Torque estimation method, torque estimation device, and torque estimation program

Abstract

A torque estimation method, a torque estimation device, and a torque estimation procedure are provided. The torque estimation method is a torque estimation method for estimating the value of the shaft torque of a rotary motion transmission mechanism. The torque estimation method of the present invention includes: a step of determining the maximum value of the torsion angle from a time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to a time point when the value of the shaft torque is estimated; and a step of determining the maximum value of the torsion angle. In the step of determining the maximum value of the torsion angle, the maximum value of the torsion angle is determined based on the difference between the measured value of the torsion angle after low-pass filtering at a first cutoff frequency and the measured value of the torsion angle after low-pass filtering at a second cutoff frequency.

Description

Technical Field

[0001] This invention relates to a torque estimation method, a torque estimation device, and a torque estimation procedure. Background Technology

[0002] Sometimes a torsion angle occurs between the input and output shafts of rotary motion transmission mechanisms such as gearboxes. Japanese Patent Application Publication No. 2009-97896 discloses a technique for estimating the shaft torque of a rotary motion transmission mechanism based on this torsion angle.

[0003] The phenomenon known as hysteresis is that when a rotary motion transmission mechanism is stopped, even if the shaft torque becomes 0, the torsional angle between the input and output shafts does not become 0. The magnitude of this hysteresis depends on the maximum value of the shaft torque from when the torsional angle becomes 0 until it returns to 0. This is disclosed in the following literature: Rached Dhaouadi and two other authors, “A New Dynamic Model of Hysteresis in Harmonic Drives”, IEEE Transactions on Industrial Electrics, Vol. 50, No. 6, December 2003.

[0004] Therefore, when estimating shaft torque based on torsion angle, it is necessary to estimate the magnitude of hysteresis and then estimate the value of shaft torque by taking into account the estimated magnitude of hysteresis. Summary of the Invention

[0005] In the technology disclosed in Japanese Patent Application Publication No. 2009-97896, in order to estimate the aforementioned hysteresis value, the value of the torsion angle is obtained as data over a long period of time, and its tendency is analyzed. However, this method requires storing the value of the torsion angle as data for a long period of time, thus consuming memory resources.

[0006] This invention was made to solve such a problem, and its purpose is to provide a torque estimation method, torque estimation device, and torque estimation program that can suppress the memory resources required for estimating the shaft torque.

[0007] One technical solution of the present invention relates to a torque estimation method for estimating the value of the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft. The torque estimation method includes:

[0008] The step of determining the maximum value of the torsion angle from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined; and

[0009] The step of estimating the value of the shaft torque based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle.

[0010] In the step of determining the maximum value of the torsion angle, the maximum value of the torsion angle is determined based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency.

[0011] In the torque estimation method of one technical solution of the present invention described above, firstly, the maximum value of the torsion angle at the estimation time point is determined based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency. Then, the value of the shaft torque is estimated based on the determined maximum value of the torsion angle and the value of the torsion angle at the estimation time point.

[0012] Thus, the torque estimation method of one technical solution of the present invention can be executed as long as at least the maximum value of the torsion angle is stored, thereby suppressing the memory resources required for estimating the shaft torque.

[0013] In the torque estimation method described above, the step of determining the maximum value of the torsion angle can also be performed as follows:

[0014] The difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency is calculated.

[0015] The time point at which the sign of the difference in torsion angles is reversed is detected as the time point at which the torsion angle reaches its extreme value.

[0016] The extreme value with the largest absolute value among the detected extreme values ​​of the torsion angle is determined as the maximum value of the torsion angle.

[0017] Thus, the torque estimation method of one technical solution of the present invention can determine the maximum value of the torsion angle as long as it stores at least the extreme value of the largest value. Therefore, it can suppress the memory resources required for estimating the shaft torque.

[0018] In the torque estimation method described above, the step of estimating the value of the shaft torque can also be performed as follows:

[0019] The hysteresis value of the shaft torque is estimated based on the maximum value of the torsion angle.

