Power management systems, methods, and programs for in-vehicle devices

An in vehicle device transfers connection information to a power management device, the connection information indicating whether the in-vehicle device can communicate with the power management device. The in-vehicle device either transfers condition information to the power management device, the condition information indicating that the in-vehicle device is ready for turning off, or sets the in-vehicle device to not communicate with the power management device when a predetermined condition is met, the predetermined condition indicative of an inability of the in-vehicle device to transfer information to the power management device. The power management device requests the connection information from the in-vehicle device and requests the condition information from the in-vehicle device. The power management device determines that the in-vehicle device is ready for turning off when both the connection information and the condition information have been received from the in-vehicle device, or no connection information has been received from the in-vehicle device because the in-vehicle device has been set to not communicate with the power management device.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2006-006527 filed on Jan. 13, 2006, including the specification, drawings and abstract thereof, is incorporated herein by reference in its entirety.

BACKGROUND

1. Related Technical Fields

Related technical fields include power management systems, methods, and programs for in-vehicle devices.

2. Description of the Related Art

Various types of in-vehicle devices have been mounted on vehicles to make drivers and fellow passengers in the vehicle more comfortable. For example, radio receivers for receiving AM broadcast and FM broadcast, TV receivers for receiving telecast signals and displaying an image, audio devices for playing an MD and/or a CD, and/or navigation devices for providing driving guidance for the vehicle may be mounted on the vehicle as in-vehicle devices.

To transfer digital data such as digitized image data, audio data, or computer data among the various types of in-vehicle devices described above, large-capacity and high-speed communication is required. Therefore, the introduction of an in-vehicle network to transfer digital data even in a small space such as within the vehicle has been proposed. For example, the MOST (Media Oriented Systems Transport) system is an example of an in-vehicle network (for example, Japanese Unexamined Patent Application Publication No. 2005-277711). The MOST system has a cyclic network. Various in-vehicle devices such as a navigation device, an audio device, a radio receiver, and an AV amplifier are connected to each other via the network. As a result; for example, digital data output from the audio device is transferred to the AV amplifier through the network and the signal input by the AV amplifier is amplified and output to a speaker.

Further, the MOST system utilizes a network protocol using fiber optics. Importantly, systems such as the MOST system control the power of the entire system collectively instead of turning on/off the power supplied to each of the in-vehicle devices in the system. For example, each in-vehicle device and a power management unit for controlling the power of the system are connected to each other with an LAN or the MOST, and request data for turning on/off the power supplied to each of the in-vehicle devices is transferred from the power management unit, so that all of the connected in-vehicle devices may be turned on or off.

SUMMARY

According to the power management system using the power management unit described above, when a program reset repeatedly occurs in any one of the in-vehicle devices, the power management unit recognizes that a new in-vehicle device is connected to the power management unit every time the program reset occurs. As a result, for each recognized new connection, the power management system continuously provides registration processing for such a newly connected in-vehicle device. Typically, before the power management unit turns each of the in-vehicle devices off, the power management unit needs to receive responses that the connected in-vehicle devices are ready for turning off from the connected in-vehicle devices and needs to send request data to turn the in-vehicle devices off. However, when the series of resets occurs as described above, the reset in-vehicle device cannot send the response that the in-vehicle device is ready for turning off. Further, because registration processing for the in-vehicle device is repeatedly executed by the power management unit, the power management unit cannot send request data to turn the in-vehicle device off. As a result, the power of the entire system cannot reliably be turned off.

Various exemplary implementations of the broad principles described herein provide systems, methods, and programs for turning the power of the entire system off and preventing the battery of the vehicle from running out even when a series of program reset occurs by some sort of program factor or non-program factor.

Various exemplary implementations provide an in-vehicle device that may transfer connection information to a power management device, the connection information indicating whether the in-vehicle device can communicate with the power management device. The in-vehicle device may either transfer condition information to the power management device, the condition information indicating that the in-vehicle device is ready for turning off, or may set the in-vehicle device to not communicate with the power management device when a predetermined condition is met, the predetermined condition indicative of an inability of the in-vehicle device to transfer information to the power management device. The functions of the in-vehicle device may be implemented by a method or program.

