Avoiding overshoot of a speed filter

Abstract

Method for reducing overshoot of an output signal of a speed filter when changing gears, for controlling the slip of a vehicle clutch with the speed filter, wherein speed values are input to the speed filter at time intervals and these are transmission input speeds and a gradient of the speed values is output as an output signal, characterized in that the gradient of the speed values is determined, wherein the determination of the gradient of the speed values is terminated as soon as no gear is engaged and if a gear is engaged again within a predetermined time, the determination of the gradient is continued by scaling the speed values used to determine the gradient before the termination of the determination of the gradient to the speed level of the gear engaged again and the determination of the gradient with the speed values newly added since a gear was engaged again and, if a predetermined,gear-dependent number of speed values is not available, the process continues with the scaled, most recent speed values.

Description

[0001] The invention relates to a method having the features according to the preamble of claim 1 and to a computer program product having the features according to the preamble of claim 6 and to a device having the features according to the preamble of claim 7.

[0002] DE 10 2008 030 481 A1 discloses a method for controlling the slip of a vehicle clutch using a speed filter.

[0003] The present invention can be advantageously employed when applying such speed filters known from the prior art to transmission input speeds. The need for an improvement in the prior art arises from the fact that these speeds rise or fall very quickly to the new target value during gear changes, and filters known from the prior art are not designed for such rapid changes.

[0004] The speed filter according to DE 10 2008 030 481 A1 calculates an averaged gradient from a series of old measured values ​​– hereinafter referred to as the stack – in each interrupt and uses this to make a prediction for the filtered speed in the current interrupt. The number of old values ​​used to calculate the gradient depends on the gear and is determined by the chatter frequency in the respective gear, so that chatter vibrations at the transmission input speeds are filtered out by averaging. The stack is updated in each interrupt by deleting the oldest value and inserting the currently measured value.

[0005] If the gradient is calculated by averaging over the stack even during the very rapid speed changes during gear changes, the filter produces a strong overshoot after the gear change, when the gradient returns to much smaller values. The reason for this is that the averaging delays the reduction in the gradient.

[0006] The object of the present invention is to avoid or at least reduce such an overshoot of the speed filter when changing gears.

[0007] The object is achieved by a method having the features according to claim 1, by a computer program product having the features according to claim 6 and by a device having the features according to claim 7.

[0008] The method according to the invention provides for the reduction of overshoot of an output signal of a speed filter during gear changes for controlling the slip of a vehicle clutch with the speed filter, wherein speed values ​​are input to the speed filter at time intervals and these are transmission input speeds and a gradient of the speed values ​​is output as an output signal.The gradient of the speed values ​​is determined, whereby the determination of the gradient of the speed values ​​is terminated as soon as no gear is engaged and if a gear is engaged again within a predetermined time, the determination of the gradient is continued by scaling the speed values ​​used to determine the gradient before the end of the determination of the gradient to the speed level of the gear that is engaged again and the determination of the gradient is continued with the new speed values ​​added since a gear was engaged again and, if a predetermined, gear-dependent number of speed values ​​is not available, additionally with the scaled, most recent speed values.

[0009] In a preferred embodiment, it is provided that the determination of the gradient of the rotational speed is determined from a predetermined, gear-dependent number of rotational speed values.

[0010] In a particularly preferred embodiment, it is provided that the scaling to the speed level of the re-engaged gear is carried out with a scaling factor which results from the oldest speed since the continuation of the determination of the gradient divided by the most recent speed before the termination of the determination of the gradient.

[0011] In a preferred embodiment, it is provided that if a gear is not engaged again within a predetermined time, as soon as a gear is engaged again, the determination of the gradient is continued only with the speed values ​​that have been newly added since a gear was engaged again.

[0012] In a preferred embodiment, the predetermined time is between 0.01 seconds and 10 seconds, preferably 0.5 to 2 seconds.

[0013] The invention also proposes a computer program product comprising a computer program that has software means for implementing the above-mentioned methods when the computer program is executed on a computer. Such a computer can be part of a control device.

[0014] According to the invention, a device for reducing overshoot of an output signal of a speed filter during gear changes in a transmission of a motor vehicle is also proposed, comprising a control device for regulating the slip of a vehicle clutch with the speed filter. Speed ​​values ​​can be input to the speed filter at time intervals, said values ​​being transmission input speeds, and a gradient of the speed values ​​can be output as an output signal.The gradient of the speed values ​​can be determined, and the control device can end the determination of the gradient of the speed values ​​as soon as no gear is engaged, and if a gear is engaged again within a predetermined time, the determination of the gradient can be continued by scaling the speed values ​​used to determine the gradient before the determination of the gradient was ended to the speed level of the gear that has been engaged again, and the determination of the gradient can be continued with the new speed values ​​added since a gear was engaged again and, if a predetermined, gear-dependent number of speed values ​​is not available, additionally with the scaled, most recent speed values.

[0015] According to the invention, the use of the above-mentioned methods for controlling a motor vehicle transmission is proposed.

[0016] Further advantages and advantageous embodiments of the invention are the subject of the following description.

[0017] The plan is to deactivate averaging during gear changes and resume averaging immediately after the gear change with the best possible stack. The difficulty lies in the fact that after the gear change, the stack would first have to be refilled before the calculation can be performed with the number of values ​​corresponding to the new gear.

[0018] The basic idea of ​​the solution is to freeze the stack, i.e. to no longer update it once the gear is disengaged. When a gear is later engaged again, the stack is thawed again and rescaled to the new speed level. Scaling means multiplying the stack entries by a scaling factor. Scaling is done with the current speed - i.e. the first and therefore oldest speed since the gradient determination was continued or since a gear was engaged again - divided by the most recent speed in the stack - i.e. divided by the most recent speed before the gradient determination was stopped. This achieves a flush connection of the stack to the speed curve in the new gear. In this way, a stack is available from the first interrupt in the new gear which supplies an improved gradient and which can be averaged over the averaging width corresponding to the new gear.