[0020] The value of the shaft torque is estimated based on the hysteresis value.

[0021] Thus, the torque estimation method of one technical solution of the present invention can estimate the hysteresis value based on a single value (the maximum value of the torsional angle), thereby suppressing the memory resources required for estimating the shaft torque.

[0022] In the torque estimation method described above, the value of the shaft torque at which the rotational motion stops can also be estimated during the step of estimating the value of the shaft torque.

[0023] The hysteresis has a significant impact on the estimated value of the shaft torque when the rotational motion stops. Therefore, the torque estimation method of one technical solution of the present invention is particularly effective in estimating the value of the shaft torque when the rotational motion stops.

[0024] The torque estimation method described above can also be used to detect the torsion angle of the input shaft and the output shaft by a first sensor installed on the input shaft and a second sensor installed on the output shaft.

[0025] One technical solution of the present invention relates to a torque estimation device for estimating the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft, the torque estimation device comprising:

[0026] The first sensor is installed on the input shaft;

[0027] The second sensor is installed on the output shaft;

[0028] A first low-pass filter and a second low-pass filter, each with a different cutoff frequency; and

[0029] The control unit estimates the value of the shaft torque based on the measured values ​​of the torsional angles of the input shaft and the output shaft detected by the first sensor and the second sensor.

[0030] The control unit,

[0031] Based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency, the maximum value of the torsion angle is determined from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined.

[0032] The value of the shaft torque is estimated based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle.

[0033] One technical solution of the present invention relates to a torque estimation program that enables a computer to execute a process for estimating the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft. The torque estimation program includes:

[0034] The step of determining the maximum value of the torsion angle from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined; and

[0035] The step of estimating the value of the shaft torque based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle.

[0036] In the step of determining the maximum value of the torsion angle, the maximum value of the torsion angle is determined based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency.

[0037] According to the present invention, a torque estimation method, a torque estimation device, and a torque estimation program are provided that can suppress the memory resources required for estimating the shaft torque. Attached Figure Description

[0038] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, and wherein:

[0039] Figure 1 It is a graph showing the relationship between the torsion angle and the magnitude of the shaft torque of a rotary motion transmission mechanism.

[0040] Figure 2 It is a graph showing the relationship between the torsion angle and the magnitude of the shaft torque of a rotary motion transmission mechanism.

[0041] Figure 3 This is a block diagram showing the configuration of the torque estimation device according to the first embodiment.

[0042] Figure 4 This is a flowchart illustrating the processing of the torque estimation method according to the first embodiment.

[0043] Figure 5 This is a flowchart illustrating the process of determining the maximum value of the torsion angle.

[0044] Figure 6 This is a graph used to explain the processing of the torque estimation method according to the first embodiment.

[0045] Figure 7 It is a graph used to illustrate the processing of extreme values ​​of the detected torsion angle. Detailed Implementation

[0046] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. In addition, for the sake of clarity, the following description and drawings have been appropriately simplified.

[0047] (First Embodiment)

[0048] <Explanation of the hysteresis in the relationship between torsion angle and shaft torque>

[0049] The torque estimation method described in this embodiment is a method for correcting estimation errors of shaft torque caused by hysteresis.

[0050] First, use Figure 1 and Figure 2 This lag is explained in detail. Figure 1 , Figure 2 This is a graph showing the relationship between the torsion angle and the magnitude of the shaft torque in a rotary motion transmission mechanism. Figure 1 The diagram illustrates two scenarios: the shaft torque starts changing from the origin P0, reaches its maximum value at point P1 and then returns to zero, and the shaft torque reaches its maximum value at point P2 and then returns to zero.

[0051] Due to the lag, the torsional angle at the point where the shaft torque recovers to 0 is not zero in any case, and takes different values ​​for the torsional angle in each case (points P3 and P4). That is, the torsional angle values ​​taken at these points P3 and P4 depend on the values ​​of points P1 and P2, i.e., the maximum value of the shaft torque.

