Gear motor and control program of gear motor

Abstract

A gear motor 100 comprises: a motor 20; a magnetic modulation gear 30 having a high-speed rotor (input shaft) 31 to which an output of the motor 20 is inputted, and an output shaft 32 of which the speed is changed with respect to the high-speed rotor 31 through a speed reduction unit; and a control device 40 that controls the output of the motor 20. The control device 40 controls the output of the motor 20 on the basis of torque-phase difference characteristics representing the relationship between an output torque of the output shaft 32 and phase difference information relating to rotational positions of the high-speed rotor 31 and the output shaft 32. Torque-angle characteristics of the output shaft 32 representing the relationship between the torque and the phase of the output shaft 32 are variable.

Description

Gear motor and control program for gear motor

[0001] The present invention relates to a gear motor and a control program for the gear motor.

[0002] Conventionally, a magnetic modulation gear is known in which a plurality of magnetic pole pieces are arranged between two magnets arranged on the inner and outer circumferences to modulate the magnetic flux distribution between the inner and outer circumferential magnets. In torque control of a gear motor provided with a magnetic modulation gear, the output of the motor has been controlled based on torque-phase difference characteristics representing the relationship between the phase difference of the input and output shafts and the output torque (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-150614

[0004] However, in the above conventional technology, the torque-angle characteristics of the output shaft were constant regardless of the angle information of the input and output shafts. The present invention has been made in view of the above circumstances, and an object thereof is to make the torque-angle characteristics variable in a gear motor provided with a magnetic modulation gear.

[0005] The present invention is a gear motor, comprising: a motor; an input shaft to which the output of the motor is input; a magnetic modulation gear having an output shaft that is speed-changed with respect to the input shaft through a speed reduction unit; and a control unit that controls the output of the motor. The control unit controls the output of the motor based on torque-phase difference characteristics representing the relationship between phase difference information regarding the rotational positions of the input shaft and the output shaft and the output torque of the output shaft, and the torque-angle characteristics of the output shaft representing the relationship between the torque and phase of the output shaft are variable.

[0006] According to the present invention, in a gear motor provided with a magnetic modulation gear, the torque-angle characteristics can be made variable.

[0007] It is a cross-sectional view of a gear motor according to an embodiment. It is a perspective view of a main part of a magnetic modulation gear according to an embodiment. It is a block diagram showing a schematic control configuration of a gear motor according to an embodiment. It is a graph showing the relationship between the phase difference and the output torque on the output shaft.

[0008] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a cross-sectional view of the gear motor body 100 of the gear motor 1 according to this embodiment. The gear motor 1 according to this embodiment includes the gear motor body 100 and a control device 40 that performs torque control of the gear motor body 100, etc. (see Figure 3). In the following description, the direction along the central axis Ax of the gear motor body 100 is called the "axial direction," the direction perpendicular to the central axis Ax is called the "radial direction," and the rotational direction around the central axis Ax is called the "circumferential direction." Furthermore, within the axial direction, the side connected to the external driven member (left side in Figure 1) is called the "load side," and the side opposite to the load side (right side in Figure 1) is called the "non-load side." Also, in the following, the "gear motor body" may be simply referred to as the "gear motor."

[0009] [Gear Motor Configuration] As shown in Figure 1, the gear motor body 100 comprises a motor 20 and a magnetic modulation gear 30, which are housed in a common casing (frame) 10. The casing 10 is formed in a substantially cylindrical shape along the axial direction, and the openings at both ends in the axial direction are covered by a non-load side cover 11 and a load side cover 13.

[0010] <Motor> The motor 20 is capable of controlling the amount of rotation angle and comprises a motor rotor 21 and a motor stator 22. The motor rotor 21 has a shaft 23, a rotor yoke 21b, and rotor magnets 21c. The rotor yoke 21b is made of a non-magnetic material and is fitted and fixed to the outer surface of the shaft 23. The rotor magnets 21c are permanent magnets such as neodymium magnets, and multiple magnets corresponding to a predetermined number of poles are attached to the portion of the outer surface of the rotor yoke 21b that is located on the inner diameter side of the motor stator 22. The motor rotor 21 is pivotally supported by two bearings (e.g., ball bearings) 12a and 12b that support the shaft 23. Of these, the non-load side bearing 12a is located between the non-load side cover 11 and the shaft 23. On the other hand, the load side bearing 12b is located on the load side of the magnetic modulation gear 30, between the output shaft 32 (output member 32b) of the magnetic modulation gear 30 (described later) and the shaft 23.

