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EP-4741770-A1 - A METHOD FOR CALIBRATING AN ANGULAR POSITION SENSOR

EP4741770A1EP 4741770 A1EP4741770 A1EP 4741770A1EP-4741770-A1

Abstract

The invention relates to a method for calibrating an angular position sensor (S), e. g. a contactless inductive position sensor (CIPOS) or a Hall sensor, arranged at an output shaft (12) of an actuator (100), wherein the actuator (100) is preferably provided for a vehicle application, e. g. for engine control, steering control, cooling control etc., wherein angular positions (V12) of the output shaft (12) obtained by the angular position sensor (S) and real angular positions (V12*) of the output shaft (12) calculated using angular positions (V11) of a motor shaft (11) will be compared.

Inventors

  • Molkenthin, Philipp
  • Constantin, Marius Alexandru

Assignees

  • HELLA GMBH & CO. KGAA

Dates

Publication Date
20260513
Application Date
20241112

Claims (13)

  1. A method for calibrating an angular position sensor (S), e. g. a contactless inductive position sensor (CIPOS) or a Hall sensor, especially arranged at an output shaft (12) of an actuator (100), wherein the actuator (100) is preferably provided for a vehicle application, e. g. for engine control, steering control, cooling control etc., and wherein the actuator (100) comprises: - an electrical motor (10), especially a brushless dc motor, configured to drive a motor shaft (11) and to provide an incremental sensor using a motor back EMF signal, - a gear mechanism (20) configured to provide a gear ratio (GR) between the motor shaft (11) and the output shaft (12) of the actuator (100), the method comprising: - operating the angular position sensor (S) to obtain angular positions (V12) of the output shaft (12), - operating the electrical motor (10) as the incremental sensor to determine angular positions (V11) and/or a number (n) of revolutions of the motor shaft (11), - calculating real angular positions (V12*) of the output shaft (12) using the angular positions (V11) and/or the number (n) of revolutions of the motor shaft (11), - comparing the angular positions (V12) of the output shaft (12) obtained by the angular position sensor (S) and the real angular positions (V12*) of the output shaft (12) calculated using the angular positions (V11) and/or the number (n) of revolutions of the motor shaft (11), - calibrating the angular position sensor (S) in dependence on the comparing.
  2. The method according to claim 1, wherein the gear ratio (GR) of the gear mechanism (20) is considered by calibrating the angular position sensor (S), especially by calculating the real angular positions (V12*) of the output shaft (12) using the angular positions (V11) of the motor shaft (11).
  3. The method according to claim 1 or 2, wherein the angular position sensor (S) is operating to obtain an angular position (V12) of the output shaft (12) every certain time slot, for example every 3 ms, during an operation of the electrical motor (10) as the incremental sensor.
  4. The method according to claim 1 or 2, wherein the angular position sensor (S) is operating to obtain a plurality of angular positions (V12) of the output shaft (12) for at least two electrical rotations and/or rollovers of the electrical motor (10), especially for at least two revolutions of the motor shaft (11), advantageously to be able to detect a maximal angular position and a minimal angular position of the output shaft (12) and/or to calculate a resolution of the angular position sensor (S).
  5. The method according to one of the preceding claims, further comprising: - operating the electrical motor (10), especially with a constant speed, e. g. 300 rad/s, as the incremental sensor for at least two electrical rotations and/or rollovers of the electrical motor (10), especially for at least two revolutions of the motor shaft (11), advantageously to be able to detect a maximal angular position and a minimal angular position of the output shaft (12) and/or calculate a resolution of the angular position sensor (S).
  6. The method according to one of the preceding claims, further comprising at least one of the following: - storing the angular positions (V12) of the output shaft (12) obtained by the angular position sensor (S), - storing the real angular positions (V12*) of the output shaft (12) calculated using the angular positions (V11) of the motor shaft (11), - calculating deviations (dV) between the angular positions (V12) of the output shaft (12) obtained by the angular position sensor (S) and the real angular positions (V12*) of the output shaft (12) calculated using the angular positions (V11) and/or the number (n) of revolutions of the motor shaft (11), - storing the deviations (dV), especially in a memory unit (mu) of the actuator (100), - calibrating the incremental sensor (S) using the deviations (dV).
  7. The method according to one of the preceding claims, comprising the following steps: - spining the electrical motor (10), - checking sensor values of the angular position sensor (S) every certain time slot, for example every 3 ms, until a first rollover of the electrical motor (10), - continuing to spin the motor (10), - checking sensor values of the angular position sensor (S) every certain time slot, for example every 3 ms, until a second rollover of the electrical motor (10), - calculating deviations (dV) between sensor values of the angular position sensor (S) and corresponding calculated positions of the output shaft (12) using the angular positions (V11) and/or the number (n) of revolutions of the motor shaft (11), - storing the deviations (dV), especially in a memory unit (mu) of the actuator (100), - calibrating the angular position sensor (S) using the deviations (dV).
  8. The method according to one of the preceding claims, wherein the method is executed during a regular operation of the actuator (100).
  9. The method according to one of the preceding claims, wherein the method is executed in a recurring, periodic, event-specific way, for example each time the actuator (100) is starting, and/or upon a request, for example of a user of the vehicle.
  10. A computer program product, comprising instructions, which, when the computer program is executed by a computer, cause the computer to carry out the method according to one of the preceding claims.
  11. An electronic control unit (ECU), comprising a memory unit (mu) and a control unit (cu), wherein in the memory unit (mu) a code is stored, wherein when the code is executed by the control unit (cu), the method according to one of the preceding claims is executed.
  12. The electronic control unit (ECU) according to the preceding claim, wherein the deviations (dV) are stored in the memory unit (mu), especially to be used for calibrating the angular position sensor (S).
  13. An actuator (100), preferably for a vehicle application, e. g. for engine control, steering control, cooling control etc., comprising an angular position sensor (S) and an electronic control unit (ECU) according to one of the preceding claims 11 or 12 configured for calibrating the angular position sensor (S).