[0052] exist Figure 2 The diagram illustrates how the shaft torque changes from the origin P0, passing through points P1, P3, P5, and P6 in the order described below, before reaching point P7. Figure 1 Similarly, if the shaft torque value returns to 0 after passing through point P1, it will not return to the origin P0 but will reach point P3 due to lag. The value of point P3 depends on the shaft torque value at point P1, as mentioned above.

[0053] After reaching point P3, when shaft torque is applied in the opposite direction, the torsion angle becomes 0 at point P5. Here, when traveling from point P5 through point P6 to point P7, the torsion angle at point P7 depends only on the shaft torque at point P6, not on the shaft torque at point P1. That is, the maximum value of the shaft torque is reset at the point when the torsion angle becomes 0. In other words, the magnitude of the hysteresis depends on the maximum value of the shaft torque from when the torsion angle becomes 0 until it returns to 0.

[0054] Furthermore, in this specification, the value of shaft torque refers to the magnitude of the shaft torque, i.e., its absolute value.

[0055] Based on the above, if the maximum value of the shaft torque from when the torsion angle becomes 0 until it returns to 0 can be known, then the hysteresis value can be estimated. Furthermore, the maximum value of the shaft torque can be estimated based on the maximum value of the torsion angle. Therefore, if the maximum value of the torsion angle from when the torsion angle becomes 0 until it returns to 0 can be known, then the hysteresis value can be estimated.

[0056] Therefore, in this embodiment, the estimation error of shaft torque caused by hysteresis is corrected by determining the maximum value of the torsion angle from when the torsion angle becomes 0 until it returns to 0.

[0057] <Composition of the Torque Estimation Device>

[0058] Next, refer to Figure 3 The torque estimation device according to the first embodiment will be described. Figure 3 This is a block diagram illustrating the configuration of the torque estimation device according to the first embodiment. Figure 3 In this embodiment, based on the torque estimation device 1, a rotary motion transmission mechanism 2, a power source 3, and a power output object component 4 are also shown.

[0059] The rotary motion transmission mechanism 2, for example, is a gearbox, which is a device for transmitting the rotary motion output by the power source 3 to the power output object component 4. The rotary motion transmission mechanism 2 has an input shaft S1 and an output shaft S2, which converts the rotary motion input to the input shaft S1 into an appropriate angular velocity and direction, and outputs it from the output shaft S2.

[0060] The power source 3 is, for example, a device capable of outputting rotary motion from an engine, motor, or the like. The power source 3 is connected to the input shaft S1.

[0061] The power output object component 4, such as the wheel of a moving body or the linkage of a robot arm, is the object whose rotational motion is output. The power output object component 4 is connected to the output shaft S2.

[0062] like Figure 3 As shown, the torque estimation device 1 includes an input shaft-side encoder 11, an output shaft-side encoder 12, a torsion angle calculation unit 13, a control unit 14, and low-pass filters LPF1 and LPF2.

[0063] The input shaft-side encoder 11 is a sensor (first sensor) mounted on the input shaft S1, which detects the rotation angle of the input shaft S1. The input shaft-side encoder 11 outputs the detected rotation angle information of the input shaft S1 to the torsion angle calculation unit 13.

[0064] The output shaft-side encoder 12 is a sensor (second sensor) mounted on the output shaft S2, which detects the rotation angle of the output shaft S2. The output shaft-side encoder 12 outputs the detected rotation angle information of the output shaft S2 to the torsion angle calculation unit 13.

[0065] The torsion angle calculation unit 13 calculates the torsion angle based on the rotation angle information of the input shaft S1 obtained from the input shaft-side encoder 11 and the rotation angle information of the output shaft S2 obtained from the output shaft-side encoder 12. The torsion angle calculated by the torsion angle calculation unit 13 contains noise, and therefore, it is output to the low-pass filters LPF1 and LPF2.

