JP2013019837A - Output correction apparatus for vehicular acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform 0-point correction corresponding to both a long-time and smooth 0-point change caused by aging and a relatively short-time 0-point change caused by a temperature change or loading onto a vehicle.SOLUTION: A long-term correction amount and a short-term correction amount are totaled to arithmetically operate a post-arbitration correction amount ΔGx, and the post-arbitration correction amount ΔGx is subtracted from a pre-correction acceleration Gx0 indicated by an output value of a G sensor 2 to arithmetically operate a G sensor value Gx after 0-point correction. The long-term correction amount is determined by extracting a long-time 0-point change by applying low-pass filtering to the output value of the G sensor 2 through short-term correction processing. Furthermore, the short-term correction amount is determined through short-term correction processing of applying filtering of a shorter cycle than that of the long-term correction processing. Moreover, a dead zone is provided in the short-term correction amount, a portion exceeding a range of that dead zone is extracted and it is defined as a final short-term correction amount to correct the short-time 0-point change in the output value of the G sensor 2.

Description

  The present invention relates to an output correction device that corrects an output of an acceleration sensor (hereinafter referred to as a G sensor) that generates an output corresponding to an acceleration in a longitudinal direction of a vehicle.

  Conventionally, Patent Document 1 discloses a technique for correcting the zero point of the G sensor. Specifically, in Patent Document 1, zero correction of the G sensor is performed based on the road surface gradient in the front-rear direction of the vehicle estimated from the road surface gradient. Then, a change amount (offset amount) from the zero point is calculated from the output value of the G sensor assumed from the road surface gradient and the actual output value of the G sensor, and a single filter constant is calculated for the calculated change amount. A high-frequency component (noise) is removed by using a low-pass filter having

JP 2006-250948 A

  However, the zero point of the G sensor changes due to a combination of a gentle change over a long time due to changes over time (aging) and a change over a relatively short time due to changes in temperature, loading on the vehicle, etc. If the change amount extracted using a low-pass filter having a single filter constant as shown in Document 1 is corrected, both changes cannot be corrected with high accuracy.

  In view of the above points, the present invention performs zero point correction corresponding to both a long-term gentle zero point change due to a change with time and a relatively short zero point change such as temperature change and loading on a vehicle. An object of the present invention is to provide an output correction device for a G sensor that can be performed.

  In order to achieve the above object, the invention according to claim 1 sets a long-term correction amount that is a correction amount for a long-time change of the zero point where the zero point of the G sensor (2) changes over a long time. Long-term change correction amount setting means (120, 125) and a short term correction amount that is a correction amount for a change in the zero point in a relatively short time in which the zero point of the G sensor (2) changes in a relatively short time. Long-term correction set by the zero-point short-term change correction amount setting means (130, 135), the zero-point long-term change correction amount setting means (120, 125), and the zero-point short-term change correction amount setting means (130, 135). And a correction means (155 to 165) that performs zero point correction by correcting the output value of the G sensor (2) based on the amount and the short term correction amount. The zero-point long-term change correction means (120, 125) applies a long term to the long-term change of the zero point by filtering the value corresponding to the output value of the G sensor (2) by the long-period filter means. A correction amount is set, and the zero-point short-term change correction means (130, 135) filters the value corresponding to the output value of the G sensor (2) by the short-period filter means to reduce the zero-point for a short time. A temporary short term correction amount with respect to the amount of change is set, and a portion where the temporary short term correction amount exceeds a predetermined dead band range is set as a final short term correction amount, and correction means (155 to 165) The zero value correction of the output value of the G sensor (2) is performed by subtracting the long term correction amount and the short term correction amount from the output value of the G sensor (2). That.

  In this way, zero point correction is performed by subtracting the long term correction amount and the short term correction amount from the output value of the G sensor (2). Thereby, it is possible to reliably correct the change of the zero point for a long time with the long term correction amount, and further reliably correct the change of the zero point for a relatively short time with the short term correction amount. Since the dead-time correction amount is provided for the short term correction amount, noise can be removed and the change of the zero point in a short time can be corrected more appropriately. Accordingly, a G sensor (0 sensor that can perform zero point correction corresponding to both a long-time gentle zero point change due to a change with time and a relatively short zero point change such as temperature change or loading on a vehicle) It becomes possible to obtain the output correction device of 2).

  In the second aspect of the present invention, the speed calculation means (11a) for calculating the wheel speed of each wheel provided in the vehicle and the vehicle speed of the vehicle, and the prime mover for generating the driving force for driving the vehicle. A road on which the vehicle is traveling on a flat road based on the driving force and the vehicle speed of the prime mover, and the vehicle speed calculated by the speed calculation means (11a) is acquired. A travel determination means (11c) and a straight travel determination means (11b) for determining whether the vehicle is traveling straight based on the wheel speed of each wheel calculated by the speed calculation means (11a); When it is determined that the vehicle is traveling on a flat road by the road travel determination means, and when it is determined that the vehicle is traveling straight by the straight travel determination means (11b), the zero-point long-term change correction means ( 120, 125) In addition, the long term correction value and the short term correction value are set by the zero point short-term change correction means (130, 135), and the zero value correction of the output value of the G sensor (2) is performed by the correction means (155 to 165). It is characterized by that.

