Position learning system for an electric shift-by-wire switching system

Abstract

A position learning system for an electric gearshift lever system which detects a load change of a motor (20) depending on the drive of a four-stage locking plate (40) and a locking spring (60) and thus learns a gear position of the electric gearshift lever system, the system having the following features: a sensor unit (100) which detects an electrical current generated in the motor (20); and a control unit (200) which receives the electrical current data from the sensor unit (100) until the switching position changes from a P to a D stage or vice versa, i.e. from the D to the P stage, then learns the switching positions of a R and an N stage based on the received current data, and then learns the switching positions of the P and D stages by an offset operation based on the learned switching positions of the R and N stages, characterized in that the control unit has: a data receiving unit (210) which calculates a low point and a high point of the electric current data based on the current data received from the sensor unit (100), and then decides whether the calculated low point and the calculated high point of the current data are valid data or not; a learning unit (220) which then learns the switching positions of the R and N stages by means of the low point of the current data when the data receiving unit (210) decides that the low and high points of the current data are the valid data; and an operation unit (230) which learns the switching positions of the P and D stages by offsetting the switching positions of the R and N stages learned in the learning unit (200) by a predetermined target value, wherein if the calculated low point and the also calculated high point of the electrical current data are each within a predetermined permissible range, the data receiving unit (210) decides that the low point and the high point of the current data are the valid data.

Description

Field of the invention

[0001] The present invention relates to a generic system for learning a position for an electric shift lever system (ie shift-by-wire shifting system). State of the art

[0002] A transmission is a core component for driving a motor vehicle, which can be used to increase or decrease the torque of an internal combustion engine depending on the driving situation of the motor vehicle and thus to transfer the driving force generated by the internal combustion engine to the wheels.

[0003] Such transmissions are usually classified into manual and automatic transmissions depending on the shifting method, but recently automatic transmissions have been used for the majority of vehicles because their operation is very convenient because a clutch does not have to be operated separately, and they also have the advantage of allowing a smooth start of the vehicle.

[0004] In this case, a driving mode of the automatic transmission can be determined by a shift lever system, wherein this shift lever system is in turn divided into a mechanical shift lever system in which a shifting operation is carried out by means of a mechanical linkage structure via a wire, and an electrical shift lever system in which a shifting operation is carried out by evaluating the electrical signals by means of a substrate instead of such a linkage structure.

[0005] Unlike the mechanical shift lever system, the electric shift lever system can enable the transmission of information about a gear selected by a driver as electrical signals without the mechanical connection between a transmission and a shift lever, thus causing no shock and vibration. Also, unlike the mechanical shift lever system, a connecting means between a lever device and a transmission can be simplified, thus preventing gear shifting due to unwanted movement of the lever. Thus, despite the disadvantage of the expensive price of the electric shift lever system, the number of vehicles adopting such an electric shift lever system is gradually increasing.

[0006] To ensure stable shift control in such an electric shift lever system, it is important to detect the position of a motor. Conventional shift lever systems attempted to detect the motor position using a Hall sensor mounted inside an electric motor. However, this Hall sensor could only measure the relative rotation of the motor, not its absolute rotation angle. This resulted in the difficulty of detecting the precise position of the motor.

[0007] To solve this problem, an attempt was proposed to attach a non-contact position sensor used in a manual shift lever to an electric motor, thereby measuring the absolute rotation angle or position of the motor. However, the update rate of a PWM (Pulse Width Modulation) signal output by the non-contact position sensor was low, making it difficult to measure the motor position even using this method.

[0008] Furthermore, a method has also been conventionally proposed in which a locking plate is locked against a wall by rotating a motor, thus preventing it from moving. After that, a time point at which a change in a Hall sensor is not detected is determined, and the absolute position of the motor is learned by setting such a time point as a reference point, thereby detecting the motor position. However, a disadvantage of this method is that the motor must be forcibly driven to learn the motor position, and a separate time is required for learning the motor position.

[0009] That is, it was very difficult to detect an accurate position of an engine simply and accurately only using the conventionally proposed methods, although accurate detection of a current position of the engine is an essential task in today's automotive technology in which an electric shift lever system is mainly applied to the vehicle, therefore, there is a need to propose a new method in which the position of the engine can be detected more accurately in order to increase the performance of the electric shift lever system.

