JP7016115B2 - Shaft joint characteristic evaluation device and characteristic evaluation method - Google Patents

Description

The present invention relates to a characteristic evaluation device and a characteristic evaluation method for evaluating the characteristics of a machine element, and more particularly to a characteristic evaluation device and a characteristic evaluation method for a shaft joint connecting two shafts.

A physical parameter identification method that characterizes a feed mechanism in a positioning device that positions a transport object, including a feed drive mechanism (linear motion mechanism) that moves the transport object in the linear motion direction by converting rotational motion into linear motion. It is known (for example, Patent Document 1). In Patent Document 1, the frequency characteristic of the positioning device is measured by using a frequency characteristic analyzer and a servo analyzer, and the resonance value and the resonance frequency are acquired from the measurement result. Then, based on the acquired resonance value and resonance frequency, the intrinsic angular frequency, damping coefficient, spring constant, and viscous friction resistance of the feed mechanism are calculated (for example, Patent Document 1).

Many feed drive mechanisms include a shaft joint that connects the rotary shaft of the motor and the screw shaft of the ball screw. It is known that the shaft joint provided in the feed drive mechanism is a mechanical element that transmits the torque of the motor to the ball screw while allowing misalignment and runout of the two shafts, and has a great influence on the characteristics of the feed drive mechanism. (For example, Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 3-282717

Atsushi Nagao, Ryuta Sato, Keiichi Shirase, Takeshi Hashimoto, Taichi Sasaki: Effects of shaft joints and ball screws on the torsional vibration mode of the feed drive system, Proceedings of the 2017 Autumn Meeting of the Japan Society for Precision Engineering, (2017), pp. 425-426.

In order to improve the performance of the feed drive mechanism, it is important to evaluate the characteristics of the shaft joint more accurately. Therefore, based on Patent Document 1, it is conceivable to connect the motor and the load by a shaft joint, measure the frequency characteristic of the gain (gain) with the drive torque of the motor as the input and the angular velocity of the motor as the output. By using the obtained frequency characteristics, the resonance value and the resonance frequency can be obtained, and thereby the torsional rigidity and the torsional elastic modulus, which are the physical parameters that characterize the shaft joint, can be identified.

However, the inventors have noted that the accuracy of the identified physical parameters may decrease due to the response characteristics of the motor system after issuing a torque command to the motor to generate the drive torque until the drive torque is generated. I found it.

Therefore, the present invention has been devised in view of the problems of the prior art, and can appropriately evaluate the characteristics of the shaft joint in consideration of the response characteristics of the motor system. The main purpose is to provide a characteristic evaluation device and a characteristic evaluation method.

In the first aspect of the present invention, a characteristic evaluation device (1, 101) for evaluating the characteristics of the shaft joint (4) connecting both shafts in order to transmit torque from the drive shaft (2) to the driven shaft (3). ), Based on the drive motor (11) that applies drive torque to the drive shaft, the rotation angle sensor (14) that acquires the rotation angle of the drive shaft, and the given torque command ( _Tref ). A motor system (5) including a motor control unit (13) that controls the drive motor and a rotary load unit (18) connected to the driven shaft in order to output torque according to the torque command. The torque command is output to the motor control unit so as to output the predetermined drive torque, and the torque corresponding to the torque command is based on the rotation angle detected by the rotation angle sensor. It has a processor (21) capable of calculating the frequency characteristic of the gain of the amplitude of the angular velocity (ω) of the rotation angle, and the processor has a response characteristic of the motor system and a state in which the shaft joint connects both shafts. It is characterized in that the characteristics of the shaft joint are calculated based on the frequency characteristics calculated in 1.

According to this, since the response characteristics of the motor system are taken into consideration in the calculation of the characteristics of the shaft joint, the characteristics of the shaft joint can be evaluated more appropriately.

In the second aspect of the present invention, the processor has a transmission function (G) as a response characteristic of the motor system until the drive motor is driven by the torque command and the corresponding torque is generated from the drive motor. ^* Using (s)), the frequency characteristic is acquired with the shaft joint connected, and the resonance frequency (f ₀ ) of the shaft joint and the gain at the resonance frequency are acquired from the frequency characteristic. The torsional rigidity (K _c ) of the shaft joint is calculated using the resonance frequency, and the viscosity coefficient ( _cc ) of the shaft joint is calculated using the transmission function, the torsional rigidity, and the gain at the resonance frequency. Is characterized by calculating.

According to this, the torsional rigidity of the shaft joint can be easily calculated by using the frequency characteristics. Further, the viscosity coefficient of the shaft joint can be calculated in consideration of the transfer function from the time when the torque command is given to the motor to the time when the torque is generated on the drive shaft. As a result, the viscosity coefficient is calculated in consideration of the response characteristics of the motor system, so that the accuracy of the calculated viscosity coefficient is improved.

In the third aspect of the present invention, the processor converts the gain at the resonance frequency into a conversion value corresponding to the gain at the resonance frequency when the transfer function is 1. , The torsional rigidity and the converted value are used to calculate the viscosity coefficient of the shaft joint.

According to this, by converting the gain at the resonance frequency using the transfer function, it can be converted into the gain when the transfer function of the motor system is 1. Thereby, the viscosity coefficient of the shaft joint can be calculated by using the model when the transfer function of the motor system is 1.

In the fourth aspect of the present invention, the processor acquires the response characteristics of the motor system by the frequency characteristics when the driving motor is driven in a state where the shaft joints are not connected to both shafts. It is characterized by doing.

According to this, by acquiring the frequency characteristics of the motor system, it is possible to calculate the transfer function from the time when the torque command is given to the motor to the time when the torque is generated on the drive shaft.

A fifth aspect of the present invention is a method for evaluating the characteristics of a shaft joint that evaluates the characteristics of the shaft joint (4) that connects both shafts in order to transmit torque from the drive shaft (2) to the driven shaft (3). Based on the drive motor (11) that applies drive torque to the drive shaft, the rotation angle sensor (14) that acquires the rotation angle of the drive shaft, and the given torque command ( _Tref ). A motor system (5) including a motor control unit (13) that controls the drive motor, a rotary load unit (18) connected to the driven shaft, and a predetermined value, in order to output torque according to the torque command. The torque command is output to the motor control unit so as to output the drive torque, and the rotation angle with respect to the torque amplitude corresponding to the torque command is based on the rotation angle detected by the rotation angle sensor. Using a characteristic evaluation device (1) capable of calculating the frequency characteristic of the gain of the angular velocity amplitude of the above, the step (ST5) of acquiring the frequency characteristic in a state where the shaft joint connects both shafts was acquired. It is characterized by executing the step (ST7, ST10) of calculating the characteristics of the shaft joint based on the frequency characteristics and the response characteristics of the motor system.

According to this, since the response characteristics of the motor system are taken into consideration in the calculation of the characteristics of the shaft joint, the characteristics of the shaft joint can be evaluated more appropriately.

In the sixth aspect of the present invention, in the step (ST5) of acquiring the frequency characteristic in the state where the shaft joint is connected, the resonance frequency (f ₀ ) of the shaft joint from the frequency characteristic, and the resonance frequency. The step of acquiring the gain (ST6), the step of calculating the torsional rigidity (K _c ) of the shaft joint using the resonance frequency (ST7), and the torque command as the response characteristic of the motor system are used. The viscosity coefficient ( _cc ) of the shaft joint is calculated using the transmission function until the drive motor is driven and the corresponding torque is generated from the drive motor, the torsional rigidity, and the gain at the resonance frequency. It is characterized by including the steps (ST9, ST10) to be performed.

According to this, the torsional rigidity of the shaft joint can be easily calculated by using the frequency characteristics. Further, the viscosity coefficient of the shaft joint can be calculated in consideration of the transfer function from the time when the torque command is given to the motor to the time when the torque is generated on the drive shaft. As a result, the viscosity coefficient is calculated in consideration of the response characteristics of the motor system, so that the accuracy of the calculated viscosity coefficient is improved.