[0066] Low-pass filters LPF1 and LPF2 are low-pass filters with different cutoff frequencies. Low-pass filters LPF1 and LPF2 perform low-pass filtering (hereinafter referred to as LPF processing) on ​​the torsion angle calculated by the torsion angle calculation unit 13 at different cutoff frequencies. Low-pass filters LPF1 and LPF2 output the LPF-processed torsion angle to the control unit 14.

[0067] Furthermore, in this embodiment, the cutoff frequency of the low-pass filter (first low-pass filter) LPF1 is set to be smaller than the cutoff frequency of the low-pass filter (second low-pass filter) LPF2, but this relationship can also be reversed.

[0068] Furthermore, from now on, the torsion angle processed by the low-pass filter LPF1 will be called the torsion angle L, and the torsion angle processed by the low-pass filter LPF2 will be called the torsion angle H.

[0069] The control unit 14 obtains the values ​​of torsion angle L and torsion angle H from the low-pass filters LPF1 and LPF2. Furthermore, based on the obtained values ​​of torsion angle L and torsion angle H, the control unit 14 estimates the value of the shaft torque acting on the rotary motion transmission mechanism 2.

[0070] Here, the control unit 14 controls the output of the power source 3, for example, based on the estimated value of the shaft torque. The control unit 14 can control the rotational motion more precisely based on the estimated value of the shaft torque.

[0071] In addition, the control unit 14 may not control the output of the power source 3, but only estimate the value of the shaft torque.

[0072] More specifically, such as Figure 3 As shown, the control unit 14 includes a subtraction operation unit 141, a maximum torsion angle reset unit 142, a maximum torsion angle detection unit 143, and a torque estimation unit 144.

[0073] The subtraction unit 141 obtains the values ​​of torsion angle L and torsion angle H from the low-pass filters LPF1 and LPF2, and calculates the value obtained by subtracting the torsion angle H from the torsion angle L, i.e., the value of (torsion angle L - torsion angle H). The subtraction unit 141 outputs the calculated value of (torsion angle L - torsion angle H) to the torsion angle maximum value detection unit 143.

[0074] The maximum torsion angle reset unit 142 obtains the value of the torsion angle L from the low-pass filter LPF1. The maximum torsion angle reset unit 142 detects the positive and negative reversal of the value of the torsion angle L, and notifies the maximum torsion angle detection unit 143 when the positive and negative reversal of the value of the torsion angle L is detected.

[0075] The maximum torsion angle detection unit 143 obtains the value of (torsion angle L - torsion angle H) from the subtraction unit 141 and detects the reversal of the positive and negative values ​​of (torsion angle L - torsion angle H). When the maximum torsion angle detection unit 143 detects the reversal of the positive and negative values ​​of (torsion angle L - torsion angle H), it regards that time point as the time point when the torsion angle reaches its extreme value and obtains the value of the torsion angle L at that time point from the low-pass filter LPF1.

[0076] If the obtained value of the torsion angle L is greater than the maximum value of the torsion angle L at that time point, the maximum value of the torsion angle detection unit 143 updates the maximum value of the torsion angle to the obtained value of the torsion angle L. The maximum value of the torsion angle detection unit 143 outputs the maximum value of the torsion angle L to the torque estimation unit 144.

[0077] Furthermore, the reason for considering the point in time when the sign of (torsion angle L - torsion angle H) is reversed as the point in time when the torsion angle reaches its extreme value will be described later.

[0078] Furthermore, upon receiving a notification from the torsion angle maximum value detection unit 143, the torsion angle maximum value reset unit 142 resets the maximum value of the torsion angle. Specifically, the maximum value of the torsion angle is updated to 0.