Various exemplary implementations provide a power management device that may request the connection information from the in-vehicle device and may request the condition information from the in-vehicle device. The power management device may determine that the in-vehicle device is ready for turning off when both the connection information and the condition information have been received from the in-vehicle device. Alternatively, the power management device may determine that the in-vehicle device is ready for turning off when no connection information has been received from the in-vehicle device because the in-vehicle device has been set to not communicate with the power management device. The functions of the power management device may be implemented by a method or program.

DETAILED DESCRIPTION OF EXEMPLARY IMPLEMENTATIONS

FIG. 1is a diagram showing an exemplary structure of a power control system1. As shown inFIG. 1, the power control system1may include an in-vehicle network including a navigation apparatus/device2, a CD player3, a radio tuner4, and/or an AV amplifier5as in-vehicle devices mounted in a vehicle. The power control system1may also include a communication master device (power management device)6for communicating and controlling each of the in-vehicle apparatuses/devices2-5. The power control system1may include a communication network7that circularly connects each of the in-vehicle devices2-5and the communication master device6.

The communication network7may be, for example, a data communication network including, for example, the MOST system. The communication master device6may include a monitor device9for displaying images and an input device10, which has a plurality of buttons, operated by a user.

The navigation device2may be an in-vehicle device for providing route guidance to a destination set by the user. A GPS11may be connected to the navigation device2. The GPS11may receive position information according to a current vehicle position. The navigation device2may read out map information for the area surrounding the current vehicle position from a memory such as an internal CD, a DVD, or a hard disk drive on the basis of the received position information and may transfer image data (map data) to the monitor device9through a transmission line on the basis of the read out information, so that the map and the current vehicle position are displayed on the monitor device9. The navigation device2may transfer audio data of the route guidance to the AV amplifier5through the communication network7. The AV amplifier5may amplify the input signal and a speaker13to output an audio guidance.

The CD player3may be an audio device for playing a CD. The CD player3may read out digital data from the CD and may transfer the digital data to the AV amplifier5through the communication network7. The AV amplifier5may amplify the input signal and the speaker13may output an audio message or music. The radio tuner4may be a receiver for receiving radio broadcasting. The radio tuner4may transfer a signal of an AM/FM broadcast received by an antenna14to the AV amplifier5through the communication network7. The AV amplifier5may amplifies the input signal and the speaker13thereby output an audio message or music. The AV amplifier5may be an amplifier for amplifying an input audio signal and the speaker13may be connected to the AV amplifier5. The AV amplifier5may amplify digital data input from the navigation device2, the CD player3, and/or the radio tuner4thereby output the digital data from the speaker13.

The communication master device6may be a control device for communicating with each of the in-vehicle devices2-5via the communication network7and may control the in-vehicle devices2-5. The monitor device9and/or the input device10may be connected to the communication master device6. When the user operates the input device10, the communication master device6may request each in-vehicle device2-5to start various programs on the basis of the operation by the user. The communication master device6may store image data in a memory, such as an internal storage device, and may display various types of images corresponding to one or more of the running in-vehicle devices (e.g., may not include the navigation device2) on the monitor device9. For example, a title of a song and/or the number of tracks may be displayed while the CD player3is running, and a frequency and/or a name of a radio station may be displayed while the radio tuner is running.

The communication master device6may control, for example, the power-on/off state of the in-vehicle devices2-5. Specifically, a key switch15may be connected to the communication master device6for turning on/off a vehicle ignition or an ACC (accessory). When the ACC is on, the communication master device6may transfer a data signal over the communication network7and may request the in-vehicle devices2-5to turn on. When the ACC is off, the communication master device6may stop transferring the data signal over the communication network7and may request the in-vehicle devices2-5to turn off. Note that a gateway ECU (electronic control unit), as an interface for receiving a vehicle signal or a diagnosis such as a CAN, may be connected to the communication network7and the key switch15may be connected to the gateway ECU.