[0010] US 2002 / 0019287 A1 discloses a generic system for learning a position for an electric gearshift lever system.

[0011] Further systems for learning a position for an electric gearshift lever system are known from JP 2018-048662 A, JP 2008-106826 A and US 2017 / 0307072 A1. Disclosure of the inventionObject of the invention

[0012] The object of the present invention is therefore to solve the problem that arises in a conventional electric shift lever system in which accurate detection of a position of an electric motor was difficult, by providing an electric shift lever system in which a change in an amount of electric current that essentially occurs in the motor depending on a change in a load of the electric motor due to an external force of a spring generated by a gap between a bead and groove shape formed in each step of a detent plate and a detent spring is detected, then a position of the motor corresponding to each of the shift positions of R (reverse) and N (neutral) is learned, and then the shift positions of P (parking) and D (drive) can be detected by an offset from the learned shift positions of R and N. Solution to the problem of the invention

[0013] To achieve the object, the present invention, according to one embodiment, provides a system for learning a position for an electric shift lever system, which has the features in claim 1. Furthermore, according to a further embodiment, the present invention provides a system for learning a position for an electric shift lever system, which has the features in claim 2. Further developments of the invention can be found in the subclaims. Effect of the invention

[0014] The position learning system for an electric shift lever system according to the invention can learn a shift position of a specific stage (e.g., R, N stage) based on a load of an electric motor and thus detect a shift position of another stage (e.g., P, D stage) by offsetting the learned shift position of the specific stage, which is why a current position of the motor can be detected even more easily and accurately than a conventional position learning system that required a separate drive of the motor.

[0015] In particular, since a position of a motor can be clearly detected by the system for learning a position for an electric shift lever system according to the invention, a time at which an electric signal is applied to the electric motor can be clearly set, so that the electric shift lever system can be controlled even more precisely and robustly. Short description of the drawings

[0016] They show: Fig. 1 a locking plate and a locking spring, the two being coupled to a rotating shaft of a motor, in a perspective view; Fig. 2 (a) a state in which a locking spring is located in a groove of a locking plate and thus a compression force is not exerted on the locking spring, and Fig. 2 (b) a state in which the locking spring is located in a bulge of the locking plate and thus the locking spring is compressed; Fig. 3 shows a concept for a system for learning a position for an electric shift lever system according to an embodiment of the present invention; Fig. 4 a change in the electrical current data depending on the rotation of a locking plate; Fig. 5 is a flowchart illustrating a gear position learning process in the position learning system for an electric shift lever system according to one embodiment of the present invention; Fig. 6 illustrates a process for learning a gear position of a four-stage detent plate in a position learning system for an electric shift lever system according to another embodiment of the present invention; and Fig. 7 is a flowchart illustrating a gear position learning process in a position learning system for an electric shift lever system according to yet another embodiment of the present invention. Preferred embodiments of the invention

[0017] The preferred embodiments of the present invention will be explained in more detail below with reference to the drawings. It should be noted that identical components are designated by identical reference numerals throughout the figures wherever possible. Furthermore, a detailed explanation of the known functions and structures, which could unnecessarily obscure a key point of the present invention, will be omitted.

[0018] Furthermore, if it is mentioned that a component is connected to or attached to another component, then it may be directly connected to or attached to the other component, but it should also be understood that another component may be interposed between such two components. Furthermore, if an element is "on" or "at" another element throughout this description, then this includes not only a case where one element is adjacent to the other element, but also a case where another element is present between two elements.

[0019] In this application, the terms such as "comprise", "comprising" and "having", or the like in this description only indicate that features, digits, steps, movements, components, parts or combinations thereof are present in this description, but should not be construed as precluding the presence or addition of one or more other features, digits, steps, movements, components, parts or combinations thereof.

[0020] On the other hand, it should be understood that the 'system' used in this description means a system that has several superstructures.

[0021] Before explaining the present invention, a conventional electric shift lever system will first be described with reference to Fig. 1 to 2 are described schematically.

[0022] Fig. 1 shows a locking plate and a locking spring, the two being coupled to a rotary shaft of a motor, in a perspective view, wherein Fig. 2 (a) shows a state in which a locking spring is located in a groove of a locking plate and thus a compression force is not exerted on the locking spring, while Fig. 2 (b) shows a state in which the locking spring is located in a bulge of the locking plate and thus the locking spring is compressed.

