Method and apparatus for providing information about the angular displacement of a direct current motor

Abstract

Driving electric motors, especially brushed electric motors, cause ripples in the supply current. The amount of pulses is proportional to the amount of revolutions of the rotor of the electric motor. In the case of a defect-free electric motor, the amount of pulses per revolution is the same. Defects in the brushes, rotor, windings and / or other components of the electric motor cause fluctuations in the pulses in the supply current per revolution of the rotor. By comparing the expected amount of pulses to the counted amount of pulses and using various physical parameters of the electric motor, various methods can be employed to correct the counted amount of pulses or otherwise provide a proper value representative of the electric motor rotor displacement. The time between counted pulses can also be used to determine the slip of a slip coupling included in a driveline to which the electric motor can be coupled.

Description

Technical Field

[0001] Its various aspects and embodiments involve processing based on changes in energy supply to provide information about the circumferential displacement of a brushed DC motor. Background Technology

[0002] The circular speed of a motor rotor can be determined by counting changes in energy supply, current, voltage, or both. By counting changes (such as ripple), the number of rotor revolutions can be determined. Thus, the amount of displacement of an actuator connected to the rotor, for example by means of a transmission system, can be determined. Patent application WO2016 / 080834 provides information on this problem. Summary of the Invention

[0003] Preferably, more accurate information is provided about the annular displacement of the rotor and / or about the displacement of the element actuated by means of the motor.

[0004] A first aspect provides a method for determining the ring position of a brushed DC motor. The method includes: monitoring a supply current to obtain an index of average ring speed; determining, based on the index, an expected time period between two consecutive pulses in the supply current; obtaining a counted number of pulses by counting the pulses in the supply current; and determining a measured time period between two counted consecutive pulses. The method further includes: adjusting the count to obtain an adjusted counted number of pulses in at least one of the following ways: if the measured time period is shorter than the expected time period by more than a first predetermined threshold, adjusting the counted number of pulses by not counting a second pulse; and if the measured time period is longer than the expected time period by more than a second predetermined threshold, adjusting the counted number of pulses by incrementing by one.

[0005] Manufacturing defects may result in flaws on the motor rotor, causing one or two additional ripples in the supply current per rotor revolution. These additional pulses can be detected by monitoring the time between pulses. The overall time interval or pulse duration between two pulses can be estimated using a specific rotor speed that can be determined by indicators. If a second pulse occurs within half the normally expected pulse time after the first pulse, this second pulse is disregarded when determining the rotational displacement of the motor rotor. This can be achieved either by counting the additional pulses and subtracting them, or by not counting the additional pulses at all.

[0006] Due to similar manufacturing problems, variations in the supply current, other reasons, or a combination thereof, a pulse may not appear where it is expected, or a pulse may not be detected at the expected time. In such cases, the time between two consecutive pulses is typically twice the expected length or at least significantly longer than expected. In this situation, the count of pulses is corrected by incrementing the count of pulses by one.

[0007] In one embodiment, the metric is at least one of supply current, supply voltage, and ambient temperature, and the method further includes finding a ring speed in a reference file corresponding to at least one of the supply current, supply voltage, and ambient temperature.

[0008] Electric motors exhibit specific characteristics regarding the relationship between current and speed relative to torque. Generally, speed and torque are negatively proportional, while current and torque are positively proportional. The point where the torque-speed curve and the torque-current curve intersect is the operating point of the motor. Given that the motor's characteristics are known and stored in reference documents, the current level provides information about the rotational speed. Knowing the rotational speed and the amount of conductors or conductor transitions on the rotor at the brush contact locations, the expected number of pulses to be counted for one rotor revolution can be determined.

[0009] In another embodiment, the metric is a time-related factor, which provides an indication of the average time interval between two consecutive pulses.

[0010] By determining the expected duration of a single pulse from an average value, an appropriate indication is provided when the next pulse can be anticipated. If the pulse occurs earlier, the count can be adjusted. Alternatively or additionally, other time-related indicators can be used.

[0011] A second embodiment provides a method for determining the position of an actuable object arranged to be driven by a brushed DC motor. The method includes: determining the position of the actuable object based on the method described in the first aspect and on an adjusted counted number of pulses.

[0012] Since the counting of pulses and the counting adjustment used to correct errors provide a proper indication of the rotor's rotational displacement, the counted amount also provides a proper indication of the driveable element connected to the motor's rotor (directly or via the drivetrain).

[0013] One embodiment includes obtaining an initial position of the actuable object, and determining the position of the actuable object based on the adjusted counted pulse quantity and the initial position of the actuable object.

[0014] The displacement can be calculated by counting the number of pulses. By adding this displacement to the initial position, the new position can be determined.

[0015] Another embodiment involves driving the actuable object by supplying a power current to a motor and monitoring the power current. If the waveform of the power current meets at least one predetermined condition, it is determined that the actuable object has reached an external position.