[0079] The torque estimation unit 144 obtains the value of the torsion angle L from the low-pass filter LPF1 and the maximum value of the torsion angle from the maximum value detection unit 143. Furthermore, the torque estimation unit 144 estimates the value of the shaft torque of the rotary motion transmission mechanism 2 based on the torsion angle L and its maximum value. Specifically, the torque estimation unit 144 estimates the magnitude of the hysteresis based on the maximum value of the torsion angle L, and estimates the value of the shaft torque of the rotary motion transmission mechanism 2 based on the estimated magnitude of the hysteresis and the value of the torsion angle L.

[0080] Furthermore, the torque estimation unit 144 can estimate the value of the shaft torque based solely on the value of the torsion angle L when the rotary motion transmission mechanism 2 continues to rotate, and estimate the value of the shaft torque based on the torsion angle L and the maximum value of the torsion angle L when the rotary motion transmission mechanism 2 stops rotating.

[0081] Furthermore, the control unit 14 includes, for example, an arithmetic unit such as a CPU (Central Processing Unit, not shown) and a storage unit such as RAM (Random Access Memory) or ROM (Read Only Memory) that stores programs and data used to estimate the shaft torque value. In other words, the control unit 14 functions as a computer, estimating the shaft torque value based on the aforementioned program.

[0082] Therefore, constitute Figure 1 The functional blocks of the control unit 14 shown can be constructed in hardware by the aforementioned CPU, storage unit, and other circuits, and in software by a program stored in the storage unit for estimating the value of the shaft torque. That is, the control unit 14 can be implemented in various ways by hardware, software, or a combination of both.

[0083] <Torque Estimation Method>

[0084] Next, use Figure 4 The process of estimating the value of the shaft torque acting on the rotary motion transmission mechanism 2 using the torque estimation device 1, i.e., the torque estimation method involved in this embodiment, will be described in detail. Figure 4 This is a flowchart illustrating the processing of the torque estimation method according to the first embodiment. Figure 4 In the explanation, please refer to the following: Figure 3 .

[0085] First, such as Figure 4 As shown, in the torque estimation device 1, the input shaft-side encoder 11 detects the rotation angle information of the input shaft S1, and the output shaft-side encoder 12 detects the rotation angle information of the output shaft S2 (step ST1).

[0086] Next, the torsion angle calculation unit 13 calculates the torsion angles of the input shaft S1 and the output shaft S2 based on the information of the rotation angle of the input shaft S1 detected by the input shaft-side encoder 11 and the information of the rotation angle of the output shaft S2 detected by the output shaft-side encoder 12 (step ST2).

[0087] Next, since the calculated torsion angle contains noise, LPF processing is performed by low-pass filter LPF1 to remove the noise (step ST3). Alternatively, LPF processing can be performed by low-pass filter LPF2.

[0088] Next, the control unit 14 determines the maximum value of the torsion angle from the time point when the torsion angle of the input shaft S1 and the output shaft S2 is 0 to the time point when the estimated shaft torque is reached (step ST4) through the processing described in detail later.

[0089] Finally, the control unit 14 estimates the value of the shaft torque of the rotary motion transmission mechanism 2 based on the measured value of the torsion angle at the time point at which the estimated shaft torque value is determined and the maximum value of the torsion angle determined in step ST4 (step ST5). Specifically, the control unit 14 estimates the magnitude of the hysteresis based on the maximum value of the torsion angle determined in step ST4, and estimates the value of the shaft torque based on the estimated magnitude of the hysteresis.

[0090] Especially when the rotational motion is stopped, the hysteresis can significantly affect the estimated value of the shaft torque. Therefore, the torque estimation device 1 according to this embodiment can also be used, particularly when estimating the value of the shaft torque when the rotational motion is stopped, by means of... Figure 4 The process shown is used to estimate the shaft torque. Alternatively, the torque estimation device 1 can calculate the shaft torque without considering hysteresis while the rotational motion continues; for example, it can be configured to calculate the shaft torque by multiplying the torsional angle by an inherent elastic constant. When configured in this way, the processing required for estimating the shaft torque can be simplified.