[0023] The electric gearshift lever system is understood to be the system that identifies an operation of a gearshift, ie gearshift lever 10, by a driver and thus changes a gear of a transmission 30 by rotating a motor due to such an operation. In particular, as in Fig. 1, the electric shift lever system is coupled to a rotating shaft of a motor 20 so that it can change a gear of a vehicle by means of a detent plate 50 rotating depending on the rotation of the motor 20 and a detent spring 60 moving up and down depending on the rotation of the detent plate 50.

[0024] Since the electric shift lever system rotates the detent plate 50 coupled to the rotating shaft of the motor 20 in this way and thus changes the gear, it is important to detect a position (which means a rotated angle) of the motor 20, but the conventional electric shift lever system has generally used a Hall sensor attached to the motor to detect a motor position.

[0025] Since the Hall sensor detects the position (rotation angle) of the motor only by counting a moment in which it passes a Hall element and thus measures the rotation angle, it can only measure a relative rotation angle of the motor but cannot detect its absolute rotation angle, which poses a problem in the conventional shift lever system that it is difficult to perform accurate shift control.

[0026] Therefore, to solve such a problem, a method has been conventionally proposed in which a locking plate is locked against a wall by rotating a motor, thus preventing it from moving, and then a time point at which a change in the Hall sensor is not detected is determined. Thus, an absolute position of the motor is learned by setting such a time point as a reference point, thus detecting the motor position. In this method, driving the motor was essential for learning a motor position, and therefore, the learning of the motor position was limited by a separate time required. Thus, even with this method, it was difficult to easily and accurately detect the motor position.

[0027] When a locking spring 60 is located in the groove portion of a locking plate 50, as shown in Fig. 2 (a), the spring is not compressed, so that only a small load is applied to a motor, whereas when the detent spring 60 is located in the bead portion of the detent plate 50, the spring is compressed, and thus a relatively large load is applied to the motor.Therefore, the inventor has paid attention to the fact that when the detent spring 60 is located in the ridge of the detent plate 50, more electric current is generated from the motor 20 than when the detent spring is located in the groove of the detent plate, so that he has attempted to provide a position learning system for an electric shift lever system in which an accurate position of the motor 20 corresponding to the gears (P, R, N, and D stages) can be learned based on a change in an amount of current generated in the motor 20 without using an additional sensor or driving the motor 20 separately, in order to overcome the problem of the conventional electric shift lever system.

[0028] Hereinafter, a system for learning a position for an electric shift lever system according to an embodiment of the present invention will be described with reference to Fig. 3 to 5 are explained in more detail.

[0029] Fig. 3 shows a concept for a system for learning a position for an electric shift lever system according to an embodiment of the present invention, Fig. 4 shows a change in the electrical current data depending on the rotation of a locking plate, and Fig. 5 is a flowchart illustrating a gear position learning process in the position learning system for an electric shift lever system according to one embodiment of the present invention.

[0030] The present invention, according to one embodiment, provides a position learning system for an electric shift lever system which detects a load change of a motor 20 depending on the drive of a four-stage detent plate 50 and a detent spring 60 and thus learns a position of the electric shift lever system, the system comprising: a sensor unit 100 which detects an electric current generated in the motor 20; and a control unit 200 which receives the electric current data from the sensor unit 100 until the shift position changes from a P to a D stage or vice versa, i.e. from the D to the P stage, then learns the shift positions of an R and an N stage based on the received current data, and then learns the shift positions of the P and D stages by an offset operation based on the learned shift positions of the R and N stages.

[0031] The four-stage locking plate is understood to be the one in which four grooves are formed, each corresponding from the left to a P, an R, an N and a D stage, wherein the term “four-stage locking plate” has the same meaning as mentioned above.

[0032] The components of the position learning system according to one embodiment of the present invention will now be explained in more detail. First, the sensor unit 100 represents a type of electric current sensor and serves to detect the amount of current generated in the motor 20. The data regarding the amount of current generated in the motor 20 detected by the sensor unit 100 (hereinafter referred to as current data) can be sent to the control unit 200 to be mentioned later and thus used for gear position learning.

