Vibration suppression device, robot system, and vibration suppression method

Abstract

The vibration suppression device (2) suppresses vibrations of a robot (3) having a sensor (24) that detects the state of the robot (3), a robot controller (21) that outputs an operation command based on a state detection value output by the sensor (24) and a set operation procedure, and an actuator (22) that operates a mechanism (23) according to the operation command. The vibration suppression device (2) outputs to the robot controller (21) an identification command that is a command regarding the operation of the mechanism (23) when identifying a system characteristic that is a characteristic of the mechanism (23), generates a stability command that avoids an unstable operation period that is an operation period of the mechanism (23) when the operation of the mechanism (23) becomes unstable based on the system characteristic identified based on the state detection value output by the sensor (24) when the mechanism (23) operates according to the identification command, and outputs the stability command to the robot controller (21) to suppress vibrations of the mechanism (23).

Description

[Technical field]

[0001] The present disclosure relates to a vibration suppression device, a robot system, and a vibration suppression method for suppressing vibrations of a robot. [Background technology]

[0002] There is a need for weight reduction in robots such as industrial robots from the viewpoint of ease of installation and maintenance of the robot. When the weight of a robot's mechanism is reduced, the rigidity of the mechanism decreases, which causes a problem that the mechanism is more susceptible to vibration. In order to achieve both weight reduction and vibration reduction, design changes are sometimes made to reduction gears and other components that can be sources of vibration. Also, a vibration suppression device is sometimes applied that modifies the robot's motion commands to make it less likely to generate vibration.

[0003] Patent Document 1 discloses a vibration suppression device that corrects an operation command by applying a biquad notch filter to prevent the transmission of vibrations at a preset frequency, thereby reducing vibrations. The vibration suppression device according to Patent Document 1 can suppress the vibrations of a robot by setting the excitation frequency of the robot to the notch frequency of the biquad notch filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6254180 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of parametric resonance caused by a robot's reducer or the like, the pump frequency, which is the frequency of the parametric resonance, is different from the frequency of the operation command. According to the technology of Patent Document 1, the notch frequency cannot be determined unless the robot is operated to generate vibration. If vibration occurs in the robot, that is, if the robot is made to perform an unstable operation, a malfunction due to the vibration of the robot may occur. Thus, according to the conventional technology disclosed in Patent Document 1, there was a problem that it was necessary to make the robot perform an unstable operation in preparation for suppressing the vibration of the robot.

[0006] The present disclosure has been made in consideration of the above, and aims to obtain a vibration suppression device that makes it possible to avoid having a robot perform unstable movements in preparation for suppressing the vibration of the robot. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the vibration suppression device according to the present disclosure is a vibration suppression device that suppresses vibrations of a robot having a sensor that detects the state of the robot, a robot controller that outputs an operation command based on a state detection value output by the sensor and a set operation procedure, and an actuator that operates a mechanism of the robot according to the operation command. Generate an identification command; Output identification command to robot controller an identification command generator for identifying a target object; The state detection value output by the sensor when the mechanism operates according to the identification command A system characteristic identifier for identifying a system characteristic based on the above. Identified system characteristics into a time-varying characteristic that changes with time and a time-unchanging characteristic that does not change with time, and outputs information on the normalized time-varying characteristic, which is a normalized time-varying characteristic, and information on the normalized non-varying characteristic, which is a normalized non-varying characteristic. This is the operating period of the mechanism when the mechanism becomes unstable. An unstable duty cycle estimator that estimates an unstable duty cycle based on a normalized fluctuation characteristic and a normalized non-fluctuation characteristic; Generates stable commands that avoid unstable operating periods The vibration suppression device according to the present disclosure includes a stability command generator for generating a stability command for the vibration suppression device. Vibrations of the mechanism are suppressed by outputting a stability command to the robot controller. Effect of the Invention

[0008] The vibration suppression device according to the present disclosure has the advantage of being able to avoid making the robot perform unstable movements in preparation for suppressing vibration of the robot. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration example of a robot system according to a first embodiment. [Diagram 2] 1 is a flowchart showing an example of an operation procedure of the vibration suppression device according to the first embodiment. [Diagram 3] FIG. 13 is a diagram showing an example of parameters used in a simulation performed by the vibration suppression device according to the first embodiment. [Figure 4] FIG. 1 is a first diagram showing an example of a result of a simulation using a vibration suppression device according to the first embodiment; [Diagram 5] FIG. 2 is a second diagram showing an example of a result of a simulation using the vibration suppression device according to the first embodiment; [Figure 6] FIG. 1 is a diagram showing an example of a configuration of a hardware circuit according to a first embodiment; [Figure 7] FIG. 1 is a diagram showing an example of the configuration of a control circuit according to a first embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vibration suppression device, a robot system, and a vibration suppression method according to embodiments will be described in detail below with reference to the drawings.

