DE102016203176B3 - Determining the contact point of an accelerator pedal actuator with an accelerator pedal - Google Patents

Abstract

A method for determining the point of contact (34) of a spring (16) of an accelerator pedal actuator (12) with an accelerator pedal lever (13) comprises: energizing a motor (14) having a rotor and a stator of the accelerator pedal actuator (12) with a predefined one Space pointer, so that the rotor covers a predefined rotor path (22); Measuring a rotor position (φ _red ) along the rotor path (22); Determining a load angle (φ _load ) along the rotor path (22), wherein the load angle (φ _load ) is calculated based on a difference of a phase angle (φ _U ) of the predefined space vector and a rotor position angle (φ _red ) at the rotor position (φ _red ) ; Determining a free-run line (36) based on the load angle (φ _load ) in a first portion (28) of the rotor path (22);
Determining a spring load line (38) based on the load angle (φ _load ) in a second section (30) of the rotor path (22); and determining the contact point (34) as the intersection of the free-running lines (36) and the spring-torque lines (38).

Description

Field of the invention

The invention relates to methods for determining the point of contact of a spring of an accelerator pedal actuator with an accelerator pedal and an accelerator pedal with a controller that is designed to perform this method.

State of the art

Pedals are used in vehicles to control the speed of the vehicle. With a pressure on the accelerator pedal, for example, a driver can control the supply of fuel to an internal combustion engine or of electrical energy to an electric drive motor.

Pedals that give the driver a haptic feedback are already in mass production. The haptic feedback here can take various forms, such. B. knocking or vibration. To create these, there are various possibilities. Often, a force is generated by an actuator, which is transmitted via a mechanical coupling to a pedal lever of the accelerator pedal.

Certain variants are limited to the integration of a vibrating element in the pedal lever, for example under a pedal tread plate, such as in DE 10026048 C2 or WO 2013024133 A1 is described.

Other variants include a motor, which comes via a coupling spring (for example, designed as a torsion spring) for transmitting power to the pedal lever into contact, and can be rotated depending on the force profile defined. In this case, it is also possible for the spring to be released from the pedal lever in a first state by the motor, or for no significant torque transfer from the spring to the pedal lever, and for the spring to be brought into contact with the motor in a second state , The more accurately the contact point of the spring with the pedal lever is known, the better a haptic signal can be generated with the pedal lever in the rule.

The DE 10 2014 224 234 B3 shows a haptic accelerator pedal with a spring and two characteristics.

DE 10 2007 046 289 A1 shows a motor controller with a Vorhaltemoment and a holding torque after detection of the speed zero for setting a holding torque.

The DE 10 2014 210 930 A1 shows an open control for adjusting an engine torque by means of a load angle.

Disclosure of the invention

Advantages of the invention

Embodiments of the present invention may advantageously contribute to producing differentiated haptic signals with accelerator pedals. Further, the touch point of a spring of an actuator for generating such signals can be accurately and easily determined.

Ideas for embodiments of the present invention may be considered, inter alia, as being based on the thoughts and findings described below.

One aspect of the invention relates to a method for determining the point of contact of a spring of an accelerator pedal actuator with an accelerator pedal. The accelerator pedal actuator may include a motor that can bring the spring into contact with the accelerator pedal and exert a force on an accelerator pedal lever via the spring. The engine can z. B. be a conventional electric motor (with brushes). However, the motor may also be a brushless DC motor (BLDC motor) or be a permanent magnet synchronous machine. In this case, a rotor of the BLDC motor or the synchronous machine is moved by electronic or electrical commutation of a stationary stator. The stator can be energized by several phases, z. B. by three to each other by 120 ° out of phase voltages or currents. From the energization results in a known manner, a current vector or a voltage vector, which is also referred to as a space vector, in a polar coordinate system. This space pointer has a length that is proportional to the amplitude (Amperage or voltage level) and has an angle with respect to one of the axes of the polar coordinate system. This energization also results in a magnetic field that can be represented by a magnetic field pointer that is in fixed relation to the space vector. Due to the magnetic field is a torque on the z. B. permanent magnetic elements having rotor exerted, so that the rotor is caused in a force-free system to align along the magnetic pointer. After the parallel alignment of the rotor to the magnetic field in the force-free system, the torque is zero (0), since then the lever arm is zero.