[0033] The case that the sensor unit 100 represents an electrical current sensor is only one embodiment of the present invention, which is why the sensor unit 100 should not be limited to the electrical current sensor, but other types of sensors can also be used in each case only if the sensors can detect the amount of current generated in the motor 20.

[0034] Second, the control unit 200 learns the shift positions of the P, R, N, and D stages based on i) the current data received from the sensor unit 100 until the gear is changed from a P stage to a D stage, or ii) the current data also received from the sensor unit until the gear is changed from the D stage to the P stage, so that it serves to cause the position learning system according to the invention to be able to accurately detect an absolute position (a rotation angle) of the motor.

[0035] More specifically, the control unit 200 can learn the switching positions of the P, R, N and D stages by means of a data receiving unit 210, learning unit 220 and operation unit 230, wherein the data receiving unit 210 serves to Fig. 4, i) to calculate a low point and a high point of the electrical current data based on the current data received from the sensor unit 100 until the gear changes from a P to a D stage or based on the current data also received from the sensor unit until the gear changes from the D to the P stage, and ii) to then decide whether the low point and the high point of the current data thus calculated are valid data or not.

[0036] If the calculated low point and the also calculated high point of the electrical current data each lie within a predetermined permissible range, then the data receiving unit 210 decides that the low point and the high point of the current data are the valid data, wherein the permissible range on which the decision about the validity of the low point and the high point of the current data is based represents a value range that corresponds to tolerances set during manufacture between the locking plate 50 and the locking spring 60 and is stored in an engine control unit (ECU), so that the data receiving unit 210 can call up a value of the permissible range stored in the engine control unit and thus use it when deciding about the validity of the current data.

[0037] For example, if the allowable range with respect to a subscript of the stream data is set to a range of 0.9 to 1.1 and the subscript of the stream data is calculated as 1 in the data receiving unit 210, then the data receiving unit 210 decides that the subscript of the stream data is valid, whereas if the subscript of the stream data is calculated as 0.8 in the data receiving unit 210, then the data receiving unit 210 decides that the subscript of the stream data is not valid and thus deletes the stream data received from the sensor unit 100.

[0038] Thereafter, the learning unit serves to learn the switching positions of the R and N stages by means of the low point of the current data when the data receiving unit 210 decides that the positions of the low and high points of the current data are the valid data.

[0039] More specifically, the four-stage detent plate 50 consists of five ridges and four grooves, wherein, when the detent plate 50 rotates, as explained above, then a gap between the detent spring 60 and the detent plate 50 is changed and thus the amount of electric current generated in the motor 20 is also changed, after which, if the detent spring 60 is located in the groove corresponding to the P-stage (or D-stage), the motor 20 is no longer rotated and thus a large load is exerted on the motor 20, so that when the detent spring 60 is located in the position of the detent plate 50 corresponding to the P-stage, then an amount of current with a large value (close to a starting torque in Fig. 4) is detected in the sensor unit 100, as in Fig. 4 shown.

[0040] In the process of shifting the gear from the P stage to the D stage, the detent spring 60 bypasses the groove of the detent plate 50 corresponding to the R and N stages. If the detent spring 60 is located in the groove of the detent plate 50 corresponding to the R and N stages, then the amount of current generated in the motor 20 is low, and therefore the learning unit 220 can i) learn a position of the bottom point appearing first in the current data when shifting the gear from the P stage to the D stage as an R stage and a position of the bottom point appearing second in such current data as an N stage, and ii) conversely, can learn a position of the bottom point appearing first in the current data when shifting the gear from the D stage to the P stage as an N stage and a position of the bottom point appearing second in such current data as an R stage.

[0041] The operation unit 230 then serves to learn the switching positions of the P-stage and the D-stage by offsetting the switching positions of the R-stage and the N-stage learned in the learning unit 220 by a predetermined target value.

[0042] As described above, the switching positions of the N-stage and the N-stage can be learned by the respective low points of the current data, however, the positions of the low points of the current data with respect to the P- and D-stage cannot be clearly determined because the locking plate 50 can no longer rotate, as shown in Fig. 4 (close to a starting and stopping torque), which is why there is a high probability that incorrect switching positions could be learned when learning the switching positions of the P and D stages using the low points of the current data.