[0011] Embodiment 1 1 is a diagram showing a configuration example of a robot system 1 according to a first embodiment. The robot system 1 includes a vibration suppression device 2 and a robot 3. The vibration suppression device 2 suppresses vibrations of the robot 3. The robot 3 is, for example, an industrial robot. Note that the vibration suppression device 2 has various built-in functions and various means, but in the first embodiment, only functions and means related to characteristic processing of the vibration suppression device 2 according to the present disclosure will be described.

[0012] The robot 3 includes a robot controller 21, an actuator 22, a mechanism 23, and a sensor 24. The robot controller 21 controls the operation of the robot 3 by outputting an operation command to the actuator 22. The actuator 22 operates the mechanism 23 according to the operation command input to the actuator 22. The actuator 22 includes a servo motor as a drive source and a reducer. The mechanism 23 includes an arm having multiple joints and an end effector attached to the tip of the arm. The servo motor, reducer, arm, and end effector are not shown in the drawings.

[0013] The sensor 24 detects the state of the robot 3. Specifically, the sensor 24 detects a physical quantity related to the posture of the robot 3 or the environment in which the robot 3 is installed. An example of the sensor 24 that detects a physical quantity related to the posture of the robot 3 is a displacement sensor, a speed sensor, an acceleration sensor, or an angular velocity sensor. An example of the physical quantity related to the posture of the robot 3 is a position, a speed, or an acceleration. An example of the sensor 24 that detects a physical quantity related to the environment in which the robot 3 is installed is a temperature sensor. An example of the physical quantity related to the environment in which the robot 3 is installed is temperature. The sensor 24 outputs a state detection value, which is a detection value of the physical quantity, to the robot controller 21. The robot controller 21 outputs an operation command based on the state detection value output by the sensor 24 and a set operation procedure. The set operation procedure is an operation procedure that is programmed in advance. Note that the physical quantity detected by the sensor 24 is not limited to the above physical quantities.

[0014] The vibration suppression device 2 and the robot 3 are connected to each other so as to be able to communicate with each other. The vibration suppression device 2 includes an identification command generator 11, a system characteristic identifier 12, a fluctuation characteristic calculator 13, an unstable operation period estimator 14, and a stability command generator 15.

[0015] The identification command generator 11 generates an identification command. The identification command is a command regarding the operation of the mechanism 23 when identifying a system characteristic, which is a characteristic of the mechanism 23. The identification command generator 11 outputs the identification command to each of the system characteristic identifier 12 and the robot controller 21.

[0016] The robot controller 21 outputs the identification command input to the robot controller 21 to the actuator 22. The actuator 22 operates the mechanism 23 in accordance with the identification command. The sensor 24 outputs to the system characteristic identifier 12 a state detection value detected when the mechanism 23 is operated in accordance with the identification command.

[0017] The system characteristic identifier 12 identifies the system characteristic based on the identification command input to the system characteristic identifier 12 and the state detection value output by the sensor 24 when the mechanism 23 operates in accordance with the identification command. The system characteristic identifier 12 outputs information on the system characteristic to the fluctuation characteristic calculator 13.

[0018] The variation characteristic calculator 13 divides the system characteristic identified by the system characteristic identifier 12 into variation characteristics that change with time and non-variable characteristics that do not change with time. The variation characteristic calculator 13 calculates normalized variation characteristics, which are normalized variation characteristics, and normalized non-variable characteristics, which are normalized non-variable characteristics. The variation characteristic calculator 13 outputs information on the normalized variation characteristics and information on the normalized non-variable characteristics to the unstable operating period estimator 14.

[0019] The unstable operation period estimator 14 estimates an unstable operation period, which is the operation period of the mechanism 23 when the operation of the mechanism 23 becomes unstable due to parametric resonance of the mechanism 23, based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic. The unstable operation period estimator 14 outputs information on the unstable operation period to the stability command generator 15. In the first embodiment, the operation period is defined as the time from the start to the completion of each repeated operation when the robot 3 performs a repetitive operation.

[0020] The stability command generator 15 generates a stability command that avoids the unstable operating period estimated by the unstable operating period estimator 14. The stability command generator 15 outputs the stability command to the robot controller 21. The robot controller 21 outputs the stability command input to the robot controller 21 to the actuator 22. The actuator 22 operates the mechanism 23 in accordance with the stability command. The stability command can also be considered an operation command for causing the mechanism 23 to perform a stable operation.

[0021] In this way, the vibration suppression device 2 outputs an identification command, which is a command regarding the operation of the mechanism 23 when identifying the system characteristics, which are the characteristics of the mechanism 23, to the robot controller 21. The vibration suppression device 2 generates a stability command that avoids an unstable operation period, which is the operation period of the mechanism 23 when the operation of the mechanism 23 becomes unstable, based on the system characteristics identified based on the state detection value output by the sensor 24 when the mechanism 23 operates in accordance with the identification command. The vibration suppression device 2 suppresses the vibration of the mechanism 23 by outputting the stability command to the robot controller 21.

