUM> through the bus line <NUM>. The command signal may be a signal that is generated by, for example, another control device that is not shown in <FIG>.

Condition (MS2): a condition that the voltage Vms is equal to or lower than a threshold value Vth. When the PU <NUM> determines that the above-described logical product is true (S32: YES), the PU <NUM> makes an IG off determination that is a determination that the start switch is off (S34). Then, the PU <NUM> determines whether the determination that the start switch is in the off state (IG off determination) is confirmed (S36). The PU <NUM> confirms the determination that the start switch is in the off state on the condition, for example, that it is determined that a sub-side off determination has been transmitted. Then, the PU <NUM> executes a process of stopping the steering main microcomputer <NUM> (S38).

In the case where the PU <NUM> executes the stop process of S38 and the case where the PU <NUM> determines in the negative in the processes of S32 and S36, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

<FIG> shows the procedures of processing executed by the auxiliary microcomputer <NUM>, the steering main microcomputer <NUM>, and the turning main microcomputer <NUM>. One of the three series of processes shown in <FIG> is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle. Another one of the three series of processes shown in <FIG> is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle. The remaining one of the three series of processes shown in <FIG> is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle. In the following, the series of processes shown in <FIG> will be described in chronological order in which these processes can actually occur.

In the series of processes shown in <FIG>, the PU <NUM> first detects a voltage Vpgs in the start line Lig connected to the auxiliary control device <NUM> (S50). The voltage Vpgs is a voltage on the anode side of the diode <NUM>. Next, the PU <NUM> transmits the voltage Vpgs to the steering main microcomputer <NUM> through the local line <NUM> (S52).

Meanwhile, the PU <NUM> of the steering main microcomputer <NUM> receives the voltage Vpgs (S60). Then, the PU <NUM> determines whether the voltage Vpgs is equal to or lower than the threshold value Vth (S62). This process is a process of determining whether the start switch <NUM> is in the off state. When the PU <NUM> determines that the voltage Vpgs is equal to or lower than the threshold value Vth (S62: YES), the PU <NUM> substitutes "<NUM>" to a determination flag Fpgs (S64). On the other hand, when the PU <NUM> determines that the voltage Vpgs is higher than the threshold value Vth (S62: NO), the PU <NUM> substitutes "<NUM>" to the determination flag Fpgs (S66). In the case where the PU <NUM> completes the process of S64 or S66, the PU <NUM> transmits the value of the determination flag Fpgs to the turning main microcomputer <NUM> through the inter-main communication line <NUM> (S68).

Meanwhile, the PU <NUM> of the turning main microcomputer <NUM> determines whether the value of the determination flag Fpgs has been received (S80). When the PU <NUM> determines that the value has been received (S80: YES), the PU <NUM> detects a voltage Vmt on the cathode sides of the diodes <NUM>, <NUM> (S82). The voltage Vmt is a voltage on the anode side of the diode <NUM>. Next, the PU <NUM> determines whether the logical product of the following Condition (MT1), and a condition that the logical sum of the following Condition (MT2) and Condition (MT3) is true, is true (S84).

Condition (MT1): a condition that a command signal for turning the start switch off has been received. In <FIG>, this is indicated as "IGOFF COMMAND HAS BEEN RECEIVED. " This command signal is input into the turning main microcomputer <NUM> through the bus line <NUM>. The command signal may be a signal that is generated by, for example, another control device that is not shown in <FIG>.

Condition (MT2): a condition that the voltage Vmt is equal to or lower than the threshold value Vth. Condition (MT3): a condition that the determination flag Fpgs is "<NUM>. " When the PU <NUM> determines that the logical product is true (S84: YES), the PU <NUM> determines that the start switch is off (IG off determination) and stores that information in the RAM <NUM> (S86). On the other hand, when the PU <NUM> determines in the negative in the process of S84, the PU <NUM> determines that the start switch is in the on state and stores that information in the RAM <NUM> (S88).

In the case where the PU <NUM> completes the process of S86 or S88 and the case where the PU <NUM> determines in the negative in the process of S80, the PU <NUM> determines whether the determination result of the start switch being off is stored in the RAM <NUM> (S90). When the PU <NUM> determines that the off determination result is stored (S90: YES), the PU <NUM> transmits information that an IG off determination (turning-side off determination) has been made on the side of the turning main microcomputer <NUM> through the inter-main communication line <NUM> (S92).

Meanwhile, the PU <NUM> of the steering main microcomputer <NUM> determines whether the determination result that the start switch is off transmitted from the turning main microcomputer <NUM> has been received (S70). When the PU <NUM> determines that the determination result has been received (S70: YES), the PU <NUM> transmits a permission signal that permits the auxiliary microcomputer <NUM> to be turned off through the local line <NUM> (S72). In the case where the PU <NUM> completes the process of S72 and the case where the PU <NUM> determines in the negative in the process of S70, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

Meanwhile, the PU <NUM> of the auxiliary microcomputer <NUM> determines whether the logical product of the following Condition (AS1) and Condition (AS2) is true (S54). Condition (AS1): a condition that the permission signal has been received.

