JPH0443217B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a so-called electric robot whose working end is driven by a drive source, for example, in which the total number of rotations and the rotation within 360 degrees of the working end are controlled. The present invention relates to an encoder device preferably implemented for detecting angles.

BACKGROUND ART In typical existing technology, the power from the rotating shaft of a motor is reduced by a speed reducer and transmitted to the working end, and the output shaft of the motor is connected to the working end in order to detect the rotation angle of the working end. Another detecting reducer having the same reduction ratio as that of the detecting reducer is provided, and the rotation angle of the reduction output shaft of the detecting reducer is detected by a potentiometer. On the other hand, the output shaft of the motor is equipped with a so-called incremental encoder, making it possible to detect the rotation angle of the output shaft within 360° with high precision. There is.

Problems to be Solved by the Invention The existing technology as described above requires a detection reducer, which increases the size of the encoder device and causes measurement errors due to backlash of the detection reducer. Ta. In addition, the incremental encoder has a structure in which a light emitting element and a light receiving element are installed on both sides of a rotating member attached to a rotating shaft to detect a transparent part or a light blocking part formed on the rotating member. If such an incremental encoder were to be operated by a battery, the power consumption of the incremental encoder would be large, so the capacity of the battery would have to be large, and the power supply associated with the encoder would have to be large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an encoder device that can detect rotational angles with high precision without increasing the size of the entire installation.

Means for Solving the Problems The present invention provides a resolver 7 which includes: (a1) a rotor 8 fixed to the rotating shaft 2; (a2) a detection coil 9 fixed to the rotor 8; (a3) A first output coil 10 connected to the detection coil 9; (a4) A first output coil 10 magnetically coupled to the first output coil 10.
Rotating transformer 14 together with output coil 10
(a5) A resolver 7 having a pair of excitation coils 11 and 12 which are provided at fixed positions shifted in the circumferential direction of the rotor 8 and magnetically coupled to the detection coil 9. , (b) an excitation device 15 that applies alternating current voltages V1 and V2 having a predetermined phase difference to each excitation coil 11 and 12; and (c) an output of the second detection coil 13 and the alternating current voltage V1 of the excitation device 15. (d) a rotation speed detection means 19, which is made of a non-magnetic material, has a right cylindrical shape, and is rotated around its axis; (d2) a plurality of first members fixed to the peripheral wall of the rotating member 20 at equal intervals in the circumferential direction, having a longitudinal axis parallel to the rotating member 20, and magnetized in the longitudinal axis direction; a permanent magnet 22; (d3) a detection head 21 having first to fifth detection elements 31 to 35 which are provided at a fixed position and are sequentially arranged at intervals in the circumferential direction in the vicinity of the rotating member 20; (d4) Each sensing element 31-35 includes: (d41) elongated ferromagnetic materials 41 and 45 arranged parallel to the axis of the rotating member 20; (d42) wound around the ferromagnetic material 41-45; (d43) Detection coils 61 to 65 that are arranged parallel to the axis of the rotating member 20 on the opposite side to the rotating member 20 with respect to the ferromagnetic materials 41 to 45 and opposite to the first permanent magnet 22; (d44) The ferromagnetic materials 41 to 45 include a core 41a and a core having a coercive force larger than that of the core 41a. 41a, and the magnetization direction of the shell 41b is reversed when the first permanent magnet 22 approaches, thereby generating an impulse-like induced voltage in the detection coils 61 to 65. (e) Rotation direction/rotation speed discrimination circuit 24, 93, (e1) set by the output of the second detection element 32 and set by the output of the fourth detection element 34; the first flip-flop 87 to be reset; (e2) the set output Q of the first flip-flop 87;
(e3) a second detection circuit 90 that detects the edge of the reset output Q of the first flip-flop 87; (e4) a second detection circuit 90 that detects the edge of the reset output Q of the first flip-flop 87; , a second flip-flop 88 that is reset by the respective outputs of the first and fifth detection elements 31 and 35, and (e5) the first and second detection circuits 89 and 9 during the output maintenance period of the second flip-flop 88.
(f) supplying power to the exciter 15 and the phase detector 16; (g) Batteries 23, 93 that supply power to rotation direction/rotation speed discrimination circuits 24, 93.