[0022] Next, a detailed description will be given of the operating principle of the vibration suppression device 2 according to the embodiment 1. The following equation (1) is an equation of motion normalized by the moment of inertia on one axis of the mechanism 23.

[0023]

number

[0024] Here, x represents the joint angle, which is the angle of the joint of the mechanism 23. The unit of x is rad. β(t) represents the coefficient of the first derivative term. The unit of β(t) is rad / s. ω 2 (t) represents the coefficient of the zeroth derivative term. ω 2 (t) is in rad 2 / s 2 It is.

[0025] Here, the coordinate transformation expressed by the following equation (2) is introduced: Hereinafter, q(t) is referred to as the transformed coordinate.

[0026]

number

[0027] D(t) in equation (2) is expressed by the following equation (3).

[0028]

number

[0029] The identification command generator 11 generates an identification command to reduce the operation speed of the mechanism 23 to a speed lower than the speed at which parametric resonance occurs. This allows the vibration suppression device 2 to operate the mechanism 23 at the time of identifying the system characteristics in a manner that does not cause parametric resonance.

[0030] The system characteristic identifier 12 identifies, as system characteristics, the coefficients of the first-order differential terms and the coefficients of the zeroth-order differential terms in the normalized equations of motion, which are equations of motion for each of the multiple axes of the mechanism 23 and are normalized with respect to inertia. That is, the system characteristic identifier 12 identifies β(t) and ω 2 The system characteristic identifier 12 identifies β(t) and ω(t) based on the state detection values. 2 (t). The system characteristic identifier 12 identifies β(t) and ω based on the state detection value. 2 The method of identifying (t) is optional.

[0031] By transforming equation (1) using equation (2), we obtain the following equation (4).

[0032]

number

[0033] However, Ω 2 (t) is expressed by the following equation (5).

[0034]

number

[0035] β(t) can be expressed as the following equation (6): ω 2 (t) can be expressed as the following equation (7).

[0036]

number

[0037]

number

[0038] where ω0 represents the damped natural frequency, b represents the normalized non-varying characteristic, g(t) represents the first normalized varying characteristic, and h(t) represents the second normalized varying characteristic.

[0039] Ω shown in Eq. (5) 2 (t) can be expressed as the following equation (8).

[0040]

number

[0041] where f(t) represents the third normalized fluctuation characteristic. ω n 2 By comparing equations (5) and (8), ω is expressed by the following equation (9). n represents the natural frequency in the normalized equation of motion after coordinate transformation.

[0042]

number

[0043] The fluctuation characteristic calculator 13 calculates the first normalized fluctuation characteristic, the second normalized fluctuation characteristic, and the third normalized fluctuation characteristic, which are normalized fluctuation characteristics, and the normalized non-variable characteristic. That is, the fluctuation characteristic calculator 13 calculates g(t), h(t), f(t), and b.

[0044] From equations (5) to (8), f(t) is expressed by the following equation (10).

[0045]

number

[0046] By substituting equation (8) into equation (4), the following equation (11) is obtained.

[0047]

number

[0048] Equation (11) can be rewritten as the following equation (12).

[0049]

number

[0050] It is assumed that the parametric resonance occurring in mechanism 23 is caused by the reducer. In this case, the number of points where the teeth of the reducer contact each other changes periodically. The first normalized variation characteristic g(t) and the second normalized variation characteristic h(t) can be approximated as square waves having the same period and phase. Therefore, according to equation (10), the third normalized variation characteristic f(t) has the same period as the excitation period and is a periodic function composed of a square wave and an impulse, which is the first-order differential term in equation (10).

[0051] The transformed coordinate, q(t), is approximated as shown in the following equation (13).

[0052]

number

[0053] The third normalized fluctuation characteristic f(t) can be expressed as the following equation (14). k (t) is expressed by the following equation (15).

[0054]

number

[0055]

number

[0056] However, f k (t) represents the kth frequency component of f(t). k -(t) represents the term of f(t) other than the k-th frequency component. k represents the k-th spectral amplitude of the fluctuation part in the coefficient of the zeroth derivative term of the normalized equation of motion after coordinate transformation. p In the first embodiment, the pump frequency is set to ω , which is the excitation frequency of the mechanism 23. e In the first embodiment, the pump frequency can also be said to be the frequency of parametric excitation.

[0057] From equation (13), the second derivative of the transformed coordinate with respect to time, q .. When (t) is calculated, the following equation (16) is obtained. .. " is written with "q" above it. .. " represents a symbol followed by

[0058]

number

[0059] By substituting equations (14) to (16) into equation (11), the following equation (17) is obtained.