Next, control structures of the in-vehicle devices2-5and the communication master device6in the power control system1according to the first example will be described with reference toFIG. 2.FIG. 2is a diagram showing exemplary control structures of the in-vehicle devices2-5and an exemplary communication master device6that may be used in the power control system1.

As shown inFIG. 2, the navigation device2may include a navigation controller (ECU21) and a current position detection section22. The navigation ECU21may include a CPU31as a calculating device and a control device for controlling the entire navigation device2. The navigation ECU21may include a memory such as a RAM32, a ROM33, and/or a flash memory34. The RAM32may be used as a working memory when the CPU31executes various calculations. Route data for a searched route, information regarding a starting time of a series of program resets caused by a program factor or a non-program factor, and a reset counter35for counting the number of resets may be stored in the RAM32.

The ROM33may store a control program, a series of reset processing programs (for example, implementing the method shown inFIG. 3) for setting an in-vehicle device not to respond to a communication from the communication master device6and for turning the in-vehicle device off when the series of resets occurs, and a power management control program (for example, implementing the method shown inFIG. 4) for controlling the power-on/off state of the in-vehicle devices on the basis of the communication provided by the communication master device6. The flash memory34may store a program read out from the ROM33. Note that, a semiconductor memory or a magnetic core may be used as the RAM32, the ROM33, or the flash memory34. Further, an MPU may be used as the calculating device and the control device instead of the CPU31.

When the communication master device6sends a data signal through the communication network7(for example, when it is ordered that the navigation device2should be turned on), the navigation ECU21may control the navigation device2to turn on (for example, implementing the method shown inFIG. 4). Meanwhile, when the communication master device6stops transferring the data signal (for example, when it is ordered that the navigation device2is turned off), the navigation ECU21may control the navigation device2to turn off. Further, when a series of program resets occurs a predetermined number of times (for example, equal to or more than 11 times) within a predetermined time period (for example, 60 seconds) due to a program factor or a non-program factor (for example, when a system reset occurs due to a hardware error when accessing software), the navigation ECU21may sets the in-vehicle device to not respond to the communication provided by the communication master device6and may controls the navigation device2to turn off (for example, implementing the method shown inFIG. 3).

The current position detection section22may include the GPS11for detecting a current vehicle position and a current time by receiving an electric wave provided by a satellite and a map database (DB)24for storing map data, so that it may be possible to specify the current vehicle position and the travel direction of the vehicle on the map.

Next, the control structure of the communication master device6will be described with reference toFIG. 2. The communication master device6may basically include a controller (communication master ECU40) and various types of additional devices such as, for example, the monitor device9, the input device10, or the key switch15connected to the communication master ECU40.

The communication master ECU40may include a CPU41as a calculating device and a control device for controlling the entire communication master device6and a memory such as an RAM42, and/or an ROM43. The RAM42may be used as a working memory when the CPU41executes various calculations. The RAM42may store IDs of in-vehicle devices, which respond to a connection acknowledgement request among the in-vehicle devices2-5. The ROM43may store a control program and a power management control program (for example, implementing the method shown inFIG. 4) for controlling the power-on/off state of the in-vehicle devices by communicating with each of the in-vehicle devices connected to the communication network7. Note that, a semiconductor memory or a magnetic core may be used as the RAM42or the ROM43. Further, an MPU may be used as the calculating device and the control device instead of the CPU41.

The communication master ECU40may send a connection acknowledgement request to each of the in-vehicle devices2-5via the communication network7and may store the IDs of the in-vehicle devices that respond to the connection acknowledgment request among the in-vehicle devices2-5, so that the communication master ECU40may recognize which in-vehicle device is currently connected. Further, when the ACC is on, the communication master ECU40may start sending data signals over the communication network7and may request each of the in-vehicle devices2-5to turn on. When the ACC is off, the communication master ECU40may send a power-off permission to each of the in-vehicle devices2-5via the communication network7. Then after all of the in-vehicle devices which are currently connected to the communication master ECU40respond to the permission, the communication master ECU40may stop sending data signals over the communication network7and requests each of the in-vehicle devices2-5to turn off (for example, implementing the method shown inFIG. 4).