[0043] Therefore, in the system for learning a position according to the invention, it can be provided that, based on the switching positions of the R and N stages accurately learned in the learning unit 220, the switching position of the P stage is learned by an offset operation of the learned switching position of the R stage by a first target value to the left and the switching position of the N stage is learned by an offset operation of the learned switching position of the N stage by a second target value to the right, so that the accuracy for detecting the position of the motor can be increased.

[0044] The first target value for learning the P-stage is understood to be a distance between the grooves corresponding to the P and N stages determined in the manufacturing process, while the second target value for learning the D-stage is understood to be a distance between the grooves corresponding to the N and D stages determined in the manufacturing process, it being understood that the first and second target values ​​are variable depending on the type of locking plate 50 used on the vehicle.

[0045] Now, a position learning system for an electric shift lever system according to another embodiment of the present invention will be described with reference to the above Fig. 3 and the Fig. 6 is explained in more detail.

[0046] Fig. 6 shows a process for learning a gear position of a two-stage detent plate in a position learning system for an electric shift lever system according to another embodiment of the present invention.

[0047] Now, according to the further embodiment of the present invention, a system for learning a position for an electric shift lever system is provided, which detects a load change of a motor 20 depending on the drive of a two-stage locking plate 50 and a locking spring 60 and thus learns a gear position of the electric shift lever system, the system having the following features: a sensor unit 100 which detects an electric current generated in the motor 20; and a control unit 200 which receives the electric current data from the sensor unit 100 until the shift position changes from a P-stage to another (non-P) as a P-stage or vice versa, iefrom the other stage (non-P) as the P stage into the P stage, then learns a position of a bead of the locking plate based on the received current data, and then learns the switching positions of the P stage and the stage other than the P stage by an offset operation based on the learned position of the bead.

[0048] The two-stage locking plate 50 is understood to mean the locking plate 50 which consists of a P-stage and a stage other than the P-stage, wherein the system for learning a position for an electric shift lever system according to the further embodiment of the present invention differs from the system for learning a position for an electric shift lever system according to the one embodiment of the present invention in that the position of the gear is learned in the two-stage locking plate 50.

[0049] Thus, the control unit 200, which constructs the position learning system according to the further embodiment of the present invention, includes a data receiving unit 210 that calculates a trough and a peak of the electric current data based on the current data received from the sensor unit 100, and then decides whether the calculated trough and the calculated peak of the current data are valid data or not; a learning unit 220 that then learns the position of the bead of the lock plate 50 using the peak of the current data when the data receiving unit 210 decides that the trough and the peak of the current data are the valid data; and an operation unit 230 that now learns the shift positions of the P-stage and the stage other than the P-stage by offsetting the position of the bead learned in the learning unit 220 by a predetermined target value.In this case, if the calculated low point and the also calculated high point of the electric current data are each within a predetermined permissible range, then the data receiving unit 210 decides that the low point and the high point of the current data are the valid data, just as explained above, therefore a concrete explanation regarding the data receiving unit 210 is omitted.

[0050] Therefore, the position learning system according to the further embodiment of the present invention is characterized in that, unlike the above embodiment, the gear position of the two-stage lock plate 50 consisting of the P stage and the stage other than the P stage is learned, therefore, in the operation unit 230, using the peak point of the current data as shown in Fig. 6, the detent spring 60 learns a position of the bead between the P-stage and the other stage (non-P) as the P-stage of the detent plate 50.

[0051] In the operation unit 230, i) a shift position of the P-stage is learned by an offset operation of the learned position of the bead of the locking plate 50 by a first target value to the left, and ii) a shift position of the stage other than the P-stage is also learned by an offset operation of the learned position of the bead of the locking plate 50 by a second target value to the right, so that the position learning system according to the further embodiment of the present invention can accurately detect a current position of the motor 20.

[0052] The first target value is understood to be a distance between a P-step and a bead of the locking plate 50, the P-step and the bead being set in the manufacturing process of the two-stage locking plate 50, while the second target value is understood to be a distance between a step other than the P-step and a bead of the locking plate 50, the other step and the bead being set in the manufacturing process of the two-stage locking plate 50, it being understood that the first and second target values ​​are variable depending on the type of locking plate 50 applied to the vehicle.

