Motor multi-turn counting device, method, drive system, joint control system

Abstract

The present invention provides a multi-turn counting device, method, drive system, and joint control system for a motor. The device includes: a first detection module for detecting back electromotive force signals of at least two-phase windings of the motor when the drive system of the motor loses power, and respectively converting the back electromotive force signals of at least two-phase windings of the motor into corresponding at least two first square-wave signals; a second detection module for detecting terminal voltage signals of at least two-phase windings of the motor when the drive system powers on and operates, and respectively converting the terminal voltage signals of at least two-phase windings of the motor into corresponding at least two second square-wave signals; a multi-turn counting MCU, where the multi-turn counting MCU is respectively connected to the first detection module and the second detection module, and the multi-turn counting MCU is used to obtain the rotation direction and number-of-turns data of the motor when the drive system loses power based on the at least two first square-wave signals, and obtain the rotation direction and number-of-turns data of the motor when the drive system powers on and operates based on the at least two second square-wave signals.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and particularly relates to a multi-turn counting device for a motor, a multi-turn counting method for a motor, a drive system for a motor, and a joint control system for a robot. Background Art

[0002] Currently, a single joint of a collaborative robot generally uses a Hall element to record the number of turns of the motor. For example, in some robot joint control solutions, a "single-turn absolute encoder + two Hall ICs (Integrated Circuit Chips)" is used to implement the function of a multi-turn absolute encoder. The single-turn absolute encoder cooperates with an optical or magnetic code disk installed at the end of the motor shaft to record the absolute position of the motor rotor. The two Hall ICs are arranged at a specific mechanical angle difference on the same plane, and two signals are output by detecting the magnetic poles of the motor rotor or a dedicated magnetic ring. The running direction and the number of turns of the motor are determined by processing and analyzing these two signals. The MCU (MicroController Unit) processes the obtained absolute position data of the motor rotor and the Hall signal data through a specific software algorithm to implement the function of the multi-turn absolute encoder. In addition, currently, a fork brake structure is adopted for a single joint of a collaborative robot, and there is a large gap between teeth. After the system power-off, the joint will be displaced due to gravity, vibration, or manual pushing. In order to effectively record the rotation direction and the number of turns of the motor even after the main power supply of the system is powered off, first, when the system detects the main power-off, the absolute position information and the multi-turn information are saved in a non-volatile memory, and the circuit subsystem for recording the number of turns of the motor is switched to battery power supply. The circuit subsystem mainly consists of a low-power Hall and an MCU, and is responsible for recording the changed direction and the number of turns information after the joint is displaced during the system power-off period. When the system is powered on again, by reading the absolute position and the multi-turn information stored in the non-volatile memory when the system is powered off and comparing them with the joint displacement information, the system resets the position of the joint to ensure that each joint returns to the position before the system power-off.

[0003] The above-mentioned solution with Hall elements has the following problems: 1. In addition to the single-turn absolute encoder requiring a dedicated code disk, the Hall element also needs to be installed with an additional magnetic ring, or the Hall element needs to be installed inside the motor to detect the magnetic poles of the permanent magnet rotor. This results in a large number of system components, a complex structure, low reliability, and affects the miniaturization design and operation stability of the joint. 2. After the system loses power, it is powered by a battery. In order to meet the battery life requirements, a low-power Hall element must be selected; at the same time, the Hall element is installed inside the joint or at the motor end, and the maximum operating temperature needs to meet above 105°C; also, because the joint reducer has a large reduction ratio, the displacement of the joint will cause a large rotation speed and acceleration of the motor, which requires the Hall element to have a large response frequency. For the above three requirements for the Hall element, the Hall elements available in the current market are extremely scarce, which undoubtedly increases the risks such as long delivery times and shortages of key materials, and is not conducive to product production. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a multi-turn counting device, method, drive system, and joint control system for a motor, which can achieve multi-turn counting of the motor when power is off and on, has a simple structure, high reliability, and is easy to produce.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A multi-turn counting device for a motor, the motor is a multi-phase motor and adopts FOC (Field-Oriented Control) drive. The device includes: a first detection module, which is used to detect the back electromotive force signals of at least two-phase windings of the motor when the drive system of the motor loses power, and convert the back electromotive force signals of at least two-phase windings of the motor into corresponding at least two first square wave signals respectively; a second detection module, which is used to detect the terminal voltage signals of at least two-phase windings of the motor when the drive system is powered on and working, and convert the terminal voltage signals of at least two-phase windings of the motor into corresponding at least two second square wave signals respectively; a multi-turn counting MCU, the multi-turn counting MCU is respectively connected to the first detection module and the second detection module, and the multi-turn counting MCU is used to obtain the rotation direction and number of turns data of the motor when the drive system loses power according to the at least two first square wave signals, and obtain the rotation direction and number of turns data of the motor when the drive system is powered on and working according to the at least two second square wave signals.