In the seventh aspect of the present invention, in the step of calculating the viscosity coefficient of the shaft joint, the transfer function (G ^* (s)) is used to obtain the gain at the resonance frequency, and the transfer function is 1. A step (ST9) of converting to a conversion value (M _f0 ) corresponding to the gain at the resonance frequency, and a step of calculating the viscosity coefficient of the shaft joint using the torsional rigidity and the conversion value (ST9). It is characterized by including ST10).

According to this, by converting the gain at the resonance frequency using the transfer function, it can be converted into the gain when the transfer function of the motor system is 1. Thereby, the viscosity coefficient of the shaft joint can be calculated by using the model when the transfer function of the motor system is 1.

The eighth aspect of the present invention includes a step of acquiring the response characteristics of the motor system by the frequency characteristics when the driving motor is driven in a state where the shaft joints are not connected to both shafts. It is good.

According to this, by acquiring the frequency characteristics of the motor system, it is possible to calculate the transfer function from the time when the torque command is given to the motor to the time when the torque is generated on the drive shaft.

A ninth aspect of the present invention is a shaft joint characteristic evaluation device (101), wherein the processor outputs the drive torque having two or more amplitudes when the shaft joint connects the two shafts. As described above, the torque command is output to the motor control unit, the frequency characteristics corresponding to the respective amplitudes are calculated, and the amplitude is based on the response characteristics of the motor system and the calculated frequency characteristics. The characteristics of the shaft joint corresponding to each of the above are calculated, and the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency of the shaft joint, the amplitude of the rotation angle at the resonance frequency, and the angular velocity at the resonance frequency. It is advisable to output the relationship between at least one of the amplitudes of the above and the characteristics of the shaft joint.

According to this, the amplitude dependence of the drive torque applied to the shaft joint of the characteristics of the shaft joint is output. As a result, the user can appropriately evaluate the input-dependent characteristics of the shaft joint, so that it is possible to predict the vibration characteristics under various operating conditions and design an appropriate control system.

In the tenth aspect of the present invention, the processor obtains the torsional rigidity of the shaft joint for each of the acquired frequency characteristics, the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency, and the said. It is preferable to output the relationship between at least one of the amplitude of the rotation angle at the resonance frequency, the amplitude of the angular velocity at the resonance frequency, and the torsional rigidity of the shaft joint.

According to this, the amplitude dependence of the drive torque of the torsional rigidity of the shaft joint is output. This makes it possible to appropriately evaluate the input dependence of the shaft joint. In addition, since the amplitude dependence of the torsional rigidity is output, the content is easily understood by the user, and the convenience of the shaft joint characteristic evaluation device is enhanced.

In the eleventh aspect of the present invention, the processor outputs the torque command to the motor control unit so as to output the drive torque having two or more amplitudes, and the frequency characteristic corresponding to each amplitude. The viscosity coefficient of the shaft joint is obtained for each of the acquired frequency characteristics, and the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency, and the amplitude of the rotation angle at the resonance frequency. It is preferable to output the relationship between at least one of the amplitudes of the angular velocities at the resonance frequency and the viscosity coefficient of the shaft joint.

According to this, the amplitude dependence of the drive torque of the viscosity coefficient of the shaft joint is output. This makes it possible to appropriately evaluate the input-dependent characteristics of the shaft joint. In addition, since the amplitude dependence of the viscosity coefficient is output, the content is easily understood by the user, and the convenience of the shaft joint characteristic evaluation device is enhanced.

A twelfth aspect of the present invention is a method for evaluating a shaft joint, in which the drive torque having two or more amplitudes is output to the motor system in a state where the shaft joint connects the two shafts, respectively. A step of acquiring the frequency characteristic corresponding to the amplitude of the above, a step of calculating the characteristic of the shaft joint corresponding to the respective amplitude based on the acquired frequency characteristic and the response characteristic of the motor system. And run.

According to this, it is possible to evaluate the amplitude dependence of the drive torque applied to the shaft joint in the characteristics of the shaft joint. This makes it possible to predict vibration characteristics and design an appropriate control system under various operating conditions.

In the thirteenth aspect of the present invention, in a state where the shaft joint is connected, a step of acquiring the frequency characteristics of two or more amplitudes, a resonance frequency of the shaft joint from the respective frequency characteristics, and the resonance of the shaft joint. A step of acquiring the gain at a frequency, a step of calculating the torsional rigidity of the shaft joint corresponding to each amplitude using the resonance frequency, the amplitude of the torque command, and the driving torque at the resonance frequency. It may include a step of outputting the relationship between at least one of the amplitude of, the amplitude of the rotation angle at the resonance frequency, the amplitude of the angular velocity at the resonance frequency, and the torsional rigidity of the shaft joint.

According to this, the amplitude dependence of the drive torque of the torsional rigidity of the shaft joint can be evaluated. This makes it possible to predict vibration characteristics under various operating conditions and design an appropriate control system, which makes it easier for the user to understand the contents.

In the fourteenth aspect of the present invention, at each of the amplitudes, the drive motor is driven by the torque command as the response characteristic of the motor system, and the transmission function until the corresponding torque is generated from the drive motor. , The step of calculating the viscosity coefficient of the shaft joint using the torsional rigidity and the gain at the resonance frequency, the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency, and the said at the resonance frequency. It may include a step of outputting the relationship between at least one of the amplitude of the rotation angle and the amplitude of the angular velocity at the resonance frequency and the viscosity coefficient of the shaft joint.

According to this, it is possible to evaluate the amplitude dependence of the drive torque of the viscosity coefficient of the shaft joint. This makes it possible to predict vibration characteristics under various operating conditions and design an appropriate control system, which makes it easier for the user to understand the contents.

As described above, according to the present invention, it is possible to provide a shaft joint characteristic evaluation device and a characteristic evaluation method capable of appropriately evaluating the shaft joint characteristics in consideration of the response characteristics of the motor system. ..

Explanatory drawing for explaining the state of the evaluation device when the drive shaft and the driven shaft are connected by the functional block of the evaluation device and the shaft joint. Hardware configuration diagram of evaluation device Explanatory drawing for explaining the state of the evaluation device when the shaft joint is removed. The figure which shows the frequency characteristic acquired with the shaft joint removed. Block diagram showing the state where the shaft joint is removed Example of frequency characteristics acquired with the drive shaft and driven shaft connected by a shaft joint 2 Figure showing vibration model of inertial system Block diagram showing the state where the drive shaft and the driven shaft are connected by a shaft joint Flow chart of evaluation process according to the first embodiment (A) A diagram showing the measurement result (solid line) of the frequency characteristic in the state where the drive shaft and the driven shaft are connected by the shaft joint A, and the calculation result (broken line) when the response characteristic of the motor system is taken into consideration, (B). ) A diagram showing the measurement results (solid line) of the frequency characteristics when the drive shaft and the driven shaft are connected by the shaft joint B, and the calculation results (broken line) when the response characteristics of the motor system are taken into consideration. The figure which shows the measurement result (solid line) of the frequency characteristic in the state which the drive shaft and the driven shaft are connected by the shaft joint A, and the calculation result (dashed line) when the delay by a motor system is ignored. Flow chart of evaluation process according to the second embodiment A graph showing the frequency characteristics when the amplitude of the torque command is (A) 1.0 Nm and (B) 3.0 Nm in the state where the drive shaft and the driven shaft are connected by the shaft joint A. With the drive shaft and driven shaft connected by the shaft joint A, the torque command amplitude obtained from the frequency characteristics when the torque command amplitude is changed in 10 ways, (A) torsional rigidity, and (B) viscosity coefficient. Graph showing the relationship with

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
The evaluation device 1 according to the present invention is a device for evaluating the characteristics of a shaft joint 4 (coupling) connecting both shafts in order to transmit the torque of the drive shaft 2 to be rotationally driven to the driven shaft 3. More specifically, the characteristic evaluation device 1 according to the present invention quantifies the torsional rigidity K _c [Nm / rad] and the viscosity coefficient c _c [Nm / (rad / s)], which are the characteristics of the shaft joint 4, respectively. Can be evaluated.