[0060]

number

[0061] Here, l(t) is expressed by the following equation (18).

[0062]

number

[0063] In equation (17), the frequency is ω p By comparing the coefficients of the cosine and sine terms, the following equations (19) and (20) are derived. p Each of the cosine and sine terms, k -ω p =ω p The term "a" is used to refer to a term in which a is a positive integer.

[0064]

number

[0065]

number

[0066] Equations (19) and (20) can be rewritten as the following equation (21).

[0067]

number

[0068] The vector and matrix in equation (21) are expressed as in the following equation (22).

[0069]

number

[0070] By using equation (22), equation (21) can be rewritten as the following equation (23).

[0071]

number

[0072] Equation (22) can be rewritten as the following equation (24), which is the equation of state.

[0073]

number

[0074] The following description will be i is the i-th eigenvalue of H expressed by the following equation (25).

[0075]

number

[0076] The excitation frequency ω is set so that the following equation (26) holds true. e By selecting ω, the operation of the mechanism 23 expressed by the formula (1) can be stabilized. e =ω p It is assumed that.

[0077]

number

[0078] Here, Re(X) represents the real part of X when X is a complex number. D . satisfies the following formula (27). . " is a "D" with " . " indicates a symbol with "

[0079]

number

[0080] However, g min represents the minimum value of g(t), which is the first normalized fluctuation characteristic.

[0081] By using equations (26) and (27), the sufficiently stable condition shown in equation (28) is derived. In the first embodiment, the sufficiently stable condition is a sufficient condition for stabilizing the operation of mechanism 23.

[0082]

number

[0083] Here, the left side of equation (28) represents the attenuation rate.

[0084] In order to stabilize the operation of the mechanism 23 expressed by the formula (1), it is necessary to set ω to satisfy the formula (28). e (=ω p ) should be selected.

[0085] The unstable operation period estimator 14 calculates ω e (=ω p ) and repeat the above calculation for multiple ω e For each of the pump frequencies, it is determined whether it is a stable pump frequency or an unstable pump frequency. A stable pump frequency is a pump frequency that satisfies the sufficiently stable condition. An unstable pump frequency is a pump frequency that does not satisfy the sufficiently stable condition. The unstable duty cycle estimator 14 determines T e is assumed to be an unstable operating period. e represents the excitation period. T e =2 π / ω e holds true.

[0086] In this way, the unstable operation period estimator 14 determines whether the pump frequency, which is the frequency of the parametric resonance, satisfies the conditional expression (28), and calculates the unstable operation period by finding the pump frequency that does not satisfy the conditional expression. The unstable operation period estimator 14 outputs information on the unstable operation period to the stability command generator 15.

[0087] The stability command generator 15 generates a stability command representing an operation adjusted to avoid the unstable operation period estimated by the unstable operation period estimator 14. The stability command generator 15 outputs the generated stability command to the robot controller 21. The robot controller 21 outputs the stability command to the actuator 22. The actuator 22 operates the mechanism 23 in accordance with the stability command. This makes it possible to cause the mechanism 23 to perform an operation desired by the user of the robot 3 without causing parametric resonance.

[0088] Next, a description will be given of an operation procedure of the vibration suppression device 2 according to embodiment 1. Fig. 2 is a flowchart showing an example of the operation procedure of the vibration suppression device 2 according to embodiment 1.

[0089] In step S1, the identification command generator 11 generates an identification command and outputs the identification command. The identification command generator 11 generates an identification command to operate the mechanism 23 at a speed lower than the operation speed by the operation command when the robot 3 is actually used. In this way, the identification command generator 11 generates an identification command to operate the mechanism 23 in a manner that does not cause parametric resonance.

[0090] In step S2, the system characteristic identifier 12 identifies the system characteristic based on the identification command generated in step S1 and the state detection value output by the sensor 24 when the mechanism 23 operates in accordance with the identification command. The system characteristic identifier 12 identifies the system characteristic based on β(t) and ω 2 Identify (t).

[0091] In step S3, the variation characteristic calculator 13 calculates normalized variation characteristics and normalized non-variable characteristics based on the system characteristics identified in step S2. The variation characteristic calculator 13 divides the system characteristics identified in step S2 into variation characteristics and non-variable characteristics to obtain the normalized variation characteristics and the normalized non-variable characteristics. The variation characteristic calculator 13 calculates the normalized variation characteristics g(t), h(t), and f(t) and the normalized non-variable characteristic b.

[0092] Steps S4 and S5 are steps for estimating an unstable operational period based on the normalized varying characteristic and the normalized non-varying characteristic obtained in step S3. In step S4, the unstable operational period estimator 14 judges a stable pump frequency and an unstable pump frequency based on a sufficiently stable condition. The unstable operational period estimator 14 calculates ω e (=ω p ) is changed, and by determining whether the sufficiently stable condition is satisfied, a stable pump frequency and an unstable pump frequency are determined.