[0091] The following uses Figure 5 The steps for determining the maximum value of the twist angle mentioned above ( Figure 4 The process in step ST4 will be explained in more detail. Figure 5 This is a flowchart illustrating the process of determining the maximum value of the torsion angle. The torque estimation device 1 according to this embodiment determines the maximum value of the torsion angle based on the difference between the measured value of the torsion angle after LPF processing at the first cutoff frequency and the measured value of the torsion angle after LPF processing at the second cutoff frequency.

[0092] First, regarding Figure 4 In step ST2, the torsion angle calculated by the torsion angle calculation unit 13 is processed by an LPF with a small cutoff frequency (hereinafter referred to as weak LPF processing) and an LPF with a large cutoff frequency (hereinafter referred to as strong LPF processing), and the torsion angle L and torsion angle H are output (step ST41). Specifically, the weak LPF processing is performed by a low-pass filter LPF1, and the strong LPF processing is performed by a low-pass filter LPF2.

[0093] Furthermore, either the torsion angle L or the torsion angle H can also be used in Figure 3 The torsion angle that underwent LPF treatment in step ST3. In this embodiment, the torsion angle is used in... Figure 3 The torsion angle L is used as the LPF angle after LPF treatment in step ST3.

[0094] Next, the subtraction unit 141 performs the process of subtracting the value of the torsion angle H from the value of the torsion angle L. That is, the subtraction unit 141 calculates the value of (torsion angle L - torsion angle H) (step ST42). Alternatively, the value of the torsion angle L can also be subtracted from the value of the torsion angle H.

[0095] Next, the maximum torsion angle detection unit 143 determines whether the sign of the value of (torsion angle L - torsion angle H) obtained in step ST42 has been reversed (step ST43).

[0096] Figure 6 It is used to represent and Figure 5 The graph shows the processing instances corresponding to steps ST41 to ST43. Figure 6 The horizontal axis of the four graphs represents the data acquired by the torque estimation device 1, which essentially represents time. Furthermore, the values ​​of the horizontal axis in these four graphs are aligned. Figure 6 The curves a to d represent the values ​​of the torsion angle, torsion angle L, torsion angle H, and (torsion angle L - torsion angle H) before LPF treatment, respectively, on the vertical axis.

[0097] Furthermore, all the measured torsional angles are recorded in these graphs, but this is for the sake of simplicity; the torque estimation device 1 does not simultaneously store all the torsional angles recorded in the graphs.

[0098] As described above, the maximum torsion angle detection unit 143 detects the point at which the sign of the value of (torsion angle L - torsion angle H) is reversed as the point at which the torsion angle reaches its extreme value. Therefore, focusing on... Figure 6 The curve d shows the time points where the signs were reversed. Lines L1 to L6 respectively contain... Figure 6 The curve d represents the time points where the positive and negative signs are reversed and is a straight line perpendicular to the horizontal axis. When referring to this straight line L1~L6 and curves b and c, it can be seen that the straight line L1~L6 does indeed pass near the time points where the torsion angles L and H reach their extreme values.

[0099] return Figure 5 Explanation of the flowchart.

[0100] If the value of (torsion angle L - torsion angle H) is not reversed (step ST43: no), proceed to step ST46 described later.

[0101] On the other hand, if the sign of the value of (torsion angle L - torsion angle H) is reversed (step ST43: Yes), the value of the torsion angle L at that time point is determined to be the extreme value of the newly detected torsion angle L. Then, it is determined whether the extreme value of the newly detected torsion angle L is greater than the maximum value of the torsion angle L at that time point (step ST44).

[0102] If the newly detected extreme value of the torsion angle L is greater than the maximum value of the torsion angle L at that time point (step ST44: Yes), the maximum value of the torsion angle L is updated to the newly detected extreme value of the torsion angle L (step ST45). Then, proceed to step ST46, which will be described later.