Condition (AS2): a condition that the voltage Vpgs is equal to or lower than the threshold value Vth. When the PU <NUM> determines that the above-described logical product is true (S54: YES), the PU <NUM> executes a process of stopping the auxiliary microcomputer <NUM> (S56). The process of stopping the auxiliary microcomputer <NUM> includes a process in which the auxiliary microcomputer <NUM> opens the switching element <NUM>. In the case where the PU <NUM> completes the process of S56 and the case where the PU <NUM> determines in the negative in the process of S54, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

On the other hand, in the case where the PU <NUM> of the turning main microcomputer <NUM> completes the process of S92, the PU <NUM> determines whether the off state of the start switch is confirmed (S94). Here, the PU <NUM> confirms the determination that the start switch is off when a condition is met such as that the determination result that the start switch is in the off state has been received from the turning sub microcomputer <NUM> by the process of S16 in <FIG>. When the determination that the start switch is off is confirmed (S94: YES), the PU <NUM> puts the turning main microcomputer <NUM> into an off state (S96).

In the case where the PU <NUM> completes the process of S96 and the case where the PU <NUM> determines in the negative in the process of S90 or S94, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

<FIG> shows the procedure of processing relating to setting of an initial value in a part of a storage area of the RAM <NUM> where a determination result of the state of the start switch is stored. The processing shown in <FIG> is realized as the PU <NUM> executes a program stored in the ROM <NUM> repeatedly, for example, on a predetermined cycle.

In the series of processes shown in <FIG>, the PU <NUM> first determines whether the turning main microcomputer <NUM> is starting (S100). When the PU <NUM> determines that the turning main microcomputer <NUM> is starting (S100: YES), the PU <NUM> sets the value in the part of the storage area of the RAM <NUM> where the determination result of the state of the start switch is stored to a determination result that the start switch is on (S102). In the case where the PU <NUM> completes the process of S102 and the case where the PU <NUM> determines in the negative in the process of S100, the PU <NUM> temporarily ends the series of processes shown in <FIG>.

Here, effects and advantages of the embodiment will be described. When the PU <NUM> of the auxiliary microcomputer <NUM> detects the voltage Vpgs, the PU <NUM> transmits the voltage Vpgs to the steering main microcomputer <NUM> through the local line <NUM>. The PU <NUM> of the steering main microcomputer <NUM> substitutes a comparison result of the voltage Vpgs and the threshold value Vth to the value of the determination flag Fpgs. Then, the PU <NUM> transmits the value of the determination flag Fpgs to the turning main microcomputer <NUM> through the inter-main communication line <NUM>. The PU <NUM> of the turning main microcomputer <NUM> determines that the start switch is in the off state when the logical sum of the condition that the value of the determination flag Fpgs is "<NUM>" and the condition that the voltage Vmt is equal to or lower than the threshold value Vth is true and moreover the IG off command has been received. Then, the PU <NUM> stores the determination result in the RAM <NUM>. When the determination result stored in the RAM <NUM> is a determination result that the start switch is in the off state, the PU <NUM> transmits that information to the steering main microcomputer <NUM> through the inter-main communication line <NUM>. When the steering main microcomputer <NUM> receives the determination result that the start switch is in the off state from the turning main microcomputer <NUM>, the steering main microcomputer <NUM> transmits a permission signal to the auxiliary microcomputer <NUM>. The PU <NUM> of the auxiliary microcomputer <NUM> puts the auxiliary microcomputer <NUM> into the off state on the condition that the permission signal is received.

In this way, by using the voltage Vpgs detected in the auxiliary control device <NUM>, the PU <NUM> of the steering main microcomputer <NUM> can determine the state of the start switch based on the voltage Vpgs in the start line Lig. That is, the voltage on the cathode sides of the diodes <NUM>, <NUM> is applied to the steering main microcomputer <NUM> and the turning main microcomputer <NUM>. Therefore, in the case where the start switch <NUM> is in the off state, when the voltage in the start line Lig decreases, a terminal voltage of the auxiliary power source <NUM> is applied to the steering main microcomputer <NUM> and the turning main microcomputer <NUM>. Thus, the steering main microcomputer <NUM> and the turning main microcomputer <NUM> cannot directly detect the voltage in the start line Lig.

At start-up when the start switch <NUM> switches from the open state to the closed state, the steering main microcomputer <NUM>, the turning main microcomputer <NUM>, and the auxiliary microcomputer <NUM> can vary from one another in start-up timing. For this reason, it sometimes takes time until communication between the steering main microcomputer <NUM> and the auxiliary microcomputer <NUM> is established and communication between the steering main microcomputer <NUM> and the turning main microcomputer <NUM> is established. On the other hand, microcomputers generally initialize stored data at start-up. When the value indicating the state of the start switch stored in the RAM <NUM> is set to a value indicating an off state as a result of initialization, due to a delay in establishing communication etc., a determination result of an off state is transmitted from the PU <NUM> to the steering main microcomputer <NUM>. As a result, a permission signal is transmitted from the PU <NUM> to the auxiliary microcomputer <NUM>, so that the PU <NUM> stops the auxiliary microcomputer <NUM>. That is, there is a concern that the auxiliary microcomputer <NUM> may stop accidentally at normal start-up when the start switch <NUM> is switched from the open state to the closed state. In this case, when supply of electricity from the battery <NUM> is interrupted thereafter due to breakage of the start line Lig etc., electricity of the auxiliary power source <NUM> that should be originally used becomes unavailable. This state may continue until the start switch <NUM> is closed again after it is temporarily opened.