[0093] In step S5, the unstable operation cycle estimator 14 calculates the unstable operation cycle. The unstable operation cycle estimator 14 calculates T e is estimated to be an unstable operating period, thereby calculating the unstable operating period.

[0094] In step S6, the stability command generator 15 generates a stability command and outputs the stability command. The stability command generator 15 generates a stability command that represents an operation adjusted to avoid the unstable operation period calculated in step S5. The stability command generator 15 outputs the generated stability command to the robot controller 21. With the above, the vibration suppression device 2 ends the operation according to the procedure shown in FIG. 2.

[0095] Next, an example of calculation of an unstable operation period by the vibration suppression device 2 according to the first embodiment will be described. Calculation of an unstable operation period by the vibration suppression device 2 will be referred to as a simulation by the vibration suppression device 2. In the following description, it is assumed that the robot 3 operates only one axis.

[0096] Fig. 3 is a diagram showing examples of parameters used in a simulation by the vibration suppression device 2 according to embodiment 1. Fig. 3 shows symbols representing the parameters, the meanings of the parameters, and example values ​​of the parameters.

[0097] In Fig. 3, the parameter "g" represents the first normalized fluctuation characteristic g(t). According to the example shown in Fig. 3, g(t) is a characteristic that varies at a frequency of 100 Ω. p That is, the frequency of g(t) is the pump frequency, ω p In FIG. 3, the parameter "h" represents the second normalized fluctuation characteristic h(t). In the example shown in FIG. 3, h(t) is a function of the frequency of 500 Ω. p That is, the frequency of h(t) is the pump frequency, ω p It is 500 times larger.

[0098] Fig. 4 is a first diagram showing an example of a result of a simulation performed by the vibration suppression device 2 according to the first embodiment. Fig. 4 shows a graph representing the relationship between the k-th spectral amplitude of f(t), which is the third normalized variation characteristic, and the excitation frequency. The vertical axis of the graph shown in Fig. 4 represents the k-th spectral amplitude of f(t). The horizontal axis of the graph shown in Fig. 4 represents the excitation frequency.

[0099] In FIG. 4, the kth spectral amplitude of f(t), i.e., f k is the excitation frequency, ω e The peak occurs when the right side of equation (12) is 0.4 Hz, that is, when the excitation period is 2.5 s, f k This shows that the

[0100] Fig. 5 is a second diagram showing an example of the results of a simulation using the vibration suppression device 2 according to the first embodiment. Fig. 5 shows a graph showing the relationship between the damping rate and the excitation period. The vertical axis of the graph shown in Fig. 5 represents the damping rate. The damping rate is expressed by the left side of equation (28). The horizontal axis of the graph shown in Fig. 5 represents the excitation period.

[0101] In Fig. 5, the excitation period T e is near 1.4 [s], 1.5 [s], 2.5 [s], and 4.2 [s], the damping rate is a positive number. When the damping rate is a positive number, the operation of the mechanism 23 becomes unstable. The stability command generator 15 generates a stability command in which the excitation frequency is adjusted so as to avoid the excitation period when the operation of the mechanism 23 becomes unstable.

[0102] In the above, for ease of explanation, g(t) and h(t) are each represented by a square wave. g(t) and h(t) may also be represented by something other than a square wave. For example, the waveforms representing g(t) and h(t) may be any step-shaped waveform that corresponds to the movement pattern desired for the robot 3. The above processing by the vibration suppression device 2 can be applied even when g(t) and h(t) are each represented by something other than a square wave.

[0103] In the above, the parametric resonance occurring in the mechanism 23 is caused by the reducer. The parametric resonance may be caused by a system characteristic that changes over time other than the reducer. In this case, the above processing by the vibration suppression device 2 can be applied even when each of g(t) and h(t) is expressed by a wave other than a square wave.

[0104] In the above, it is assumed that the robot 3 operates only one axis. When the vibration suppression device 2 moves multiple axes of the mechanism 23, the vibration suppression device 2 applies the above method to all axes. At that time, the stability command generator 15 generates a stability command for each of the multiple axes based on the union of the unstable operation periods estimated for each of the multiple axes of the mechanism 23. The vibration suppression device 2 can suppress vibration when moving multiple axes by generating a stability command for each axis for the union of the unstable operation periods calculated for all axes.

[0105] According to the first embodiment, the vibration suppression device 2 operates the mechanism 23 by outputting an identification command to identify the system characteristics, and generates a stability command in which an unstable operation period is avoided based on the identified system characteristics. When operating the mechanism 23 by the identification command, it is not necessary to generate parametric resonance. When making adjustments to suppress the vibration of the robot 3, the robot 3 can be made to operate quietly and stably. That is, the vibration suppression device 2 can generate a stability command for suppressing the vibration of the robot 3 without causing the robot 3 to generate vibration. Therefore, the vibration suppression device 2 can avoid making the robot 3 perform an unstable operation in preparation for suppressing the vibration of the robot 3. The vibration suppression device 2 can avoid problems caused by making the robot 3 perform an unstable operation.