[0011] The motor stator 22 is constructed by winding a coil 22b around a stator core 22a made of laminated steel plates. The stator core 22a is made of a soft magnetic material such as a compacted magnetic core, amorphous material, or SPCC. The motor stator 22 is arranged concentrically on the outer diameter side of the motor rotor 21 and is held in the casing 10 with the stator core 22a fitted inside the casing 10.

[0012] <Magnetic Modulation Gear> The magnetic modulation gear 30 is positioned on the load side of the motor 20 and reduces (changes the speed of) the rotational input from the motor 20 and outputs it to the load side. The magnetic modulation gear 30 and the motor 20 share a common shaft (motor rotor 21 and high-speed rotor 31). Specifically, the magnetic modulation gear 30 comprises a high-speed rotor (input shaft) 31, an output shaft 32, an outer pole magnet 33, and a temperature sensor 37.

[0013] Figure 2 is a perspective view of the main part (reduction section) of the magnetic modulation gear 30. As shown in Figures 1 and 2, the high-speed rotor 31 comprises a shaft 23 and rotor yoke 21b common to the motor rotor 21 of the motor 20, and an internal pole magnet 31a. The shaft 23 and rotor yoke 21b extend axially from the motor 20 to the magnetic modulation gear 30. Of these, the axial ends of the shaft 23 extend from the rotor yoke 21b, and these ends are supported by the bearings 12a, 12b described above. The internal pole magnet 31a is a permanent magnet such as a neodymium magnet, and multiple magnets with different polarities are attached to the outer circumferential surface of the rotor yoke 21b so that they are arranged alternately (including multiple alternating) in the circumferential direction. The internal pole magnet 31a may be a single ring shape, or it may be divided and arranged in the circumferential direction. Note that the rotor yoke 21b may be separate from the motor 20 and the magnetic modulation gear 30.

[0014] The output shaft 32 is arranged concentrically with the high-speed rotor 31 on the outer diameter side and the load side of the high-speed rotor 31. The output shaft 32 has a pole piece 32a arranged on the outer diameter side of the inner pole magnet 31a and an output member 32b connected to the load side of the pole piece 32a. The pole piece 32a is made of laminated steel plate, and multiple pole pieces are arranged at predetermined intervals in the circumferential direction. However, the pole piece 32a may be made of a soft magnetic material, such as a powder core, amorphous material, or SPCC. The number of pole pieces 32a is, as will be described later, the number of outer pole pairs (number of pole pairs of outer pole magnets 33) ± the number of inner pole pairs (number of pole pairs of inner pole magnets 31a), and is generally the number of outer pole pairs + the number of inner pole pairs. Two adjacent pole pieces 32a in the circumferential direction may be connected by a thin connecting portion or by a non-magnetic material. The output member 32b is fixed to the load-side resin portion 32c, which is fixed to both axial ends of the magnetic pole piece 32a, for example, with bolts. The load-side end of the output member 32b is exposed from the load-side cover 13 and connected to a driven member (not shown). The output shaft 32 is rotatably supported by the casing 10 and the load-side cover 13 via a bearing 32e provided on the non-load side of the magnetic pole piece 32a and a bearing 32f provided on the load side of the magnetic pole piece 32a. Of these, the non-load-side bearing 32e is positioned between a stainless steel ring member 32g fixed to the resin portion 32c on the non-load side of the magnetic pole piece 32a and the casing 10. On the other hand, the load-side bearing 32f is positioned between the load-side cover 13 and the output member 32b.

[0015] The outer pole magnet 33 is arranged concentrically with a predetermined gap on the outer diameter side of the magnetic pole piece 32a. The outer pole magnet 33 has more pole pairs than the inner pole magnet 31a of the high-speed rotor 31, and multiple outer pole magnets with opposite polarities are arranged alternately (including multiple alternating pairs) in the circumferential direction. The outer pole magnet 33 is attached to the inner circumferential surface of the yoke portion 33a fitted inside the casing 10 and functions as a stator. The outer pole magnet 33 may be a single ring shape, or it may be divided into sections arranged in the circumferential direction. The inner pole magnet 31a, magnetic pole piece 32a, and outer pole magnet 33 constitute the reduction unit according to the present invention, and reduce (change the speed of) the output shaft relative to the input shaft.