  Ideally, the gravitational acceleration component is not included in the output value of the G sensor (2) on a flat road, and noise caused by turning the vehicle is not included in a straight traveling state. For this reason, if the output value of the G sensor (2) is not 0, it is the amount of change (offset) from the 0 point. Accordingly, if the vehicle is traveling straight on a flat road, it is possible to optimally extract the amount of change from the zero point, and to correct the zero point of the G sensor (2) accurately. It becomes possible.

  In the invention according to claim 3, when the absolute value of the change amount of the long term correction amount exceeds the upper limit value, the zero-point long-term change correction means (120, 125) sets the upper limit value as the long term correction amount. Set the long term correction amount by performing the upper / lower limit guard that uses the lower limit value as the change amount of the long term correction amount as the change amount or when the absolute value of the change amount of the long term correction amount is below the lower limit value It is characterized by doing.

  Thus, the upper and lower limit guards can be applied to the long term correction amount. Thereby, it can prevent that the variation | change_quantity of long term correction amount is set to the value away from the assumed value.

  In the invention according to claim 4, when the absolute value of the change amount of the short term correction amount exceeds the upper limit value, the zero point short-term change correction means (130, 135) sets the upper limit value as the short term correction amount. As the amount of change, or when the absolute value of the change amount of the short term correction amount is below the lower limit value, the upper and lower limit guards are used to set the short term correction amount using the lower limit value as the change amount of the short term correction amount. It is characterized by doing.

  Thus, the upper and lower limit guards can be applied to the short term correction amount. Thereby, it can prevent that the variation | change_quantity of short term correction amount is set to the value away from the assumed value.

  In addition, about the range of the dead zone used by the zero point short-term change correction means (130, 135), as described in, for example, claim 5, using an assumed noise value and an output value of the G sensor (2). It can be set based on the amount of change at the zero point of the output value of the G sensor (2) that affects the control to be executed.

  In the above first to fifth aspects, the present invention is grasped as an output correction device for a G sensor for a vehicle. As described in claim 6, the present invention is used as an output correction method for a G sensor for a vehicle. It can also be grasped. Thereby, the same effect as that of the invention described in claim 1 can be obtained.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

It is the figure which showed the block configuration of the vehicle control system to which the output correction apparatus of G sensor concerning 1st Embodiment of this invention was applied. It is the flowchart which showed the detail of G sensor 0 point correction process. 6 is a timing chart when G sensor zero point correction processing is performed, in which (a) is a timing chart showing a state when zero point correction of acceleration Gx0 by long term correction processing is performed, and (b) is a long term. It is a timing chart which shows a mode when the zero point correction | amendment of the acceleration Gx0 by the short term correction process is performed after the correction process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described. Here, an output correction apparatus that performs zero point correction of the G sensor according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a diagram showing a block configuration of a vehicle control system to which an output correction device for a G sensor according to this embodiment is applied. The configuration of the vehicle control system will be described with reference to this figure.

  As shown in FIG. 1, the vehicle control system performs zero point correction of the G sensor 2 by the output correction device 1, and performs various controls on the G sensor value Gx after the zero point correction of the G sensor 2 is performed through the in-vehicle LAN 3. It is output to ECU4, meter 5, navigation system 6, etc. For example, various control ECUs 4 or the like execute vehicle control or the like using the G sensor value Gx after the zero point correction. The output correction device 1 is configured by an ECU or the like, but does not have to be an independent ECU provided for performing zero point correction. For example, the function for performing zero point correction of the G sensor 2 in a brake ECU or the like. May be incorporated as.

  The output correction device 1 receives the output values of the G sensor 2 and the wheel speed sensor 7 and also receives information from the engine ECU 8 and corrects the zero point of the G sensor 2 based on these inputs.

  Specifically, the output correction device 1 is configured to include a steady travel detection unit 11 and a correction unit 12, and the zero correction of the G sensor 2 is performed based on information obtained by the correction unit 12 from the steady travel detection unit 11. Execute.

  The steady running detection means 11 detects that the vehicle is running steady. Steady running is assumed to be straight running on a flat road (horizontal road), and the steady running detection means 11 inputs the output value of the wheel speed sensor 7 and information on the engine torque from the engine ECU 8. Based on these, it is detected that the vehicle is in steady running. Specifically, the steady travel detection means 11 includes a speed calculation means 11a, a straight travel determination means 11b, a flat road travel determination means 11c, a constant speed travel determination means 11d, and a steady travel determination means 11e. .