The contact point can be specified, for example, as the absolute angle of rotation of the rotor of the motor of the accelerator pedal actuator. Under the absolute angle of rotation is z. B. to understand a rotor position, which may be more than 360 °. So it is z. Example, in a gear ratio between the rotor and the rotation angle sensor possible that a complete revolution of the rotor by 360 ° causes only one rotation of the rotation angle sensor by 36 °, so here is the translation 10: 1. In order to effect a 360 ° rotation on the rotation angle sensor, an absolute rotation of the rotor by 3600 ° would be necessary. The space vector would therefore also 3600 °, ie 10 full revolutions, rotated, assuming a single pair of poles. With 2 or more pole pairs, the number of revolutions is multiplied by the number of pole pairs.

Also, the touch point can be given as a waypoint, traversed by the tip of the spring. By "touch point" can be understood, for example, a waypoint, in which the spring mechanically, z. B. immediately, comes in contact with the accelerator pedal. However, it can be understood that point under which the spring an additional, with increasing distance z. B. rising, torque on the accelerator pedal exerts. Waypoints before the touch point are then waypoints where the spring is at best loosely in contact with the accelerator pedal, but does not apply torque to the accelerator pedal.

According to an embodiment of the invention, the method comprises: energizing a stator of a motor comprising a rotor and the stator of the accelerator pedal actuator with a predefined space vector such that the rotor covers a predefined rotor path. The rotor path can also be referred to as a motor path. In other words: The rotor is entrained with the rotating field and is in this way by a predefined angular position, for. B. 1800 ° rotor path turned. The method further comprises: measuring a rotor position along the rotor path; Determining a load angle along the rotor path, wherein the load angle is calculated based on a difference of a phase angle of the predefined space vector and a rotor position angle at the rotor position; Determining a free-run line based on the load angle in a first portion of the rotor path; Determining a spring load line based on the load angle in a second portion of the rotor path; Determining the contact point as the intersection of the free-running line and the spring moment line.

Initially, the rotor may be in a home position (at the beginning of the engine travel) at a waypoint before the touchpoint. Waypoints in front of the touchpoint are then waypoints where the spring is loosely in contact with the accelerator pedal, but no torque on the accelerator pedal exercises. The stator can then be energized, for example, with a space vector constant frequency, the stator can be energized with three or more phases. The energization can be maintained until the rotor has reached an end position (one end of the rotor path) at which the spring has securely touched the pedal lever.

As long as the rotor is in motion, the current motor position can be determined with a motor travel sensor or a rotor position sensor. The motor travel sensor may be a rotor position sensor that can determine the current relative rotational angle of the rotor with respect to the stator of the motor. From the relative angle of rotation can be determined by counting an absolute rotation angle, which can be used as a rotor position and from which the rotor position angle can be calculated.

From the current rotor position, a load angle can be determined, which can be calculated from a difference of the rotor position angle and a phase angle of the space vector. As mentioned above, the rotor position angle can be based on a relative rotational angle between rotor and stator. The detection of a relative angle can also be realized after a possible gear unit. The phase angle is defined by the space vector in the polar coordinate system. The polar coordinate system can for example be spanned with two axes, an α-axis and a β-axis. In this case, the α-axis represents the real part and the β-axis represents the imaginary part of the space vector (the imaginary part may be denoted by the symbol "j", for example). As described above, the space vector generates a magnetic rotating field which applies a magnetic force to the rotor. The greater the load angle formed between the space vector and the rotor position, the greater the torque which acts on the rotor (the load angle is proportional to the lever arm). Thus, the load angle can be used as a measure of a load torque acting on the rotor (eg friction or the additionally acting spring torque).