The CD player3may include a controller (CD player ECU25). The radio tuner4may include a controller (radio tuner ECU26). The AV amplifier5may include a controller (AV amplifier controller ECU27). Note that although the details of the CD player ECU25, the radio tuner ECU26, and the AV amplifier ECU27are not described here, each of the ECUs may include a CPU and an internal storage device such as an RAM, an ROM, and/or a flash memory as in the case of the navigation ECU21. Further, the RAMs of these in-vehicle devices may store a storage range for storing a starting time of a series of program resets due to, for example, a program factor. A reset counter for counting the number of resets may be included in the RAMs. Further, in the ROMs, a series of reset processing programs (for example, implementing the method shown inFIG. 3) and a power management control program (for example, implementing the method shown inFIG. 4) described later may be stored as in the case of the navigation device.

Next, an exemplary reset method will be described with reference toFIG. 3. The exemplary method may be implemented, for example, by one or more components of the above-described system1. However, even though the exemplary structure of the above-described system1may be referenced in the description, it should be appreciated that the structure is exemplary and the exemplary method need not be limited by any of the above-described exemplary structure. For example, the method may be stored in the form of a program in the ROMs and/or the RAMs of the ECUs21and25-27and may be executed by each of the CPUs of the ECUs21and25-27after the in-vehicle devices corresponding to the ECUs are turned on.

The method may be embodied as a program for setting the in-vehicle devices not to respond to the communication provided by the communication master device6and for turning the in-vehicle devices off when the series of program reset occurs due to a program factor or a non-program factor (for example, when a system reset occurs due to a hardware error when just accessing a software).

As shown inFIG. 3, it is determined whether the method is properly terminated without resetting in Step1(hereinafter referred to as S1). Specifically, when an ACC off sequence run flag is set on a procedure in S10and when the power is properly turned off, it is determined that the method is properly terminated.

When it is determined that the method is properly terminated (S1=YES), the reset counter in the RAM is initialized and the counter value (CT) is set as “0” (S2).

In S3, a current time T obtained by an RTC (Real Time Clock) is stored, for example, by the CPU in the RAM. Note that, the current time T stored in the RAM in S3may be used in S15as a starting time of a series of resets while it is determined whether a condition for turning off is met or not. In S4, a communication control processing for responding to a connection acknowledgment request provided by the communication master device6or for receiving a request to start various types of control program is executed.

In S5, the standard control processing for in-vehicle devices corresponding to communication control processing in S4is executed. Specifically, for example, the navigation device2may execute a destination setting processing, a route search processing, and/or a guidance processing along the route on the basis of the instruction from the communication master device6. Alternatively, for example, the CD player3may play a CD, pause the CD, and/or fast-forward the CD on the basis of the instruction from the communication master device6.

In S6, it is determined whether the method is reset due to a program factor or a non-program factor (for example, when a system reset occurs due to a hardware error when accessing software). When it is determined that the method is reset (S6=YES), the procedure returns to S1. When it is determined that the method is not reset (S6=NO), the procedure goes to S7.

In S7, it is determined whether the power-off permission sent from the communication master device6is received. When it is determined that the power-off permission is not received (S7=NO), the procedure returns to S4and various control processing is again executed. When it is determined that the power-off permission is received (S7=YES), a response to the power-off permission is sent to the communication master device6and the communication master device6is informed of the device being ready for turning off (S8).

In S9, it is determined whether data signal transfer on the communication network7is terminated, that is, whether the communication master device6requests for turning the in-vehicle device off. When it is determined that data signal transfer is not terminated (S9=NO), the method does not progress until the data signal transfer is terminated. When it is determined that data signal transfer is terminated (S9=YES), the method goes to S10.

