Control device, mechanical system, and display device

Abstract

This control device comprises: a temperature acquiring unit that acquires a detected temperature; a friction force calculation unit that calculates a viscous friction force generated in an actuator of a machine at the detected temperature and a reference temperature; and a control unit that limits, on the basis of the viscous friction force, the operation of the machine so as not to exceed the ability of the actuator.

Description

[Technical Field]

[0001] The present invention relates to a machine control technology, and more particularly to a control device, a machine system, and a display device that have a function for dealing with changes in viscous friction. [Background technology]

[0002] Conventionally, a technique has been proposed that generates an excessive error alarm and stops machine operation when the position error, which is the deviation between the commanded movement amount and the actual movement amount of a servo motor, exceeds a specified value (see, for example, Patent Document 1). However, if a machine is left in a low-temperature environment for a certain period of time, the kinetic viscosity of the lubricant that lubricates the machine's actuator increases. When the cooled machine begins to operate, the increased viscous friction force generated in the actuator may cause an operation command that exceeds the servo motor's capacity, increasing the deviation between the commanded position and the actual position. This may cause the position error to exceed a specified value, triggering an excessive error alarm. In this case, an abnormality is detected and the machine operation is stopped, but this may also lead to the shutdown of the entire system, including the machine, causing adverse effects on production, operations, etc.

[0003] On the other hand, when the machine is in a high-temperature environment, the dynamic viscosity of the lubricant decreases, reducing the viscous frictional force generated in the actuator, preventing the position error from exceeding the specified value and causing an error escalation alarm. However, in a high-temperature environment, it is possible to somewhat relax operational limitations on the servo motor's speed, acceleration, etc. at a reference temperature (e.g., room temperature) without exceeding the actuator's capabilities. The following documents are known as background art related to this application.

[0004] Patent Document 1 describes a method for solving the problem that, when a threshold value for position error at the maximum rotation speed of a motor is set, it takes a long time to detect an abnormality when the motor rotation speed is low. The method involves performing a simulation of a servo control system approximated by a first-order transfer function in which the reciprocal of the position gain of the servo control system is used as a time constant, in parallel with the drive control of the servo motor, and generating an excessive error alarm when the position error obtained by the simulation and the actual position error obtained by servo control exceed a predetermined value.

[0005] Patent Document 2 describes that when a robot is operated in a low-temperature environment, the grease (lubricant) used in the mechanical parts, including the motor and reducer, hardens and friction increases compared to a room-temperature environment, so that the estimated disturbance value exceeds the threshold even though no collision actually occurs, resulting in a false detection of a collision.Therefore, it is described that the robot's control device determines whether the robot's drive shaft is in a low-temperature environment, and if it is determined that it is in a low-temperature environment, the threshold is revised upward from the value for a room-temperature environment.

[0006] Patent Document 3 describes a servo control device that performs simulations of position control and speed control, compares the output of a speed controller with the output of a simulated speed controller, generates a friction model from the output of the comparison section, and performs compensation based on the output of the friction model, with the aim of more accurately determining frictional force that changes with time and temperature, dynamically switching the friction coefficient in response to time changes and temperature changes without being dependent on the changes in time or temperature, and always maintaining high control performance for position control and flexible control.

[0007] Patent Document 4 describes a robot control device that controls a detection means for detecting robot collisions so that it becomes difficult to detect robot collisions when a predetermined condition indicating that the robot temperature is low is met, in order to solve the problem that, when a configuration is adopted in which the threshold value for disturbance values ​​is changed depending on whether the elapsed time since the motor power was turned on exceeds a specified value, collisions cannot be detected even when the robot temperature is not low and friction is not large because the threshold value has been changed, and the problem that, when a configuration is adopted in which the threshold value for disturbance values ​​is changed depending on whether the change in the estimated value of the friction coefficient is below a specified value, it is not possible to determine whether the estimated value of the friction coefficient has converged due to friction changes in areas where the robot temperature is low, and collisions cannot be detected.