In a first section of the rotor path, in which it is assumed that the spring has not yet touched the pedal lever or is not yet operatively connected, it can therefore be assumed that only one friction torque (eg a constant friction torque) acts on the engine , d. h., That in the first section of the load angle and the torque is constant. From the determined measuring points of the load angle along the first section, an idle straight line can be determined (for example by averaging), which reproduces this constant load angle or constant torque. This also corresponds to a first state (no active connection spring-motor).

In the second section of the rotor path, where it is assumed that the spring has already touched the pedal lever, it can be assumed that the friction torque and the spring act on the motor (second state). In the second section a linear dependence (with offset) for the load angle can be assumed - with increasing tension of the spring the torque exerted by the spring against the motor increases. Due to a z. B. constant amplitude of the space vector and the consequent constant magnetic field, which acts on the rotor, now the load angle must increase. Because with increasing load angle (up to 90 °) results in an increasing torque, which compensates for the increasing torque of the spring. At 90 ° load angle, the torque is maximum. If the spring torque were then further increased, the rotor could no longer follow the stator magnetic field, and the rotor would "slip through".

From the determined measuring points of the load angle along the second section, a spring load straight line can be determined (for example by averaging), which reproduces this dependence. Thus, the method can be applied to any type of mechanical springs, such as torsion springs, as long as they have a substantially linear characteristic.

The point of contact of the spring with the pedal lever can now be determined from the intersection of the two straight lines. At the rotor position at which the constant dependence (ie constant load angle, ie constant angular difference between the space vector and rotor position angle in the polar coordinate system) changes into a linear dependence (load angle increases linearly with increasing rotation angle of the space vector of the stator), it can be assumed that the spring Has touched the pedal lever. It can be helpful if the amplitude or length of the space vector remains constant. In principle, the method is also possible with non-constant speed and non-constant amplitude of the space vector.

The procedure that does not require regulation, d. H. is an open-loop method, is less susceptible to interference from motor ripple and requires no special controller development for its operation. In this case, motor ripple example, torque fluctuations that result from a not 100% symmetrical structure of the stator windings. In closed-loop operation, on the other hand, larger torque fluctuations can occur as a controller attempts to compensate for disturbances. The method is therefore even more robust against interference with higher accuracy compared to known methods.

According to one embodiment of the invention, a motor torque along the rotor path is determined from the load angle. As described above, the load angle can be used as a measure of the torque acting on the rotor (load torque). This determination of the engine torque can without the help of other sensors such. As current sensors, whereby costs can be saved.

According to one embodiment of the invention, the engine torque is determined based on a mathematical engine model. The mathematical engine model may include one or more mathematical functions in which the load angle may be used to calculate the engine torque. This calculation can be done online, ie in a controller that performs the method. For a BLDC motor or permanent magnet synchronous machine, the motor model may be based on an inverse motor model. In other words, from the known equations for the voltages U _d and U _q in a rotor-fixed dq coordinate system can be calculated back to the prevailing currents I _d and I _q for the stationary case and with the currents to the motor torque.

According to one embodiment of the invention, the Leerwegstraad and / or the spring load line are determined from the engine torque. The calculated engine torques over the rotor path, and in particular in the first portion and the second portion of the rotor path, may be used to determine parameters for the two straight lines.

According to one embodiment of the invention, the idle straight is based on an averaged over the first section Leerwegmoment. For example, the idle straight without slope with a constant Leerwegmoment be parameterized. This Leerwegmoment can be formed as an average over the first section.

According to one embodiment of the invention, the spring load straight line is based on averaged over the second section spring constant. For example, the spring load straight line can be parameterized with a spring constant as a constant pitch and a spring offset torque. The two parameters can be determined, for example, with a regression line over the second section.

According to an embodiment of the invention, parameters of the idle straight lines in the first section and / or parameters of the spring load straight in the second section are estimated by means of a recursive average. In other words: If the number of measurements is unknown, the mean value can be determined by a known recursion formula. For example, with each new determination of the rotor position angle, an existing mean value can be corrected from a measured value or from the engine torque calculated therefrom, for example by adding a correction value to the existing mean value.