  The speed calculation means 11a calculates the wheel speed of each wheel based on the output value of the wheel speed sensor 7, and calculates the vehicle speed (estimated vehicle speed) by a known method based on the calculated wheel speed.

  The straight travel determination unit 11b detects that the vehicle is traveling straight based on the wheel speed of each wheel calculated by the speed calculation unit 11a. For example, the straight traveling determination unit 11b determines that the vehicle is traveling straight if the difference between the wheel speeds, for example, the wheel speeds of the left wheel and the right wheel are within a predetermined range.

  The flat road traveling determination unit 11c determines whether or not the vehicle is traveling on a flat road. For example, when the flat road traveling determination unit 11c acquires information on the engine torque from the engine ECU 8, whether or not the vehicle speed assumed in correspondence with the acquired engine torque matches the vehicle speed calculated by the speed calculation unit 11a. (For example, whether or not the difference between these vehicle speeds is within a predetermined range) is determined. If they match (if the vehicle speed difference is within the predetermined range), it is determined that the road is a flat road.

  The constant speed traveling determination means 11d determines whether or not the vehicle is traveling at a constant speed. For example, it can be determined that the vehicle is traveling at a constant speed based on the fact that the vehicle speed calculated by the speed calculation means 11a is a constant value. The essential condition for steady driving does not include that the vehicle is traveling at a constant speed, but does not include the influence of the acceleration component during constant speed traveling, and the more accurate change amount (offset) of the G sensor 2 In the present embodiment, constant speed traveling is also included in one of the conditions for determining that steady traveling is being performed. However, as described above, since constant speed traveling is not an essential condition for steady traveling, the condition during constant speed traveling may be removed to determine steady traveling.

  The steady travel determination unit 11e determines whether or not the vehicle is in steady travel based on the determination results of the straight travel determination unit 11b, the flat road travel determination unit 11c, and the constant speed travel determination unit 11d. That is, the steady travel determination means 11e is determined to be traveling straight by the straight travel determination means 11b, is determined to be traveling on a flat road by the flat road travel determination means 11c, and is driven at a constant speed by the constant speed travel determination means 11d. If it is determined that the vehicle is in the middle, it is determined that the vehicle is in steady running. When the steady running determination means 11e determines that steady running is in progress, the detection result of the steady running detection means 11 indicates that the vehicle is in steady running, that is, an output indicating that the G sensor 2 is corrected for 0-point correction. Output to the sensor correction unit 12.

  The G sensor correction unit includes a front / rear G deviation calculation means 12a, a correction amount calculation means 12b, and a correction amount arbitration means 12c.

  The front-rear G deviation calculating means 12a calculates the acceleration Gx0 during steady running based on the output value of the G sensor 2, and calculates the G sensor deviation Diff # Gx. The G sensor deviation Diff # Gx is a change amount (offset amount) of the acceleration Gx0 indicated by the output value of the G sensor 2 from the original acceleration, and is calculated from the acceleration Gx0 obtained from the output value of the G sensor 2 by the speed calculation means 11a. It is calculated as the difference between the calculated acceleration DVT0 calculated by differentiating the calculated vehicle speed, that is, the value obtained by subtracting the acceleration to be originally extracted. This G sensor deviation Diff # Gx includes a long-time gentle 0 point change (offset) due to aging (aging), and a relatively short 0 point change due to temperature changes and loading on the vehicle ( Offset) is included.

  The correction amount calculation unit 12b calculates correction amounts corresponding to the two offsets based on the G sensor deviation Diff # Gx calculated by the front and rear G deviation calculation unit 12a. For example, in the correction amount calculation means 12b, based on the G sensor deviation Diff # Gx, a correction amount (hereinafter referred to as a long term) corresponding to an offset caused by a gradual 0 point change based on a moving average calculation or the like. A correction amount corresponding to an offset caused by a change in the zero point in a relatively short time (hereinafter referred to as a short term correction amount). In addition, the correction amount calculation means 12b applies an upper / lower limit guard to the amount of change of each correction amount, or provides a dead zone when performing correction based on the short term correction amount, so that the final long term correction amount or short circuit is provided. The term correction amount is calculated. The width of the dead zone is set in consideration of both the assumed noise value and the 0 point change amount of the G sensor 2 that affects various controls.

  The correction amount arbitration unit 12c performs zero point correction of the G sensor 2 based on the long term correction amount and the short term correction amount calculated by the correction amount calculation unit 12b. The G sensor value Gx after zero point correction is calculated by the correction amount adjusting means 12c, and this G sensor value Gx is output to various control ECUs 4, the meter 5, the navigation system 6 and the like through the in-vehicle LAN 3.

  As described above, the output correction device 1 for the G sensor 2 according to the present embodiment is configured. Next, the G sensor zero point correction process executed by the output correction apparatus 1 configured as described above will be described.

  FIG. 2 is a flowchart showing details of the G sensor zero point correction process. The G sensor zero-point correction process shown in this figure is executed every predetermined control period (for example, 5 seconds) when the ignition switch is turned on.