[0008] Patent Document 5 describes a motor control device that aims to appropriately estimate the friction force acting on the output shaft of a motor and compensate for disturbances caused by the friction force without requiring highly accurate modeling of friction characteristics or highly accurate identification of related physical quantities.The motor control device receives as control inputs a current command value to the motor, the motor rotation speed, and a measured value of the torsional torque of the output shaft connected to the motor via a reduction gear mechanism, and is equipped with a disturbance observer device that suppresses disturbances caused by friction torque acting on the output shaft of the motor.The disturbance observer device calculates a torque compensation value that compensates for the friction torque based on the control input, and a sensitivity function that represents the characteristics of the compensation value calculation is set based on the motor rotation speed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2-184281 [Patent Document 2] Japanese Patent Application Publication No. 11-15511 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-146572 [Patent Document 4] Japanese Patent Application Publication No. 2020-019117 [Patent Document 5] Japanese Patent Publication No. 2020-198657 Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the problems of the prior art, an object of the present invention is to provide a machine control technique that can deal with changes in viscous friction. [Means for solving the problem]

[0011] One aspect of the present disclosure is a temperature acquisition unit that acquires a detected temperature, a friction force calculation unit that calculates a viscous friction force generated in an actuator of a machine at the detected temperature and a reference temperature, and a friction force calculation unit that calculates a viscous friction force generated in an actuator of a machine based on an amount of change in the viscous friction force between the detected temperature and the reference temperature. motion A control unit that limits the operation of the machine so that it does not exceed its capacity. the control unit includes an upper limit calculation unit that calculates an upper limit value of the velocity or acceleration of the actuator or the machine based on the amount of change in the viscous friction force, and a command limiting unit that limits an operation command of the actuator or the machine so that the operation of the actuator or the machine does not exceed the upper limit value. A control device is provided. Another aspect of the present disclosure is a device including a machine, a temperature sensor, a temperature acquisition unit that acquires a detected temperature from the temperature sensor, a friction force calculation unit that calculates a viscous friction force generated in an actuator of the machine at the detected temperature and a reference temperature, and a friction force calculation unit that calculates a viscous friction force generated in an actuator of the machine based on an amount of change in the viscous friction force between the detected temperature and the reference temperature. motion A control unit that limits the operation of the machine so that it does not exceed its capacity. the control unit includes an upper limit calculation unit that calculates an upper limit value of the velocity or acceleration of the actuator or the machine based on the amount of change in the viscous friction force, and a command limiting unit that limits an operation command of the actuator or the machine so that the operation of the actuator or the machine does not exceed the upper limit value. Provide a mechanical system. [Effects of the Invention]

[0012] According to one aspect and another aspect of the present disclosure, even when the viscous friction force increases due to a low-temperature environment, the operational limitations of the machine are strengthened so as not to exceed the capacity of the actuator, thereby preventing the generation of an excessive position error alarm and allowing the machine to continue operating. On the other hand, when the viscous friction force decreases due to a high-temperature environment, the operational limitations of the machine are relaxed so as not to exceed the capacity of the actuator, allowing the machine to operate at a relatively high speed. In this disclosure, the term "imposing operational restrictions" includes not only strengthening the operational restrictions on the machine when the viscous friction force increases due to a low-temperature environment, but also relaxing the operational restrictions on the machine when the viscous friction force decreases due to a high-temperature environment. According to another aspect of the present disclosure, when it is determined that the temperature condition is such that an operational restriction is imposed on the machine, the operation command of the actuator or machine that has imposed the operational restriction is highlighted on the display unit, so that the user can visually grasp the operation command of the actuator or machine that has been restricted and can easily recognize that the machine is not operating as intended. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram of a mechanical system according to an embodiment. [Figure 2] FIG. 1 is a functional block diagram of a mechanical system according to an embodiment. [Figure 3] FIG. 2 is a user interface diagram of the teaching device (display device) of the embodiment. [Figure 4] 10 is a flow chart of a cold state of a mechanical system according to one embodiment. [Figure 5] 10 is a flow chart of a high temperature condition of a mechanical system according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, the same or similar components are assigned the same or similar reference numerals. Furthermore, the embodiments described below do not limit the technical scope of the invention described in the claims and the meaning of terms. In this specification, the term "low temperature" means a temperature (e.g., less than 10°C) lower than a reference temperature (e.g., 25°C), and the term "high temperature" means a temperature (e.g., above 40°C) higher than the reference temperature. It should also be noted that in this specification, the term "frictional force" includes not only frictional force in the narrow sense but also frictional torque.