According to one embodiment, the space vector has a constant angular velocity. For example, the length of the space pointer may be constant. As a result, the retroactive calculation of the engine torque can be significantly simplified.

According to one embodiment of the invention, the motor path is divided into the first section, a middle section and the second section, the middle section being selected based on an assumed touch point. The start and end positions of the individual sections can be predefined based on empirical values.

Another aspect of the invention relates to an accelerator pedal for a vehicle.

According to one embodiment of the invention, the accelerator pedal comprises an accelerator pedal lever, an accelerator pedal actuator with a motor having a rotor and a stator, and a spring, which is arranged between the engine and the accelerator pedal lever, so that by means of the motor via the spring haptic signals the accelerator pedal lever can be generated; and a controller configured to drive the motor to receive measurement signals from an engine travel sensor of the engine and to perform the method of any one of the preceding claims. For example, the engine may be a BLDC motor or a permanent-magnet synchronous machine. The motor can be either a sensor for detecting the mechanical rotor position on the rotor shaft itself or on any axis after a potential transmission, which is rigidly connected to the output of the transmission, be applied. By model-based determination of the engine torque can then be determined with the accelerator pedal, a contact point of the spring with the accelerator pedal lever.

Brief description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which neither the drawings nor the description are to be construed as limiting the invention.

1 schematically shows an accelerator pedal according to an embodiment of the invention.

2 shows a diagram with a motor torque via a rotor path, which from the accelerator pedal of the 1 is produced.

3 shows a diagram with variables and their dependencies, which are used in a method according to an embodiment of the invention.

4 shows a diagram with a load angle of the accelerator pedal from the 1 is produced.

5 shows a diagram with an engine torque resulting from the load angle of 4 was calculated.

6 FIG. 12 is a diagram illustrating a calculation of a friction torque according to an embodiment of the invention. FIG.

7 FIG. 12 is a diagram illustrating a calculation of a spring constant according to an embodiment of the invention. FIG.

The figures are only schematic and not to scale. Like reference numerals designate the same or equivalent features in the figures.

Embodiments of the invention

1 shows an active accelerator pedal 10 with an actuator 12 in a pedal lever 13 of the accelerator pedal 10 can generate haptic signals. The actuator 12 includes z. B. a conventional motor or a brushless DC motor (BLDC motor) 14 or a permanent magnet synchronous machine 14 that is on a mechanical spring 16 can act, which is mechanically connected to the accelerator pedal or can be brought into connection or in operative connection. For example, with the BLDC motor 14 short shocks or vibrations over the spring 16 in the pedal lever 13 be generated. The feather 16 can z. B. may be formed as a linearly acting coil spring. However, it may also be formed as a coil spring in the manner of a watch spring which spirals around an axis of the accelerator pedal lever.

The movements of the BLDC motor 14 be from a controller 18 causes the BLDC motor 14 can be supplied with a space vector U _αβ constant length (U ₀ ) and constant rotational speed (dφ _U / dt), which is modulated accordingly (in principle, the method can also be performed with a space pointer not constant length or non-constant rotational speed). Next, the controller 18 Signals from one in the BLDC motor 14 integrated motor travel sensor 20 or rotor position sensor 20 receive from which the controller 18 a rotor position of the BLDC motor 14 (such as the angle of rotation between its rotor and stator) can determine. 2 shows a rotor path 22 , It can be seen that the spring 16 not over the entire rotor path 22 with the spring 16 must be in contact or operative connection. For example, the spring 16 in one area 24 the entire engine path 22 not with the pedal lever 13 in operative connection.