[0053] As explained above and as in Fig. 6, it is also only described that with respect to the bead of the two-stage locking plate 50, the P stage is on the left and the stage other than the P stage is on the right, however, the switching positions of the P stage and the stage other than the P stage can be exchanged with each other according to another embodiment, so that in this case it is natural that in the operation unit 230 i) a switching position of the P stage can be learned by an offset operation of the learned position of the bead of the locking plate 50 by a first target value to the right, and ii) a switching position of the stage other than the P stage can also be learned by an offset operation of the learned position of the bead of the locking plate 50 by a second target value to the left.

[0054] Finally, a system for learning a position for an electric shift lever system according to yet another embodiment of the present invention is described with reference to the above Fig. 3 and the Fig. 7 is explained in more detail.

[0055] This shows Fig. 7 is a flowchart illustrating a gear position learning process in a position learning system for an electric shift lever system according to still another embodiment of the present invention.

[0056] Now, according to the further exemplary embodiment of the present invention, a system for learning a position for an electric gearshift lever system is provided, which system detects a load change of a motor 20 depending on the drive of a four-stage locking plate 50 and a locking spring 60 and thus learns a gear position of the electric gearshift lever system, the system having the following features: a sensor unit 100 which detects an electric current generated in the motor 20; and a control unit 200 which receives the electric current data from the sensor unit 100 until the gear position changes from a P to a D stage and vice versa, ie from the D to the P stage, and then, based on the received current data, when the gear position changes from the P to the D stage orlearns the switching positions of an R and an N stage from the D stage to the P stage, and then learns the switching positions of the P and D stages by means of an offset operation based on the learned switching positions of the R and N stages.

[0057] Here, the control unit 200 includes a data receiving unit 210 that calculates a low point and a high point of the electric current data based on the current data received from the sensor unit 100, and then decides whether the calculated low point and the calculated high point of the current data are valid data or not; a learning unit 200 that then learns the switching positions of the R- and N-stages using the low point of the current data if the data receiving unit decides that the low point and the high point of the current data are the valid data; and an operation unit 230 that now learns the switching positions of the P-stage and D-stage by offsetting the switching positions of the R- and N-stages learned in the learning unit 200 by a predetermined target value, similar to the above-explained position learning system according to one embodiment of the present invention.

[0058] However, the position learning system according to the still further embodiment of the present invention differs from the above position learning system according to the one embodiment of the present invention not in that the shift positions of the R and N stages are learned based on the current data when the gear is shifted from the P stage to the D stage or from the D stage to the P stage, but in that the shift positions of the R and N stages are learned using all the current data until the gear is completely shifted from the P stage to the D stage and thereafter again from the D stage to the P stage.

[0059] More specifically, the position learning system of the present invention detects an electric current by means of the sensor unit 100, and therefore a current measurement delay occurs in the sensor unit 100 or a delay occurs in the filtering process, so that a case may also be caused that the position of the bottom or the top of the current data is delayed.

[0060] Furthermore, in the learning unit 220 for the position learning system according to yet another embodiment of the present invention, it is provided that i) the shift positions of a first R and a first N stage are learned based on the electrical current data when changing a gear from the P stage to the D stage, and ii) the shift positions of a second R and a second N stage are learned based on the electrical current data when changing the gear from the D stage to the P stage, iii) after which an average value of the shift positions of the first R and the first N stage and of the second R and the second N stage is calculated and thus the final shift positions of the R and the N stage are learned, so that the delay that occurs in the process of changing the gear from the P stage to the D stage and the delay that occurs in the process of changing the gear from the D stage to the P stage can be compensated,Consequently, the position learning system according to the still further embodiment of the present invention can learn the shift positions of the R and N stages more accurately.