[0106] Furthermore, the vibration suppression device 2 can output a stability command by processing in a short time compared to a case where a convolution operation of a plurality of signals is performed. When a parameter changes at high speed, the vibration suppression device 2 can generate a stability command that matches the change in the parameter. The vibration suppression device 2 can suppress parametric resonance caused by a parameter that changes at high speed. The vibration suppression device 2 can suppress parametric resonance even when there is a time change in inertia, friction, or rigidity in each axis of the robot 3.

[0107] In the above, the robot 3 is an industrial robot, but is not limited to this. The robot 3 may be a service robot, a rescue robot, a medical robot, a care robot, an entertainment robot, a forestry robot, an agricultural robot, or the like. Furthermore, the vibration suppression device 2 is applicable to vibration suppression of devices in general that include a controller that outputs an operation command based on a state detection value and a set operation procedure, and an actuator that operates a mechanism according to the operation procedure. The robot 3 according to the first embodiment is also intended to include such devices in general.

[0108] Next, a description will be given of hardware that realizes the vibration suppression device 2. The vibration suppression device 2 is realized by using a processing circuit. The processing circuit may be a dedicated circuit, or may be a circuit in which a processor executes software.

[0109] When the processing circuit is a dedicated circuit, the vibration suppression device 2 is realized, for example, by a hardware circuit shown in Fig. 6. Fig. 6 is a diagram showing an example of the configuration of a hardware circuit 30 according to the first embodiment. The hardware circuit 30 includes an input unit 31, a processing circuit 32, and an output unit 33.

[0110] The input unit 31 is an interface circuit that receives data input from outside the hardware circuit 30 and provides the data to the processing circuit 32. The output unit 33 is an interface circuit that sends data from the processing circuit 32 to the outside of the hardware circuit 30.

[0111] The processing units of the vibration suppression device 2, that is, the identification command generator 11, the system characteristic identifier 12, the fluctuation characteristic calculator 13, the unstable operation period estimator 14, and the stability command generator 15, are realized by a dedicated circuit, the processing circuit 32. The processing circuit 32 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit that combines these. The processing units of the vibration suppression device 2 may be realized by the processing circuit 32 on a function-by-function basis, or each function may be realized collectively by the processing circuit 32.

[0112] When the processing circuit is realized by software, the processing circuit is, for example, a control circuit shown in Fig. 7. Fig. 7 is a diagram showing an example of the configuration of a control circuit 34 according to the first embodiment. The control circuit 34 includes an input unit 31, an output unit 33, a processor 35, and a memory 36. The input unit 31 of the control circuit 34 is an interface circuit that receives data input from outside the control circuit 34 and provides the data to the processor 35. The output unit 33 of the control circuit 34 is an interface circuit that sends data from the processor 35 or the memory 36 to outside the control circuit 34.

[0113] When the processing circuit is the control circuit 34 shown in FIG. 7, the processing section of the vibration suppression device 2 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 36. The processing circuit realizes the function of the processing section of the vibration suppression device 2 by the processor 35 reading and executing the program stored in the memory 36. That is, the processing circuit includes the memory 36 for storing the program that will result in the processing of the vibration suppression device 2 being executed. It can also be said that these programs cause a computer to execute the procedures and methods of the vibration suppression device 2.

[0114] The processor 35 is a CPU (Central Processing Unit). The processor 35 may be a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor). The memory 36 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc). The processing unit of the vibration suppression device 2 may be realized by combining the control circuit 34 and the processing circuit 32 shown in FIG. 6.

[0115] The programs stored in the memory 36 may be provided in a state stored in a recording medium such as a CD (Compact Disc)-ROM or a DVD-ROM, or may be provided via a communication line.

[0116] Next, the hardware for realizing the robot controller 21 shown in Fig. 1 will be described. The robot controller 21 is realized by using a processing circuit, similar to the vibration suppression device 2. The robot controller 21 has the configuration of the hardware circuit 30 shown in Fig. 6, or has a configuration similar to the control circuit 34 shown in Fig. 7. The function of the robot controller 21 may be realized by combining a configuration similar to the processing circuit 32 shown in Fig. 6 and a configuration similar to the control circuit 34 shown in Fig. 7.

[0117] The vibration suppression device 2 may be connected to the robot 3 via a network. The network may be, for example, a wide area network (WAN) such as the Internet, or may be a local area network (LAN). The vibration suppression device 2 may be configured by a server built in a cloud environment.