In an initial position (1) at which the rotor path 22 begins, stands the pen 16 not with the pedal lever 13 in contact or not in operative connection. That is, the spring 16 does not transmit any additional torque dependent on the travel to the accelerator pedal lever 13 , At a contact point (2) contacts the spring 16 the pedal lever 13 or occurs the spring 16 with the pedal lever in operative connection and can now an additional torque on the pedal lever 13 transfer. Then to an end position ( 3 ), at which the Rotorweg 22 ends, becomes the spring 16 through the engine 14 in one area 26 contracts or tensioned and therefore exerts a torque against the motor opposite to the motor direction 14 or its rotor. A motor position on the rotor path 22 For example, with an absolute angle of rotation φ _{red of} the rotor of the motor 14 be given to the stator.

The diagram shows that on the engine 14 acting torque M _motor (which may also be referred to as T _motor or T _mot or T _Mot ) when the rotor path 22 is passed through the engine at a constant speed. Between the initial position (1) and the contact point (2), a constant torque counteracts the direction of rotation of the rotor, which is based for example on internal frictional forces of the arrangement. Between the contact point (2) and the end position (3), the torque increases linearly, depending on the spring constant of the spring 16 , Because with increasing compression of the spring 16 or rotation of the spring 16 increases the force exerted by the spring against the direction of rotation of the rotor torque. In a linear acting spring results in a first approximation, the spring force, which is still for the determination of the torque with the z. B. must be multiplied as a constant assumed lever arm, z. In accordance with the relation F = c x, where F is the spring force, c is the spring constant and x is the distance traveled by the spring 16 is compressed.

The procedure starts z. B. at the lower mechanical end stop and does not necessarily reach the upper mechanical end stop, but the rotor moves far enough so that the spring is actuated in the relevant work area. The method may be performed, for example, at the beginning of the driving operation or at the end of the driving operation. An execution of the method is basically also possible during the driving operation.

Regarding the 3 to 6 A method will now be described with which the touch point (2) or its position on the rotor path 22 can be determined. The procedure may be by the controller 18 be carried out, with only the signals of the motor travel sensor 20 must be evaluated.

Overall, the BLDC engine 14 over the entire rotor path 22 Open-loop (ie without regulation) controlled. This can be done by the stator of the BLDC motor 14 be energized with a space vector, the length or amplitude of this space vector z. B. remains constant and wherein the angular velocity of the space vector z. B. is chosen constant. The space pointer can z. B. from three mutually offset by a respective constant phase control voltages can be generated. In this way, the space vector moves with quasi-constant (angular) speed between the initial position (1) and the end position (3). Preferably, the amplitude or the length of the space vector is chosen to be so large that at the rotor also at the end of the rotor path 22 a sufficiently large torque is available to the opposite torque of friction and the spring 16 at the end of the rotor way 22 to compensate.

In the 3 the three phases of the control voltage A, B, C and the space vector U _{αβ are} shown in the polar coordinate system. By specifying a in its length and its rotational speed constant space pointer is in the engine 14 z. B. by means of the stator windings generates a rotating field at a constant speed, the speed of the motor 14 or the rotor of the motor 14 leads, in turn, through the rotor position sensor 20 can be measured.

This spinner tows the engine 14 or the rotor of the motor 14 through the areas 24 . 26 , depending on the friction in the area 24 an almost constant _load angle φ _load between the phase angle φ _{U of} the predetermined rotating field and actually measured electrical rotor position angle φ sets _red . For example, assuming there is no friction and no counter torque, the _load angle φ _{load would be} about 0 ° (zero degrees). In the area 26 results in a linear dependence due to the spring constant of the spring 16 , The _load angle φ _load thus increases with increasing counter torque (load moment) of the spring 16 because the amplitude of the space vector is kept constant. Only by an enlargement of the lever arm of the rotor to the force or to the point of application of the force of the magnetic field of the stator (constant from the amount) can be additionally by the spring 16 impressed counter torque can be compensated. The length of the lever arm here depends on the _load angle φ _load .

A control voltage for the motor 14 or for the stator of the motor 14 is through a controller 18 generated such that a space vector with a phase angle φ _U in the stator fixed αβ system rotates at a constant angular velocity. The polar coordinate system can for example be spanned with two axes, an α-axis and a β-axis. In this case, the α-axis represents the real part and the β-axis represents the imaginary part of the space vector (the imaginary part may be denoted by the symbol "j", for example). Acts a constant load torque on the engine 14 , the space vector U _{αβ can} still be described in the rotor-fixed dq system as a constant phase angle. The rotor position angle or the rotor position φ _red can be determined from the signal of the rotor position sensor 20 through the controller 18 be determined.