  First, in step 100, the acceleration Gx0 and the wheel speed VW ** of each wheel VW ** (note that the output value of the G sensor 2 and the output value of the wheel speed sensor 7 and the acquisition of information from the engine ECU 8) * Is a subscript indicating each wheel, and means the left front wheel FL, the right front wheel FR, the left rear wheel RL, and the right rear wheel RR) and engine torque. Subsequently, in step 105, it is determined whether or not it is immediately after the ignition switch is turned on. That is, immediately after the ignition switch is turned on, idling is not stable, and the relationship between the engine torque and the vehicle speed is not ideal. For this reason, immediately after the ignition switch is turned on, it is determined that the correction amount used for the zero point correction of the G sensor 2 is not suitable for updating, and is used for the zero point correction only when an affirmative determination is made in this step 105. The process proceeds to processing for updating the correction amount and performing zero point correction. For example, since the elapsed time since starting by various control ECU4, engine ECU8, etc. is counted with the counter, the count value is acquired through in-vehicle LAN3 etc., and if the count value is less than a predetermined value, the ignition switch It is determined that it is immediately after being turned on.

  Further, in step 110, it is determined whether or not the G sensor correction permission condition is satisfied. The G sensor correction permission condition is a condition indicating that the correction amount used for the zero point correction of the G sensor 2 may be updated. Here, the vehicle is in steady running, that is, straight running on a flat road. The G sensor correction permission condition is set to be inside. Ideally, the gravitational acceleration component is not included in the output value of the G sensor 2 on a flat road, and noise caused by turning of the vehicle is not included in a straight traveling state. If the output value is not 0, it becomes the amount of change (offset) from the 0 point, and the amount of change from the 0 point can be optimally extracted.

  For this reason, when the steady running detection means 11 detects that the vehicle is running steady and an output indicating that is output, it is determined that the G sensor correction permission condition is satisfied. If an affirmative determination is made here, in the next steps 115 to 160, the process proceeds to processing for updating the correction amount used for zero point correction and performing zero point correction. These processes are executed by the front / rear G deviation calculating means 12a, the correction amount calculating means 12b or the correction amount adjusting means 12c included in the G sensor correction unit 12.

  In step 115, G sensor deviation calculation is performed. This process is executed by the longitudinal G deviation calculating means 12a, and the calculated acceleration DVT0 calculated by differentiating the vehicle speed calculated by the speed calculating means 11a from the acceleration Gx0 indicated by the output value of the G sensor 2, that is, originally desired to be taken out. A G sensor deviation Diff # Gx, which is a value obtained by subtracting the acceleration, is calculated.

  Next, in step 120 and step 125, a long term correction process is executed. First, in step 120, long term correction amount calculation and filter processing are performed. In the long term correction amount calculation, the long term correction amount is calculated based on the G sensor deviation Diff # Gx calculated in step 115. The long term correction amount can be either positive or negative depending on the mounting state of the G sensor 2 and the like. Here, the G sensor deviation Diff # Gx calculated for each predetermined control cycle is accumulated, and the long term correction amount is calculated by calculating the moving average of the accumulated G sensor deviation Diff # Gx. For example, the G sensor deviation Diff # Gx is stored every time the control cycle reaches the first predetermined number of times (for example, every 60 cycles of the control cycle), and the sum is divided by the first predetermined number of times to obtain the G sensor deviation Diff # Gx. Is repeated to calculate a moving average of G sensor deviation Diff # Gx. Then, as a filtering process, a moving average of the obtained G sensor deviation Diff # Gx is applied to a low-pass filter for noise removal. The low-pass filter is set for the long time because the long term correction amount is calculated for a long time. As a result, the long term correction amount is set by removing the high frequency component from the moving average of the G sensor deviation Diff # Gx.

  In step 125, the upper and lower limit guards are applied to the amount of change in the long term correction amount set in step 120. The upper / lower limit guard is when the absolute value of the change amount of the long term correction amount set in step 120 exceeds the assumed upper limit (maximum correction amount) or falls below the lower limit (minimum correction amount). In addition, the absolute value of the change amount of the long term correction amount is set to the upper limit value or the lower limit value, thereby guarding the change amount of the long term correction amount. When the upper / lower limit guard is applied, a value obtained by adding the absolute value of the change amount set to the upper limit value or the lower limit value to the long term correction amount set in the previous control cycle. Set to the long term correction amount in the current control cycle. Specifically, if the change amount of the long term correction amount is a positive value, the upper limit value or the lower limit value is added. If the change amount is a negative value, the upper limit value or the lower limit value is subtracted. This value is set as the long term correction amount for the current control cycle. In this way, the upper and lower limit guards are applied to the long term correction amount, and the change amount of the long term correction amount can be prevented from being set to a value away from the assumed value.