[0016] The temperature sensor 37 is attached to the outer pole magnet 33 and detects the temperature of the outer pole magnet 33. While contact-type sensors such as thermocouples, resistance thermometers, and thermistors can be used as the temperature sensor 37, it is not limited to these as long as it can measure the temperature of the object being detected. For example, a non-contact sensor, such as an infrared detector, can be used to measure the temperature from a position away from the object being detected.

[0017] <Rotation Detection Configuration> The gear motor 1 (gear motor body 100) is equipped with a first rotation sensor 35 and a second rotation sensor 36 that measure the rotation angle (position) of the shaft 23 and the output shaft 32. The first rotation sensor 35 and the second rotation sensor 36 are located inside the casing 10. However, the first rotation sensor 35 and the second rotation sensor 36 may be located outside the casing 10.

[0018] The first rotation sensor 35 is an input shaft-side sensor that measures the rotation angle of the shaft 23, and has a detected part 351 that rotates integrally with the shaft 23, and a sensor part 352 that detects the detected part 351. The detected part 351 is composed of a disk (or ring) fixed to the shaft 23 at a position facing the load-side surface of the non-load-side cover 11. The detected part 351 is mounted concentrically with the shaft 23 and rotates together with the shaft 23 around the central axis Ax. On the non-load-side surface of the detected part 351, for example, a code is formed that can be read optically or magnetically from the non-load side along the circumference centered on the central axis Ax. Also, if the detected part 351 is formed in the shape of a ring, these codes may be formed on the outer or inner circumference of the ring. The sensor part 352 is fixed to the load-side surface of the non-load-side cover 11. The sensor part 352 is positioned in close proximity to and facing the detected part 351. The sensor unit 352 is composed of, for example, an optical sensor or magnetic sensor capable of reading the code of the detected unit 351.

[0019] The second rotation sensor 36 is an output shaft-side sensor that measures the rotation angle on the output shaft 32 side, and has a detected part 361 that rotates integrally with the output shaft 32, and a sensor part 362 that detects the detected part 361. The detected part 361 is composed of a disk (or ring) fixed to the outer circumference of the output member 32b of the output shaft 32. The detected part 361 is mounted concentrically with the output shaft 32 and rotates together with the output shaft 32 around the central axis Ax. On the load-side surface of the detected part 361, for example, an optically or magnetically readable code is formed along the circumference centered on the central axis Ax. Also, if the detected part 361 is formed in a ring shape, these codes may be formed on the outer or inner circumference of the ring. The sensor part 362 is fixed to the non-load-side surface of the load-side cover 13. The sensor part 362 is positioned in close proximity to and opposite the detected part 361. The sensor unit 362 is composed of, for example, an optical sensor or a magnetic sensor capable of reading the code of the detected unit 361.

[0020] The first rotation sensor 35 and the second rotation sensor 36 are not particularly limited in type, as long as they can detect the rotation of the shaft 23 and the output shaft 32. They may be rotary encoders that output rotational displacement as a digital signal, resolvers that output as an analog signal, or other rotation detectors. Furthermore, the first rotation sensor 35 and the second rotation sensor 36 may be of different types. In this embodiment, an example of arrangement where the detected part and the sensor part face each other in the axial direction is shown, but the positional relationship between these detected part and sensor part is not particularly limited. For example, if the code of the detected part is formed on the outer or inner circumference of the ring, the sensor part may be placed on the outer or inner diameter side of the detected part, so that the detected part and the sensor part face each other in the radial direction.

[0021] [Gear Motor Operation] In the gear motor 1 (gear motor body 100), when the motor 20 is driven and an input torque is applied to the shaft 23, the high-speed rotor 31 of the magnetic modulation gear 30 rotates together with the shaft 23. Then, in the magnetic modulation gear 30, the spatial magnetic flux waveform formed by the inner pole magnet 31a of the high-speed rotor 31 is modulated to the same frequency as the outer pole magnet 33 by the magnetic pole piece 32a of the output shaft 32. Then, torque is transmitted to the output shaft 32 using the magnetic force between the magnetic pole piece 32a and the outer pole magnet 33, and output to a driven member (not shown) connected to the output shaft 32. Alternatively, the output shaft 32 (magnetic pole piece 32a) may be fixed, and the outer pole magnet 33 may be mounted on a rotatable low-speed rotor, and the output may be taken from the low-speed rotor.