Function In the encoder device according to the present invention, a rotating member 20 is provided on the rotating shaft to be detected, and a plurality of first permanent magnets 22 are fixed to this rotating member 20. Due to the proximity of the permanent magnet 22 to each of the first to fifth detection elements 31 to 35 in the detection head 21, the ferromagnetic materials 41 to
45 is reversed, thereby generating an impulse-like induced voltage in the detection coils 61-65. , 88 and first and second detection circuits 89,
90, and counter means 91, 92, and 93 for up-down counting, it is possible to detect the direction of rotation, the angle of rotation within at least 360 degrees, and the number of rotations of the rotating member 20. Such a configuration can be realized in a small size, and the power consumption of the first and second flip-flops 87, 88, the first and second detection circuits 89, 90, and the counter means 91, 92, 93 is negligible. Therefore, the power consumption of the battery 23 can be reduced.

In particular, according to the present invention, the resolver 7 detects an angle less than 360 degrees, and the rotation direction/number of rotations discrimination circuit 2
By energizing only 4 and 93 with the power of the battery 23, the positive and negative rotational speeds of the rotating shaft 2 can be detected. Means 95,9
Even when the power is restored in step 6, the rotation angle of the rotating shaft can be detected with high accuracy.

Embodiment FIG. 1 is a block diagram of an electric robot equipped with an encoder device according to the present invention. In this electric robot, the rotating shaft 2 of the motor 1 has gears 3a,
3b, and the output shaft 5
The working end 6 is rotationally driven. The rotating shaft 2 of the motor 1 is provided with a resolver 7 that detects the rotation angle during one rotation.

FIG. 2 is an electrical circuit diagram of one embodiment of the resolver 7. A rotor 8 that rotates integrally with the rotating shaft 2 of the motor 1 is provided with coils 9 and 10. A coil 1 fixed at a fixed position is arranged around the rotor 8.
1 and 12 are provided, and the coils 11 and 12 are electrically offset from each other by 90°. Further, another coil 13 is provided around the rotor 8 and is magnetically coupled to the coil 10.
constitutes a rotary transformer 14.

Referring also to FIG. 1, a voltage V1 is applied from the exciter 15 to the coil 11 of the resolver 7 via the line
is given and the voltage V1 is also applied to the line l
2 to the phase detector 16. Further, a voltage V2 is applied from the excitation device 15 to the coil 12 of the resolver 7 via the line l3. This voltage V
1 and V2 are shown by the first and second equations.

V1=Vsinωt (1) V2=Vcosωt (2) When the rotor 8 rotates in the direction of the arrow 17 (see FIG. 2), the output voltage V3 from the coil 13 of the resolver 7 is expressed by the third equation.

V3=Kv·sin(ωt+θ) (3) Kv is the maximum coupling coefficient, θ is the rotation angle of the rotor 8, and this rotation angle θ is in the range of 0° to 360°.

This output voltage V3 is applied to the phase detector 16 via line l4. The phase detector 16 detects the phase difference between the voltage V3 indicated by reference numeral m1 in FIG. 3 and the voltage V1 indicated by reference numeral m2 in FIG. is converted into a digital value and delivered to the arithmetic circuit 18 via line l5. In this way, the rotation angle within 360 degrees of the rotation shaft 2 can be detected with high precision based on the rotation angle signal representing the rotation angle θ of the rotation shaft 2 from the line 15.

A rotation speed detection means 19 is provided in relation to the rotation shaft 2 of the motor 1 .