  Note that the processing of step 120 and step 125 is executed by the correction amount calculation means 12b, but the portion of the correction amount calculation means 12b that performs these processings corresponds to the zero-point long-term change correction amount setting means, and is long. A filter for extracting the amount of change at zero point in time corresponds to the long-period filter means.

  Subsequently, in steps 130 to 150, short term correction processing is executed. First, in step 130, short term correction amount calculation and filter processing are performed. Also in the short term correction amount calculation, the short term correction amount (temporary short term correction amount) is calculated based on the G sensor deviation Diff # Gx calculated in step 115. Also here, the G sensor deviation Diff # Gx calculated every predetermined control period is accumulated, and the short term correction amount is calculated by calculating the moving average of the accumulated G sensor deviation Diff # Gx. For example, every time the control cycle reaches the second predetermined number of times (for example, every two cycles of the control cycle), the G sensor deviation Diff # Gx is stored, and the sum is divided by the second predetermined number of times to obtain the G sensor deviation Diff # Gx. Is repeated to calculate a moving average of G sensor deviation Diff # Gx. Then, as a filtering process, a moving average of the obtained G sensor deviation Diff # Gx is applied to a low-pass filter for noise removal. The low-pass filter is set in accordance with the short term because the short term correction amount is calculated in a short time. As a result, a value obtained by removing a high frequency component from the moving average of the G sensor deviation Diff # Gx is set as the short term correction amount.

  In step 135, an upper and lower limit guard is applied to the amount of change in the short term correction amount set in step 130. The upper and lower limit guards indicate that the absolute value of the change amount of the temporary short term correction amount set in step 130 exceeds an assumed upper limit value (maximum correction amount) or falls below a lower limit value (minimum correction amount). In this case, the absolute value of the change amount of the short term correction amount is set to the upper limit value or the lower limit value, thereby guarding the change amount of the short term correction amount. When the upper / lower limit guard is applied, a value obtained by adding the absolute value of the change amount set to the upper limit value or the lower limit value to the short term correction amount set in the previous control cycle is set. Set the short term correction amount in the current control cycle. Specifically, if the amount of change in the short term correction amount is a positive value, the upper limit value or lower limit value is added. If the change amount is a negative value, the upper limit value or lower limit value is subtracted. This value is set as the short term correction amount in the current control cycle. In this way, the upper and lower limit guards are applied to the short term correction amount, and it is possible to prevent the change amount of the short term correction amount from being set to a value away from the assumed value.

  The processing of step 130 and step 135 is also executed by the correction amount calculation means 12b, but the portion of the correction amount calculation means 12b that performs these processings corresponds to the zero point short-term change correction amount setting means. A filter for extracting the amount of change at 0 point in time corresponds to the short-period filter means.

  Here, the G sensor deviation Diff # Gx is used both in the calculation of the long term correction amount in step 120 and in the calculation of the short term correction amount in step 130. The number of deviations Diff # Gx is made different, and the first predetermined number in the calculation of the long term correction amount is larger than the second predetermined number in the short term calculation.

  In the calculation of the long term correction amount, it is assumed that the median value of the long-time G sensor deviation Diff # Gx is calculated using the G sensor deviation Diff # Gx sampled for a long time. In other words, the G sensor deviation used for the calculation of the moving average is included so that the influence of the gentle zero point change for a long time due to the change with time is included and the influence of the zero point change for a relatively short time is reduced. The number of Diff # Gx is increased. On the other hand, in the calculation of the short term correction amount, the G sensor deviation Diff # Gx sampled in a relatively short time is used to include a change in the G sensor deviation Diff # Gx in a relatively short time. In other words, the G sensor deviation Diff # Gx used in the calculation of the moving average is included so that the effects of changes in a relatively short time due to temperature changes, loading on the vehicle, etc. are included, and the effects of the changes appear greatly. The number is reduced. For this reason, as described above, the first predetermined number in the calculation of the long term correction amount is larger than the second predetermined number in the short term calculation.

  Thereafter, the process proceeds to step 140, where it is determined whether or not the short term correction amount is out of the dead zone. Here, the dead zone indicates a case where the absolute value of the short term correction amount is equal to or smaller than a predetermined value. In order to remove a minute correction amount that occurs when noise is added to the output value of the G sensor 2 or the like. When the short term correction amount is included in the dead zone, the short term correction is not performed.

  Therefore, if an affirmative determination is made in step 140, the process proceeds to step 145, and the dead zone processing is performed based on the short term correction amount calculated in step 130 or the short term correction amount multiplied by the upper and lower limit guards set in step 135. A value obtained by reducing the predetermined value set as is set as a new short term correction amount. Specifically, since the short term correction amount can be either plus or minus, if the short term correction amount is a positive value so that the absolute value of the short term correction amount is reduced, the short term correction amount is determined from the predetermined value. If the value obtained by subtracting the value and the short term correction amount is negative, a value obtained by adding the predetermined value to the short term correction amount is set as a new short term correction amount.