In S10, the ACC off sequence run flag is set on the basis of the completion of the program. In S11, the CPU turns off the in-vehicle device.

When it is determined that the program is not successfully terminated in S1(S1=NO), that is, it is determined that the program is reset and crashed, the current time t obtained by the RTC is stored in the RAM (S12). Note that, the current time t stored in the RAM in S12is used as a starting time of last reset while it is determined whether the power-off condition is met in S15. In S13, “1” is added for the reset counter value (CT) in the RAM.

In S14, it is determined whether the count of the reset counter (CT) in the RAM is 1, that is, whether the first program reset occurs after the program is terminated. When it is determined that the count of the reset counter (CT) in the RAM is 1 (S14=YES), the procedure returns to S3to store the starting time T of the series of resets.

When it is determined that the count of the reset counter (CT) in the RAM is other than 1 (S14=NO), it is further determined whether the power-off condition is met (S15). The power-off condition here means a condition to determine whether a response to the power-off permission can be sent to the communication master device6. Specifically, the condition may be that the series of program resets occurs a predetermined number of times (for example, equal to or more than 11 times) within a predetermined time period (for example, 60 seconds). Then, when “t<T+60 sec” is true according to the starting time T of the series of resets stored in S3or S18and the starting time t of the last reset stored in S12, and when the count of the reset counter (CT) is greater than 10 (CT>10), it is determined that the power-off condition is met.

When it is determined that the power-off condition is met (S15=YES), the in-vehicle device is set not to respond to the communication provided by the communication master device6(S16) and the procedures goes to S9. Note that, the in-vehicle device set not to respond to the communication provided by the communication master device6in S9is not recognized by the communication master device6as an in-vehicle device connected to the communication network7(S25inFIG. 4), so that even if any one of the in-vehicle devices is repeatedly reset, the communication master device6stops transferring a data signal and requests the entire power control system1to turn off.

When it is determined that the power-off condition is not met (S15=NO), it is further determined whether the count of the reset counter CT is greater than 10 (CT>10), that is, whether it takes equal to or more than 60 seconds for the in-vehicle device to be repeatedly reset equal to or more than 11 times (S17).

As a result, when it is determined that the count of the reset counter CT is greater than 10 (CT>10) (S17=YES), the CPU stores the current time T obtained by the RTC to re-count the number of the series of resets (S18). In S19, the CPU initializes the count of the reset counter (CT) in the RAM and set the count as “1” (S19). Then the procedure goes to S4. Note that, the current time T stored in the RAM in S18is used as a starting time of the series of resets while it is determined whether the power-off condition is met in S15.

When it is determined that the count of the reset counter (CT) is equal to or less than 10 (CT>10) (S17=NO), that is, that the number of the reset during the series of resets is less than 11 times since the number of times starts being counted, the procedures goes to S4and the number of reset is ongoingly counted.

Next, an exemplary power management method will be described with reference toFIG. 4. The exemplary method may be implemented, for example, by one or more components of the above-described system1. However, even though the exemplary structure of the above-described system1may be referenced in the description, it should be appreciated that the structure is exemplary and the exemplary method need not be limited by any of the above-described exemplary structure.

For example, the method my be embodied as a program stored in the ROM and/or the RAM of each of the ECUs21,25-27, and40and executed by the communication master ECU40of the communication master device6and the ECUs21and25-27of the in-vehicle devices.

The first portion of the method, which, for example, may be executed by the CPU41will be described. First, in S21, the CPU41determines whether the key switch15(ACC) is turned on. When it is determined that the ACC is not on (S21=NO), the power management processing method is terminated. When it is determined that the ACC is on (S21=YES), the CPU41starts transferring a data signal over the communication network7for turning on the power of the in-vehicle device in S22. In S23, the CPU41transfers a connection acknowledgement request to each of the in-vehicle devices2-5connected through the communication network7.