[0103] On the other hand, if the extreme value of the newly detected torsion angle L is smaller than the maximum value of the torsion angle L at that time point (step ST44: No), the maximum value of the torsion angle L is not updated, and it is determined whether the sign of the torsion angle L is reversed (step ST46).

[0104] If the positive and negative values ​​are reversed (step ST46: Yes), it is determined that there is a time point when the value of the torsion angle L becomes 0, the maximum value of the torsion angle L is reset (step ST47), and the process ends directly.

[0105] On the other hand, if the positive and negative values ​​are not reversed (step ST46: No), the maximum value of the torsion angle L is not reset, and the process returns to step ST41. That is, steps ST41 to ST46 are repeated until the maximum value of the torsion angle L is reset. When the maximum value of the torsion angle L is reset, the process restarts. Figure 5 The processing shown.

[0106] When the maximum value of the torsion angle L is determined through the process described above, the control unit 14 only needs to store the maximum value of the torsion angle. Therefore, by determining the maximum value of the torsion angle through such processing, the memory resources required for estimating the shaft torque can be suppressed.

[0107] Furthermore, steps ST43 to ST45 performed by the maximum torsion angle detection unit 143 and step ST46 performed by the maximum torsion angle reset unit 142 are actually performed in parallel.

[0108] <Method for determining the extreme values ​​of the twist angle>

[0109] As described above, the torque estimation device 1 of this embodiment determines the time point when the sign of the value of (torsion angle L - torsion angle H) is reversed as the time point when the torsion angle L reaches its extreme value. Hereinafter, using... Figure 7 The reasons why the extreme value of the torsion angle L can be determined through such processing are explained in detail.

[0110] Figure 7 It is a graph used to illustrate the processing of extreme values ​​of the detected torsion angle. Figure 7 This is a graph depicting the value of the torsion angle relative to time, with the graphs of torsion angle 101L and torsion angle 101H shown overlaid. The torsion angles 101L and 101H were obtained by applying weak LPF processing and strong LPF processing, respectively, to the torsion angles with maximum values.

[0111] Here, point P8 is the point where the torsion angle 101L reaches its maximum value, and this moment is set as time t1. Additionally, point P9 is the point where the torsion angles L and H intersect, and this moment is set as time t2.

[0112] When LPF processing with different cutoff frequencies is applied to the torsion angle, the increase or decrease in the value of the torsion angle processed with a larger cutoff frequency is delayed compared to the torsion angle processed with a smaller cutoff frequency. Therefore, when observing... Figure 7 When looking at the curves of torsion angles 101L and 101H, it can be seen that the curve of torsion angle 101H is delayed relative to that of torsion angle 101L.

[0113] Furthermore, this can be described as generating pseudo-time difference by performing LPF processing with different cutoff frequencies.

[0114] When the torsion angles 101L and 101H have maximum values, such as Figure 7 As shown, the moment when the curves of torsion angle 101L and torsion angle 101H intersect, i.e., time t2, is used as the boundary, and the magnitudes of the values ​​of torsion angle 101L and torsion angle 101H are interchanged.

[0115] That is, time t2 corresponds to the time point where the sign of the value of (torsion angle L - torsion angle H) is reversed.

[0116] Time t2 is not the same as the time t1 when the torsion angle L strictly reaches its maximum value. Therefore, by adjusting the cutoff frequencies of the weak and strong LPF processes, the difference between time t1 and time t2 can be reduced to within the error range. Thus, if the cutoff frequencies of the weak and strong LPF processes are appropriately set, the time point when the sign of (torsion angle L - torsion angle H) is reversed can also be determined as the time point when the torsion angle L reaches its extreme value.

[0117] Based on the reasons explained above, the torque estimation device 1 according to this embodiment can also determine the time point when the sign of the value of (torsion angle L - torsion angle H) is reversed as the time point when the torsion angle L reaches its extreme value. With this determination, the torque estimation device 1 according to this embodiment does not need to store the value of the torsion angle in order to determine the extreme value of the torsion angle L, thus suppressing memory resources.