[0022] Here, the reduction ratio R of the magnetic modulation gear 30 is expressed by the following equation (1) when the output is taken from the output shaft 32 (magnetic pole piece 32a), and by the following equation (2) when the output is taken from the outer pole magnet 33. R = Np / Ni ... (1) R = No / Ni ... (2) where Np is the number of magnetic pole pieces 32a, No is the number of pole pairs of the outer pole magnet 33, and Ni is the number of pole pairs of the inner pole magnet 31a. In addition, the following relationship (3) holds between the number of magnetic pole pieces Np, the number of outer pole pairs No, and the number of inner pole pairs Ni. Np = Ni + No ... (3)

[0023] [Gear Motor Torque Control] The torque control of the gear motor body 100 by the control device 40 will be explained. Figure 3 is a block diagram showing the schematic control configuration of the gear motor 1. Figure 4 is a graph showing the relationship between the phase difference and output torque (T-Δθ characteristic) at the output shaft 32.

[0024] In the magnetic modulation gear 30 of the gear motor 1, as described above, the output shaft 32 rotates with a predetermined reduction ratio R relative to the rotation angle (position) of the shaft 23. At this time, when a phase difference (phase difference angle) occurs in the output shaft 32 due to a delay in the rotation angle of the output shaft 32 with respect to the rotation angle of the output shaft 32 (reference position described later) corresponding to the reduction ratio R, an output torque is generated in the output shaft 32. The output torque generated in the output shaft 32 and the phase difference have, for example, a sinusoidal correlation (see Figure 4), and the following equation (5) holds true. Here, Fa is the magnetomotive force amplitude of the inner pole magnet 31a, Fb is the magnetomotive force amplitude of the outer pole magnet 33, and P1 is the permeance amplitude of the magnetic pole piece 32a. The control device 40 according to this embodiment controls the torque of the gear motor 1 by varying the relationship between the torque and phase of the output shaft 32 (T-θp characteristic) based on the relationship between the output torque and phase difference (T-Δθ characteristic) generated in the output shaft 32. In the following description, θi, θp, and θo are mechanical angles. Furthermore, if the initial phases of the magnetic modulation gear 30 are θi_ini and θp_ini, the following equation (6) holds. In this context, the rotation angle where θp_ini = θp and θi_ini = θi is sometimes referred to as the "reference position."

[0025] Specifically, in torque control of the gear motor 1, as shown in Figure 3, the phase difference output unit 41 of the control device 40 first calculates the target phase difference θ* of the output shaft 32 to output the target output torque. Here, the phase difference output unit 41 first multiplies the stiffness K at the reference position (i.e., θi = 0) by a predetermined stiffness coefficient Kg* (>0). The data for the stiffness K at the reference position is known (solid curve (0) in Figure 4), and the phase difference output unit 41 stores this in advance as, for example, table data. Next, the phase difference output unit 41 subtracts the initial value of the angle (initial angle) θp_ini from the angle θp of the output shaft 32 (magnetic pole piece 32a) from the reference position, and multiplies by the number of magnetic pole pieces Np. θp is the rotation angle of the output shaft 32 detected by the second rotation sensor 36. Similarly, the initial value of the angle (initial angle) θi_ini is subtracted from the angle θi of the output shaft 32 from the reference position, and the result is multiplied by the internal pole logarithm Ni. θi is the rotation angle of the shaft 23 detected by the first rotation sensor 35. Next, the phase difference output unit 41 takes the difference between Np(θp - θp_ini) and Ni(θi - θi_ini) calculated up to this point, multiplies it by Kg*・K to obtain the target output torque T*, and then converts this to a phase difference to calculate the target phase difference θ*. Note that in addition to sin⁻¹, the reciprocal of the linearly approximated stiffness may also be used for the conversion to phase difference.

[0026] Here, the stiffness coefficient Kg*, the initial angle θp_ini of the output shaft 32, and the initial angle θi_ini of the shaft 23 are arbitrary values ​​and are set appropriately according to the desired stiffness required for the gear motor 1 (magnetic modulation gear 30). In this way, by appropriately setting the stiffness coefficient Kg*, the initial angle θp_ini of the output shaft 32, and the initial angle θi_ini of the shaft 23, the T-Δθ characteristic can be made seemingly variable, as shown by the dotted line in Figure 4, for example. That is, the torque-angle characteristic of the magnetic modulation gear 30 can be actively controlled by the phase difference (phase difference angle). Note that although the stiffness coefficient Kg* is used as a ratio value to the stiffness K at the reference position, linear or nonlinear values ​​may be directly input instead of these multiplied values ​​(Kg*・K).