FIG. 4 is a perspective view of the rotation speed detection means 19. Referring also to FIG. 1, the rotation speed detection means 19
, a rotating member 20 in the shape of a right cylinder, and a detection head 21
including. The rotating member 20 is made of a non-magnetic material, such as aluminum or stainless steel, and is fixed coaxially to the rotating shaft 2 of the motor 1. A plurality of permanent magnets 22 are fixed to the peripheral wall of the rotating member 20 at equal intervals in the circumferential direction. The permanent magnet 22 extends longitudinally in a straight line, and the longitudinal direction of the permanent magnet 22 is parallel to the rotational axis of the rotating member 20. This permanent magnet 22 is magnetically coupled to a detection head 21 mounted in a fixed position. The output of the detection head 21 is input to a rotation direction discrimination circuit 24 powered by a battery 23, and
0 rotation direction and rotation speed N are detected.

The detection head 21 detects the rotating direction 1 of the rotating member 20.
Detection elements 31, 3 spaced apart at 7
It is composed of 2, 33, 34, and 35. The detection elements 31, 32, 33, 34, 35 each include a ferromagnetic material 41, 42, 43, 44, 45, a permanent magnet 51, 52, 53, 54, 55, and a detection coil 61, 62, 63, 64, 65. include.

FIG. 5 is a developed view in the circumferential direction for explaining the relationship between one permanent magnet 22 fixed to the rotating member 20 and one detection element 31. The magnetization directions of the permanent magnet 22 and the permanent magnet 51 are opposite to each other, and the permanent magnet 2
2 has a stronger magnetizing force than the permanent magnet 51. The external magnetic field applied to the ferromagnetic material 41 is caused by the permanent magnet 22 rotating in the rotation direction 17.
It changes as shown in FIG. 6 due to the influence of the magnetic field 70 caused by the magnetic field 70 and the magnetic field 71 caused by the permanent magnet 51. 6.2 shows the output of the detection coil 61, and FIG. 6.3 shows the position of the permanent magnet 22.

FIG. 7 is a cross-sectional view showing the state of magnetization of the ferromagnetic material 41 that occurs when the permanent magnet 22 passes near the ferromagnetic material 41. The ferromagnetic material 41 has a core 41a and a shell 41b having different coercive forces. Here, a description will be given assuming that a material is used in which the coercive force of the shell 41b is stronger than that of the core 41a. The ferromagnetic material 41 has a permanent magnet 22 as the fifth
When at position P1 in the figure, as shown in FIG. 6, the core 41a is influenced by a weak negative magnetic field, and the core 41a with a small coercive force is magnetized in the direction of the external magnetic field 80, and the shell 41b with a large coercive force is magnetized in the opposite direction. It is magnetized in the direction of . Therefore, the ferromagnetic material 41 is in the state shown in FIG. 71. When the permanent magnet 22 reaches the position P2 near the ferromagnetic material 41, the external magnetic field 80 applied to the ferromagnetic material 41 becomes larger than the coercive force of the core 41a, and the direction of magnetization of the core 41a is reversed, as shown in FIG. becomes the state of When the permanent magnet 22 reaches position P3, the direction of the external magnetic field 80 is reversed again, and the core 41
The direction of magnetization of a is also reversed, resulting in the state shown in FIG. 73.

FIG. 8 shows that the external magnetic field of the ferromagnetic material 41 is as shown in FIG.
This is a hysteresis loop when it changes as follows. A large jump in the internal magnetic flux density occurs when changing from the state shown in FIG. 7 1 to the state shown in FIG. 7 2, and a small jump occurs when changing from the state shown in FIG. 7 2 to the state shown in FIG. 7 3. As shown in FIG. 6, a relatively high impulse voltage is generated in the detection coil 61 during the former jump, and a small voltage is generated during the latter jump. The peak value of the former generated voltage is, for example, 0.5 to 12V, and its half-value width is approximately 20μ.
seconds, and the signal-to-noise ratio is good. Since the latter generated voltage is sufficiently smaller than the former generated voltage and has a direction opposite to that of the former generated voltage, it is ignored by the rotation direction discrimination circuit 24, which will be described later.