  If a negative determination is made at step 140, the routine proceeds to step 150, where the short term correction amount calculated at step 130 or the short term correction amount multiplied by the upper / lower limit guard set at step 135 is set to zero as dead zone processing. Set.

  Then, the process proceeds to step 155 to calculate a post-arbitration correction amount ΔGx that takes into account the long term correction amount and the short term correction amount. Specifically, the short term correction amount set in step 145 or 150 is added to the long term correction amount set in step 120 or the short term correction amount to which the upper / lower limit guard is applied in step 125. Then, the post-arbitration correction amount ΔGx is calculated. Thereafter, the process proceeds to step 160, and the post-arbitration correction amount ΔGx calculated in step 155 is subtracted from the acceleration Gx0 indicated by the output value of the G sensor 2 during the current control cycle, whereby the G sensor after the zero point correction. The value Gx is calculated. At the same time, the post-arbitration correction amount ΔGx is stored as the previous acceleration correction amount ΔGx # last, and the process ends.

  On the other hand, if a negative determination is made in step 105 or step 110 described above, the process proceeds to step 165. In this case, since it is not appropriate to update the correction amount for zero point correction (that is, acceleration correction amount ΔGx # last), this time control is performed using the previously stored acceleration correction amount ΔGx # last. The G sensor value Gx after zero point correction is calculated by subtracting the previous acceleration correction amount ΔGx # last from the acceleration Gx0 indicated by the output value of the G sensor 2 during the period. In this way, the G sensor zero point correction process is completed.

  FIG. 3 shows a timing chart when the G sensor zero point correction process as described above is performed. FIG. 3A shows a state in which the zero point correction of the acceleration Gx0 by the long term correction process is performed. FIG. 3B shows the acceleration Gx0 of 0 by the short term correction process after the long term correction process. The situation when point correction is performed is shown.

  In the flowchart shown in FIG. 2, the long term correction amount and the short term correction amount are obtained, and a value obtained by adding them is used as the post-arbitration correction amount ΔGx from the acceleration Gx0 before correction indicated by the output value of the G sensor 2. Since it is subtracted, the process of subtracting only the long term correction process as shown in FIG. 3A is not performed. Here, in order to facilitate understanding of the long term correction process, the timing chart shown in FIG. In addition, since the long-term correction process, which is subject to correction over time, can have a slow zero point change over a long period of time, for example, is a long span of several years, it is actually a target of the short-term correction process. There is a larger difference than that shown in FIG. 3 compared with the time when the change of the zero point can occur in a relatively short time, but here, for the sake of simplicity, the length to be corrected by the long term correction It is described in such a manner that a gradual change of 0 point occurs in a shorter period than the actual time.

  First, it is assumed that the zero point of the acceleration Gx0 indicated by the output value of the G sensor 2 gradually deviates from time T0 in FIG. In that case, the long-term correction amount is calculated in the above-described long-term correction processing, and the post-arbitration correction amount ΔGx including the long-term correction amount is removed from the acceleration Gx0. Thereby, the acceleration Gx0 before correction indicated by the output value of the G sensor 2 is subtracted by the long term correction amount, the G sensor value Gx after zero point correction becomes 0.00G, and the zero point offset is removed.

  Next, if the zero point is shifted as the vehicle is loaded at time T1, the long term correction amount that is suddenly calculated in step 120 at that moment increases. Therefore, ideally, the long term correction amount changes as indicated by the broken line in the drawing, but the change amount of the long term correction amount is too large and the upper and lower limit guards described in step 125 are applied. It will be. Therefore, the absolute value of the change amount of the long term correction amount is limited by the upper limit value (maximum correction amount) set by the upper and lower limit guards, gradually approaching the ideal long term correction amount, and the ideal long term correction at time T2. It matches the term correction amount.

  Then, when the vehicle is no longer loaded at time T3, the long term correction amount calculated in step 120 suddenly again at that moment again decreases. Therefore, ideally, the long term correction amount changes as indicated by the broken line in the figure, but the change amount of the long term correction amount is too large, and the upper and lower limit guards are again applied. Therefore, the absolute value of the change amount of the long term correction amount is limited by the upper limit value (maximum correction amount) set by the upper and lower limit guards, gradually approaching the ideal long term correction amount, and an ideal long term at time T4. It matches the term correction amount.

  Subsequently, as shown in FIG. 3B, during the period from the time point T0 to the time point T1, there is no change in the zero point, which is a correction target in the short term correction process, in a relatively short time. The amount is zero. When the vehicle is loaded at time T1, a short term correction amount is generated accordingly. When the short term correction amount falls outside the range of the dead zone, a value obtained by subtracting a predetermined value corresponding to the dead zone from the short term correction amount is set as the final short term correction amount. By adding this short term correction amount to the long term correction amount, a post-arbitration correction amount ΔGx is calculated and subtracted from the acceleration Gx0 before the correction indicated by the output value of the G sensor 2, so that the zero point corrected value is obtained. The G sensor value is set to Gx.