[0016] This embodiment provides information about the external location. This information can be used for calibrating the actuable element or stopping the motor to prevent damage.

[0017] A third embodiment provides an apparatus for providing information about the ring speed of a DC motor. The apparatus includes a monitoring module and a processing module. The monitoring module is arranged to monitor a supply current to obtain an index of the average ring speed. The processing module is arranged to determine an expected time period between two consecutive pulses in the supply current based on the index, obtain a counted number of pulses by counting the pulses in the supply current, and determine a measured time period between two counted consecutive pulses. The processing unit is further arranged to adjust the count to obtain an adjusted counted number of pulses in at least one of the following ways: if the measured time period is shorter than the expected time period by more than a first predetermined threshold, the counted number of pulses is adjusted by subtracting one; and if the measured time period is longer than the expected time period by more than a second predetermined threshold, the counted number of pulses is adjusted by increasing one.

[0018] A fourth aspect provides a control system for actuating an actuable element of a motor vehicle. The system includes the means according to the third aspect, a DC motor, and a transmission system for connecting the DC motor to the actuable element. The transmission system includes: a first transmission element connected to the DC motor; and a second transmission element arranged to be connected to the actuable element. In this transmission system, the first transmission element and the second transmission element are arranged to engage with each other such that if the coupling torque between the first transmission element and the second transmission element is less than a predetermined torque level, the first transmission element and the second transmission element move together, and if the coupling torque is greater than the predetermined torque level, the first transmission element and the second transmission element slide relative to each other.

[0019] The fifth aspect provides a rearview mirror module comprising the system according to the fourth aspect and a rearview mirror as the actuable element.

[0020] A sixth aspect provides a motor vehicle that includes a control system according to the fourth aspect and the said actuable element. Attached Figure Description

[0021] Its various aspects and embodiments will now be further explained with reference to the accompanying drawings. In the drawings,

[0022] Figure 1 The electric motor is shown connected to the rearview mirror via the drivetrain;

[0023] Figure 2 A schematic diagram showing local control elements in the vehicle network connected to the battery and electric motor;

[0024] Figure 3 A first flowchart depicting a method for adjusting ripple count and accurately determining rotor displacement is shown;

[0025] Figure 4 The graph depicts the relationship between the ripple time period and time.

[0026] Figure 5 A second flowchart depicting an alternative method for determining ripple counts is shown; and

[0027] Figure 6 The second flowchart depicts a method for sliding detection. Detailed Implementation

[0028] Figure 1 A DC motor 100 is shown connected to a rearview mirror 160 via a drivetrain 170. The motor 100 includes a housing 102, within which a rotor 110 is disposed. A first conductor 112 and a second conductor 114 are disposed on the rotor 110. Additionally, one or more additional conductors are disposed on the rotor 110. The conductors are configured to supply current from brush contacts 116 to a first electromagnet 122 and a second electromagnet 126, which are coils disposed on the rotor 110. A first permanent magnet 124 and a second permanent magnet 128 are also disposed in the housing 102. Therefore, the DC motor 100 is a commercially available and known type of electric motor.

[0029] The transmission system 170 includes a sliding coupling 130 disposed between the rotor 110 and the worm gear 140. The transmission system 170 also includes a toothed gear or gear 150 preferably disposed on a wheel axle 158. The connection between the worm gear 140 and the gear 150 allows for a significant reduction in rotational speed, preferably on the order of 50 or 50 times.

[0030] The first sliding coupling 130 includes a first sliding component 132 connected to the rotor 100 and a second sliding component 134 connected to the worm gear 140. In normal operation, the first sliding component 132 and the second sliding component 134 rotate together. If the torque between the worm gear 140 and the rotor 110 exceeds a predetermined torque threshold, the second sliding component 134 stalls while the first sliding component 132 continues to rotate; in this operating state, the sliding coupling 130 is in a sliding mode. If the sliding coupling 130 begins to slip, typically the entire transmission system 170 will first stall. Subsequently, the sliding coupling will enter a sliding mode. Depending on the characteristics of the contact surfaces of the first sliding component 132 and the second sliding component 134, the sliding coupling 130 will remain in sliding operation or alternate between sliding and stall modes.

[0031] Additionally or alternatively, a second sliding coupling is provided in gear 150. In this embodiment, gear 150 includes an outer ring 152 and an inner ring 154. A second sliding coupling 156 is provided between the inner ring 152 and the outer ring 154. The operation of the second sliding coupling 156 is similar to that of the first sliding coupling 130. A rearview mirror is connected to the inner ring 156.

[0032] Although in this embodiment the electric motor 100 is used to actuate the rearview mirror 160, in other embodiments, other actuable components of the car or other motor vehicle may be actuated. Such actuable components may be the entire rearview module including the mirror and mirror adjustment device, a grille shutter, a brakeable spoiler or other air deflector, a wiper, a door, or a combination thereof.