[0118] According to the first embodiment, the vibration suppression device 2 outputs an identification command to the robot controller 21, generates a stability command that avoids an unstable operation period, which is an operation period of the mechanism 23 when the operation of the mechanism 23 becomes unstable, based on the system characteristics identified based on the state detection value output by the sensor 24 when the mechanism 23 operates according to the identification command, and outputs the stability command to the robot controller 21 to suppress vibration of the mechanism 23. The vibration suppression device 2 can generate a stability command for suppressing vibration of the robot 3 even if the robot 3 does not generate vibration in the preparatory operation. This makes it possible for the vibration suppression device 2 to avoid making the robot 3 perform unstable operations in preparation for suppressing vibration of the robot 3.

[0119] The vibration suppression device 2 also includes an identification command generator 11 that generates an identification command, a system characteristic identifier 12 that identifies a system characteristic based on the identification command and a state detection value output by a sensor 24 when the mechanism 23 operates according to the identification command, a fluctuation characteristic calculator 13 that divides the identified system characteristic into a fluctuation characteristic and a non-fluctuation characteristic and outputs information on the normalized fluctuation characteristic and information on the normalized non-fluctuation characteristic, an unstable operation period estimator 14 that estimates an unstable operation period based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic, and a stability command generator 15 that generates a stability command in which the estimated unstable operation period is avoided. This allows the vibration suppression device 2 to generate a stability command for suppressing vibration of the robot 3 even if the robot 3 does not generate vibration in the preparatory operation. The vibration suppression device 2 also allows parametric resonance caused by parameters that change at high speed to be suppressed.

[0120] Furthermore, the identification command generator 11 generates an identification command to reduce the operating speed of the mechanism 23 below the speed at which parametric resonance may occur. This allows the vibration suppression device 2 to avoid the occurrence of parametric resonance in preparation for suppressing vibrations of the robot 3.

[0121] The system characteristic identifier 12 also identifies, as system characteristics, the coefficient of the first-order differential term and the coefficient of the zeroth-order differential term in the equation of motion for each of the multiple axes of the mechanism 23, which is a normalized equation of motion normalized with respect to inertia. The coefficient of the first-order differential term, β(t), is expressed by the above formula (6). The coefficient of the zeroth-order differential term, ω 2 (t) is expressed by the above formula (7). As a result, the vibration suppression device 2 can suppress parametric resonance even when there is a time change in inertia, friction, or rigidity in each axis of the robot 3.

[0122] Moreover, the unstable operating period estimator 14 determines whether or not the pump frequency, which is the frequency of the parametric resonance, satisfies the conditional expression, and calculates the unstable operating period by finding the pump frequency that does not satisfy the conditional expression. Moreover, the conditional expression is expressed by the above-mentioned expression (28). This allows the vibration suppression device 2 to estimate the unstable operating period based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic.

[0123] Moreover, the pump frequency is set to the excitation frequency of the mechanism 23. This enables the vibration suppression device 2 to generate a stable command in which an unstable operation period is avoided.

[0124] Furthermore, the stability command generator 15 generates a stability command for each of the multiple axes based on the union of the unstable operation periods estimated for each of the multiple axes of the mechanism 23. This enables the vibration suppression device 2 to suppress vibrations occurring when the multiple axes of the mechanism 23 are moved.

[0125] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of the embodiments can be combined with other known technologies. Part of the configurations of the embodiments can be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0126] 1 robot system, 2 vibration suppression device, 3 robot, 11 identification command generator, 12 system characteristic identifier, 13 fluctuation characteristic calculator, 14 unstable operation period estimator, 15 stability command generator, 21 robot controller, 22 actuator, 23 mechanism, 24 sensor, 30 hardware circuit, 31 input section, 32 processing circuit, 33 output section, 34 control circuit, 35 processor, 36 memory.

Claims

1. A vibration suppression device for suppressing vibration of a robot, the device comprising: a sensor for detecting a state of the robot; a robot controller for outputting an operation command based on a state detection value output by the sensor and a set operation procedure; and an actuator for operating a mechanism of the robot in accordance with the operation command, an identification command generator that generates an identification command that is a command regarding an operation of the mechanism when identifying a system characteristic that is a characteristic of the mechanism, and outputs the identification command to the robot controller; a system characteristic identifier that identifies the system characteristic based on the identification command and the state detection value output by the sensor when the mechanism operates in accordance with the identification command; a fluctuation characteristic calculator that divides the identified system characteristics into fluctuation characteristics that change over time and non-fluctuating characteristics that do not change over time, and outputs information on normalized fluctuation characteristics that are normalized fluctuation characteristics and information on normalized non-fluctuating characteristics that are normalized non-fluctuating characteristics; an unstable operation period estimator that estimates an unstable operation period, which is an operation period of the mechanism when operation of the mechanism becomes unstable due to parametric resonance of the mechanism, based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic; a stability command generator that generates a stability command that avoids the estimated unstable operating period; The stability command is output to the robot controller to suppress vibration of the mechanism. A vibration suppression device characterized by:

2. The identification command generator generates the identification command to reduce the speed of the mechanism's operation below the speed at which the parametric resonance occurs.