[0007] The multi-turn counting device for the motor further includes: an external battery, which is used to supply power to the first detection module and the multi-turn counting MCU when the drive system loses power.

[0008] The first detection module includes at least two first detection units corresponding to at least two-phase windings one by one. Each first detection unit includes: a switch circuit, one end of the switch circuit is connected to the lead-out wire of a corresponding phase winding; a first voltage divider, the input end of the first voltage divider is connected to the other end of the switch circuit; a zero-crossing detection circuit, one input end of the zero-crossing detection circuit is connected to the output end of the first voltage divider to access the back electromotive force signal of a phase winding after being reduced in voltage by the first voltage divider and convert it into a corresponding first square-wave signal, and the output end of the zero-crossing detection circuit is connected to the multi-turn counting MCU.

[0009] The second detection module includes at least two second detection units corresponding to at least two-phase windings one by one. Each second detection unit includes: a second voltage divider, the input end of the second voltage divider is connected to the drive wire of a corresponding phase winding. Wherein, the drive system of the motor includes a motor drive circuit, and the drive wires of the multi-phase windings of the motor are connected to the lead-out wires of the multi-phase windings of the motor one by one to realize the connection between the motor drive circuit and the motor; a digital-to-analog converter, the input end of the digital-to-analog converter is connected to the output end of the second voltage divider, and the digital-to-analog converter is used to convert the terminal voltage signal of a phase winding after being reduced in voltage by the second voltage divider into a corresponding analog signal; a comparator circuit, one input end of the comparator circuit is connected to the output end of the digital-to-analog converter, and the comparator circuit is used to convert the analog signal corresponding to a phase winding into a corresponding second square-wave signal, and the output end of the comparator circuit is connected to the multi-turn counting MCU.

[0010] The multi-turn counting MCU is specifically configured to judge the rotation direction of the motor according to the phase difference between the at least two first square-wave signals or the phase difference between the at least two second square-wave signals, and determine the number-of-turns data of the motor according to the number of pulses of the at least two first square-wave signals or the number of pulses of the at least two second square-wave signals.

[0011] A method for counting the multi-turns of a motor. The motor is a multi-phase motor and adopts FOC drive. The method includes the following steps: detecting the back electromotive force signals of at least two-phase windings of the motor when the drive system of the motor is powered off, and respectively converting the back electromotive force signals of the at least two-phase windings of the motor into corresponding at least two first square-wave signals; detecting the terminal voltage signals of at least two-phase windings of the motor when the drive system is powered on and working, and respectively converting the terminal voltage signals of the at least two-phase windings of the motor into corresponding at least two second square-wave signals; obtaining the rotation direction and the number-of-turns data of the motor when the drive system is powered off according to the at least two first square-wave signals, and obtaining the rotation direction and the number-of-turns data of the motor when the drive system is powered on and working according to the at least two second square-wave signals.

[0012] Among them, the back electromotive force signal is reduced in amplitude and then input into a zero-crossing detection circuit to be converted into a corresponding first square wave signal; the terminal voltage signal is reduced in amplitude and then subjected to analog-to-digital conversion to be converted into a corresponding analog signal, and the analog signal is input into a comparator circuit to be converted into a corresponding second square wave signal.

[0013] Among them, the rotation direction of the motor is judged according to the phase difference between the at least two first square wave signals or the phase difference between the at least two second square wave signals, and the number of turns data of the motor is determined according to the number of pulses of the at least two first square wave signals or the number of pulses of the at least two second square wave signals.

[0014] A driving system for a motor, comprising: the above-mentioned multi-turn counting device for the motor; a motor driving circuit, which is used to drive and control the motor in a FOC driving mode when the driving system is powered on and working; a single-turn encoder, which is used to obtain the single-turn position data of the motor when the driving system is powered on and working; a memory, which is used to store the rotation direction and the number of turns data of the motor when the driving system loses power; a driving MCU, which is respectively connected to the motor driving circuit, the multi-turn counting MCU, the memory and the single-turn encoder, and the driving MCU is used to read the rotation direction and the number of turns data of the motor when the driving system loses power from the memory when the driving system is powered on again after losing power, so as to restore the state before power-off of the motor, and the driving MCU is also used to implement the multi-turn encoder function according to the rotation direction, the number of turns data and the single-turn position data of the motor when the driving system is powered on and working.

[0015] A joint control system for a robot, comprising: the driving system of the above-mentioned motor; a motor; a reducer, which is arranged between the motor and the joint to be controlled.