[0033] Figure 2 Showing the operation Figure 1 The diagram shows a control system for the regulating system. Figure 2 The diagram shows a control module 200 for controlling the operation of the regulating system, a battery 220 for supplying power to the electric motor 110, a central vehicle control unit 212 coupled to the control module 200 via a vehicle bus 214, buttons 216 or a set of buttons as user input units, and a regulating system 180. The vehicle bus 214 can operate according to the CAN protocol, LIN protocol, other protocols, or combinations thereof.

[0034] Battery 220 is shown coupled to control module 200, and it is also coupled to central vehicle control unit 212. Button 216 is connected to central vehicle control unit 212 for providing user commands. Control module 200 is coupled to regulation system 180.

[0035] The control module 200 includes a switch 206 for switching power from battery 220 to motor 110 of regulating system 180. A current sensor 208 is disposed between switch 206 and regulating system 180. The current sensor 208 is arranged to sense the current switched by switch 206 and supplied to motor 110.

[0036] Optionally, an additional voltage sensor is provided. Switch 206 and current sensor 208 are connected to local control unit 202. Local control unit 202 is also connected to local memory 204.

[0037] Combining Figure 3 The flowchart 300 shown further discusses in detail the other functionalities of the control module 200 and the regulation system 180. The various components of the flowchart are briefly summarized in the following list.

[0038] 302 Start Process

[0039] 304 Receive Input Command

[0040] 306 Determine the initial position

[0041] 308 Determine the end position

[0042] 310 Determine the required number of counts.

[0043] 312 Start the motor

[0044] 314 Determine the expected time between pulses

[0045] 316 counting pulses +1

[0046] 318 Determine the time since the previous pulse.

[0047] What time period is below 320?

[0048] 322 or higher time periods?

[0049] 324 How to achieve the required number of pulses?

[0050] 326 Turn off the motor

[0051] 328 storage locations

[0052] 330 End Process

[0053] 342 Decrease the count by one

[0054] 344 Increment the count by one

[0055] 352 Determine the relationship between this time period and other times.

[0056] 354 or above the threshold?

[0057] 356 Stop the motor

[0058] 358 Store the location as the initial location.

[0059] 360 End Process

[0060] The process begins at start / stop frame 302 and continues to step 304, where a user input command is received. The user input command is provided via button 216 and communicated to the local control unit 202 via the central vehicle control unit 212 and vehicle bus 214. Alternatively, the command is provided directly to the local control unit 202 via button 216. In step 306, the initial or current position of the rearview mirror 160 is determined. Preferably, the position of the rearview mirror 160 is obtained from the local memory 204.

[0061] Subsequently, the end position is determined in step 308. The end position can be determined in several ways. The end position of the rearview mirror 160 can be based on a memory location, such as being stored in local memory 204. Alternatively or additionally, the end position can be determined by a user command provided via button 216. User commands provided via button 216 or other input devices can indicate a specific absolute end position, or a movement with a specific amount, and thus indicate a relative end point of the movement.

[0062] The pulse count is determined based on the initial position and the determined final position of the rearview mirror 160. A first conductor 112, a second conductor 114, and further conductors are provided on the rotor 110 of the motor 100. Preferably, at least three conductors are provided for supplying current to at least three windings. The conductors on the rotor 110 are separated by an insulator.

[0063] At each transition from one rotor conductor to another at the brush contact 116 (and therefore the other brush contact opposite to brush contact 116), a slight change occurs in the supply current to the motor 100. With three windings, two brush contacts, and three conductors, six pulses occur in one revolution of the rotor 110 and, in the case of full engagement, in one revolution of the worm gear 140. If the rotor 110 of the motor 100 carries more conductors, more pulses occur in the supply current during one revolution of the rotor 110.

[0064] Based on the amount of pulses in the power supply current during one revolution of rotor 110 and the transmission ratio of transmission system 170, in step 310, the amount of pulses appearing in the power supply current for a specific movement of gear 150 or rearview mirror 160 (e.g., from initial position to final position). Subsequently or simultaneously, in step 312, a power supply current for driving motor 100 can be provided to motor 100.

[0065] The process proceeds by determining the expected time between pulses in step 314. This can be done in several ways. First, the number of pulses is counted at specific time intervals, and the average duration of the pulses is determined. The pulse duration can be determined as the duration of the first and last counted pulses from top to top, from one rising slope to another, from one falling slope to another, or other combinations thereof.

[0066] Alternatively or additionally, the amount of pulse is determined based on at least one of the estimated rotational speed of the motor 100, the supply current to the motor, and the supply voltage. This can be performed by means of the current sensor 208 and additionally or alternatively by an optional voltage sensor. Data is available within the control module 200, and particularly in the local memory 204, to determine the rotational speed of the rotor 110. The motor has specific characteristics regarding the relationship between current and speed and torque. Generally, speed and torque are negatively proportional, and current and torque are positively proportional.