As shown in FIG. 1, the characteristic evaluation device 1 includes a motor system 5 provided with a drive shaft 2, a driven device 6 provided with a driven shaft 3, an analysis device 7, and an input / output device 8. When evaluating the characteristics of the shaft joint 4, the shaft joint 4 to be evaluated is arranged so as to connect the drive shaft 2 and the driven shaft 3.

The motor system 5 includes a drive motor 11, a current sensor 12, a servo driver 13 (motor control unit), a rotation angle sensor 14, and a differentiator 15.

The drive motor 11 is a general-purpose servomotor, and the output shafts to be the drive shafts 2 are arranged so as to be substantially horizontal, and a drive torque _Tm is applied to the drive shafts 2. The current sensor 12 is a sensor that measures the current value of the current (hereinafter referred to as the drive current) flowing through the drive motor 11. The servo driver 13 supplies a drive current to the drive motor 11, and causes the drive motor 11 to output a torque (hereinafter referred to as a command torque value) corresponding to the torque command _Tref input from the analyzer 7. The drive motor 11 is controlled by controlling the current value. More specifically, the servo driver 13 feedback-controls the drive current so that the deviation between the current value acquired by the current sensor 12 and the current value corresponding to the command torque value becomes zero. That is, the servo driver 13, the current sensor 12, and the drive motor 11 form a current loop (feedback loop), and the servo driver 13, the current sensor 12, and the drive motor 11 cooperate to control the torque. As a result, it functions as a servo system 16 (servo mechanism) that automatically drives the drive shaft 2 to output a drive torque T _m corresponding to the control amount.

The rotation angle sensor 14 is a so-called rotary encoder for measuring the rotation angle of the drive shaft 2, and may include any optical, magnetic, or capacitive detection element.

The differentiator 15 is connected to the rotation angle sensor 14 and the analysis device 7. The differentiator 15 acquires the rotation angle of the drive shaft 2 from the rotation angle sensor 14, differentiates the rotation angle with respect to time, calculates the angular velocity ω, and outputs the angular velocity ω to the analyzer 7.

In addition to the driven shaft 3, the driven device 6 includes a rotational load unit 18 connected to the driven shaft 3 and applying a load to the rotational movement of the driven shaft 3. The rotational load unit 18 may be configured by a disk or the like having a predetermined moment of inertia. Further, the rotary load unit 18 may be configured by a motor having substantially the same shape as or different in size from the drive motor 11. At this time, the output shaft of the motor may be fixed to the driven shaft 3. The driven device 6 itself may be configured by a motor having substantially the same shape as or different in size from the driving motor 11. When the motor is used as the driven device 6, the output shaft may be used as the driven shaft 3. When the motor is used as the rotary load unit 18 or the motor is used as the driven device 6, the motor is added to the driven shaft 3 by giving commands such as torque, the rotation angle of the driven shaft 3, or the angular velocity of the driven shaft 3. The load can be changed. This makes it possible to perform a characteristic test of the shaft joint 4 in which the load state is changed.

The analyzer 7 outputs a torque command _ref to the servo driver 13, and is based on the rotation angle of the drive shaft 2, more specifically, the angular velocity ω, which is the time derivative of the rotation angle calculated by the differentiator 15. It is a device that calculates the characteristics of the joint 4. As shown in FIG. 2, the analysis device 7 is composed of a computer equipped with known hardware, has one or more processors 21 that execute processing based on a predetermined program, and a memory 22 that holds data and the like necessary for the processing. And. The memory 22 includes a RAM 23 (Random Access Memory) that functions as a work area of the processor 21, and a ROM 24 (Read Only Memory) that stores programs, data, and the like executed by the processor 21. In the present embodiment, the analysis device 7 further includes a storage device 25 such as an HDD or SSD, and a plurality of input / output ports 26 (see FIG. 1) for connecting peripheral devices and the like.

The input / output device 8 is a device for receiving input from the user and displaying the acquired characteristics of the shaft joint 4 to the user, and is connected to the analysis device 7 via the input / output port 26. The input / output device 8 includes an input device 27 such as a keyboard and a mouse used by the user for various settings in the analysis device 7, and an output device 28 including a liquid crystal monitor for displaying analysis results. The input / output device 8 may be configured by a computer including a monitor and a keyboard.

The servo driver 13 is also connected to the analysis device 7 via the input / output port 26. As a result, the analysis device 7 and the servo driver 13 can communicate with each other. For example, the analysis device 7 can output the torque command _ref to the servo driver 13 via the input / output port 26. The differentiator 15 is also connected to the analyzer 7 via the input / output port 26. As a result, the analysis device 7 can communicate with the differentiator 15, and for example, the analysis device 7 can acquire the angular velocity ω of the drive shaft 2 from the differentiator 15.

The analysis device 7 includes a storage unit 31, a frequency characteristic acquisition unit 32, a motor system response acquisition unit 33, and a shaft joint characteristic evaluation unit 34. The frequency characteristic acquisition unit 32, the motor system response acquisition unit 33, and the shaft joint characteristic evaluation unit 34 are each realized by executing an evaluation program for acquiring the characteristics of the shaft joint 4 by the processor 21.

The storage unit 31 is realized by the memory 22, and appropriately stores information necessary for processing of the frequency characteristic acquisition unit 32, the motor system response acquisition unit 33, and the shaft joint characteristic evaluation unit 34. Further, the storage unit 31 stores the moment of inertia _Jm of the rotor of the drive motor 11 and the moment of inertia _Jl of the rotary load unit 18. However, it is assumed that accurate values of the moment of inertia _Jm of the rotor of the drive motor 11 and the moment of inertia _Jl of the rotary load unit 18 are known based on their design specifications.

The frequency characteristic acquisition unit 32 outputs a torque command _Tref to the servo driver 13 so as to output a torque that vibrates with a predetermined amplitude while changing the frequency. At the same time, the frequency characteristic acquisition unit 32 acquires the angular velocity ω from the differentiator 15. Next, the frequency characteristic acquisition unit 32 calculates the amplitude ratio of the angular velocity ω to the torque instructed by the torque command _Tref , that is, the amplitude of the command torque value (hereinafter referred to as the velocity response parameter M). Then, the speed response parameter M is converted into a gain (hereinafter, gain G) using the equation (1).

The frequency characteristic acquisition unit 32 changes the frequency within a predetermined range and outputs the torque command _ref to show the relationship between the frequency and the gain of the angular velocity ω of the rotation angle with respect to the amplitude of the torque corresponding to the torque command _ref . Acquire frequency characteristics (see, for example, FIGS. 4 and 6).

However, the torque command _Tref output by the frequency characteristic acquisition unit 32 may be, for example, an M-series signal that causes the drive motor 11 to output a torque whose amplitude changes randomly as a drive torque T _m , or a pulse. It may be an impulse signal that outputs a torque whose amplitude changes like this as a drive torque T _m . At this time, the frequency characteristic acquisition unit 32 acquires the time change of the gain, then Fourier-converts the time change of the torque corresponding to the torque command _Tref and the time change of the gain, and uses both of them to perform the relationship between the frequency and the gain. It is advisable to acquire the frequency characteristics indicating.

As shown in FIG. 3, in the motor system response acquisition unit 33, the frequency characteristic acquisition unit 32 drives the drive motor 11 to acquire and acquire the frequency characteristics (see FIG. 4) in a state where the shaft joint 4 is not connected. The response characteristics of the motor system 5 are identified from the frequency characteristics.