[0016] Advantages of the present invention:

[0017] In the present invention, the first detection module detects the back electromotive force signals of at least two-phase windings of the motor when the driving system of the motor loses power, and the second detection module detects the terminal voltage signals of at least two-phase windings of the motor when the driving system of the motor is powered on and working, and obtains the rotation direction and the number of turns data of the motor according to the square wave signals converted from the detected signals. Thus, multi-turn counting of the motor when power is off and on can be achieved. Compared with using Hall elements for multi-turn counting, there is no need to use a magnetic ring, nor to install the device inside the motor, and there is no need to consider the requirements and selection of Hall element power consumption, heat resistance, response frequency, etc. Therefore, the structure is simple, the reliability is high, and it is easy to produce. Description of the drawings

[0018] Figure 1 Schematic block diagram of the multi-turn counting device for the motor according to the embodiment of the present invention;

[0019] Figure 2 Schematic block diagram of the multi-turn counting device for the motor according to an embodiment of the present invention;

[0020] Figure 3 Schematic structural diagram of the joint control system of the robot according to an embodiment of the present invention;

[0021] Figure 4 Flow chart of the multi-turn counting method for the motor implemented by the present invention;

[0022] Figure 5 Schematic waveform diagram of the back electromotive force signal according to a specific embodiment of the present invention;

[0023] Figure 6 Schematic waveform diagram of converting the back electromotive force signal into a square wave signal according to a specific embodiment of the present invention;

[0024] Figure 7 Schematic diagram of the phase difference and pulse number of the two-phase square wave signal according to a specific embodiment of the present invention;

[0025] Figure 8 Schematic waveform diagram of the terminal voltage signal according to a specific embodiment of the present invention;

[0026] Figure 9 Schematic waveform diagram of sequentially converting the terminal voltage signal into an analog signal and a square wave signal according to a specific embodiment of the present invention.

[0027] Reference numerals:

[0028] First detection module 10, second detection module 20, multi-turn counting MCU 30, external battery 40, motor drive circuit 50, single-turn encoder 60, memory 70, drive MCU 80, motor 90, reducer 100;

[0029] Switch circuit one 11, switch circuit two 12, first voltage divider one 13, first voltage divider two 14, zero-crossing detection circuit one 15, zero-crossing detection circuit two 16;

[0030] Second voltage divider one 21, second voltage divider two 22, digital-to-analog converter one 23, digital-to-analog converter two 24, comparator circuit one 25, comparator circuit two 26. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] The motor multi-turn counting device and the drive system of the motor in the embodiments of the present invention are preferably applicable to the joint control system of a robot. The motor in the embodiments of the present invention is a multi-phase motor, for example, it can be a three-phase brushless DC motor, a three-phase permanent magnet synchronous motor, a five-phase brushless DC motor, etc. The motor in the embodiments of the present invention adopts FOC drive, for example, it can be driven and controlled by the SPWM (Sinusoidal Pulse Width Modulation) chopping method.

[0033] As Figure 1 shown, the motor multi-turn counting device in the embodiments of the present invention includes a first detection module 10, a second detection module 20, and a multi-turn counting MCU 30. Among them, the first detection module 10 is used to detect the back electromotive force signals of at least two-phase windings of the motor when the drive system of the motor is powered off, and convert the back electromotive force signals of at least two-phase windings of the motor into corresponding at least two first square wave signals respectively; the second detection module 20 is used to detect the terminal voltage signals of at least two-phase windings of the motor when the drive system is powered on and working, and convert the terminal voltage signals of at least two-phase windings of the motor into corresponding at least two second square wave signals respectively; the multi-turn counting MCU 30 is respectively connected to the first detection module 10 and the second detection module 20, and the multi-turn counting MCU 30 is used to obtain the rotation direction and number of turns data of the motor when the drive system is powered off according to at least two first square wave signals, and obtain the rotation direction and number of turns data of the motor when the drive system is powered on and working according to at least two second square wave signals.

[0034] Furthermore, as Figure 2 shown, the motor multi-turn counting device in the embodiments of the present invention further includes an external battery 40, and the external battery 40 is used to supply power to the first detection module 10 and the multi-turn counting MCU 30 when the drive system is powered off.

[0035] In an embodiment of the present invention, the first detection module 10 includes at least two first detection units corresponding to at least two-phase windings one by one. Each first detection unit includes: a switch circuit, one end of the switch circuit is connected to the lead wire of the corresponding phase winding; a first voltage divider, the input end of the first voltage divider is connected to the other end of the switch circuit; a zero-crossing detection circuit, one input end of the zero-crossing detection circuit is connected to the output end of the first voltage divider to access the back electromotive force signal of the phase winding after voltage reduction by the first voltage divider and convert it into a corresponding first square wave signal, and the output end of the zero-crossing detection circuit is connected to the multi-turn counting MCU.