When the permanent magnet 22 rotates in the opposite direction to the rotational direction 17, a large impulse voltage of the same polarity is similarly induced in the detection coil 61.

Detection elements 32, 33, 34, and 35 are also detection elements 3
It has the same configuration as 1, and generates similar voltages in the detection coils 62, 63, 64, and 65 when the permanent magnet 22 rotates.

Since the detection head 21 is thus composed of a permanent magnet, a ferromagnetic material, and a detection coil,
Permanent magnet 22 without the need for any power source
rotation can be reliably detected.

FIG. 9 shows the configuration of a rotational direction discrimination circuit 24 which processes the output of the detection head 21 and determines the rotational speed and rotational direction of the rotating member 20. Detection coil 61, 6
The outputs of 2, 63, 64, and 65 are respectively B'', A,
Let them be B, A', and B'. A, A', B, B', B, B'' are waveform shaping circuits 81, 82, 83, 84, respectively.
85 and the waveform is shaped. The outputs of the waveform shaping circuits 81 and 82 are respectively output from the flip-flop 8.
It is input to the set input terminal and reset input terminal of 7. The positive output and negative output of the flip-flop 87 are input to rise detection circuits 89 and 90, respectively, and a signal △ when the flip-flop 87 is reset from the reset state and a signal △ when the flip-flop 87 is reset from the set state are obtained. is output.

The outputs of the waveform shaping circuits 84 and 85 are output to the OR circuit 8
6 and its output is input to flip-flop 88.
input to the reset input terminal. The output of the waveform shaping circuit 83 is input to a set input terminal of a flip-flop 88. By inputting the positive output signal 〓 of the flip-flop 88 and the output △〓 of the rising edge detection circuit 89 to the AND circuit 91, the rotation direction 1 is determined.
A rotation pulse (CW) in the opposite direction of 7 is output, and the output of the flip-flop 88 and the rising edge detection circuit 9 are output.
By inputting the output △〓 of 0 to the AND circuit 92, a rotation pulse (CCW) in the rotation direction 17 is output.

Figure 10 shows signals A, A', B, B', B'', A, B,
The relationship diagram of (CW) and (CCW) is shown. AND circuit 9
The outputs of 1 and 92 are applied to the up input terminal and the down input terminal of an up-down counter 93 via lines l6 and l7, respectively. The up-down counter 93 counts the rotation pulses, and when the count reaches a predetermined number of rotations, it outputs a signal indicating the rotation speed N of the rotation shaft 2 to the arithmetic circuit 18 via the line 18. In the arithmetic circuit 18,
A signal representing the rotational speed N given via line l8 and a rotation angle θ given via line l5.
A signal representing the total rotation angle of the rotary shaft 2 is derived from line l9. In addition,
The rotational direction discrimination circuit 24 and the up-down counter 93 are realized by semiconductor circuits, and therefore, power consumption is small. The rotation direction discrimination circuit 24 and the up-down counter 93 are powered by the battery 23.

The phase detector 16 and the excitation device 15 are connected to a power supply circuit 9 that transforms and rectifies power from a commercial AC power supply 95.
It is powered by the power of 6. Rotation direction discrimination circuit 24, phase detector 16 and excitation device 15
is constantly energized when detecting the rotation angle, and its power consumption is large. During a power outage of the commercial AC power supply 95, the phase detector 16 and the excitation device 15
is disabled and rotation angle detection stops. Rotation direction discrimination circuit 24 and up/down counter 9
3 remains energized by the battery 23 even during a power outage. Therefore, the rotating member 20
When the rotation direction is angularly displaced, the rotation direction is discriminated by the rotation direction discrimination circuit 24, and the count value of the up-down counter 93 is changed and stored. Therefore, even if the motor 1 is deenergized due to a power outage of the commercial AC power supply 95 and the working end 6 is angularly displaced due to its gravity etc., and the rotating shaft 2 is accordingly angularly displaced, the rotation speed detection means 19, Rotation direction discrimination circuit 2
4 and the up-down counter 93, the rotational speed N of the rotating shaft 2 is constantly detected.