[0027] Next, the phase difference calculation unit 42 of the control device 40 determines the current phase difference (phase difference angle) Δθfb between the shaft 23 and the output shaft 32. Specifically, the phase difference calculation unit 42 determines θi and θp based on the rotation angle of the shaft 23 detected by the first rotation sensor 35 and the rotation angle of the output shaft 32 detected by the second rotation sensor 36. Then, the phase difference calculation unit 42 calculates the current phase difference Δθfb using the following equation (4): Δθfb = Np・θp - Ni・θi ... (4) Note that the order of processing with the phase difference output unit 41 is not particularly limited.

[0028] Next, the calculation unit 43 of the control device 40 calculates the deviation θcmd between the target phase difference θ* and the current phase difference Δθfb. Specifically, the calculation unit 43 subtracts the current phase difference Δθfb of the output shaft 32, output from the phase difference calculation unit 42, from the target phase difference θ* of the output shaft 32, output from the phase difference output unit 41, to calculate the phase difference deviation θcmd.

[0029] Next, the control device 40 performs angle difference control (≒torque control) based on the calculated phase difference deviation θcmd, for example, using a PI controller 45, and inputs a predetermined amount of movement to the motor 20 through the motor driver 46. As a result, the motor 20 is controlled so that a target phase difference θ* is generated in the output shaft 32, and a target output torque corresponding to the desired rigidity of the magnetic modulation gear 30 is generated in the output shaft 32.

[0030] [Technical Effects of This Embodiment] According to this embodiment, the output of the motor 20 is controlled based on a torque-phase difference characteristic (T-Δθ characteristic) that represents the relationship between phase difference information regarding the rotational position of the high-speed rotor (input shaft) 31 and the output shaft 32, and the output torque of the output shaft 32, and the torque-angle characteristic (T-θp characteristic) of the output shaft 32 is variable. As a result, when controlling the output of the motor 20 based on the T-Δθ characteristic, the T-θp characteristic, i.e., the torque-angle characteristic of the magnetic modulation gear 30, can be changed. Therefore, in a gear motor 1 equipped with a magnetic modulation gear 30, the torque-angle characteristic can be varied.

[0031] Furthermore, according to this embodiment, the T-Δθ characteristic is made variable by multiplying a predetermined coefficient (stiffness coefficient Kg* and initial angles θp_ini, θi_ini) with respect to a reference characteristic when the high-speed rotor 31 and output shaft 32 are in a magnetically stable rotational position. This allows the torque-angle characteristic to be suitably varied by appropriately setting the coefficient according to the required stiffness of the magnetic modulation gear 30.

[0032] Furthermore, according to this embodiment, phase difference information regarding the rotational position of the high-speed rotor 31 and the output shaft 32 is acquired based on the rotational angles measured by the first rotation sensor 35 (input shaft side sensor) which measures the rotational angle on the input shaft side, and the second rotation sensor 36 (output shaft side sensor) which measures the rotational angle on the output shaft side. As a result, the output torque can be actively controlled without the need to provide a dedicated torque sensor for torque detection.

[0033] Furthermore, according to this embodiment, the target phase difference θ* is calculated based on the rotation angle measured by the second rotation sensor 36, the current phase difference Δθfb of the output shaft 32 is calculated based on the phase difference information, and the output of the motor 20 is controlled based on the difference between the current phase difference Δθfb and the target phase difference θ*. This makes it possible to perform torque control by taking into account not only the phase difference between the high-speed rotor 31 and the output shaft 32, but also the position (phase) of the output shaft 32.

[0034] Furthermore, according to this embodiment, the first rotation sensor 35 and the second rotation sensor 36 are arranged within a casing 10 (enclosure) that integrally houses the motor 20 and the magnetic modulation gear 30. This allows the two rotation sensors to be suitably arranged within the casing 10 in an oil-free environment.

[0035] [Other] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiments, the rotational position (phase) of the shaft was calculated in the torque control of the gear motor 1, but the torque corresponding to the said rotational position may be used. In other words, the output of the motor 20 may be controlled from the difference between the current output torque and the target output torque.