More specifically, the motor system response acquisition unit 33 has a block diagram (for example, a diagram) corresponding to the frequency characteristics acquired when the shaft joint 4 is not connected and the state where the shaft joint 4 is not connected. The response band w is identified so as to match the frequency characteristics calculated based on 5). Various known methods such as the least squares method and the search for a numerical solution are used as a method for matching the frequency characteristics acquired when the shaft joint 4 is not connected with the frequency characteristics calculated by the block diagram. be able to.

The response band w referred to here corresponds to a so-called cutoff frequency converted into an angular velocity ω, and is one of the parameters related to the response characteristics of the motor. In the present embodiment, the response band w corresponds to a parameter when the response characteristic of the motor system 5 is expressed as the transfer function G ^* (s) of the first-order lag system. After the torque command _Tref is input to the servo driver 13, a predetermined delay occurs before the drive torque _Tm is generated on the drive shaft 2. Therefore, for example, when a torque command _Tref is input to the servo driver 13 to generate a torque that vibrates in a sinusoidal manner while increasing the frequency (that is, the angular velocity ω), the motor becomes the torque command _Tref at a frequency generally equal to or higher than the cutoff frequency. It becomes difficult to follow, and the magnitude of the drive torque _Tm actually output to the drive shaft 2 becomes smaller than the torque to be output to the drive shaft 2 by the torque command _Tref . However, the response band w may be a parameter when the response characteristics of the motor system 5 are expressed as a high-order transfer function.

More specifically, when a torque command _Tref that vibrates at an angular velocity ω is given to the drive motor 11, the drive shaft 2 actually has a magnitude of the amplitude of the torque (command torque value) to be output to the drive shaft 2. When the ratio of the magnitude of the amplitude of the drive torque T _m output to is expressed in decibel units, the angular velocity ω whose value is -3 dB is the response band w. 2π times the response band w corresponds to the cutoff frequency, and the cutoff frequency corresponds to the reciprocal of the time from when the torque command T _ref is given until the drive torque T _m is generated on the drive shaft 2 (hereinafter, delay time). .. In the frequency band smaller than the cutoff frequency, the amplitude of the drive torque T _m is approximately equal to the amplitude of the torque command T _ref , and in the frequency band larger than the cutoff frequency, the amplitude of the drive torque T _m becomes the torque command T _ref as the frequency increases. It is smaller than the amplitude. In other words, in the response band w, when the angular velocity ω (that is, frequency) is increased from the angular velocity region in which the motor system 5 sufficiently follows the torque command _Tref , the amplitude of the drive torque _Tm is the torque command. It becomes smaller than the amplitude of _Torf and corresponds to the angular velocity ω at which the two begin to deviate from each other. When the frequency characteristic acquisition unit 32 completes the identification of the response band w, the frequency characteristic acquisition unit 32 outputs the response band w to the shaft joint characteristic evaluation unit 34.

The shaft joint characteristic evaluation unit 34 calculates the characteristics of the shaft joint 4 based on the response characteristics of the motor system 5 and the frequency characteristics acquired when the shaft joint 4 connects the drive shaft 2 and the driven shaft 3. ..

Specifically, the shaft joint characteristic evaluation unit 34 first obtains the peak gain G from the frequency characteristics acquired in the state where the shaft joint 4 connects the drive shaft 2 and the driven shaft 3, as shown in FIG. The corresponding frequency is acquired and the resonance frequency is set to _f0 . Further, the shaft joint characteristic evaluation unit 34 acquires the gain G at the resonance frequency f ₀ from the frequency characteristics acquired when the shaft joint 4 connects the drive shaft 2 and the driven shaft 3, and gain ^exp at the resonance frequency f ₀ . Let G _f0 .

Next, the shaft joint characteristic evaluation unit 34 calculates the torsional rigidity K _c by substituting the resonance frequency f ₀ into the equation (2).

However, J ₁ and J ₂ in the equation (2) are the moments of inertia [kgm ² ] on the drive motor 11 side and the rotational load unit 18 side, respectively, and J ₁ is the moment of inertia J _m of the rotor of the drive motor 11. Half of the moment of inertia of the shaft joint 4 to be evaluated is the sum of J _c / 2, and J ₂ is the sum of the moment of inertia J _l of the rotary load unit 18 and half of the moment of inertia of the shaft joint 4 to be evaluated J _c / 2. .. The moment of inertia J _c of the shaft joint 4 to be evaluated is input by the user when the characteristics of the shaft joint 4 are evaluated.

Equation (2) is an equation (2) showing a resonance frequency f ₀ when the drive motor 11 and the rotational load unit 18 connected by the shaft joint 4 shown below are considered as a vibration model of a two inertial system shown in FIG. Corresponds to the solution of 3) for K _c .

Next, the shaft joint characteristic evaluation unit 34 substitutes the gain ^exp G _f0 at the resonance frequency _f0 obtained based on the frequency characteristic into the left side (G) of the equation (1), and converts it into the speed response parameter ^exp M _f0 . do.

After that, the shaft joint characteristic evaluation unit 34 uses the calculated torsional rigidity K _c , the response band w, and the moments of inertia J ₁ and J ₂ to set the velocity response parameter ^exp M _f 0 at the resonance frequency f ₀ as follows. Based on the equation (4), it is converted into the conversion speed response parameter M _fo (conversion value). The converted speed response parameter M _fo is the limit when the response band w at the resonance frequency f ₀ is infinite (when the delay time is zero), that is, when the transfer function from the torque command T _ref to the drive torque T _m is 1. Corresponds to the speed response parameter.

However, M for in equation (4) is the torque predicted to be generated in the drive shaft 2 when the motor system 5 is approximated as a first-order _lag system with respect to the magnitude of the amplitude of the torque command value at the resonance frequency f ₀ . It is a ratio of the magnitudes of the amplitudes and is calculated using the following equation (5).

However, _Mfow is not limited to the equation (4), and may be calculated by considering the motor system 5 as a higher-order system.

Next, the shaft joint characteristic evaluation unit 34 uses the torsional rigidity K _c , the converted speed response parameter M _fo , and the moments of inertia J ₁ and J ₂ , and the viscosity coefficient c _c based on the following equation (6). Is calculated.

In the formula (6), the state in which the drive shaft 2 and the driven shaft 3 are connected by the shaft joint 4 is modeled by the vibration model of FIG. 7 and expressed as a block diagram (FIG. 8), and the drive motor 11 is generated. It is obtained by calculating the transfer function G (s) from the driving torque T _m to the angular velocity ω. However, the transfer function G (s) is given by the following equation (7).

Further, using the equation (7), the velocity response parameter M _f0 at the resonance frequency f ₀ is expressed as the equation (8).

By solving the equation (8) with respect to the viscosity coefficient _cc , the above equation (6) can be obtained.

The speed response parameter M _f0 shown in the equation (8) is a speed response parameter at the resonance frequency f ₀ of the transfer function G (s) from the drive torque T _m generated by the drive motor 11 to the angular velocity ω. However, as shown in FIGS. 1 and 8, in the measurement, the torque command _ref is output and the frequency characteristic is acquired by measuring the angular velocity ω. Therefore, after the torque command _ref is output, the drive is used. It is necessary to consider the delay from the motor 11 to the generation of the drive torque _Tm , that is, the delay of the motor system 5.

The velocity response parameter M _f0all when the motor system 5 is approximated as a first-order lag system can be expressed by the equation (9).

However, M for is calculated by _deriving a transfer function G ^* (s) from the drive motor 11 until the corresponding drive torque T _m is generated by driving the drive motor 11 by the torque command T _ref . When the motor system 5 is approximated as a first-order lag system, the transfer function G ^* (s) is given by the following equation (10). As shown in the equation (10), the transfer function G ^* (s) includes the response band w as a parameter.