[0067] The point where the torque-speed curve and the torque-current curve intersect is the operating point of the electric motor 100. Given the characteristics of the electric motor 100, the current level provides information about the rotational speed. Knowing the rotational speed and the quantity or transitions between conductors on the rotor 110 at the brush contacts 106, the number of pulses to be counted for one revolution of the rotor 110 can be determined.

[0068] In one example of determining the expected number of pulses that can be combined with the process described above, the expected time between pulses is multiplied by the number of brush contacts in motor 100. During the use of motor 100, the position of the brushes changes over time. For example, in a two-brush motor, the angular distance between the two brushes varies. This causes the first time interval between the number of odd pulses and the number of even pulses to differ from the second time interval between the number of even pulses and the number of odd pulses. This problem is solved by multiplying the expected time between pulses by the number of brush contacts in motor 100, thus improving counting accuracy.

[0069] Subsequently, pulses are counted in the supply current to motor 100. The pulses are counted using a current sensor 208 and a local control unit 202. One or both of these may be equipped with other electronic devices for determining the occurrence of a pulse, such as a comparator, a trigger unit, others, or combinations thereof. Once a pulse is determined, the counter value is incremented by one in step 316. Before the first count, the counter value can be reset, for example, by setting it to zero.

[0070] In step 318, the time period between the counted pulses and the previous pulse is determined. Alternatively, the time from the counted pulses to the next pulse is determined. The determined time period is then evaluated as an acceptable range of pulse times. Although the motor 100 is designed to operate at a more or less constant speed when supplied with a more or less constant current, the pulse period will vary. One reason for this could be a manufacturing defect in the motor, such as a slight difference in the distance between transitions in the conductors on the rotor 110. Another reason could be variations in the supply current, for example, due to interference from other devices powered by the battery 220.

[0071] Alternatively, in step 318, the time between the multiple pulses is determined. Preferably, the time interval between the multiple pulses is determined such that the number of pulses is equal to or a multiple thereof, the amount of brush contact in the motor 100. As described above, such a counting method increases accuracy by eliminating or at least reducing the effects of wear and brush displacement.

[0072] Figure 4 A graph 400 is shown depicting the relationship between the pulse duration measured in a practical example and the elapsed time. Normal operation is provided during the first time period 410. Figure 4 The diagram shows that the pulse duration during normal operation varies as a function of time within a certain range. Therefore, to determine whether a measured pulse duration constitutes compliant operation, the pulse duration is preferably within a specific range rather than at a specific value.

[0073] Preferably, the acceptable pulse time range is determined based on the expected pulse time determined in step 314. The acceptable pulse time range can be set to the range from the expected pulse time (or estimated pulse time) minus an absolute or relative margin (e.g., 5%, 10%, or 20%) to the expected pulse time plus that margin.

[0074] In step 320, it is determined whether the time interval between the two determined consecutive pulses is below an acceptable pulse time range. In a preferred embodiment, this is two directly consecutive pulses. In another embodiment, the time interval is determined between a plurality of pulses, the number of which is preferably equal to or a multiple of the number of brushes of the motor 100.

[0075] If the time interval between the two determined consecutive pulses is less than the acceptable pulse time range, the process branches to step 342, where the count is decremented by one. One reason for this is that an excessively short time interval between the two determined pulses would provide an indication of pulses due to errors (rather than the transition from the first conductor 112 to the second conductor 114 via the brush contact 116). This could be due to manufacturing errors, detection errors, or a combination thereof in the system of the motor 100.

[0076] If it is determined in step 326 that the time interval between the two determined consecutive pulses is above the acceptable pulse time range, the process branches to step 344, where the count value is incremented by one. In this way, the counted pulse quantity is corrected for erroneous counts or incorrectly lost counts. This allows the counted pulse quantity to provide an appropriate estimate of the rotational speed of rotor 110 and worm gear (and thus the position of rearview mirror 160).

[0077] The process then continues to step 324, where the corrected (if necessary) count is compared to the quantity determined in step 310. If these quantities match or differ by less than a predetermined threshold (expressed as a quantity or ratio (percentage)), the process continues to step 326, where the power to motor 100 is turned off by means of switch 206. The process continues to step 328, where information about the position of the rearview mirror is stored in a memory such as local memory 204, and the process ends at step 330. If it is determined in step 324 that the quantity of the counted pulses is lower than or significantly lower than the quantity determined in step 310, the process branch returns to step 316.

[0078] After step 318 has been performed by determining the time interval between the two pulses, the process preferably branches off to step 352 in addition to proceeding to step 320. In step 352, the time interval between the pulses is determined over time. This can be performed using linear regression or other algorithms to determine the relationship between the derivative (local or average) of the time interval between pulses and time.

[0079] In step 354, the derivative value is tested. If the derivative value of the pulse time with respect to the elapsed time is below a certain threshold, the process loops back to step 318. If the variation (especially an increase) in the time interval between two consecutive pulses is too high, this could be an indication of slippage in sliding coupling 130 and / or the second sliding coupling 156. Slippage of the sliding coupling occurs if the torque on the sliding coupling is above a certain threshold. This could be the case if the rearview mirror 160 moves against the mating part and cannot move further or can only move with excessive force that would cause damage. Slippage begins in the second time interval 420, as... Figure 4 As shown.