While the rotor of the rotor of the engine 14 now the rotor way 22 Now, the following steps are repeated by the controller 18 (periodically) to determine the touch point (2).

In a first step, the current rotor position φ becomes _{red of} the motor 14 with the rotor position sensor 20 determined. To the signals of the engine travel sensor 20 or rotor position sensor 20 To be able to interpret, a basic adaptation may be necessary, which is known for example from methods for identifying the rotor position in an active accelerator pedal or a throttle valve. In this embodiment, for. B. no directly on the engine 14 arranged rotor position sensor 20 necessary.

From the rotor position φ _red can then _load angle φ _load according to φ _load = φ _U - φ _red be determined. The _load angle φ _load thus results as an angular difference from the phase angle φ _{U of} the space vector and the angle of the rotor position φ _red .

4 shows a diagram with a normalized _load angle φ _load , which is plotted over the time t and that of a real signal of a Motowegsensors 20 or rotor position sensor 20 was determined. There the space hand of the stator of the motor 14 is moved at a constant speed, the rotor position φ is _red proportional to the time t.

In a second step, the motor voltage U _{dq is calculated} in the rotor-fixed dq system according to U _d = U ₀ · cos (φ _load ) U _q = U ₀ · sin (φ _load )

U ₀ corresponds to the length of the space vector U _αβ .

From this, the engine torque T _mot can then be calculated by means of an inverse stationary engine model (the engine torque T _mot can also be regarded as the torque of the rotor).

In this case, L _d and L _{q are} inductances transformed into the dq system, R _{mot is} a resistance of the winding and ω _{el is} the angular frequency based on the voltage vector or the space vector U _αβ . N is the pool pair number of the BLDC motor or a permanent-magnet synchronous machine, I _d and I _q are the currents calculated from the inverse motor model and _{mot is} the motor constant.

ergeben, wirken sich vernachlässigbar auf die Berechnung des Motordrehmoments T_mot aus.The mistakes that occur when neglecting the current dynamics

have negligible effect on the calculation of the engine torque T _mot .

5 shows a diagram with a motor torque T _mot , which is plotted in _red about a rotor position φ and from the _load angle φ _load the 4 was calculated. The rotor position φ _red is specified in the pedal coordinate system, for example, the translation of a transmission was included.

Like from the 5 is apparent, the engine torque T _mot in a first section 28 almost constant while in a second section 30 increases linearly. To define the sections 28 . 30 became a middle section 32 of the rotor way 22 omitted, in which the point of contact 34 must be located. The end positions of the sections 28 . 30 for example, can be stuck in the controller 18 be predetermined. The end position of the first section 28 can be near the contact point 34 lie. The end position of the second section 30 may be just before or on the mechanical limit stop (in 3 at the right end).

Based on these sections 28 . 30 The controller now sets parameters for a free-running straight line 36 or a spring load straight line 38 determined from the engine torque T _mot in a third step.

Is the engine located 14 or the rotor of the motor 14 or the rotor position φ _red in the first section 28 , is used as the parameter of the free-space line 36 , which is assumed to be a constant function, an idle travel torque T _{L is} recursively estimated. This is in the 6 shown. For each new measuring point of the rotor position φ _red , an associated engine torque is calculated and included for the averaging of the Leerweggeraden. The calculated mean value for the idle travel torque T _L at the end of the first section 28 is then used as a parameter for the empty path 36 accepted.