2. The vibration suppression device according to claim 1.

3. The system characteristic identifier identifies, as the system characteristic, a coefficient of a first-order differential term and a coefficient of a zeroth-order differential term in a normalized equation of motion normalized with respect to inertia, the normalized equation of motion being for each of a plurality of axes of the mechanism.

2. The vibration suppression device according to claim 1.

4. The damped natural frequency is ω 0 , the normalized fluctuation characteristics, ie, the first normalized fluctuation characteristic and the second normalized fluctuation characteristic, are denoted by g(t) and h(t), respectively, and the normalized non-variable characteristic is denoted by b, The coefficient β(t) of the first derivative term is expressed by the following equation (1): The coefficient of the zeroth-order derivative term, ω 2 (t) is expressed by the following formula (2):

4. The vibration suppression device according to claim 3. [Equation 1] [Equation 2]

5. The unstable operating period estimator determines whether or not a pump frequency, which is a frequency of the parametric resonance, satisfies a conditional expression, and calculates the unstable operating period by finding the pump frequency that does not satisfy the conditional expression.

4. The vibration suppression device according to claim 3.

6. When X is a complex number, the real part of X is Re(X), and the i-th eigenvalue in H expressed by the following equations (4) and (5) is s i , the damped natural frequency is ω 0 , the normalized non-variable characteristic is b, the first normalized variable characteristic which is the normalized variable characteristic is g(t), and the minimum value of g(t) is g min , the pump frequency is ω p , the natural frequency in the normalized equation of motion after coordinate transformation is ω n , and the k-th spectral amplitude of the fluctuation part in the coefficient of the zeroth-order differential term of the normalized equation of motion after coordinate transformation is defined as f k As, The conditional expression is expressed by the following expression (3):

6. The vibration suppression device according to claim 5. [Equation 3] [Equation 4] [Equation 5]

7. The pump frequency is set to the excitation frequency of the mechanism.

6. The vibration suppression device according to claim 5.

8. The stability command generator generates the stability command for each of a plurality of axes based on a union of the unstable operation periods estimated for each of the plurality of axes included in the mechanism.

2. The vibration suppression device according to claim 1.

9. Robots and a vibration suppression device that suppresses vibrations of the robot, the robot includes a sensor that detects a state of the robot, a robot controller that outputs an operation command based on a state detection value output by the sensor and a set operation procedure, and an actuator that operates a mechanism of the robot in accordance with the operation command; The vibration suppression device is an identification command generator that generates an identification command that is a command regarding an operation of the mechanism when identifying a system characteristic that is a characteristic of the mechanism, and outputs the identification command to the robot controller; a system characteristic identifier that identifies the system characteristic based on the identification command and the state detection value output by the sensor when the mechanism operates in accordance with the identification command; a fluctuation characteristic calculator that divides the identified system characteristics into fluctuation characteristics that change over time and non-fluctuating characteristics that do not change over time, and outputs information on normalized fluctuation characteristics that are normalized fluctuation characteristics and information on normalized non-fluctuating characteristics that are normalized non-fluctuating characteristics; an unstable operation period estimator that estimates an unstable operation period, which is an operation period of the mechanism when operation of the mechanism becomes unstable due to parametric resonance of the mechanism, based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic; a stability command generator that generates a stability command that avoids the estimated unstable operating period; The vibration suppression device suppresses vibration of the mechanism by outputting the stability command to the robot controller. A robot system characterized by:

10. A vibration suppression method for suppressing vibration of a robot having a sensor that detects a state of the robot, a robot controller that outputs an operation command based on a state detection value output by the sensor and a set operation procedure, and an actuator that operates a mechanism of the robot in accordance with the operation command, comprising: generating an identification command that is a command regarding an operation of the mechanism when identifying a system characteristic that is a characteristic of the mechanism, and outputting the identification command to the robot controller; identifying the system characteristics based on the identification command and the state detection value output by the sensor when the mechanism operates in accordance with the identification command; a step of dividing the identified system characteristics into fluctuating characteristics that change over time and non-varying characteristics that do not change over time, and obtaining normalized fluctuating characteristics that are normalized fluctuating characteristics and normalized non-varying characteristics that are normalized non-varying characteristics; a step of estimating an unstable operation period, which is an operation period of the mechanism when operation of the mechanism becomes unstable due to parametric resonance of the mechanism, based on the normalized fluctuation characteristic and the normalized non-fluctuation characteristic; generating a stability command that avoids the estimated unstable operating period, and outputting the stability command to the robot controller to suppress vibration of the mechanism. A vibration suppression method characterized by:

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