Description

The invention is related to a method for calibrating an angular position sensor, especially a contactless inductive position sensor (CIPOS) or a Hall sensor, of an actuator, preferably for a vehicle application, e. g. for engine control, steering control, cooling control etc. Besides, the invention is related to a corresponding computer program product and corresponding electronic control unit configured to execute respective method. Further, the invention is related to a corresponding actuator with an angular position sensor and a respective electronic control unit configured for calibrating the angular position sensor. Actuators for vehicle applications usually require internal angular position sensors, e. g. a contactless inductive position sensor (CIPOS), a Hall sensor or the like, at the output shaft for proper operation. One possible application is cooling control for components in electric cars, e.g. battery etc. Actuators may be driven by a brushless motor and need to know the motor position very well in order to define the correct commutation timing. A Brushless motor may use either a "sensorless drive solution" and BEMF signal or a "sensored drive solution" (using a motor position sensor, like Hall switches, Hall sensor, another CIPOS sensor or the like) to determine the motor position. The actuator internal angular position sensors at the output shaft of the actuators will be usually calibrated after actuator assembly. For this aim, external angular position sensors with considerably high precision are usually used to calibrate the actuator internal angular position sensors at the output shaft of the actuators. Drawbacks are however that production time and effort of actuators are increased due to this calibration process. Synchronization of signals between the external angular position sensors and the actuator internal angular position sensor at the output shaft is challenging. Also, the output shaft of the actuator must be connected free of backlash to an external angular position sensor as any backlash compromises calibration result. The resolution of the actuator internal angular position sensor at the output shaft is also limited due to constraints in the communication interface and thus limiting the benefit of the calibration process. The aim of the present invention is to at least partially overcome at least one of the above-mentioned disadvantages. Preferably, the aim of the present invention is to provide an improved method for calibrating an angular position sensor, which may be executed with reduced time and effort, which requires reduced computational and physical resources and which provides improved results of the angular position sensor after calibrating process. Besides, the aim of the present invention is to provide a corresponding computer program product and corresponding electronic control unit configured to execute the respective method. Further, the aim of the present invention is to provide a corresponding actuator with an angular position sensor and a respective electronic control unit configured for calibrating the angular position sensor. The invention provides: a method for calibrating an angular position sensor, e. g. a contactless inductive position sensor (CIPOS) or a Hall sensor, especially arranged at an output shaft of an actuator, wherein the actuator is preferably provided for a vehicle application, e. g. for engine control, steering control, cooling control etc. The actuator comprising: an electrical motor, especially a brushless dc motor, configured to drive a motor shaft and to provide an incremental sensor using a motor back EMF signal,a gear mechanism configured to provide a gear ratio between the motor shaft and the output shaft of the actuator. The angular position sensor may be mounted at an output shaft of an actuator or in other gear stages of the gear mechanism. There may be actuators, where the exact position of the output shaft may be needed. There may be also actuators, where other gear stages and their positions may be of interest. The output shaft within the meaning of the invention may therefore be a particular shaft in one of the stages in the gear mechanism. The method comprising: operating the angular position sensor to obtain angular positions of the output shaft,operating the electrical motor as the incremental sensor to determine angular positions and/or a number of revolutions of the motor shaft (which is especially equal to the number of electrical rotations and/or rollovers of the electrical motor),calculating real angular positions of the output shaft using the angular positions and/or the number of revolutions of the motor shaft,comparing the angular positions of the output shaft obtained by the angular position sensor and the real angular positions of the output shaft calculated using the angular positions and/or the number of revolutions of the motor shaft,calibrating the angular position sensor in dependence on the comparing. Back