  Similarly, when the vehicle is no longer loaded at time T3, the short term correction amount is generated again. Then, the short term correction amount is set in the same manner as at the time T1, and the short term correction amount is added to the long term correction amount to calculate the post-arbitration correction amount ΔGx. Then, the post-arbitration correction amount ΔGx is subtracted from the pre-correction acceleration Gx0 indicated by the output value of the G sensor 2 to obtain the zero-point corrected G sensor value Gx.

  As described above, the post-arbitration correction amount ΔGx is calculated by combining the long term correction amount and the short term correction amount, and the post-arbitration correction amount ΔGx is subtracted from the pre-correction acceleration Gx0 indicated by the output value of the G sensor 2. The G sensor value Gx after zero point correction is calculated. The long term correction amount is obtained by a long term correction process in which a long period filter is applied. A long-term correction amount obtained by applying a low-pass filter to the output value of the G sensor 2 to extract a long-term change in the zero point is used as a long term correction amount to correct the long-time change in the zero point of the G sensor 2. I am doing so. Further, the short term correction amount is obtained by a short term correction process in which a filter having a shorter cycle is applied than in the long term correction process. A short-term correction amount corresponding to the zero point change amount that occurs in a relatively short time corresponding to the output value of the G sensor 2 is obtained, and a dead zone is provided in the short-term correction amount, and a portion exceeding the dead zone range is extracted. As a final short term correction amount, the change of the zero point of the output value of the G sensor 2 in a short time is corrected.

  Thereby, it is possible to reliably correct the change of the zero point for a long time with the long term correction amount, and further reliably correct the change of the zero point for a relatively short time with the short term correction amount. Since the dead-time correction amount is provided for the short term correction amount, noise can be removed and the change of the zero point in a short time can be corrected more appropriately. Therefore, the G sensor 2 can perform zero point correction corresponding to both a long-time gentle change of 0 point due to a change with time and a relatively short time change of 0 point such as a temperature change or loading on a vehicle. The output correction apparatus 1 can be obtained.

(Other embodiments)
In the above embodiment, the long term correction amount and the short term correction amount are calculated based on the accumulated G sensor deviation Diff # Gx, and then the filtering process is performed, so that the amount of change of the zero point for a long time or a relatively short time is calculated. The amount of change at 0 is extracted. However, this is merely an example of a method for extracting the change amount of the zero point for a long time or the change amount of the zero point for a relatively short time, and a value (for example, an output value) corresponding to the output value of the G sensor 2. Itself or G sensor deviation (Diff # Gx) is filtered by the long-period filter means to extract the long-term change of 0 points, or is filtered by the short-period filter means to be relatively short-term 0 points What is necessary is just to extract the amount of change.

  In the above-described embodiment, the long term correction amount and the short term correction amount are obtained, and are simultaneously subtracted from the acceleration Gx0 before correction indicated by the output value of the G sensor 2. On the other hand, the short term correction amount is obtained based on the value after subtracting the long term correction amount from the acceleration Gx0 before correction, and then the long term correction amount is subtracted from the acceleration Gx0 before correction. The G sensor value Gx after zero point correction may be acquired by further subtracting the short term correction amount from the value. In this case, the short term correction amount is obtained based on the value after subtracting the long term correction amount from the acceleration Gx0 before correction. In this case as well, basically, the output value of the G sensor 2 before correction is indicated. Therefore, the short term correction amount is obtained based on the value corresponding to the acceleration Gx0.

  In the above embodiment, the zero value of the G sensor 2 is corrected on a flat road that would ideally not include the gravitational acceleration component in the output value of the G sensor 2, and the engine torque is used. It is determined that the road is flat. This is because the above embodiment has been described on the assumption that the vehicle is equipped with an engine, and the determination of a flat road is made using the engine torque. Of course, the driving force for driving the vehicle is used. If it is a prime mover to be generated, a flat road may be determined from the relationship between the driving force other than the engine and the vehicle speed.

  DESCRIPTION OF SYMBOLS 1 ... Output correction device, 2 ... G sensor, 3 ... In-vehicle LAN, 4 ... Various control ECU, 5 ... Meter, 6 ... Navigation system, 7 ... Wheel speed sensor, 8 ... Engine ECU, 11 ... Steady-running detection means, 11a ... speed calculation means, 11b ... straight travel determination means, 11c ... flat road travel determination means, 11d ... constant speed travel determination means, 11e ... steady travel determination means, 12 ... G sensor correction unit, 12a ... front and rear G deviation calculation means, 12b: Correction amount calculation means, 12c: Correction amount arbitration means

Claims (6)