When the motor system 5 can be approximated as a first-order lag system, the measured velocity response parameter ^exp M _f0 is equal to M f0 _all (Equation (11)).

When the motor system 5 can be approximated as a first-order lag system, by substituting the equation (11) into the equation (9), the measured velocity response parameter ^exp M _f0 is set to the limit where the response band w is infinite (delay time). Is zero), that is, it can be converted into the speed response parameter M _f0 when the transfer function from the torque command T _ref to the drive torque T _m is 1. As can be understood from the equations (9) and (11), the equation (4) corresponds to the conversion equation.

When the shaft joint characteristic evaluation unit 34 completes the calculation of the viscosity coefficient c _c , the shaft joint characteristic evaluation unit 34 causes the output device 28 to display the torsional rigidity K _c and the viscosity coefficient c _c .

When the user inputs a predetermined input to the input / output device 8 in order to acquire the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint 4, the processor 21 of the analysis device 7 implements the evaluation method of the shaft joint 4. Therefore, the evaluation program is executed to perform the evaluation process shown in the flowchart of FIG. Hereinafter, the details of the evaluation process will be described with reference to FIG. 9. However, when the evaluation process is started, it is assumed that the shaft joint 4 is not connected to either the drive shaft 2 or the driven shaft 3.

When the evaluation process is started, first, the frequency characteristic acquisition unit 32 acquires the frequency characteristic (ST1). As a result, the drive motor 11 is driven in a state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3, and the frequency characteristics are acquired. After that, the motor system response acquisition unit 33 acquires the response characteristics of the motor system 5 by using the frequency characteristics acquired in a state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3 (ST2). More specifically, the motor system response acquisition unit 33 acquires the response band w, which is a parameter included in the transfer function G ^* (s), from the frequency characteristics in a state where the shaft joint 4 is not connected.

When the acquisition of the response band w is completed, the processor 21 causes the output device 28 to display a screen prompting the output device 28 to connect the drive shaft 2 and the driven shaft 3 by the shaft joint 4, and the shaft joint 4 to be evaluated of the corresponding shaft joint 4 is displayed. The input of the moment of inertia J _c is accepted (ST3). After that, the processor 21 determines whether or not the user has input the moment of inertia J _c of the shaft joint 4 to the input device 27 (ST4). When there is an input, the frequency characteristic acquisition unit 32 acquires the frequency characteristic (ST5). As a result, the frequency characteristics in the state where the shaft joint 4 is connected are acquired. If there is no input, the user waits until the input device 27 receives an input indicating that the connection of the shaft joint 4 is completed.

When the frequency characteristics in the state where the shaft joint 4 is connected are acquired, the shaft joint characteristic evaluation unit 34 determines the resonance frequency f ₀ and the resonance frequency f of the shaft joint 4 from the frequency characteristics in the state where the shaft joint 4 is connected. The gain (gain) G _f0 at ₀ is acquired (ST6).

Next, the shaft joint characteristic evaluation unit 34 calculates the torsional rigidity K _c of the shaft joint 4 using the equation (1) using the resonance frequency f ₀ (ST7). After that, the shaft joint characteristic evaluation unit 34 calculates the speed response parameter ^exp M _f0 from the gain ^exp G _f0 at the resonance frequency f ₀ based on the equation (3) (ST8). Further, the shaft joint characteristic evaluation unit 34 converts the calculated speed response parameter ^exp M _f0 into the converted speed response parameter M _fo corresponding to the speed response parameter using the response band w (ST9). After that, the shaft joint characteristic evaluation unit 34 calculates the viscosity coefficient c _c of the shaft joint 4 from the torsional rigidity K _c and the converted speed response parameter M _fo using the equation (5). When the calculation of the viscosity coefficient c _c of the shaft joint 4 is completed, the shaft joint characteristic evaluation unit 34 causes the output device 28 to display the calculated torsional rigidity K _c and the viscosity coefficient c _c (ST10).

When the display of the torsional rigidity K _c and the viscosity coefficient c _c is completed, the processor 21 finishes the evaluation process.

Next, the operation of the characteristic evaluation device 1 according to the present invention will be described by taking the case of evaluating a predetermined shaft joint A as an example. When the user starts the evaluation process, first, the frequency characteristics in a state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3 are acquired (ST1). In FIG. 4, the frequency characteristics acquired at this time are shown by solid lines. After that, the motor system response acquisition unit 33 fits the transfer function corresponding to the block diagram corresponding to the state in which the shaft joint 4 is not connected to the acquired frequency characteristics by the least squares method, and the response band w. Is calculated, and the transfer function G ^* (s) is acquired (ST2). When the transfer function corresponding to the frequency characteristic calculated based on the block diagram shown in FIG. 5 is fitted to the frequency characteristic shown in FIG. 4, the response band w is 1200 rad / s (~ 191 Hz at the cutoff frequency). Calculated. In FIG. 4, the frequency characteristic calculated using the calculated response band w is shown by a broken line. As shown by the broken line in FIG. 4, since the frequency characteristics in the state where the shaft joint 4 is not connected can be reproduced by the theoretically calculated response band w, the motor system 5 is sufficient as a primary delay system. It is considered that the response band w can be approximated and calculated accurately. Further, in FIG. 4, it can be confirmed that the measured gain G is gently bent in the vicinity of the cutoff frequency (w / 2π) corresponding to the response band w.

After that, a display prompting the output device 28 to connect the shaft joint 4 is displayed, and the input of the moment of inertia J _c of the shaft joint 4 is accepted (ST2). When the user connects the shaft joint 4 to be evaluated and inputs the moment of inertia J _c of the shaft joint 4 (ST4), the frequency characteristics are acquired in the state where the shaft joint 4 connects the drive shaft 2 and the driven shaft 3. (ST5). FIG. 10A shows the measurement results of the frequency characteristics when the shaft joint A connects both shafts.

Next, the shaft joint characteristic evaluation unit 34 acquires the resonance frequency f ₀ and the gain ^exp G _f 0 at the resonance frequency f ₀ from the frequency characteristics acquired when the shaft joint 4 connects the drive shaft 2 and the driven shaft 3. (ST6). After that, the shaft joint characteristic evaluation unit 34 calculates the torsional rigidity K _c of the shaft joint 4 using the resonance frequency f ₀ (ST7), and calculates the speed response parameter ^exp M _f0 from the gain ^exp G f ₀ at the resonance frequency f ₀ . (ST8). Further, the shaft joint characteristic evaluation unit 34 converts the speed response parameter ^exp M _f0 into the converted speed response parameter M _fo using the response band w (ST9), and then calculates the viscosity coefficient c _c (ST10).

For the shaft joint A, the torsional rigidity K _c is calculated to be 5026 Nm / rad and the viscosity coefficient c _c is calculated to be 0.0142 Nm / (rad / s) based on the frequency characteristics shown in FIG. 10 (A). When the calculation is completed and the torsional rigidity K _c and the viscosity coefficient c _c are displayed, the evaluation process is completed.

FIG. 10B shows the measurement results of the frequency characteristics when the characteristics of the shaft joint B different from the shaft joint A are evaluated in the same manner. For the shaft joint B, the torsional rigidity K _c is calculated to be 5026 Nm / rad and the viscosity coefficient c _c is calculated to be 0.0142 Nm / (rad / s) based on the frequency characteristics shown in FIG. 10 (B).

Since the response band w is not affected by the rotational load or the shaft joint 4 for evaluation, when the characteristics of the shaft joint B are evaluated after the characteristics of the shaft joint A are evaluated, the process is executed from step ST3 of the evaluation process. You may. In this way, the value of the response band w once determined can be used as it is for the test of the other shaft joint 4.

In FIGS. 10A and 10B, the frequency characteristics calculated using the calculated torsional rigidity K _c and the viscosity coefficient c _c are shown by broken lines. As shown in FIGS. 10A and 10B, the frequency characteristics calculated using the torsional rigidity K _c and the viscosity coefficient c _c , and the frequency characteristics obtained by the measurement (frequency characteristics acquired in step ST1). ) Can be understood to indicate a good match.