In S24, the CPU41receives responses to the connection acknowledgment request (sent in S23) from the in-vehicle devices. In S25, IDs of in-vehicle devices, which responded to the connection acknowledgment request among all of the in-vehicle devices, are stored in the RAM42. Therefore, it may be specified which in-vehicle device is currently connected to the communication master device6. Then the CPU41executes system communication processing such as a request for starting a control program for each of the connected in-vehicle devices in S26.

In S27, the CPU41determines whether the key switch15(ACC) is turned off. When it is determined that the ACC is not off (S27=NO), the IDs of the in-vehicle devices stored in the RAM42in S25are initialized (S28), and the procedure returns to S23. Then the connection acknowledgment request is again transferred and the IDs of only in-vehicle devices that respond to the request are stored.

As described above, the ECUs21and25-27of the in-vehicle devices are set not to respond to the communication provided by the communication master device6when the series of program resets occurs a predetermined number of times within a predetermined time period (S16inFIG. 3). As a result, the in-vehicle devices which are set not to respond to the communication provided by the communication master device6do not respond to the connection acknowledgement request, so that, in S25, the CPU41does not recognize such in-vehicle devices as the in-vehicle devices connected to the communication master device6(that is, the CPU41assumes that such in-vehicle devices do not exist).

The recognition processing of the in-vehicle devices that are connected to the communication master device6is exemplified inFIGS. 5A and 5B. When, for example, the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5respond to the connection acknowledgment request, the IDs of the in-vehicle devices2-5are stored in the RAM42as shown in S25inFIG. 5A. The CPU41recognizes that the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5are connected to the communication master device6. When, for example, the navigation device2is repeatedly reset and is set not to respond to the communication provided by the communication master device6(S16inFIG. 3), the navigation device2will not respond to the connection acknowledgement request. As a result, in S25, only the IDs of the CD player3, the radio tuner4, and the AV amplifier5are stored in the RAM42as shown in FIG. B. Thus, the CPU41recognizes that only the CD player3, the radio tuner4, and the AV amplifier5are connected to the communication master device6.

When it is determined that the ACC is off in S27(S27=YES), the CPU41sends the power-off permission to each of the in-vehicle devices connected through the communication network7for determining whether the in-vehicle devices are ready for turning off (S29).

In S30, the CPU41receives responses to the power-off permission (sent from each of the in-vehicle devices in S29). In S31, it is determined whether all expected responses to the power-off permission are received from all in-vehicle devices, which responded to the connection acknowledgement request in S25. For example, when only the IDs of the CD player3, the radio tuner4, and the AV amplifier5are stored in the RAM42, the CPU41determines whether the responses to the power-off permission from the CD player3, the radio tuner4, and the AV amplifier5are received.

When it is determined that the responses to the power-off permission from all of the in-vehicle devices which responded to the connection acknowledgement request are not received (S31=NO), the CPU41waits until receiving all responses to the power-off permission. When it is determined that the all expected responses to the power-off permission from the in-vehicle devices which responded to the connection acknowledgement request are received (S31=YES), the CPU41stops transferring the data signal over the communication network7to turn the in-vehicle devices off (S32). As a result, the in-vehicle devices connected to the communication network7are turned off.

Next, the portions of the method that, for example, may be executed by the CPUs of the in-vehicle devices2-5connected to the communication master device6will be described.

In S41, the CPU determines whether the data signal sent from the communication master device6is received. When it is determined that the data signal is received (S41=YES), the in-vehicle device is turned on (S42). When it is determined that the data signal is not received (S41=NO), the power management processing method is terminated.

Another control processing is executed for the in-vehicle device in S43. Specifically, for example, according to the navigation device2, a destination setting processing, a route search processing, and/or a route guidance processing along the set route may be executed on the basis of the request from the communication master device6. According to the CD player3, a CD playing processing, a pausing processing, and/or a fast-forwarding processing may be executed on the basis of the request from the communication master device6.

In S44, the connection acknowledgement request sent from the communication master device6is received. In S45, the response to the connection acknowledgement request is sent to the communication master device6, so that the communication master device6may specify which in-vehicle device is currently connected to the communication master device6.