[0036] The second detection module 20 includes at least two second detection units corresponding to at least two-phase windings one by one. Each second detection unit includes: a second voltage divider, the input end of the second voltage divider is connected to the drive wire of the corresponding phase winding. Wherein, the drive system of the motor includes a motor drive circuit, and the drive wires of the multi-phase windings of the motor are connected to the lead wires of the multi-phase windings of the motor one by one to realize the connection between the motor drive circuit and the motor; a digital-to-analog converter, the input end of the digital-to-analog converter is connected to the output end of the second voltage divider, and the digital-to-analog converter is used to convert the terminal voltage signal of the phase winding after voltage reduction by the second voltage divider into a corresponding analog signal; a comparator circuit, one input end of the comparator circuit is connected to the output end of the digital-to-analog converter, and the comparator circuit is used to convert the analog signal corresponding to the phase winding into a corresponding second square wave signal, and the output end of the comparator circuit is connected to the multi-turn counting MCU.

[0037] Taking the motor as a three-phase motor and detecting the back electromotive force signals and terminal voltage signals of two-phase windings as an example, refer to Figure 3, the first detection module 10 may include a first switch circuit 11, a second switch circuit 12, a first voltage divider 13, a second voltage divider 14, a first zero-crossing detection circuit 15, and a second zero-crossing detection circuit 16. Among them, one end of the first switch circuit 11 is connected to the lead wire of one phase winding of any two-phase windings of the motor, and one end of the second switch circuit 12 is connected to the lead wire of the other phase winding of any two-phase windings of the motor. The first switch circuit 11 and the second switch circuit 12 can close the switch when the drive system of the motor loses power and open the switch when the drive system of the motor is powered on and working; the input end of the first voltage divider 13 is connected to the other end of the first switch circuit 11, and the input end of the second voltage divider 14 is connected to the other end of the second switch circuit 12; one input end of the first zero-crossing detection circuit 15 is connected to the output end of the first voltage divider 13 to access the back electromotive force signal of one phase winding after being reduced by the first voltage divider 13 and convert it into a corresponding first square wave signal. The output end of the first zero-crossing detection circuit 15 is connected to the multi-turn counting MCU 30. One input end of the second zero-crossing detection circuit 16 is connected to the output end of the second voltage divider 14 to access the back electromotive force signal of the other phase winding after being reduced by the second voltage divider 14 and convert it into a corresponding first square wave signal. The output end of the second zero-crossing detection circuit 16 is connected to the multi-turn counting MCU 30.

[0038] Refer to Figure 3, the second detection module 20 may include a first second voltage divider 21, a second second voltage divider 22, a first digital-to-analog converter 23, a second digital-to-analog converter 24, a first comparator circuit 25 and a second comparator circuit 26. Among them, the input end of the first second voltage divider 21 is connected to one phase winding drive line of any two-phase windings of the motor, and the input end of the second second voltage divider 22 is connected to the other phase winding drive line of any two-phase windings of the motor. Among them, the drive system of the motor includes a motor drive circuit, and the three-phase winding drive lines of the motor are connected to the three-phase winding lead-out lines of the motor one by one to realize the connection between the motor drive circuit and the motor; the input end of the first digital-to-analog converter 23 is connected to the output end of the first second voltage divider 21, and the first digital-to-analog converter 23 is used to convert the terminal voltage signal of one phase winding after being reduced by the first second voltage divider 21 into a corresponding analog signal. The input end of the second digital-to-analog converter 24 is connected to the output end of the second second voltage divider 22, and the second digital-to-analog converter 24 is used to convert the terminal voltage signal of the other phase winding after being reduced by the second second voltage divider 22 into a corresponding analog signal; one input end of the first comparator circuit 25 is connected to the output end of the first digital-to-analog converter 23, and the first comparator circuit 25 is used to convert the analog signal corresponding to one phase winding into a corresponding second square wave signal. The output end of the first comparator circuit 25 is connected to the multi-turn counting MCU 30. One input end of the second comparator circuit 26 is connected to the output end of the second digital-to-analog converter 24, and the second comparator circuit 26 is used to convert the analog signal corresponding to the other phase winding into a corresponding second square wave signal. The output end of the second comparator circuit 26 is connected to the multi-turn counting MCU 30.

[0039] It should be understood that the phase difference situation of at least two first or second square wave signals has a corresponding relationship with the motor rotation direction, and the number of pulses of any first or second square wave signal has a corresponding relationship with the number of turns of the motor. Therefore, the multi-turn counting MCU 30 can specifically judge the motor rotation direction according to the phase difference between at least two first square wave signals or the phase difference between at least two second square wave signals, and determine the turn number data of the motor according to the number of pulses of at least two first square wave signals or the number of pulses of at least two second square wave signals. The more the number of first square wave signals or second square waves selected, the more accurate the obtained motor rotation direction and turn number data, but the data processing volume of the multi-turn counting MCU 30 will increase correspondingly. Therefore, the number of first square wave signals or second square waves can be selected according to actual needs.