Next, the effect of the characteristic evaluation device 1 according to the present invention will be described. Generally, the motor system 5 has a predetermined response characteristic, and when the torque command T _ref is input, the drive torque T _m that coincides with the torque command T _ref is not instantaneously generated in the drive shaft 2. As an example, after the torque command T _ref is input, there is a predetermined delay until the drive torque T _m is generated, and the drive torque T _m generated on the drive shaft 2 is a predetermined time until it matches the torque command T _ref . In some cases, it takes time (that is, delay time). In such a case, the drive torque T _m generated in the drive shaft 2 is the torque corresponding to the torque command T _ref (that is, the transmission from the torque command T _ref to the drive torque T _m , especially at a frequency higher than the cutoff frequency. It is smaller than the torque when the function is assumed to be 1. That is, the gain obtained by measuring using the motor system 5 is a model that does not consider the response characteristics of the motor system 5, especially in the frequency band higher than the cutoff frequency, that is, the drive torque _Tm from the torque command _Tref . The transfer function up to 1 is 1, and after the torque command T _ref is input, the gain becomes smaller than the expected gain based on the model in which the drive torque T _m corresponding to the torque command T _ref is generated instantly. Therefore, when the physical parameters are calculated using a model that does not consider the response characteristics of the motor system 5 based on the frequency characteristics measured with the shaft joint 4 connected, the calculated physical parameters are the original physics of the shaft joint 4. It may differ from the value of the parameter, that is, the true value. In particular, as shown in FIGS. 10A and 10B, when the resonance frequency f ₀ is larger than the response band w (191 Hz), the physical parameters are physical parameters using a model that does not consider the response characteristics of the motor system 5. Is calculated, it is predicted that the difference between the calculated physical parameter and the true value will be large.

In order to consider the influence of the response characteristics of the motor system 5 on the evaluation of physical parameters, the response characteristics of the motor system 5 with respect to the frequency characteristics (see FIG. 10A) acquired with the shaft joint A connected. , And the torsional rigidity K _c and the viscosity coefficient c _c were calculated. More specifically, the torsional rigidity K _c and the viscosity coefficient c _c were obtained by assuming that the measured velocity response parameter ^exp M _f0 was M _f0 and substituting it into the equation (5). The obtained torsional rigidity K _c and the viscosity coefficient c _c were 5026 Nm / rad and 0.0380 Nm / (rad / s), respectively.

In FIG. 11, the frequency characteristics acquired with the shaft joint A connected are calculated using the solid line, the torsional rigidity K _c acquired ignoring the response characteristics of the motor system 5, and the viscosity coefficient c _c . The frequency characteristics are shown by two-dot chain lines. As shown in FIG. 10 (A), it can be understood that the measured frequency characteristic (solid line) and the calculated frequency characteristic (broken line) are different from each other as compared with the case of FIG. 10 (A). That is, as shown in FIG. 10A, the characteristic evaluation device 1 according to the present invention can reproduce the frequency characteristics measured more accurately by calculation (simulation), so that the physical parameters of the shaft joint 4 to be identified can be determined. It can be understood that it is closer to the true value. That is, by using the characteristic evaluation device 1, the response characteristics from the torque command _Tref to the motor for calculating the characteristics of the shaft joint 4 until the drive torque _Tm is generated by the drive motor 11 are taken into consideration. This makes it possible to more appropriately evaluate the characteristics of the shaft joint 4.

As described above, by using the characteristic evaluation device 1 (characteristic evaluation method) according to the present invention, the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint 4 can be obtained, and the characteristics of the shaft joint 4 can be inspected. Will be. Further, by changing the input torque command _Def and changing the amplitude of the torque output from the drive motor 11 for evaluation, it is clarified how the characteristics of the shaft joint 4 change depending on the usage state. can do. Further, by using the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint 4 acquired by the characteristic evaluation device 1, the characteristics of the mechanical device in which the shaft joint 4 is incorporated can be simulated more accurately.

Further, since the value of the response band w once determined can be used as it is for the test of the other shaft joint 4, it is not necessary to acquire the response band w every time the shaft joint 4 is replaced, and a plurality of shaft joints 4 are used. The characteristics of the can be evaluated more quickly.

<< Second Embodiment >>
The characteristic evaluation device 101 according to the second embodiment has a dependency on the amplitude of the torque command T _ref of the torsional rigidity K _c of the shaft joint 4 and a dependency on the amplitude of the torque command T _ref of the viscosity coefficient c _c of the shaft joint 4. To get. In order to acquire the amplitude dependence, the processor 21 of the characteristic evaluation device 101 according to the second embodiment executes an evaluation program different from that of the evaluation device 1 according to the first embodiment, and an evaluation process different from that of the first embodiment. I do. Hereinafter, the details of the evaluation process will be described with reference to FIG. However, as in the first embodiment, it is assumed that the shaft joint 4 is not connected to either the drive shaft 2 or the driven shaft 3 when the evaluation process is started.

When the evaluation process is started, the processor 21 receives a plurality of torque amplitude values for instructing the servo driver 13 to output (ST11). At this time, when the upper limit value and the lower limit value of the amplitude and the number of the values of the amplitude to be set are input to the input / output device 8, the processor 21 sets the number of the values between the upper limit value and the lower limit value. By dividing based on, the value of the amplitude of the torque for giving an output instruction may be accepted.

Next, the frequency characteristic acquisition unit 32 outputs a torque command _Tref so as to output the torque vibrating with the amplitude received by the servo driver 13 while changing the frequency, and acquires the frequency characteristics at each amplitude (ST12). .. As a result, the drive motor 11 is driven in a state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3, and the frequency characteristics at each amplitude are acquired. After that, the motor system response acquisition unit 33 acquires the response characteristics of the motor system 5 at each amplitude by using the frequency characteristics acquired in the state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3. ST13). More specifically, the motor system response acquisition unit 33 acquires the response band w, which is a parameter included in the transfer function G ^* (s), from the frequency characteristics of the respective amplitudes in a state where the shaft joint 4 is not connected. ..

When the acquisition of the response band w is completed, the processor 21 causes the output device 28 to display a screen prompting the output device 28 to connect the drive shaft 2 and the driven shaft 3 by the shaft joint 4, and the shaft joint 4 to be evaluated of the corresponding shaft joint 4 is displayed. The input of the moment of inertia J _c is accepted (ST14). After that, the processor 21 determines whether or not the user has input the moment of inertia J _c of the shaft joint 4 to the input device 27 (ST15).

When the inertial moment J _c is input, the frequency characteristic acquisition unit 32 outputs a torque command _Tref so as to output a torque that vibrates at the input amplitude while changing the frequency, and each amplitude. (ST16). As a result, the frequency characteristics in the state where the shaft joint 4 is connected at each amplitude are acquired. If there is no input, the user waits until the input device 27 receives an input indicating that the connection of the shaft joint 4 is completed.

When the frequency characteristics of each of the input amplitude values in the state where the shaft joint 4 is connected are acquired, the shaft joint characteristic evaluation unit 34 obtains each frequency characteristic from the respective frequency characteristics in the state where the shaft joint 4 is connected. The resonance frequency f ₀ of the shaft joint 4 with respect to the amplitude and the gain (gain) G _f 0 at the resonance frequency f ₀ are acquired (ST17).

Next, the shaft joint characteristic evaluation unit 34 calculates the torsional rigidity _Kc of the shaft joint 4 for each amplitude by using the resonance frequency f ₀ at each amplitude and the equation (1) (ST18). After that, the shaft joint characteristic evaluation unit 34 calculates the velocity response parameter ^exp M _f0 for each amplitude from the gain ^exp G _f0 at the resonance frequency f ₀ based on the equation (3) (ST19).