As a countermeasure, in this embodiment, at start-up of the turning main microcomputer <NUM>, the PU <NUM> switches the determination result of the state of the start switch to a determination result that the start switch is in the on state in the process of initializing the RAM <NUM>. This helps prevent a permission signal from being accidentally transmitted to the auxiliary microcomputer <NUM> due to the aforementioned delay in communication etc..

The embodiment having been described above can further produce the following effects and advantages. (<NUM>) A communication line in which the gateway <NUM> is interposed is not provided in the communication line between the auxiliary control device <NUM> and the outside. Thus, the number of components of the steering control system can be reduced, and the cost can be reduced. In this case, however, the auxiliary microcomputer <NUM> cannot receive an off command for the start switch from the outside. In the case where the PU <NUM> of the auxiliary microcomputer <NUM> itself determines the state of the start switch from the voltage Vpgs alone, the reliability of the determination result is lower compared with when reception of the off command is taken into account. Therefore, it is particularly advantageous to generate a permission signal by determining the state of the start switch outside the auxiliary control device <NUM>.

The correspondence relationships between items in the above-described embodiment and items described in the section "SUMMARY OF THE INVENTION" are as follows. In the following, the correspondence relationships are shown according to the numbers of the solutions described in the section "SUMMARY OF THE INVENTION. " [<NUM>] The driving control device corresponds to the steering main control device <NUM> and the turning main control device <NUM>. The auxiliary control device corresponds to the auxiliary control device <NUM>. The main power source corresponds to the battery <NUM>. The auxiliary power source corresponds to the auxiliary power source <NUM>. The supply path corresponds to the start line Lig. The storage process corresponds to the processes of S86 and S88. The permission signal transmission process corresponds to the process of S72. The initial value process corresponds to the process of S102. The storage device corresponds to the RAM <NUM>. The permission signal reception process corresponds to the process of S54. The stop process corresponds to the process of S56. [<NUM>] This solution corresponds to being able to execute the process of S86 or S88 after the value of the determination flag Fpgs is received in the process of S80. [<NUM>] The voltage transmission process corresponds to the process of S52. The voltage reception process corresponds to the process of S60. The off determination process corresponds to the processes of S62 to S66 and S84. [<NUM>] The voltage detection process corresponds to the process of S82. [<NUM>] This solution corresponds to the output voltages of the diodes <NUM>, <NUM> being applied to the steering main microcomputer <NUM> and the turning main microcomputer <NUM>. [<NUM>] This solution corresponds to the auxiliary control device <NUM> being connected to only the steering main control device <NUM> through the local line <NUM> in <FIG>. [<NUM>] The driving circuit of the reaction force actuator corresponds to the inverter <NUM>. The driving circuit of the turning actuator corresponds to the inverter <NUM>. The steering-side determination process corresponds to the processes of S62 to S66. The turning-side determination process corresponds to the process of S84. The steering-side determination result transmission process corresponds to the process of S68. The steering-side determination result reception process corresponds to the process of S80. The turning-side determination result transmission process corresponds to the process of S92. The turning-side determination result reception process corresponds to the process of S70.

Claim 1:
A power supply device comprising a driving control device (<NUM>, <NUM>) and an auxiliary control device (<NUM>) that are installed in a vehicle,
the driving control device including a steering control device (<NUM>) and a turning control device (<NUM>),
the vehicle including a main power source (<NUM>), an auxiliary power source (<NUM>), and a supply path (Lig),
the auxiliary power source being a power source that stores electricity supplied from the main power source,
the supply path being a path that supplies electricity from the main power source to electronic equipment inside the vehicle and being configured to be opened and closed according to a state of a start switch (<NUM>) of the vehicle, wherein:
the driving control device is a device that controls a state of equipment installed in the vehicle while using either the main power source (<NUM>) or the auxiliary power source (<NUM>) as a power source; and
the auxiliary control device (<NUM>) is a device that controls a state of the auxiliary power source (<NUM>); characterized in that
the driving control device is configured to execute a storage process (S86, S88), a permission signal transmission process (S72), and an initial value process (S102), the storage process being a process of storing, in a storage device, a state of the start switch (<NUM>) determined based on a signal from an outside of the driving control device, the permission signal transmission process being a process of transmitting a permission signal when the state of the start switch (<NUM>) stored in the storage device is an off state, the initial value process being a process of, at start-up of the driving control device, setting an initial value of the state of the start switch stored in the storage device to a value indicating an on state; and
the auxiliary control device (<NUM>) is configured to execute a permission signal reception process (S54) and a stop process (S56), the permission signal reception process being a process of receiving the permission signal, the stop process being a process of putting control of supply of electricity from the auxiliary power source (<NUM>) to the driving control device into an off state when the permission signal is received.