[0040] According to the multi-turn counting device of an electric motor according to an embodiment of the present invention, the first detection module detects the back electromotive force signals of at least two-phase windings of the electric motor when the drive system of the electric motor loses power, and the second detection module detects the terminal voltage signals of at least two-phase windings of the electric motor when the drive system of the electric motor powers on and works, and obtains the running direction and the number-of-turns data of the electric motor according to the square wave signals converted from the detected signals. Thus, multi-turn counting of the electric motor when losing power and powering on can be achieved. Compared with using Hall elements for multi-turn counting, there is no need to use a magnetic ring, and there is no need to install the device inside the electric motor body, and there is no need to consider the requirements and selection of aspects such as the power consumption, heat resistance, and response frequency of Hall elements. Therefore, the structure is simple, the reliability is high, and it is easy to produce.

[0041] Based on the multi-turn counting device of an electric motor according to the above embodiment, the present invention further proposes a multi-turn counting method of an electric motor, a drive system of an electric motor, and a joint control system of a robot.

[0042] As Figure 4 shown, the multi-turn counting method of an electric motor according to an embodiment of the present invention includes the following steps:

[0043] S1. When the drive system of the electric motor loses power, detect the back electromotive force signals of at least two-phase windings of the electric motor, and convert the back electromotive force signals of at least two-phase windings of the electric motor into corresponding at least two first square wave signals respectively.

[0044] Specifically, the back electromotive force signal can be input into a zero-crossing detection circuit after voltage reduction to be converted into a corresponding first square wave signal.

[0045] S2. When the drive system powers on and works, detect the terminal voltage signals of at least two-phase windings of the electric motor, and convert the terminal voltage signals of at least two-phase windings of the electric motor into corresponding at least two second square wave signals respectively.

[0046] Specifically, the terminal voltage signal can be subjected to analog-to-digital conversion after voltage reduction to be converted into a corresponding analog signal, and the analog signal is input into a comparator circuit to be converted into a corresponding second square wave signal.

[0047] S3. Obtain the running direction and the number-of-turns data of the electric motor when the drive system loses power according to at least two first square wave signals, and obtain the running direction and the number-of-turns data of the electric motor when the drive system powers on and works according to at least two second square wave signals.

[0048] Specifically, the running direction of the electric motor can be judged according to the phase difference between at least two first square wave signals or the phase difference between at least two second square wave signals, and the number-of-turns data of the electric motor can be determined according to the number of pulses of at least two first square wave signals or the number of pulses of at least two second square wave signals.

[0049] The multi-turn counting method for a motor according to an embodiment of the present invention detects the back electromotive force signals of at least two-phase windings of the motor when the drive system of the motor loses power, detects the terminal voltage signals of at least two-phase windings of the motor when the drive system of the motor is powered on and working, and obtains the running direction and number of turns data of the motor according to the square wave signals converted from the detected signals. Thus, multi-turn counting of the motor when power is off and on can be achieved. Compared with using a Hall element for multi-turn counting, there is no need to use a magnetic ring, nor to install the device implementing the method inside the motor body, and there is no need to consider requirements and selection of aspects such as Hall element power consumption, heat resistance, and response frequency. Therefore, this method is easy to implement and has high reliability.

[0050] The drive system of the motor according to an embodiment of the present invention is included in Figure 3 the joint control system of a robot. The drive system of the motor according to an embodiment of the present invention, in addition to including the multi-turn counting device of the motor in any of the above embodiments, as Figure 3 shown, further includes a motor drive circuit 50, a single-turn encoder 60, a memory 70, and a drive MCU 80. Among them, the motor drive circuit 50 is used to drive and control the motor in a FOC drive manner when the drive system is powered on and working; the single-turn encoder 60 is used to obtain the single-turn position data of the motor when the drive system is powered on and working; the memory 70 is used to store the running direction and number of turns data of the motor when the drive system loses power; the drive MCU 80 is connected to the motor drive circuit 50, the multi-turn counting MCU 30, the memory 70, and the single-turn encoder 60 respectively. In addition to providing a FOC drive signal to the motor drive circuit 50 and controlling the memory 70 to store the running direction and number of turns data of the motor obtained by the multi-turn counting MCU 30 when the drive system loses power, the drive MCU 80 is also used to read the running direction and number of turns data of the motor when the drive system loses power from the memory 70 when the drive system is powered on again after losing power, so as to restore the state before power-off of the motor, and to implement the multi-turn encoder function according to the running direction, number of turns data, and single-turn position data of the motor when the drive system is powered on and working.

[0051] In an embodiment of the present invention, the first detection module 10 and the multi-turn counting MCU 30 can be arranged on the same circuit board, and the second detection module 20, the motor drive circuit 50, the memory 70, and the drive MCU 80 can be arranged on the same circuit board. As Figure 3 shown, the first detection module 10 and the multi-turn counting MCU 30 can be arranged on the first circuit board, and a battery interface is arranged on the first circuit board. The battery interface is used to connect an external battery 40. As Figure 3As shown in the figure, the second detection module 20, the motor drive circuit 50, the memory 70, and the drive MCU 80 can be disposed on the second circuit board. The second circuit board is provided with a motor interface and an encoder interface. The motor interface is used to connect the drive lines of the motor's multi-phase windings (taking three phases as an example in the figure) to the lead-out lines of the motor's multi-phase windings in a one-to-one correspondence, so as to connect the motor drive circuit 50 to the motor. The encoder interface is used to connect the drive MCU 80 to the single-turn encoder 60.