[0118] Furthermore, as a method related to the aforementioned method for determining the extreme value of the torsion angle, the following approach can be conceived: subtracting the torsion angle value from the torsion angle value before a predetermined time, and determining the time point at which the sign of this value is reversed as the time point when the torsion angle reaches its extreme value. However, this method requires storing the torsion angle value for at least a predetermined amount of time, thus making it difficult to suppress the memory resources required for torque estimation.

[0119] By configuring it as described above, the torque estimation device 1 according to this embodiment can suppress the memory resources required for estimating shaft torque.

[0120] The torque estimation method involved in this embodiment can also be executed by the torque estimation program mounted on the torque estimation device 1.

[0121] Furthermore, the program includes a set of commands (or software code) for causing the computer to perform one or more functions described in the embodiments, when read by the computer. The program may also be stored on a non-transitory computer-readable medium or a physical storage medium. As non-limiting examples, computer-readable media or physical storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray disc or other optical disc storage, magnetic tape, magnetic tape, disk storage, or other magnetic storage devices. The program may also be transmitted on a transient computer-readable medium or communication medium. As non-limiting examples, transient computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0122] The present invention has been described above based on the above embodiments, but the present invention is not limited to the above embodiments. Of course, it includes various modifications, alterations and combinations that can be made by those skilled in the art within the scope of the invention as described in the claims of this application.

Claims

1. A torque estimation method for estimating the value of the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft, the torque estimation method comprising: The step of determining the maximum value of the torsion angle from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined; and The step of estimating the value of the shaft torque based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle. In the step of determining the maximum value of the torsion angle, the maximum value of the torsion angle is determined based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency.

2. The torque estimation method according to claim 1, In the step of determining the maximum value of the twist angle, The difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency is calculated. The point at which the sign of the difference in torsion angles reverses is detected as the point at which the torsion angle reaches its extreme value. The extreme value with the largest absolute value among the detected extreme values ​​of the torsion angle is determined as the maximum value of the torsion angle.

3. The torque estimation method according to claim 1, In the step of estimating the value of the shaft torque The hysteresis value of the shaft torque is estimated based on the maximum value of the torsion angle. The value of the shaft torque is estimated based on the hysteresis value.

4. The torque estimation method according to claim 1, In the step of estimating the value of the shaft torque, the value of the shaft torque at which the rotational motion stops is estimated.

5. The torque estimation method according to any one of claims 1 to 4, The torsion angles of the input shaft and the output shaft are detected by a first sensor mounted on the input shaft and a second sensor mounted on the output shaft.

6. A torque estimation device for estimating the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft, the torque estimation device comprising: The first sensor is installed on the input shaft; The second sensor is installed on the output shaft; A first low-pass filter and a second low-pass filter, each with a different cutoff frequency; and The control unit estimates the value of the shaft torque based on the measured values ​​of the torsional angles of the input shaft and the output shaft detected by the first sensor and the second sensor. The control unit, Based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency, the maximum value of the torsion angle is determined from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined. The value of the shaft torque is estimated based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle.

7. A torque estimation program that enables a computer to perform a process of estimating the shaft torque of a rotary motion transmission mechanism having an input shaft and an output shaft, the torque estimation program comprising: The step of determining the maximum value of the torsion angle from the time point when the measured value of the torsion angle of the input shaft and the output shaft is 0 to the time point when the estimated value of the shaft torque is determined; and The step of estimating the value of the shaft torque based on the measured value of the torsion angle at the time point at which the value of the shaft torque is estimated and the maximum value of the torsion angle. In the step of determining the maximum value of the torsion angle, the maximum value of the torsion angle is determined based on the difference between the measured value of the torsion angle after low-pass filtering at the first cutoff frequency and the measured value of the torsion angle after low-pass filtering at the second cutoff frequency.

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