[0080] If the derivative of the pulse time with respect to the elapsed time is above a certain threshold, the process continues to step 356, where the power to the motor is turned off. The position of the rearview mirror 160 is then stored in memory. The stored position data may be the angle of the mirror, or simply an indication of a specific external position of the rearview mirror 160 within its trajectory. The process then ends at step 360.

[0081] Figure 5 The flowchart 500 shown illustrates another method for providing more accurate ripple counts. The various components of the flowchart are briefly summarized in the following list.

[0082] 502 Start Process

[0083] 504 Receive Input Command

[0084] 506 Determine the initial position

[0085] 508 Determine the end position

[0086] 510 Determine the required number of counts.

[0087] 512 Start the motor

[0088] 514 Obtain the motor winding resistance

[0089] 516 Obtain the sampling frequency

[0090] 518 Sample Power Supply Voltage

[0091] 520 Sample Supply Current

[0092] 522 Determine the anti-EMF

[0093] 524. Increment the value in memory.

[0094] 526 Ripple detected?

[0095] 528 Is the memory value a multiple of the determined value?

[0096] 530 to the next sample

[0097] 532. Increase the ripple count by a determined factor.

[0098] 534 Reset the multiplier to 1

[0099] 536 Set the memory value to 0

[0100] 538 How to achieve the required number of pulses?

[0101] 540 Stop the motor

[0102] 542 Store the location as the initial location.

[0103] 544 End of process

[0104] The process begins at start / stop box 502 and continues to step 504, where a user input command is received. The user input command is provided via button 216 and communicated to the local control unit 202 via the central vehicle control unit 212 and vehicle bus 214. Alternatively, the command is provided directly to the local control unit 202 via button 216. In step 506, the initial or current position of the rearview mirror 160 is determined. Preferably, the position of the rearview mirror 160 is obtained from the local memory 204.

[0105] Subsequently, the end position is determined in step 508. The end position can be determined in several ways. The end position of the rearview mirror can be based on a memory location, such as being stored in local memory 204. Alternatively or additionally, the end position can be determined by a user command provided via button 216. User commands provided via button 216 or other input devices can indicate a specific absolute end position, or a movement with a specific amount, and thus indicate a relative end point of the movement.

[0106] Based on the initial position and the determined final position of the rearview mirror 160, the pulse count or the number of revolutions of the rotor 110 is determined. A first conductor 112, a second conductor 114, and more conductors are provided on the rotor 110 of the motor 100. Preferably, at least three conductors are provided for supplying current to at least three windings. The conductors on the rotor 110 are separated by an insulator.

[0107] At each transition point from one rotor conductor to another at brush contact 116 (and the other brush contact opposite brush contact 116), a slight variation occurs in the supply current to motor 100. With three windings, two brush contacts, and three conductors, six pulses occur in one revolution of rotor 110 and in one revolution of worm gear 140 when fully engaged. If rotor 110 of motor 100 carries more conductors, more pulses occur in the supply current during one revolution of rotor 110.

[0108] Based on the amount of pulses in the supply current during one revolution of rotor 110 and the transmission ratio of transmission system 170, the amount of pulses appearing in the supply current for a specific motion (e.g., from initial position to final position) is determined in step 510. Subsequently or simultaneously, in step 512, a supply current for driving motor 100 may be provided to motor 100.

[0109] The process proceeds by obtaining the motor winding resistance in step 514. This can be accomplished in several ways. In a first embodiment, the motor winding resistance value is obtained from a memory that already stores typical values ​​of the motor winding resistance. Alternatively or additionally, the resistance value is determined while the motor is being powered, such that the back EMF (electromagnetic force) is negligible.

[0110] Subsequently, the sampling frequency is determined in step 516, either simultaneously with or before determining the winding resistance, wherein the supply current to the motor is sampled. Therefore, this step can also be performed before step 512. This can be a standard value stored in memory or a dynamic value. This step may include setting the actual sampled value, reading the value only from memory, obtaining the value in other ways, or a combination thereof.

[0111] With the electric motor running, samples are obtained from the motor's supply voltage and supply current in step 518. The supply voltage value can be measured practically separately, or alternatively or additionally obtained from the vehicle's control network as the battery voltage. At substantially the same time, the value of the motor's supply current is sampled in step 520.

[0112] In step 520, an approximate inverse EMF is determined by multiplying the sampled current value by the sampled voltage value. This approximation is permitted for the following reasons:

[0113] The anti-EMF (BEMF) is defined as:

[0114]

[0115] Where V bat R is the supply voltage or battery voltage, I is the winding resistance, ε is the supply current, and di / dt is the derivative of the supply current with time.