[0052] According to the motor drive system of the embodiment of the present invention, by adopting the above-mentioned multi-turn counting device for the motor, the multi-turn counting of the motor during power-off and power-on can be achieved. The structure is simple, the reliability is high, and it is easy to produce.

[0053] In addition to including the motor drive system of any of the above embodiments, the joint control system of the robot according to the embodiment of the present invention, as Figure 3 shown, further includes a motor 90 and a reducer 100. The reducer 100 is disposed between the motor 90 and the joint to be controlled.

[0054] According to the joint control system of the robot of the embodiment of the present invention, by adopting the above-mentioned motor drive system, the multi-turn counting of the motor during power-off and power-on can be achieved. The structure is simple, the reliability is high, and it is easy to produce.

[0055] Next, in combination with Figure 3 and One some waveform diagrams, the multi-turn counting device, method, drive system, and joint control system of the embodiment of the present invention will be further described in detail.

[0056] Generally speaking, the multi-turn counting device of the embodiment of the present invention has two working states: system power-off and system power-on. After the system is powered off, when the joint of the robot is displaced due to gravity, vibration, or manual pushing, that is, the motor 90 is dragged, an electromotive force signal will be generated. The electromotive force signal whose frequency and amplitude are positively correlated with the motor speed is converted into a square wave signal. Using this square wave signal, the number of turns and the running direction of the motor 90 can be recorded, and the recording of the motor state change during system power-off can be realized; when the system is powered on and running, the motor 90 is driven by the SPWM modulation method. The motor winding current is approximately a sine waveform. At this time, the winding terminal voltage waveform is a square wave signal with a variable pulse width, and the amplitude is the DC bus voltage. The pulse width is proportional to the amplitude of the winding current. The winding terminal voltage is subjected to voltage reduction, digital-to-analog conversion, and analog-to-digital conversion to generate a square wave signal. Using this square wave signal, the number of turns and the running direction of the motor 90 can be recorded, and the multi-turn counting function can be realized.

[0057] Specifically, when the drive system of the motor 90 loses power, the first detection module 10 and the multi-turn counting MCU 30 on the first circuit board are switched to be powered by the external battery 40, and together with the speed reducer 100 and the motor 90, they form a motor rotation number recording system. When an external force acts on the robotic arm of the robot, causing the speed reducer 100 to rotate, the speed reducer drives the motor shaft to rotate. Due to the large speed ratio, the motor 90 will rotate at a faster speed. At this time, a back electromotive force voltage waveform is generated on the winding of the motor 90, and the waveform is as Figure 5 shown.

[0058] In the first detection module 10, the switch circuit one 11 and the switch circuit two 12 close the switches, and the two opposite back electromotive force signals are respectively connected to the first voltage divider one 13 and the first voltage divider two 14. Both voltage dividers can be resistor voltage dividing circuits. By setting an appropriate voltage division ratio, the back electromotive force signals are processed to reduce the voltage, so as to meet the input voltage requirements of the subsequent zero-crossing detection circuit. The negative input terminals of the zero-crossing detection circuit one 15 and the zero-crossing detection circuit two 16 are grounded. When the signal at the positive input terminal is higher than the GND voltage, the zero-crossing detection circuit can output a high-level signal. When the signal at the positive input terminal is lower than the GND voltage, the zero-crossing detection circuit can output a low-level signal, thereby forming a first square wave signal. The conversion process of the first detection module 10 for the back electromotive force signal of any one phase is as Figure 6 shown.

[0059] For a multi-phase motor, there is a phase difference between the back electromotive force signals output by each phase winding. Therefore, if more than two back electromotive force signals are arbitrarily selected, after being processed by the first detection module 10, first square wave signals with the same phase difference can be output. In the embodiment of the present invention, taking the A and B phases of a three-phase motor as an example, the output first square wave signals are as Figure 7 shown.

[0060] As Figure 7 shown, there is a phase difference between the first square wave signals of the A and B phases. For different rotation directions of the motor, the rotation direction of the motor 90 can be determined by judging the polarity of the phase difference. For example, a positive value represents forward rotation, and a negative value represents reverse rotation. Then, by counting the number of pulses of the first square wave signals of the A and B phases, the number of rotations of the motor 90 can be determined. For example, if the motor 90 generates 10 pulses during operation and a total of 20 pulses are detected for any one of the first square wave signals, then the motor 90 rotates two circles. If a higher accuracy of the motor rotation number is required, the first square wave signal can be further frequency-divided, and the frequency division coefficient is determined by the accuracy requirement of the system. Thus, by increasing the number of pulses generated by the motor for one rotation, the accuracy of detecting the motor rotation can be improved. The higher the number of pulses generated per single rotation, the higher the detection accuracy of the motor rotation number.