In S46, the power-off permission sent from the communication master device6is received. In S47, the response to the power-off permission is sent to the communication master device6, so that the communication master device6may determine whether the currently connected in-vehicle device is ready for turning off.

In S48, the CPU determines whether the data signal is no longer transferred from the communication master device6. When it is determined that the data signal is no longer transferred (S48=YES), the corresponding in-vehicle device is turned off (S49). When it is determined that the data signal is still transferred, (S48=NO), the CPU waits until the transfer of the data signal stops.

As described in detail above, according to the power control system1, when it is determined that any one of the in-vehicle devices (the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5) connected to the communication master device6is repeatedly reset and that the corresponding program is reset a predetermined number of times (for example, equal to or more than 11 times) within a predetermined time period (for example, 60 seconds) (S15=YES), the in-vehicle device is set not to respond to the communication provided by the communication master device6(S16). Meanwhile, when the communication master device6recognizes in-vehicle devices which responded to the connection acknowledgement request as currently connected in-vehicle devices (S25) and when it is determined that all expected responses to the power-off permission from all of the currently connected in-vehicle devices are received (S31=YES), the communication master device6requests the in-vehicle devices to turn off (S32).

Therefore, even if a series of program resets occurs by some sort of program factor or non-program factor (for example, when a system reset occurs due to a hardware error when accessing software. e.g., a crash) and there is an in-vehicle device which does not send condition information indicating that the in-vehicle device is ready for turning off to the power management device, the power management system ignores the existence of such in-vehicle device. As a result, the power of the entire system may be turned off in spite of the system reset. As a result, the in-vehicle devices will not remain on after the vehicle engine stops, thereby conserving the power of the vehicle's battery.

Another exemplary power management method will be described with reference toFIG. 6. Again, the exemplary method may be implemented, for example, by one or more components of the above-described system1. However, even though the exemplary structure of the above-described system1may be referenced in the description, it should be appreciated that the structure is exemplary and the exemplary method need not be limited by any of the above-described exemplary structure.

There may be a difference between the power control system1and the power control system that may execute the method ofFIG. 6. The power control system that may execute the method ofFIG. 6, may initialize IDs of in-vehicle devices stored in the RAM42of the communication master device6only when it is determined that a new in-vehicle device is connected and re-recognizes which in-vehicle device is connected to the communication master device6.

The method ofFIG. 6may be implemented by a program stored in the ROM and/or the RAM of the ECUs21,25-27, and40and may be repeatedly executed by the CPUs in certain intervals.

The first portion of the method, which, for example, may be executed by the CPU41will be described. First, in S101, the CPU41determines whether the key switch15is turned ACC on. When it is determined that the ACC is not on (S101=NO), the power management processing method is terminated.

When it is determined that the ACC is on (S101=YES), the CPU41starts transferring a data signal over the communication network7to request the in-vehicle devices to turn on in S102. In S103, the CPU41sends the connection acknowledgement request to each of the in-vehicle devices (for example, the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5) connected through the communication network7.

In S104, the CPU41receives responses to the request in S103sent from the in-vehicle devices. In S105, the IDs of the in-vehicle devices which responded to the request among all of the in-vehicle devices are stored in the RAM42, so that it may be specified which in-vehicle device is currently connected to the communication master device6.

In S106, the CPU41determines whether any in-vehicle device, which is newly connected to the communication network7, is detected. When the program reset occurs according to the in-vehicle device connected to the communication network7, the response to the connection acknowledgement request is sent to the communication master device6again to inform the connection of the in-vehicle device. Therefore, when the program of any one of the in-vehicle devices2-5connected to the communication master device6is reset, the communication master device6detects the new connection of the in-vehicle device.

When it is determined that the connection of the new in-vehicle device is detected (S106=YES), the IDs of the in-vehicle devices stored in the RAM42in S105are initialized (S107), and the procedure returns to S103. The connection acknowledgement request is again sent and the IDs of the in-vehicle devices, which responded to the request, are registered.