Is the engine located 14 or the rotor of the motor 14 or the rotor position φ _red in the second section 30 , are used as parameters of the spring load line 38 , which can be parameterized as k ₁ · φ + k ₂ , whose slope k _{1 is} recursively estimated as a spring constant and an offset k ₂ . The second section 30 is z. B. defined from a threshold value for the engine torque, which is higher than the maximum calculated engine torque in the first section 28 , This can be done analogously to the estimation for the Leerwegmoment T _L. The 7 shows the evolution of the estimate of the spring constant k ₁ over the second section 30 , The estimates for the spring constant k ₁ and the offset k ₂ at the end of the second section 30 are then used as parameters for the spring load straight 38 accepted.

If the engine 14 the complete rotor way 22 has passed through, then the calculated touch point 34 from the estimated values for the parameters T _L , k ₁ , k ₂ . The position of the touch point 34 on the rotor way 22 results from the position of the intersection of the Leerweggeraden 36 and the spring load line 38 ,

Finally, it should be noted that terms such as "comprising," "comprising," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a multitude. Reference signs in the claims are not to be considered as limiting.

Claims (6)

Method for determining the touch point ( 34 ) a spring ( 16 ) an accelerator pedal actuator ( 12 ) with an accelerator pedal lever ( 13 ), the method comprising: - energizing an engine ( 14 ), which has a rotor and a stator, the accelerator pedal actuator ( 12 ) with a predefined space vector so that the rotor has a predefined rotor path ( 22 ) covers; Measuring a rotor position (φ _red ) along the rotor path ( 22 ); Determining a load angle (φ _load ) along the rotor path ( 22 ), wherein the load angle (φ _load ) is calculated based on a difference of a phase angle (φ _U ) of the predefined space vector and a rotor position angle (φ _red ) at the rotor position (φ _red ); wherein a motor torque (T _Mot ) along the rotor path ( 22 ) is determined from the load angle (φ _load ) - determining a free-motion straight line ( 36 ) based on the load angle (φ _load ) in a first section ( 28 ) of the rotor path ( 22 ); Determining a spring load straight line ( 38 ) based on the load angle (φ _load ) in a second section ( 30 ) of the rotor path ( 22 ); - determining the contact point ( 34 ) as the intersection of the free-passage lines ( 36 ) and the spring load line ( 38 ); where the empty path straight line ( 36 ) and / or the spring load line ( 38 ) are determined from the engine torque (T _Mot ); where the empty path straight line ( 36 ) on one over the first section ( 28 ) averaged idle travel torque (T _L ) based; and / or wherein the free-space path ( 36 ) is parameterized without a slope with a constant Leerwegmoment (T _L ); the spring load straight line ( 38 ) on one over the second section ( 30 ) averaged spring constant (k ₁ ); and / or wherein the spring load straight line ( 38 ) is parameterized with a spring constant (k ₁ ) as a constant pitch and a spring offset torque. The method of claim 1, wherein the engine torque (T _Mot ) is determined based on a mathematical engine model. Method according to one of the preceding claims, wherein the space vector has a constant angular velocity (dφ _U / dt) and wherein in particular the length of the space vector (U ₀ ) is constant. Method according to one of the preceding claims, wherein parameters of the Leerweggeraden ( 36 ) in the first section ( 28 ) and / or parameters of the spring load straight line ( 38 ) in the second section ( 30 ) are estimated using a recursive mean. Method according to one of the preceding claims, wherein the rotor path ( 22 ) in the first section ( 28 ), a middle section ( 32 ) and the second section ( 30 ), the middle section ( 32 ) is selected based on an assumed touch point. Accelerator pedal ( 10 ) for a vehicle, the accelerator pedal ( 10 ) comprising: an accelerator pedal lever ( 13 ); an accelerator pedal actuator ( 12 ) with a motor ( 14 ), which has a rotor and a stator, and a spring ( 16 ) between the engine ( 14 ) and the accelerator pedal lever ( 13 ) is arranged so that by means of the engine ( 14 ) over the spring ( 16 ) haptic signals on the accelerator pedal lever ( 13 ) are producible; a controller ( 18 ) designed to remove the engine ( 14 ), measuring signals from a rotor travel sensor ( 20 ) of the motor ( 14 ) and to carry out the method according to one of the preceding claims.

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