[0061] The rotation direction and number of turns data of the motor 90 are recorded by the multi-turn counting MCU 30. When the drive system is powered on again, the change data of the motor 90 after power-off is sent to the drive MCU 80 through a communication interface (such as a serial port). At the same time, the drive MCU 80 reads the motor position data stored in the memory 70 before power-off to obtain the motor position change amount, thereby performing correction processing on the joint position.

[0062] When the drive system of the motor 90 is powered on and working, a servo control system is composed of a reducer 100, a motor 90, a single-turn encoder 60, a multi-turn counting MCU 30, a motor drive circuit 50, a memory 70, and a drive MCU 80. The multi-turn encoder function is realized through the single-turn encoder 60, the second detection module 20, and the multi-turn counting MCU 30. The motor winding terminal voltage using the SPWM modulation method is as Figure 8 shown, and its pulse width changes periodically.

[0063] The amplitude of the motor winding terminal voltage is the DC bus voltage, and the voltage value is relatively high and cannot be directly connected to the digital-to-analog converter. Therefore, in the second detection module 20, the winding terminal voltage is first reduced by the second voltage divider one 21 and the second voltage divider two 22, and the voltage division ratio is selected according to the actual circuit. The signals output by the second voltage divider one 21 and the second voltage divider two 22 are still square wave signals, and then through the digital-to-analog converter one 23 and the digital-to-analog converter two 24, the digital square wave signal is converted into an analog signal. Then the output analog signal is connected to the comparator circuit one 25 and the comparator circuit two 26, and the comparison threshold voltage VREF can be reasonably set. When the input voltage is greater than VREF, the comparator outputs a high-level signal. When the input voltage is less than VREF, the comparator outputs a low-level signal, thereby forming a second square wave signal. The conversion process of the second detection module 20 for the terminal voltage signal of any phase is as Figure 9 shown.

[0064] From Figure 9 it can be seen that the selection of the magnitude of VREF determines the pulse width of the second square wave signal, and the specific parameters can be set according to the actual circuit requirements. After the winding terminal voltage signal is subjected to digital-to-analog conversion, the actually fitted analog signal is the current waveform of each phase winding, except that there is no negative current, and there is a phase difference between the current waveforms of each phase winding. The frequency of the current waveform reflects the speed information of the motor. Therefore, arbitrarily select the terminal voltage signals of two-phase windings of the motor, and two second square wave signals with a phase difference can be output through the processing of the second detection module 20. The output second square wave signal can also be seen in Figure 7 .

[0065] Similarly, there is a phase difference between the second square-wave signals of phases A and B. For different rotation directions of the motor, the rotation direction of the motor 90 can be determined by judging the polarity of the phase difference. For example, a positive value represents forward rotation, and a negative value represents reverse rotation. Then, by counting the number of pulses of the second square-wave signals of phases A and B, the number of turns the motor 90 has run can be determined. For example, if the motor 90 generates 10 pulses during operation and a total of 20 pulses are detected for any one of the second square-wave signals, then the motor 90 has rotated two turns.

[0066] The data of the rotation direction and the number of turns of the motor 90 are recorded by the multi-turn counting MCU 30 and sent to the driving MCU 80 through the communication interface. The driving MCU 80 can implement the multi-turn encoder function through software algorithms based on the obtained single-turn position data and the data of the rotation direction and the number of turns of the motor.

[0067] In a specific embodiment of the present invention, the encoder can be an absolute encoder, that is, the single-turn encoder in any of the above embodiments is a single-turn absolute encoder with a code disk, and the multi-turn encoder function implemented in any of the above embodiments is a multi-turn absolute encoder function.

[0068] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The meaning of "plurality" is two or more, unless otherwise specifically defined.

[0069] In the present invention, unless otherwise clearly defined and limited, the terms such as "mounted", "connected", "connected to", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0070] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature is at a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature is at a lower horizontal height than the second feature.