When it is determined that the connection of the new in-vehicle device is not detected (S106=NO), a system communication processing such as a request for starting control programs for the connected in-vehicle devices is executed (S108).

In S109, the CPU41determines whether the key switch15is turned ACC off. When the ACC is not off (S109=NO), the procedure returns to the determination processing in S106and it is further determined whether there is any in-vehicle device which is newly connected.

When it is determined that the ACC is off (S109=YES), the power-off permission is sent to each of the in-vehicle devices (for example, the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5) connected through the communication network7for determining whether such in-vehicle devices are ready for turning off (S110).

In S111, the CPU41receives the responses to the power-off permission in S110sent from each of the in-vehicle devices. In S112, it is determined whether all expected responses to the power-off permission from all of the in-vehicle devices, which responded to the connection acknowledgement request in S105, are received. For example, when the IDs of the CD player3, the radio tuner4, and the AV amplifier5other than the navigation device2are stored in the RAM42, the CPU41determines whether the responses to the power-off permissions from the CD player3, the radio tuner4, and the AV amplifier5are received.

When it is determined that all expected responses to the power-off permission from all of the in-vehicle devices which responded to the connection acknowledgement request are not received (S112=NO), the CPU41waits until all expected responses are received. When it is determined that all responses to the power-off permission from all of the in-vehicle devices which responded to the connection acknowledgement request are received (S112=YES), the data signal transfer over the communication network7stops to make the in-vehicle devices turn off (S113), so that the in-vehicle devices connected to the communication network7are controlled to turn off.

Note that, processing described in S121-S129, for example, executed by the CPUs of the in-vehicle devices2-5connected to the communication master device6according to the power management processing program is same as the processing described in S41-S49executed by the CPUs of the in-vehicle devices2-5according to the power management method ofFIG. 4. Thus, a detail description thereof is not repeated.

As described above, when it is determined that any one of the in-vehicle devices2-5connected to the communication master device6is repeatedly reset and that the program of the in-vehicle device is reset a predetermined number of times (for example, equal to or more than 11 times) within a predetermined time period (for example, 60 seconds), the in-vehicle device may be set not to respond to the communication provided by the communication master device6. When the communication master device6recognizes only in-vehicle devices which responded to the connection acknowledgement request as the currently connected in-vehicle devices (S105) and when it is determined that all expected responses to the power-off permission from the connected in-vehicle devices are received (S112=YES), the communication master device6requests the in-vehicle devices to turn of (S113). Therefore, even if a series of program resets occurs by some sort of program factor or non-program factor (for example, when a system reset occurs due to a hardware error when accessing software) and there is an in-vehicle device which does not send condition information indicating that the in-vehicle device is ready for turning off to the power management device, the power management system ignores the existence of such in-vehicle device. Thus, the power of the entire system may be turned off. As a result, the power-on state of the in-vehicle devices may not continue after the vehicle engine stops and it may conserve the power of the vehicle's battery.

While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.

For example, according to the first and the second examples, the navigation device2, the CD player3, the radio tuner4, and the AV amplifier5are described as the in-vehicle devices mounted in the vehicle. However, such in-vehicle devices used in the power control system1are not limited to the particular devices described above. For example, an MD player, a DVD player, an ETC device, or any other device requiring power may be used.

Further, according to the above examples, the power-off condition to not respond to the communication provided by the communication master device6is when the in-vehicle device is reset a predetermined number of times within a predetermined time period. However, if it is possible to determine that the in-vehicle devices cannot respond to the power-off permission to the communication master device6based on other conditions. For example, the condition may be only that the program is reset a predetermined number of times.

Further, according to the above examples, the system in which the communication master device6and the in-vehicle devices2-5are connected to each other through the MOST is described as an example of the power control system for in-vehicle devices. However, any system in which the communication master device6and the in-vehicle devices2-5are connected to each other may be used. For example, a system in which the communication master device6and the in-vehicle devices2-5are connected to each other through the LAN may be used. Further, as a communication method, an optical communication with the fiber, an electric communication with an electric signal, or a radio communication may be used.