An output correction device for an acceleration sensor for a vehicle that corrects that an output value of an acceleration sensor (2) that detects acceleration in the longitudinal direction of the vehicle is deviated from an assumed zero point when no acceleration is generated. And
A zero-point long-term change correction amount setting means (120, 125) for setting a long-term correction amount that is a correction amount for a long-time change in the zero point that changes over a long time from the zero point of the acceleration sensor (2);
A zero-point short-term change correction amount setting for setting a short-term correction amount that is a correction amount for a change of the zero point in a relatively short time in which the zero point of the acceleration sensor (2) changes in a relatively short time than the long time. Means (130, 135);
Based on the long-term correction amount and the short-term correction amount set by the zero-point long-term change correction amount setting means (120, 125) and the zero-point short-term change correction amount setting means (130, 135), the acceleration Correction means (155 to 165) that performs zero point correction by correcting the output value of the sensor (2),
The zero-point long-term change correcting means (120, 125) filters the value corresponding to the output value of the acceleration sensor (2) with respect to the long-time zero-point change by filtering the value by the long-period filter means. Set the long term correction amount,
The zero-point short-term change correction means (130, 135) applies a filter by a short-period filter means to a value corresponding to the output value of the acceleration sensor (2), so that the short-term change amount of the zero point is reduced. A temporary short term correction amount is set, and a portion where the temporary short term correction amount exceeds a predetermined dead zone is set as a final short term correction amount.
The correction means (155 to 165) subtracts the long term correction amount and the short term correction amount from the output value of the acceleration sensor (2), thereby correcting the output value of the acceleration sensor (2) to zero. An output correction device for an acceleration sensor for a vehicle, characterized in that: Speed calculating means (11a) for calculating the wheel speed of each wheel provided in the vehicle and calculating the vehicle speed of the vehicle;
Information on the driving force of the prime mover that generates the driving force for driving the vehicle is input, the vehicle speed calculated by the speed calculation means (11a) is acquired, and the driving force of the prime mover and the vehicle speed are obtained. A flat road running judging means (11c) for judging whether the vehicle is running on a flat road,
Straight travel determination means (11b) for determining whether the vehicle is traveling straight based on the wheel speed of each wheel calculated by the speed calculation means (11a);
When it is determined by the flat road traveling determination means that the vehicle is traveling on a flat road, and when the straight traveling determination means (11b) determines that the vehicle is traveling straight ahead, the 0 The long term correction value and the short term correction value are set by the long-term change correction means (120, 125) and the zero-point short-term change correction means (130, 135), and by the correction means (155-165). The output correction device for an acceleration sensor for a vehicle according to claim 1, wherein the output value of the acceleration sensor (2) is corrected to zero.   The zero-point long-term change correction means (120, 125), when the absolute value of the change amount of the long term correction amount exceeds the upper limit value, sets the upper limit value as the change amount of the long term correction amount, or 3. The long term correction amount is set by performing an upper / lower limit guard that uses the lower limit value as a change amount of the long term correction amount when the absolute value is below the lower limit value. The output correction apparatus of the acceleration sensor for vehicles described in 2.   The zero-point short-term change correction means (130, 135), when the absolute value of the change amount of the short term correction amount exceeds the upper limit value, sets the upper limit value as the change amount of the short term correction amount, or 4. The short term correction amount is set by performing an upper / lower limit guard that uses the lower limit value as a change amount of the short term correction amount when the absolute value is below the lower limit value. The output correction apparatus of the acceleration sensor for vehicles as described in any one of these.   The zero-point short-term change correction means (130, 135) is configured to affect the control executed using the noise value assumed for the dead zone and the output value of the acceleration sensor (2). The output correction device for an acceleration sensor for a vehicle according to any one of claims 1 to 4, wherein the output correction device is set based on a change amount of the output value of 0). This is an output correction method for an acceleration sensor for a vehicle that corrects that the output value of the acceleration sensor (2) for detecting the acceleration in the longitudinal direction of the vehicle deviates from the zero point assumed when no acceleration is generated. And
Setting a long-term correction amount that is a correction amount for a long-time change in the zero point, in which the zero point of the acceleration sensor (2) changes over a long time;
Setting a short term correction amount that is a correction amount for a change in the zero point in a relatively short time in which the zero point of the acceleration sensor (2) changes in a relatively short time than the long time;
Performing zero point correction by correcting the output value of the acceleration sensor (2) based on the long term correction amount and the short term correction amount,
In the step of setting the long term correction amount, the long term correction for the change of the zero point for a long time is performed by filtering a value corresponding to the output value of the acceleration sensor (2) by a long period filter means. Set the amount,
In the step of setting the short term correction amount, a provisional short term with respect to the change amount of the zero point in the short time is obtained by filtering a value corresponding to the output value of the acceleration sensor (2) by a short period filter means. While setting a correction amount, a portion where the temporary short term correction amount exceeds a predetermined dead band range is set as the final short term correction amount,
In the step of performing the zero point correction, the zero value correction of the output value of the acceleration sensor (2) is performed by subtracting the long term correction amount and the short term correction amount from the output value of the acceleration sensor (2). An output correction method for an acceleration sensor for a vehicle.

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