[0116] Considering that the supply current contacts essentially under steady-state operation and assuming that the reverse EMF is linearly related to the ring frequency of the rotor 110 of the motor 100, the last term can be neglected, and the equation can be rewritten as:

[0117] V bat -R·I=K e ·f

[0118] Where K e K is a constant related to the characteristics of the motor. e It can be stored in memory for retrieval during processing. Alternatively or additionally, K can be determined directly and instantly using the above formula by obtaining the winding resistance, battery voltage, ring frequency, and average current. eBy dividing the sampling frequency fs by the motor's ring frequency f (which defines the number of samples per revolution or per ripple cycle, denoted as n), the following equation is derived for the sum of the product of the supply current and supply voltage per revolution or per ripple cycle of the motor:

[0119]

[0120] Where K e And fs is a constant, and the sum of the inverse EMF per sample is constant at the end of each revolution or each ripple cycle. A pulse is detected at each revolution or each ripple cycle. If no ripple is detected at the end of each revolution or each ripple cycle, and the sum of the inverse EMF per sample is essentially equal to K. e The product of fs and the sum of the inverse EMFs for each sample is lost. If the sum of the inverse EMFs for each sample is not substantially equal to K... e If the product of fs or a multiple thereof is detected, and a pulse is detected, then an erroneous pulse has been detected. These issues are addressed in the following steps.

[0121] The inverse EMF (battery voltage minus resistance multiplied by current) for each sample, calculated as above, is added to the memory value initially set to zero in step 524. Subsequently, the process checks for ripple detection in step 526. If no ripple is detected in this case, the process branches back to step 518 via step 530.

[0122] If ripple is detected in the supply current, the process continues to step 528 to verify whether the memory value is equal to K. e The product of fs or its multiples. If the memory value is K. e The multiple of the product with fs may indicate that the previous ripple of the supply current has been lost. In this case, the motor rotor has rotated many revolutions or the supply current has generated ripple equal to that multiple. In this case, in step 532, the value of the multiple is increased to the determined number of motor revolutions or the number of ripples in the supply current.

[0123] In another example, every second ripple or every first ripple is ignored. More generally, only every nth ripple is evaluated, where n is the amount of brushes of motor 100 or a multiple thereof. In this embodiment, the value of n in the above summation equation is preferably equal to the amount of sample per revolution.

[0124] It should be noted that steps 526 and 528 can be interchanged to achieve the same effect: if ripple is detected, check the memory value, and if the memory value is substantially equal to K... e The product of fs and the ripple count is then calculated. Alternatively, if the memory value is essentially equal to K... eThe product of fs and ripple is expected and counted when detected. Essentially, in this particular context, it means that a certain threshold will be considered to account for the range of product parameters. For example, winding resistance may vary from product to product. The threshold can be a fixed value or a dynamic value, such as one linearly related to transient memory values.

[0125] Once the revolutions or ripple count has been updated, the multiplier is reset to 1 in step 534, and the memory value is reset to 0. In step 538, the number of ripples or revolutions is tested against the value obtained in step 510.

[0126] If the counted amount matches or differs from the amount determined in step 510 by less than a predetermined threshold (expressed as an amount or ratio (percentage)), the process continues to step 540, where the power to the motor 100 is turned off by means of switch 206. The process continues to step 542, where information about the position of the rearview mirror is stored in a memory such as local memory 204, and the process ends at step 544. If it is determined in step 538 that the amount of the counted pulses is lower than or significantly lower than the amount determined in step 510, the process branches back to step 518.

[0127] For the second flowchart 500, it should be noted that several steps can be interchanged with the first flowchart 300. In one embodiment, based on the first flowchart, if the memory value is not substantially equal to the determined value, the detected pulses are not counted. Additionally or alternatively, if no pulse is detected and the memory value is substantially equal to the determined value or a multiple thereof, the pulse or multiple pulses are incremented to the (corrected) pulse count.

[0128] In addition to those already discussed in conjunction with the first flowchart 300, Figure 4 A third time period 430 is also shown, in which the pulse duration has decreased compared to the maximum duration at the end of the second time period 420. Subsequently, a higher pulse duration is detected in the fourth time period 440, followed by a fifth time period 450 in which a lower pulse duration is detected.

[0129] This phenomenon is called stall slip, in which one or more components of the sliding coupling alternately slip or remain stationary. In the case of slippage, the outer ring 152 ( Figure 1 The rotor 110 stalls and rotates, a configuration achieved by the sliding of at least one of the sliding couplings. Without sliding, the sliding coupling does not slide and the rotor 110 stalls. In another configuration, the sliding in the third time period 430 is greater than that in the fourth time period 440. Actual behavior depends on the materials used in the sliding coupling, the forces engaging the two sliding parts, other factors, or a combination thereof.

[0130] To more advancedly detect slippage in the transmission system 170 and its exit from the slippage state, a more refined process can be used. Figure 6 The third flowchart 600 shown illustrates one example. The components of the second flowchart 600 are briefly summarized in the following list. The process shown in the second flowchart 600 can be executed in parallel with the process shown in the first flowchart 300, in sequence, or completely independently of the process shown in the first flowchart 300.