After the power is restored, the motor 1, phase detector 16, and excitation device 15 are energized by the power from the power supply circuit 96. The arithmetic circuit 18 is also energized. When the rotary shaft 2 is rotationally driven again by the motor 1, the rotation angle θ is again changed by the resolver 7.
is detected.

In this way, the resolver 7 can measure the rotation angle θ within 360° with high precision. Furthermore, the detection coils 61 to 65 are made of ferromagnetic materials 41 to 45 whose magnetization strength rapidly changes depending on the increase or decrease of the external magnetic field.
By winding the detection coils 61 to 65
A high induced electromotive force can be obtained when the magnetic field increases or decreases, and the outputs of these detection coils 61 to 65 are used by the rotation direction discrimination circuit 24 and up/down counter 93 powered by the battery 23. Since the rotating direction is determined and the rotation pulses are counted, the position of the rotating member 20 and therefore the rotating shaft 2 can be detected even in the event of a power outage. Therefore, the encoder device according to the present invention can be used as a so-called absolute encoder.

Although the rotational speed detection means 19 was composed of ferromagnetic materials 41 to 45 and detection coils 61 to 65 in the above-mentioned embodiment, according to the concept of the present invention, the following composition may also be used. good. That is, a rotating disk member made of non-magnetic metal or synthetic resin is integrally fixed to the rotating shaft 2, and one permanent magnet is fixed to one surface of the rotating disk member. Two reed switches capable of detecting magnetism are placed at fixed positions spaced apart in the circumferential direction of the rotating disk member, and the rotation direction and rotation speed are detected based on the output from the reed switches. It's okay.

As is clear from the above-mentioned FIGS. 4 and 5, the permanent magnets 51 to 55 are made of ferromagnetic materials 41 to 4.
5 on the opposite side of the rotating member 20 and parallel to the axis of the rotating member 20. As is clear from FIG. 7, the ferromagnetic material 41 has a core 41a.
and a shell 41b surrounding the core 41a. The rising edge detection circuits 89 and 90 detect rising waveforms, ie, edges, of the set output Q and reset output of the flip-flop 87, as described above. Counter means 91, 92, and 93 count up and down each output of each rise detection circuit 89, 90 during a period when the output of flip-flop 88 is maintained, that is, during a period when its set output Q is at a high level.

Effects As described above, according to the present invention, both the rotating member 20 and the plurality of first permanent magnets 22 fixed thereto rotate around the axis of the rotating member 20, thereby causing the first permanent magnets of the detection head 21 to rotate. ~The magnetization direction of the shell 41b of the ferromagnetic materials 41-45 in the fifth detection elements 31-35 is reversed, thereby generating an impulse-like induced voltage in the detection coils 61-65, and the output thereof is and second flip-flops 87, 88, first and second detection circuits 8
9, 90 and the counter means 91, 92, 93, it is possible to detect the rotation angle as well as the rotation direction. be able to detect.