[0036] Furthermore, when calculating the target phase difference θ* of the output shaft 32, the influence of the ambient temperature may be taken into consideration. In this case, for example, multiple data points for stiffness K at a reference position are stored for each ambient temperature, and based on the temperature detected by the temperature sensor 37, the data point for stiffness K corresponding to the detected temperature is selected, and then the target phase difference θ* is calculated. This allows for more accurate torque control by taking the influence of temperature into account.

[0037] Furthermore, in the above embodiment, a configuration was described in which the outer pole magnet is fixed and the output torque is extracted from the magnetic pole piece. However, as mentioned above, the output torque may also be extracted from the outer pole magnet. In this case as well, it can be implemented using the same approach as the torque control described above.

[0038] Furthermore, the motor and the magnetic modulation gear may be separate components. Various modifications described above can be adapted to configurations similar to those described in, for example, Japanese Patent Application Publication No. 2022-150614. In the above embodiment, the control device controls the operation of the gear motor, but the control unit and computer according to the present invention are not particularly limited as long as they are the entities that execute the control processing, and include so-called controllers and motor drivers. The mode of control execution is also not particularly limited; for example, the control system unit of the controller (excluding the driver 46 of the control device 40) may be incorporated into the motor driver's control algorithm. Other details shown in the above embodiment can be modified as appropriate without departing from the spirit of the invention.

[0039] As described above, the present invention is useful for making the torque-angle characteristics variable in a gear motor equipped with a magnetic modulation gear.

[0040] 1 Gear motor 10 Casing 20 Motor 30 Magnetic modulation gear 31 High-speed rotor (input shaft) 32 Output shaft 35 First rotation sensor (input shaft side sensor) 36 Second rotation sensor (output shaft side sensor) 40 Control device (control unit, computer) 100 Gear motor body K Stiffness Kg Stiffness coefficient Ni Number of inner pole pairs No Number of outer pole pairs Np Number of magnetic pole pieces R Reduction ratio T* Target output torque Δθfb Phase difference (current) θ* Target phase difference θcmd Deviation (between current phase difference and target phase difference) θp_ini Initial angle of the output shaft

Claims

1. A gear motor comprising: a motor; a magnetic modulation gear having an input shaft to which the output of the motor is input and an output shaft whose speed is changed relative to the input shaft via a reduction unit; and a control unit for controlling the output of the motor, wherein the control unit controls the output of the motor based on a torque-phase difference characteristic representing the relationship between phase difference information relating to the rotational position of the input shaft and the output shaft and the output torque of the output shaft, and the torque-angle characteristic of the output shaft, which represents the relationship between the torque and phase of the output shaft, is variable.

2. The gear motor according to claim 1, wherein the control unit pre-stores a reference torque-phase difference characteristic when the input shaft and the output shaft are in a magnetically stable rotational position, and varies the torque-angle characteristic of the output shaft by multiplying the reference characteristic by a predetermined coefficient.

3. The gear motor according to claim 1, further comprising an input shaft sensor for measuring the rotation angle of the input shaft and an output shaft sensor for measuring the rotation angle of the output shaft.

4. The gear motor according to claim 3, wherein the control unit acquires the phase difference information based on the rotation angle measured by the input shaft sensor and the output shaft sensor, respectively.

5. The gear motor according to claim 3, wherein the control unit calculates a target phase difference for outputting a target output torque based on the rotation angles measured by the input shaft sensor and the output shaft sensor, calculates the current phase difference of the output shaft based on the phase difference information, and controls the output of the motor based on the difference between the current phase difference and the target phase difference.

6. The gear motor according to claim 3, comprising a housing that integrally houses the motor and the magnetic modulation gear, wherein the input shaft side sensor and the output shaft side sensor are arranged within the housing.

7. A control program for a gear motor comprising: a motor; a magnetic modulation gear having an input shaft to which the output of the motor is input; an output shaft whose speed is changed relative to the input shaft via a reduction unit; and a control unit for controlling the output of the motor, wherein the control program causes a computer to function as a control unit that controls the output of the motor based on a torque-phase difference characteristic representing the relationship between phase difference information relating to the rotational positions of the input shaft and the output shaft and the output torque of the output shaft, and the torque-angle characteristic of the output shaft, which represents the relationship between the torque and phase of the output shaft, is variable.

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