[0061] Furthermore, the operation unit 230 can now calculate the switching position of the P-stage by shifting the switching position of the R-stage by a first set value to the left and then learn it, and can now calculate the switching position of the P-stage by shifting the switching position of the N-stage by a second set value to the right and then learn it, whereby the concrete explanation regarding this is the same as the above explanation, which is why a concrete explanation for it is omitted. List of reference symbols 10 gear shifters 20 engine 21 Rotating shaft 30 gearboxes 50 locking plate 60 locking spring 100 sensor units 200 control unit 210 Data receiving unit 220 learning units 230 operating unit

Claims

[1] A position learning system for an electric gearshift lever system which detects a load change of a motor (20) depending on the drive of a four-stage locking plate (40) and a locking spring (60) and thus learns a gear position of the electric gearshift lever system, the system having the following features: a sensor unit (100) which detects an electrical current generated in the motor (20); and a control unit (200) which receives the electrical current data from the sensor unit (100) until the switching position changes from a P to a D stage or vice versa, i.e. from the D to the P stage, then learns the switching positions of a R and an N stage based on the received current data, and then learns the switching positions of the P and D stages by an offset operation based on the learned switching positions of the R and N stages, characterized by that the control unit has: a data receiving unit (210) which calculates a low point and a high point of the electric current data based on the current data received from the sensor unit (100), and then decides whether the calculated low point and the calculated high point of the current data are valid data or not; a learning unit (220) which then learns the switching positions of the R and N stages by means of the low point of the current data when the data receiving unit (210) decides that the low and high points of the current data are the valid data; and an operation unit (230) which learns the switching positions of the P and D stages by offsetting the switching positions of the R and N stages learned in the learning unit (200) by a predetermined target value, wherein if the calculated low point and the also calculated high point of the electrical current data are each within a predetermined permissible range, the data receiving unit (210) decides that the low point and the high point of the current data are the valid data. [2] A position learning system for an electric gearshift lever system which detects a load change of a motor (20) depending on the drive of a two-stage locking plate (50) and a locking spring (60) and thus learns a gear position of the electric gearshift lever system, the system having the following features: a sensor unit (100) which detects an electrical current generated in the motor (20); and a control unit (200) which receives from the sensor unit (100) the electrical current data until the switching position changes from a P-stage to a stage other than the P-stage or vice versa, i.e. from the stage other than the P-stage to the P-stage, subsequently learns a position of a bead of the locking plate (50) based on the received current data, and then learns the switching positions from the P-stage and the stage other than the P-stage by an offset operation based on the learned position of the bead, characterized by that the control unit has: a data receiving unit (210) which calculates a low point and a high point of the electric current data based on the current data received from the sensor unit (100), and then decides whether the calculated low point and the calculated high point of the current data are valid data or not; a learning unit (220) which then learns the position of the bead of the locking plate (50) by means of the peak of the current data when the data receiving unit (210) decides that the peak and the lowest points of the current data are the valid data; and an operation unit (220) which learns the switching positions of the P-stage and the stage other than the P-stage by the offset operation of the position of the bead learned in the learning unit (220) by a predetermined target value, wherein if the calculated low point and the also calculated high point of the electric current data are each within a predetermined permissible range, then the data receiving unit (210) decides that the low point and the high point of the current data are the valid data. [3] System according to claim 2, characterized bythat the operating unit (220) calculates the switching position of the P-stage by shifting the position of the bead of the locking plate (50) by a first setpoint value to the left and then learns this, and by shifting the position of the bead of the locking plate (50) by a second setpoint value to the right, it calculates the switching position of the other stage as the P-stage and then learns this. [4] System according to claim 1, characterized bythat the control unit (200) receives the electrical current data from the sensor unit (100) until the switching position changes from a P to a D stage and vice versa, ie from the D to the P stage, then learns the switching positions of an R and an N stage based on the received current data when the switching position changes from the P to the D stage or from the D to the P stage, and then learns the switching positions of the P and D stages by means of an offset operation based on the learned switching positions of the R and N stages. [5] System according to claim 4, characterized bythat the learning unit (220) now learns the switching positions of a first R and a first N stage based on the electrical current data when changing a gear from the P to the D stage, and now learns the switching positions of a second R and a second N stage based on the electrical current data when changing the gear from the D to the P stage, after which it computationally determines an average value of the switching positions of the first R and the first N stage as well as of the second R and the second N stage and thus learns the final switching positions of the R and the N stage. [6] System according to claim 1 or 4, characterized bythat the operating unit (230) calculates the switching position of the P-stage by shifting the switching position of the R-stage by a first setpoint value to the left and then learns this, and that the operating unit (230) calculates the switching position of the P-stage by shifting the switching position of the N-stage by a second setpoint value to the right and then learns this.

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