In particular, according to the present invention, the resolver 7 provides 360
It is possible to detect the angle of the rotation axis 2 of less than degrees,
Even when the power supply means 95 and 96 that supply power to the excitation device 15 and phase detector 16 provided in connection with the resolver 7 recover from a power failure, the rotation direction/rotation speed discrimination circuits 24 and 93 Batsuteri 2
Power is constantly supplied from 3, and the positive and negative rotational speeds are detected, so that the rotational speed and rotation angle can be accurately detected even when the power supply means 95 and 96 recover from a power outage. is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electric robot equipped with an encoder device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of an embodiment of a resolver 7, and FIG. 3 is an input voltage V1 and an output voltage in the resolver 7. A waveform diagram of V3, FIG. 4 is a perspective view of the rotation speed detection means 19,
5 is a developed view of the rotating member 20 in the circumferential direction, FIG. 6 is a diagram for explaining the relationship between changes in the external magnetic field applied to the ferromagnetic material 41 and the output of the detection coil 61, and FIG. 7 is a diagram showing the ferromagnetic material 41. 8 is a diagram showing a hysteresis loop of the ferromagnetic material 41, FIG. 9 is a block diagram of the rotation direction discrimination circuit 24, and FIG. 10 is a diagram of the detection coil. 3 is a time chart showing the process of processing an output signal. 1...Motor, 2...Rotating shaft, 7...Resolver,
15... Excitation device, 16... Phase detector, 18...
... Arithmetic circuit, 19 ... Rotation speed detection means, 20 ...
Rotating member, 21...Detection head, 23...Battery, 4...Rotation direction discrimination circuit, 31, 32, 3
3, 34, 35... detection element, 41, 42, 4
3,44,45...Ferromagnetic material, 22,51,5
2,53,54,55...Permanent magnet, 61,6
2, 63, 64, 65...Detection coil, 81, 8
2, 83, 84, 85...Waveform shaping circuit, 86...
OR circuit, 87, 88... flip-flop,
89, 90... Rise detection circuit, 91, 92...
AND circuit, 93...up-down counter.

Claims (1)

[Claims] 1. (a) A resolver 7 comprising: (a1) a rotor 8 fixed to the rotating shaft 2; (a2) a detection coil 9 fixed to the rotor 8; and (a3) a detection coil 9. (a4) a first output coil 10 connected to the coil 9; (a4) a first output coil 10 magnetically coupled to the first output coil 10;
Rotating transformer 14 together with output coil 10
(a5) A resolver 7 having a pair of excitation coils 11 and 12 which are provided at fixed positions shifted in the circumferential direction of the rotor 8 and magnetically coupled to the detection coil 9. , (b) an excitation device 15 that applies alternating current voltages V1 and V2 having a predetermined phase difference to each excitation coil 11 and 12; and (c) an output of the second detection coil 13 and the alternating current voltage V1 of the excitation device 15. (d) a rotation speed detection means 19, which is made of a non-magnetic material, has a right cylindrical shape, and is rotated around its axis; (d2) a plurality of first members fixed to the peripheral wall of the rotating member 20 at equal intervals in the circumferential direction, having a longitudinal axis parallel to the rotating member 20, and magnetized in the longitudinal axis direction; a permanent magnet 22; (d3) a detection head 21 having first to fifth detection elements 31 to 35 which are provided at a fixed position and are sequentially arranged at intervals in the circumferential direction in the vicinity of the rotating member 20; (d4) Each detection element 31-35 includes: (d41) a longitudinal ferromagnetic material 41-45 disposed parallel to the axis of the rotating member 20; (d42) wound around the ferromagnetic material 41-45; (d43) Detection coils 61 to 65 that are arranged parallel to the axis of the rotating member 20 on the opposite side to the rotating member 20 with respect to the ferromagnetic materials 41 to 45 and opposite to the first permanent magnet 22; (d44) The ferromagnetic materials 41 to 45 include a core 41a and a core having a coercive force larger than that of the core 41a. 41a, and the magnetization direction of the shell 41b is reversed when the first permanent magnet 22 approaches, thereby generating an impulse-like induced voltage in the detection coils 61 to 65. (e) Rotation direction/rotation speed discrimination circuit 24, 93, (e1) set by the output of the second detection element 32 and set by the output of the fourth detection element 34; the first flip-flop 87 to be reset; (e2) the set output Q of the first flip-flop 87;
(e3) a second detection circuit 90 that detects the edge of the reset output Q of the first flip-flop 87; (e4) a second detection circuit 90 that detects the edge of the reset output Q of the first flip-flop 87; , a second flip-flop 88 that is reset by the respective outputs of the first and fifth detection elements 31 and 35, and (e5) the first and second detection circuits 89 and 9 during the output maintenance period of the second flip-flop 88.
(f) supplying power to the exciter 15 and the phase detector 16; (g) a battery 23 that supplies power to the rotation direction/rotation speed discrimination circuits 24 and 93.