[0131] 602 Start Process

[0132] 604 Power on the motor

[0133] 606 Determine the ripple period

[0134] 608 Stores ripple period information and timestamp

[0135] 610 Regression of the relationship between time and ripple period

[0136] 612. Set a sliding indicator?

[0137] Is the slope of 614 positive?

[0138] 616 Save the timestamp as the end time

[0139] 618. Is the start time to end time above the threshold?

[0140] 620 Obtain the lower boundary of the current signal

[0141] 622 Obtain the upper boundary of the current signal

[0142] 624 Calculate ripple count

[0143] 626 End Process

[0144] 632 Slope > Threshold?

[0145] 634 Save the time as the start time

[0146] 636 Set a sliding marker

[0147] 642 Clear the sliding icon

[0148] The process begins at start / stop frame 602 and proceeds by powering on the motor in step 604. In step 606, ripple period information is acquired. As a time period, the ripple period can be determined in any way, either as the actual time between two consecutive ripples as described above, or as an average or estimated time period, for example, based on determining the elapsed time for a specific number of ripple counts. In step 608, the ripple period information is stored along with a timestamp and accumulated along with data regarding previous ripple periods.

[0149] In step 610, a linear regression of the relationship between time and ripple period is performed. Preferably, a local linear regression is used, although other methods may also be used to determine the local or average slope of the relationship between ripple period and time.

[0150] In step 612, it is tested whether the sliding flag has been set. If not, the process branches to step 632. In step 632, it is tested whether the slope determined in step 610 is above a specific (preferably, predetermined) threshold. If not, the process branches back to step 606. If the slope is above the specific threshold, the system time is saved as the start time in step 634, and the sliding flag is set in step 636. Subsequently, the process branches back to step 606.

[0151] If it is determined in step 612 that a sliding flag has been set, the process proceeds to step 614, where the slope determined in step 610 is positive. If the slope is determined to be positive, the process branches back to step 606. If the slope is determined to be non-positive (negative or zero), the system time is saved as the end time in step 616. Subsequently, in step 618, it is tested whether the interval between the saved start time and the saved end time is above a specific (e.g., predetermined) threshold. If not, the sliding flag is cleared in step 642, and the process branches back to step 606.

[0152] If the time interval between the start and end times is above a threshold, the process proceeds to step 620, in which the lower boundary of the ripple period is determined, and then to step 622, in which the upper boundary of the ripple period is determined. Based on the determined lower and upper boundaries, the ripple count is determined in step 624. The process then ends at start / end frame 626.

[0153] In summary, drive motors, especially brushed motors, cause ripple in the supply current. The number of pulses is proportional to the number of revolutions of the motor's rotor. In the case of a defect-free motor, the number of pulses per revolution is the same. Defects in the motor's brushes, rotor, windings, and / or other components cause fluctuations in the pulses in the supply current per rotor revolution. By comparing the expected number of pulses with the number of counted pulses and using various physical parameters of the motor, various methods can be employed to correct the number of counted pulses or otherwise provide appropriate values ​​representing the motor's rotor displacement. The time between the counted pulses can also be used to determine the slippage of sliding couplings included in the transmission system to which the motor can be coupled.

[0154] In the above description, it will be understood that when an element such as a layer, region, or substrate is referred to as "on another element" or "to another element," the element is directly on that other element, or there may be intermediate elements present. It will also be understood that the values ​​given in the above description are given by way of example, and other values ​​are possible and / or can be sought.

[0155] Furthermore, the invention can be implemented with fewer components than those provided in the embodiments described herein, where one component performs multiple functions. Similarly, the invention can be implemented using more components than depicted in the figures, where the function performed by one component provided in the embodiments is distributed across multiple components.

[0156] It should be noted that the accompanying drawings are merely illustrative representations of embodiments of the invention given by way of non-limiting example. For clarity and brevity, features are described herein as part of the same or separate embodiments; however, it should be understood that the scope of the invention may include embodiments having all or some of the said features. The word "comprising" does not exclude the presence of other features or steps besides those listed in the claims. Furthermore, the words "a" and "an" should not be construed as limited to "only one," but are used to mean "at least one," and do not exclude a plurality.

[0157] Those skilled in the art will readily understand that various parameters and values ​​disclosed herein can be modified without departing from the scope of the invention, and that the various disclosed and / or claimed embodiments can be combined.

[0158] As is customary, reference numerals in the claims do not limit the scope of the claims, but are inserted only to enhance the readability of the claims.