[0019] If a new gear is shifted whose predefined, gear-dependent number of speed values ​​is greater than the predefined, gear-dependent number of speed values ​​of the previously engaged gear, the scaled speed values ​​of the previously engaged gear are added to the newly determined speed values ​​in the new gear to calculate the average. In each interrupt, a newly determined speed value in the new gear is added and the averaging width is increased by one until it has reached the value intended for the new gear and the predefined, gear-dependent number of speed values ​​for the new gear is available. The current stack for the new gear is then updated according to the usual procedure: The current stack for the new gear is updated in each interrupt by deleting the oldest value and inserting the most recently measured value.

[0020] Conversely, if a new gear is engaged whose predefined, gear-dependent number of speed values ​​is smaller than the predefined, gear-dependent number of speed values ​​of the previously engaged gear, the newly determined speed values ​​in the new gear - as long as their number is still smaller than the predefined, gear-dependent number of speed values ​​of the newly engaged gear - are added to the scaled most recent speed values ​​of the previously engaged gear to calculate the average, so that the predefined, gear-dependent number of speed values ​​of the newly engaged gear is used to calculate the average.

[0021] Typically, a PSG is operated with two gears engaged. However, in certain situations it may be necessary to forgo preselecting a gear in the inactive sub-gearbox for reasons of convenience. In this case, the stack could remain frozen for a very long time and would have little or no value when thawed. Therefore, the stack freezing time can be calibrated. If no new gear is engaged after this time has elapsed, the contents of the stack are discarded. As soon as a gear is engaged again, the stack is initialized by filling all elements with the currently measured speed - i.e. the first and therefore oldest speed since the gradient determination was continued or since a gear was engaged again. In this case, the averaging width must also be set to one. It is then gradually increased by one in each interrupt until it reaches the value intended for the gear.Alternatively, initialization can of course be omitted or performed with any other desired value, provided that the first assignment since the determination of the gradient was continued or since a gear was engaged again is made with the currently measured speed - i.e. the first and therefore oldest speed since the determination of the gradient was continued or since a gear was engaged again - and the averaging width is set to one. In the next interrupt, the second memory position in the stack is assigned the speed measured in this interrupt - i.e. the second and therefore second oldest speed since the determination of the gradient was continued or since a gear was engaged again, and the averaging width is set to two. The stack is assigned, the averaging width is set and the gradient is determined in the same way until the value specified for the gear is reached.The process then continues as described above: The stack is updated in each subsequent interrupt by deleting the oldest value, inserting the currently measured value, and using this to determine the gradient as long as a gear is engaged.

[0022] The strategy prevents overshoots of the speed filter used in the LuK PSG software after gear changes. To this end, the calculation of the speed gradient is stopped as soon as no gear is engaged. When a gear is engaged again after a calibratable period, the old speeds used to calculate the gradient are scaled to the speed level of the new gear. Otherwise, the old speeds are discarded and reinitialized as soon as a gear is engaged again.

Claims

[1] Method for reducing overshoot of an output signal of a speed filter during gear changes, for controlling the slip of a vehicle clutch with the speed filter, wherein speed values ​​are input to the speed filter at time intervals and these are transmission input speeds and a gradient of the speed values ​​is output as an output signal, characterized bythat the gradient of the speed values ​​is determined, whereby the determination of the gradient of the speed values ​​is terminated as soon as no gear is engaged and if a gear is engaged again within a predetermined time, the determination of the gradient is continued by scaling the speed values ​​used to determine the gradient before the determination of the gradient was terminated to the speed level of the gear that has been engaged again and the determination of the gradient is continued with the speed values ​​newly added since a gear was engaged again and, if a predetermined, gear-dependent number of speed values ​​is not available for this purpose, additionally with the scaled, most recent speed values. [2] Method according to claim 1, characterized by that the determination of the speed gradient is determined from a predetermined, gear-dependent number of speed values. [3] Method according to claim 1, characterized bythat the scaling to the speed level of the re-engaged gear is carried out with a scaling factor which results from the oldest speed since the continuation of the determination of the gradient divided by the most recent speed before the end of the determination of the gradient. [4] Method according to claim 1, characterized by that if a gear is not engaged again within a specified time, as soon as a gear is engaged again, the determination of the gradient is continued only with the speed values ​​that have been newly added since a gear was engaged again. [5] Method according to one of claims 1 to 4, characterized by that the specified time is between 0.01 seconds and 10 seconds, preferably 0.5 to 2 seconds. [6] A computer program product comprising a computer program comprising software means for carrying out a method according to any one of claims 1 to 5 when the computer program is executed on a computer. [7] Device for reducing overshoot of an output signal of a speed filter during gear changes in a transmission of a motor vehicle, comprising a control device for controlling the slip of a vehicle clutch with the speed filter, wherein speed values ​​can be input to the speed filter at time intervals and these are transmission input speeds and a gradient of the speed values ​​can be output as an output signal, characterized bythat the gradient of the speed values ​​can be determined and wherein the control device can end the determination of the gradient of the speed values ​​as soon as no gear is engaged and if a gear is engaged again within a predetermined time, the determination of the gradient can be continued by scaling the speed values ​​used to determine the gradient before the end of the determination of the gradient to the speed level of the gear that is engaged again and the determination of the gradient can be continued with the speed values ​​that have been newly added since a gear was engaged again and, if a predetermined, gear-dependent number of speed values ​​is not available for this purpose, additionally with the scaled, most recent speed values. [8] Use of the method according to claims 1 to 5 for controlling a motor vehicle transmission.