Further, the shaft joint characteristic evaluation unit 34 uses the response band w to convert the velocity response parameter ^exp M _f0 calculated for each amplitude into the converted velocity response parameter M _fo (ST20). After that, the shaft joint characteristic evaluation unit 34 calculates the viscosity coefficient c _c of the shaft joint 4 at each amplitude using the equation (5) from the torsional rigidity K _c at each amplitude and the converted speed response parameter M _fo . (ST21). When the calculation of the viscosity coefficient c _c of the shaft joint 4 is completed, the shaft joint characteristic evaluation unit 34 has the relationship between the amplitude of the torque command T _ref and the torsional rigidity K _c , and the amplitude of the torque command T _ref and the viscosity coefficient c _c . The relationship between the above and the output device 28 is displayed (ST22). At this time, the shaft joint characteristic evaluation unit 34 tells the input / output device 8 that the torsional rigidity K _c and the viscosity coefficient c _c depend on the amplitude of the torque command _ref , as shown in FIGS. 13 (A) and 13 (B). The sex may be illustrated by a graph.

When the display of the amplitude dependence of the torsional rigidity K _c and the viscosity coefficient c _c is completed, the processor 21 ends the evaluation process.

Next, the effect of the characteristic evaluation device 101 configured in this way will be described. The processor 21 of the characteristic evaluation device 101 of the shaft joint 4 according to the present embodiment servos a torque command T _ref so as to output a drive torque T _m having two or more amplitudes in a state where the shaft joint 4 connects both shafts. It is output to the driver 13 (motor control unit) to calculate the frequency characteristics corresponding to each amplitude. Based on the response characteristics of the motor system 5 and the calculated frequency characteristics, the characteristics of the shaft joint 4 corresponding to each of the amplitudes are calculated. More specifically, the processor 21 obtains the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint 4 for each of the acquired frequency characteristics, and determines the relationship between the amplitude and the torsional rigidity K _c of the shaft joint 4. The relationship between the amplitude and the viscosity coefficient c _c of the shaft joint 4 is output as a graph.

FIG. 13 (A) shows the frequency characteristics of the gain of the shaft joint A when the amplitude of the torque command _Tref is set to 1.0 Nm and FIG. 13 (B) shows the case where the amplitude is set to 3.0 Nm. In FIGS. 13A and 13B, it can be understood that there is a slight difference in the measurement result of the frequency characteristic depending on the amplitude of the torque command _ref . More specifically, as shown by the triangles in FIGS. 13A and 13B, the gain at the resonance frequency _f0 near 800 Hz is smaller when the amplitude of the torque command _Tref is 3.0 Nm. You can see that it is. The torque command is obtained by measuring the frequency characteristics by changing the amplitude setting of the torque command T _ref and obtaining the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint A at each of the amplitudes of the torque command T _ref from the results. The relationship between the amplitude of the torque and the _torsional rigidity K _c and the viscosity coefficient c _c can be evaluated.

In FIG. 14 (A), the frequency characteristics of the gain of the shaft joint A are measured by changing the amplitude of the torque command _Tref in 10 ways, and the torsional rigidity K _c and the viscosity coefficient c _c of the shaft joint A at each torque amplitude are measured. The horizontal axis is the amplitude of the torque command T _ref and the vertical axis is the torsional rigidity K _c , and in FIG. 14B, the horizontal axis is the amplitude of the torque command T _ref and the vertical axis is the viscosity coefficient c _c . The graphs for the case of In FIGS. 14A and 14B, the same measurement is performed 5 times for each of the amplitudes set by the torque command _ref in order to obtain more accurate values. The solid lines in FIGS. 14A and 14B are approximate curves showing the tendency of change.

From FIGS. 14 (A) and 14 (B), it can be seen that in the shaft joint A, the amplitude of the torque command _ref tends to increase, the torsional rigidity K _c decreases, and the viscosity coefficient _cc tends to increase. In this way, by understanding the tendency of change with respect to the amplitude of the torque command _Tref , it is possible to appropriately evaluate the input-dependent characteristics of the shaft joint 4, predict the vibration characteristics under various operating conditions, and appropriately. Control system design becomes possible.

In the present embodiment, the amplitude dependence of the torque command T _ref of the torsional rigidity K _c of the shaft joint 4 and the amplitude dependence of the torque command T _ref of the viscosity coefficient c _c are output. This makes it possible to appropriately evaluate the input-dependent characteristics of the shaft joint 4. Further, since the amplitude dependence of the torque command _Tref of the characteristics of the shaft joint 4 is output as the amplitude dependence of the torsional rigidity K _c and the viscosity coefficient _cc , the contents thereof can be easily understood by the user, and the shaft joint 4 can be easily understood. The convenience of the characteristic evaluation device 101 is enhanced.

Although the present invention has been described above based on specific embodiments, these embodiments are merely examples, and the present invention is not limited to these embodiments. Not all of the evaluation methods and the components of the evaluation program are indispensable, and they can be appropriately selected as long as they do not deviate from the scope of the present invention.

In the second embodiment, the horizontal axis of the graph is the amplitude of the torque command _ref , but the present invention is not limited to this embodiment. The horizontal axis of the graph is the amplitude of the torque command T _ref , the amplitude of the drive torque T _m at the resonance frequency f ₀ , the amplitude of the rotation angle of the motor shaft (drive shaft 2) at the resonance frequency f ₀ , and the motor shaft at the resonance frequency f ₀ . It may be at least one of the amplitudes of the angular velocity ω of (drive shaft 2).

When the amplitude of the rotation angle of the motor shaft (drive shaft 2) at the resonance frequency f ₀ or the amplitude of the angular velocity ω of the motor shaft (drive shaft 2) at the resonance frequency f ₀ is the horizontal axis, the resonance frequency f ₀ is measured. The target shaft joint may be acquired in advance by measurement, design, or the like, or may be acquired based on the frequency characteristics acquired under a predetermined torque command _Tref . .. Further, the resonance frequency f ₀ may be obtained by using the frequency characteristics acquired in each of the torque command _Tref , and the amplitude of the angle of rotation corresponding to the resonance frequency f ₀ or the amplitude of the angular velocity ω may be used as the horizontal axis.

The frequency characteristics at each of the amplitudes of the torque command _Tref may be measured a plurality of times, or may be measured only once. When the frequency characteristics are measured multiple times, the repeatability of the results can also be evaluated.

In the second embodiment, in step ST12, the frequency characteristic corresponding to the amplitude of the input torque command _Tref was acquired in the state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3. , Not limited to this aspect. More specifically, when the change due to the amplitude of the torque command _ref of the frequency characteristic is small in the state where the shaft joint 4 is not connected to the drive shaft 2 and the driven shaft 3, the amplitude of the input torque command _ref is small. The frequency characteristics corresponding to the above may be substituted by the frequency characteristics acquired in each predetermined amplitude, and the processing after step ST12 may be performed.

In the second embodiment, the shaft joint characteristic evaluation unit 34 graphically shows the dependence of the torsional rigidity K _c and the viscosity coefficient _cc on the amplitude of the torque command _Tref on the input / output device 8. It is not limited to this aspect. The shaft joint characteristic evaluation unit 34 informs the input / output device 8 of the relationship between the amplitude of the torque command _Tref and the torsional rigidity _Kc , or the relationship between the amplitude of the torque command _Tref and the viscosity coefficient _cc . It may be output by a function or the like.