Claims

1. A method for providing information about the circular position of a DC motor, the method comprising: Monitor power supply parameters, including the supply current of the DC motor, and obtain at least one value of at least one monitored parameter; Determine the expected pulse timing of the pulse that is expected to appear in the supply current; as well as If a pulse is detected at the expected pulse time, then count the pulses. in: The monitored power parameters include the supply voltage of the DC motor; and The values ​​of the power supply parameters are obtained by sampling at a sampling frequency; The method further includes: Obtain the resistance value of the motor windings; determine the expected pulse time based on the power supply parameters, the winding resistance value, and the sampling frequency. The method further includes: Multiply the winding resistance value and the supply current value at each sampling point; The difference between the supply voltage of the subsequent sample and the product of the resistance value of the winding and the supply current value is added together to obtain the power supply product sum; Electromagnetic force parameters are determined based on the following relationship. K e : Where Vbat is the supply voltage, R is the winding resistance, I is the supply current, and f is the motor's ring frequency; and The expected pulse moment is determined as the moment when the product of the power supply and the electromagnetic force parameter are substantially equal to the product of the sampling frequency.

2. The method according to claim 1, further comprising: If no pulse is detected at the expected pulse time, then the subsequent expected pulse time is determined; Once a pulse is detected in the supply current at the subsequent expected pulse time, the detected pulse is added to the number of pulses that have not been detected at the expected pulse time since the last detected pulse.

3. The method according to claim 1 or 2, wherein, Determining the expected pulse timing includes: Determine the basic expected pulse period between two subsequent pulses; The expected pulse timing is determined by multiplying the basic expected pulse period by the number of brush contacts included in the DC motor or a multiple thereof.

4. A method for determining the position of an actuable object arranged to be driven by a brushed DC motor, the method comprising: The method according to any one of claims 1-3; as well as The position of the actuable object is determined based on the adjusted count of pulses.

5. The method according to claim 4, further comprising: Obtain the initial position of the actuable object; The position of the actuable object is determined based on the adjusted counted pulse quantity and the initial position of the actuable object.

6. The method according to claim 5, further comprising: The actuable object is driven by supplying power current to the motor; Monitor the power supply current; If the waveform of the power supply current meets at least one predetermined condition, it is determined that the actuable object has reached the external position.

7. The method of claim 6, further comprising setting the external position as the initial position.

8. The method according to claim 6, wherein, The predetermined condition is that the measured time period exceeds a predetermined threshold.

9. The method according to any one of claims 4 to 8, further comprising: Receive a command for actuating the actuable object; A DC power supply is provided to the DC motor for actuating the actuable object according to the command.

10. An apparatus for providing information about the circular speed of a DC motor, the apparatus comprising: A monitoring module is configured to monitor power parameters including the supply current of the DC motor and obtain at least one value of at least one monitored parameter. The processing module is arranged as follows: Determine the expected pulse timing of the pulse expected to appear in the supply current; and If a pulse is detected at the expected pulse time, the pulses are counted; in: The monitored power parameters include the supply voltage of the DC motor; and The values ​​of the power supply parameters are obtained by sampling at a sampling frequency; The processing module is further configured as follows: Obtain the resistance value of the motor windings; The expected pulse timing is determined based on the values ​​of the power supply parameters, the resistance value of the winding, and the sampling frequency. The processing module is also configured at each sampling point: Multiply the winding resistance value and the supply current value at each sampling point; The difference between the supply voltage of the subsequent sample and the product of the resistance value of the winding and the supply current value is added together to obtain the power supply product sum; Electromagnetic force parameters are determined based on the following relationship. K e : Where Vbat is the supply voltage, R is the winding resistance, I is the supply current, and f is the motor's ring frequency; and The expected pulse moment is determined as the moment when the product of the power supply and the electromagnetic force parameter are substantially equal to the product of the sampling frequency.

11. The apparatus according to claim 10, wherein, The processing module is further configured as follows: The average ring speed index is obtained based on the supply current; Based on the aforementioned indicators, the expected time interval between two consecutive pulses in the power supply current is determined to determine the expected pulse timing. The number of pulses counted is obtained by counting the pulses in the supply current. Determine the measured time interval between two consecutive counted pulses; The count is adjusted using at least one of the following methods to obtain the adjusted counted pulse quantity; If the measured time period is shorter than the expected time period by more than a first predetermined threshold, the number of counted pulses is adjusted by subtracting one. If the measured time period is longer than the expected time period by more than a second predetermined threshold, the number of counted pulses is adjusted by increasing by one.

12. A control system for actuating an actuable element of a motor vehicle, the system comprising: The apparatus according to any one of claims 10 to 11; DC motor; A transmission system for connecting the DC motor to the actuable element; The transmission system includes: The first drive element connected to the DC motor; and A second transmission element is arranged to be connected to the actuable element; The first transmission element and the second transmission element are arranged to engage with each other such that if the coupling torque between the first transmission element and the second transmission element is lower than a predetermined torque level, the first transmission element and the second transmission element move together, and if the coupling torque is higher than the predetermined torque level, the first transmission element and the second transmission element slide relative to each other.

13. A rearview mirror module comprising the system of claim 12 and a rearview mirror as the actuable element.

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