[0071] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0072] In addition, each functional unit in various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0073] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations of the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A motor multi-turn counting device, characterized in that: The motor is a multi-phase motor and is driven by FOC. The device includes: a first detection module, configured to detect back electromotive force signals of at least two phase windings of the motor when a drive system of the motor is powered off, and convert the back electromotive force signals of at least two phase windings of the motor into corresponding at least two first square wave signals; a second detection module, configured to detect terminal voltage signals of at least two-phase windings of the motor when the drive system is powered on, and convert the terminal voltage signals of at least two-phase windings of the motor into corresponding at least two second square wave signals; a multi-turn counting MCU, the multi-turn counting MCU being connected to the first detection module and the second detection module respectively, the multi-turn counting MCU being used to obtain the running direction and the number of turns of the motor when the drive system is powered off according to the at least two first square wave signals, and to obtain the running direction and the number of turns of the motor when the drive system is powered on according to the at least two second square wave signals, The first detection module includes at least two first detection units corresponding to at least two phase windings, each of which includes: a switch circuit, one end of which is connected to the lead wire of the corresponding phase winding; a first voltage divider, an input end of which is connected to the other end of the switch circuit; a zero-crossing detection circuit, one input end of which is connected to the output end of the first voltage divider to receive the back electromotive force signal of the phase winding after being reduced by the first voltage divider and convert it into a corresponding first square wave signal, and the output end of the zero-crossing detection circuit is connected to the multi-turn counting MCU. The second detection module includes at least two second detection units corresponding one-to-one to at least two-phase windings, and each second detection unit includes: a second voltage divider, the input end of the second voltage divider is connected to the drive line of the corresponding one-phase winding, wherein the drive system of the motor includes a motor drive circuit, and the drive lines of the multi-phase windings of the motor are connected one-to-one to the lead lines of the multi-phase windings of the motor to realize the connection between the motor drive circuit and the motor; a digital-to-analog converter, the input end of the digital-to-analog converter is connected to the output end of the second voltage divider, and the digital-to-analog converter is used to convert the terminal voltage signal of the one-phase winding after being reduced by the second voltage divider into a corresponding analog signal; a comparator circuit, one input end of the comparator circuit is connected to the output end of the digital-to-analog converter, and the comparator circuit is used to convert the analog signal corresponding to the one-phase winding into a corresponding second square wave signal, and the output end of the comparator circuit is connected to the multi-turn counting MCU.

2. The motor multi-turn counting device according to claim 1, characterized in that: Also includes: An external battery is used to supply power to the first detection module and the multi-turn counting MCU when the drive system loses power.

3. The motor multi-turn counting device according to claim 1 or 2, characterized in that: The multi-turn counting MCU is specifically used to determine the running direction of the motor based on the phase difference between the at least two first square wave signals or the phase difference between the at least two second square wave signals, and to determine the number of turns data of the motor based on the number of pulses of the at least two first square wave signals or the number of pulses of the at least two second square wave signals.

4. A motor multi-turn counting method based on the motor multi-turn counting device according to any one of claims 1 to 3, characterized in that: The motor is a multi-phase motor and is driven by FOC. The method includes the following steps: detecting back electromotive force signals of at least two phase windings of the motor when the driving system of the motor is powered off, and converting the back electromotive force signals of at least two phase windings of the motor into corresponding at least two first square wave signals respectively; When the drive system is powered on, terminal voltage signals of at least two phase windings of the motor are detected, and the terminal voltage signals of at least two phase windings of the motor are converted into corresponding at least two second square wave signals respectively; The running direction and number of revolutions of the motor when the drive system is powered off are obtained according to the at least two first square wave signals, and the running direction and number of revolutions of the motor when the drive system is powered on are obtained according to the at least two second square wave signals.

5. The motor multi-turn counting method according to claim 4, characterized in that: in, The back electromotive force signal is reduced in amplitude and input into a zero-crossing detection circuit to be converted into a corresponding first square wave signal; The terminal voltage signal is reduced in amplitude and then subjected to digital-to-analog conversion to be converted into a corresponding analog signal, and the analog signal is input into a comparator circuit to be converted into a corresponding second square wave signal.

6. The motor multi-turn counting method according to claim 4 or 5, characterized in that: in, The running direction of the motor is determined based on the phase difference between the at least two first square wave signals or the phase difference between the at least two second square wave signals, and the number of revolutions of the motor is determined based on the number of pulses of the at least two first square wave signals or the number of pulses of the at least two second square wave signals.

7. A motor drive system, characterized in that: include: The motor multi-turn counting device according to any one of claims 1 to 3; A motor drive circuit, configured to drive and control the motor using a FOC drive mode when the drive system is powered on; A single-turn encoder, configured to obtain single-turn position data of the motor when the drive system is powered on; a memory, the memory being used to store data on the running direction and number of revolutions of the motor when the drive system loses power; A driving MCU is respectively connected to the motor driving circuit, the multi-turn counting MCU, the memory and the single-turn encoder. The driving MCU is used to read the running direction and number of turns data of the motor when the drive system is powered off from the memory when the drive system is powered on again after power off, so as to restore the state of the motor before power off. The driving MCU is also used to realize the multi-turn encoder function according to the running direction, number of turns data and single-turn position data of the motor when the drive system is powered on.

8. A robot joint control system, characterized in that: include: The motor drive system according to claim 7; Motor; A reducer is arranged between the motor and the joint to be controlled.

Images