1: Characteristic evaluation device 2: Drive shaft 3: Driven shaft 4: Shaft joint 5: Motor system 6: Driven device 7: Analytical device 8: Input / output device 11: Drive motor 12: Current sensor 13 : Servo driver (motor control unit)
14: Rotation angle sensor 15: Differentiator 16: Servo system 18: Rotation load unit 21: Processor 22: Memory 23: RAM
24: ROM
25: Storage device 26: Input / output port 27: Input device 28: Output device 31: Storage unit 32: Frequency characteristic acquisition unit 33: Motor system response acquisition unit 34: Shaft joint characteristic evaluation unit 101: Characteristics according to the second embodiment Evaluation device G ^* (s): Transfer function K _c : Torsional rigidity M _fo : Converted speed response parameter (converted value)
T _m : Drive torque c _c : Viscosity coefficient f ₀ : Resonance frequency w: Response band ω: Angular velocity

Claims (14)

A characteristic evaluation device that evaluates the characteristics of a shaft joint that connects both shafts in order to transmit torque from the drive shaft to the driven shaft.
The drive motor that applies drive torque to the drive shaft, the rotation angle sensor that acquires the rotation angle of the drive shaft, and the torque command to output the torque according to the given torque command. A motor system that includes a motor control unit that controls the drive motor,
The rotary load unit connected to the driven shaft and
The torque command is output to the motor control unit so as to output the predetermined drive torque, and the rotation with respect to the torque amplitude corresponding to the torque command is based on the rotation angle detected by the rotation angle sensor. With a processor capable of calculating the frequency characteristics of the gain of the angular velocity amplitude of the angle,
The processor is characterized in that it calculates the characteristics of the shaft joint based on the response characteristics of the motor system and the frequency characteristics calculated when the shaft joint connects both shafts. Characteristic evaluation device. The processor
As the response characteristic of the motor system, a transfer function is used until the drive motor is driven by the torque command and the corresponding torque is generated from the drive motor.
Obtaining the frequency characteristics with the shaft joint connected,
The resonance frequency of the shaft joint and the gain at the resonance frequency are obtained from the frequency characteristics.
Using the resonance frequency, the torsional rigidity of the shaft joint is calculated.
The characteristic evaluation device for a shaft joint according to claim 1, wherein the viscosity coefficient of the shaft joint is calculated using the transfer function, the torsional rigidity, and the gain at the resonance frequency. The processor
Using the transfer function, the gain at the resonance frequency is converted into a conversion value corresponding to the gain at the resonance frequency when the transfer function is 1.
The characteristic evaluation device for a shaft joint according to claim 2, wherein the viscosity coefficient of the shaft joint is calculated using the torsional rigidity and the converted value. The processor is characterized in that the response characteristic of the motor system is acquired by the frequency characteristic when the driving motor is driven in a state where the shaft joint is not connected to both shafts. The characteristic evaluation device for a shaft joint according to any one of claims 3. It is a characteristic evaluation method of a shaft joint that evaluates the characteristics of the shaft joint connecting both shafts in order to transmit torque from the drive shaft to the driven shaft.
The drive motor that applies drive torque to the drive shaft, the rotation angle sensor that acquires the rotation angle of the drive shaft, and the torque command to output the torque according to the given torque command. A motor system that includes a motor control unit that controls the drive motor,
The rotary load unit connected to the driven shaft and
The torque command is output to the motor control unit so as to output the predetermined drive torque, and the rotation with respect to the torque amplitude corresponding to the torque command is based on the rotation angle detected by the rotation angle sensor. Using a characteristic evaluation device that can calculate the frequency characteristics of the gain of the amplitude of the angular velocity of the angle,
A step of acquiring the frequency characteristic in a state where the shaft joint connects the two shafts,
A method for evaluating a characteristic of a shaft joint, which comprises performing a step of calculating the characteristic of the shaft joint based on the acquired frequency characteristic and the response characteristic of the motor system. The step of acquiring the frequency characteristic with the shaft joint connected, and
The step of acquiring the resonance frequency of the shaft joint and the gain at the resonance frequency from the frequency characteristics,
The step of calculating the torsional rigidity of the shaft joint using the resonance frequency, and
The drive motor is driven by the torque command as the response characteristic of the motor system, and the transmission function until the corresponding torque is generated from the drive motor, the torsional rigidity, and the gain at the resonance frequency are used. The method for evaluating the characteristics of a shaft joint according to claim 5, further comprising a step of calculating the viscosity coefficient of the shaft joint. The step of calculating the viscosity coefficient of the shaft joint is
A step of converting the gain at the resonance frequency into a conversion value corresponding to the gain at the resonance frequency when the transfer function is 1.
The method for evaluating a characteristic of a shaft joint according to claim 6, further comprising a step of calculating a viscosity coefficient of the shaft joint using the torsional rigidity and the converted value. 5. A aspect of claim 5, wherein the response characteristic of the motor system is acquired by the frequency characteristic when the drive motor is driven in a state where the shaft joint is not connected to both shafts. The method for evaluating the characteristics of a shaft joint according to any one of claims 7. The processor outputs the torque command to the motor control unit so as to output the drive torque having two or more amplitudes in a state where the shaft joint connects the two shafts, and corresponds to each of the amplitudes. The frequency characteristics are calculated, and the characteristics of the shaft joint corresponding to each of the amplitudes are calculated based on the response characteristics of the motor system and the calculated frequency characteristics. It is characterized by outputting the relationship between at least one of the driving torque amplitude at the resonance frequency of the shaft joint, the rotation angle amplitude at the resonance frequency, and the angular velocity amplitude at the resonance frequency and the characteristics of the shaft joint. The characteristic evaluation device for the shaft joint according to claim 1. The processor obtains the torsional rigidity of the shaft joint for each of the acquired frequency characteristics, and obtains the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency, and the amplitude of the rotation angle at the resonance frequency. The characteristic evaluation device for a shaft joint according to claim 9, wherein the relationship between at least one of the amplitudes of the angular velocity at the resonance frequency and the torsional rigidity of the shaft joint is output. The processor outputs the torque command to the motor control unit so as to output the drive torque having two or more amplitudes, acquires the frequency characteristic corresponding to each amplitude, and acquires the frequency characteristic. For each, the viscosity coefficient of the shaft joint is obtained, and the amplitude of the torque command, the amplitude of the drive torque at the resonance frequency, the amplitude of the rotation angle at the resonance frequency, and the amplitude of the angular velocity at the resonance frequency. The characteristic evaluation device for a shaft joint according to claim 9 and 10, wherein the relationship between at least one of them and the viscosity coefficient of the shaft joint is output. A step of outputting the driving torque having two or more amplitudes to the motor system in a state where the shaft joint connects the two shafts and acquiring the frequency characteristics corresponding to the respective amplitudes.
The fifth aspect of claim 5, wherein the step of calculating the characteristics of the shaft joint corresponding to the respective amplitudes based on the acquired frequency characteristics and the response characteristics of the motor system is executed. How to evaluate the characteristics of shaft joints. With the shaft joint connected, the step of acquiring the frequency characteristics of two or more amplitudes, and
A step of acquiring the resonance frequency of the shaft joint and the gain at the resonance frequency from each of the frequency characteristics.
Using the resonance frequency, the step of calculating the torsional rigidity of the shaft joint corresponding to each of the amplitudes, and
At least one of the amplitude of the torque command, the amplitude of the driving torque at the resonance frequency, the amplitude of the rotation angle at the resonance frequency, the amplitude of the angular velocity at the resonance frequency, and the torsional rigidity of the shaft joint. The method for evaluating a shaft joint according to claim 12, further comprising a step of outputting the relationship of the above. At each of the amplitudes, the drive motor is driven by the torque command as the response characteristic of the motor system, and the transmission function until the corresponding torque is generated from the drive motor, the torsional rigidity, and the resonance frequency. In the step of calculating the viscosity coefficient of the shaft joint using the gain in
At least one of the amplitude of the torque command, the amplitude of the driving torque at the resonance frequency, the amplitude of the rotation angle at the resonance frequency, the amplitude of the angular velocity at the resonance frequency, and the viscosity coefficient of the shaft joint. The characteristic evaluation method for a shaft joint according to claim 13, further comprising a step of outputting a relationship.

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