[0015] An example of the configuration of a machine system 1 according to an embodiment will be described in detail below. Fig. 1 is a configuration diagram of the machine system 1 according to this embodiment, Fig. 2 is a functional block diagram of the machine system 1 according to this embodiment, and Fig. 3 is a user interface diagram of a teaching device 30 (display device) according to this embodiment. The machine system 1 includes a machine 10 and a control device 20 that controls the machine 10. Furthermore, the machine system 1 further includes a teaching device 30 that instructs the machine 10 and checks its status, although this is not essential.

[0016] The machine 10 is configured as an articulated robot, but is not limited to this, and in other embodiments, the machine 10 may be configured as other industrial robots (robot arms) such as single-joint robots, dual-arm robots, and parallel link robots. Alternatively, in another embodiment, the machine 10 may not be an industrial robot, but may be configured as other types of robots such as humanoids. Alternatively, in yet another embodiment, the machine 10 may not be a robot, but may be configured as other industrial machines such as construction machines or agricultural machines, or other machines such as vehicles or aircraft.

[0017] The machine 10 includes a base 11 and a rotating body 12 supported rotatably relative to the base 11 about a first axis J1. The machine 10 also includes a first arm 13 supported rotatably relative to the rotating body 12 about a second axis J2 perpendicular to the first axis J1, a second arm 14 supported rotatably relative to the first arm 13 about a third axis J3 parallel to the second axis J2, and a three-axis wrist unit 15 attached to the tip of the second arm 14. The machine 10 may also include a tool 16 attached to the tip of the wrist unit 15. The tool 16 includes, for example, a hand, a cutting tool, a fastening tool, a welding tool, a sealing tool, etc.

[0018] As described above, machine 10 includes multiple links capable of relative movement, such as rotating body 12, first arm 13, second arm 14, and wrist unit 15. Because machine 10 of this embodiment is a multi-axis machine, it includes multiple actuators 17 that respectively drive the multiple links (see FIG. 2 ). However, this is not limited to this, and in other embodiments that are single-axis machines, machine 10 may include only one actuator 17. Actuator 17 is provided at a link connection portion (e.g., a robot joint portion). Actuator 17 is configured as an electric actuator including an electric motor such as a servo motor, or an electric motor connected to mechanical elements such as a shaft, bearings, gears, and reducers. However, this is not limited to this, and in other embodiments, it may be configured as an actuator of another type that uses other energy sources, such as hydraulic, pneumatic, or magnetic, or a combination of these.

[0019] Furthermore, the actuator 17 is configured as a rotary actuator including a rotary motor, but is not limited to this, and in other embodiments, it may be configured as a linear actuator including a linear motor. Mechanical elements of the actuator 17, such as the shaft, bearings, and gears, are lubricated with a lubricant (not shown), such as grease or lubricating oil. Since the dynamic viscosity of the lubricant changes depending on the temperature, the viscous friction force generated in the actuator 17 also changes.

[0020] Therefore, the machine system 1 further includes a temperature sensor 18. The temperature sensor 18 is configured with a thermocouple, a thermistor, a resistance temperature detector, or the like. The temperature sensor 18 is an existing temperature sensor mounted on the actuator 17 (e.g., an electric motor), but is not limited thereto. In other embodiments, the temperature sensor 18 may be a temperature sensor mounted in a lubrication chamber that lubricates the actuator 17 (e.g., a reducer or a bearing), a temperature sensor mounted inside or outside the machine 10, a temperature sensor mounted on the control device 20 or the teaching device 30, or a temperature sensor disposed near the control device 20 or the teaching device 30. The existing temperature sensor 18 detects the temperature of the actuator 17 (e.g., the windings, stator core, bearings, etc. of the electric motor), while other temperature sensors 18 detect the temperature of the lubricant in the lubrication chamber or the ambient temperature inside or outside the machine 10 (the temperature of the fluid surrounding the machine 10). The ambient temperature outside the machine 10 is what is known as the environmental temperature.

[0021] The control device 20 is configured with a known programmable logic controller (PLC), but is not limited to this and may be configured with other computer devices in other embodiments. The control device 20 includes a processor, memory, input / output interface, timer, etc. (not shown), which are connected to each other by a bus. The processor includes a central processing unit (CPU), a micro processing unit (MPU), etc., the memory includes a random access memory (RAM), a read only memory (ROM), etc., and the input / output interface includes an A / D converter, a D / A converter, etc.

[0022] As shown in Fig. 3, the control device 20 controls the operation of the machine 10 in accordance with an operation program 35 taught by the teaching device 30. The operation program 35 includes various operation commands 36, such as a position command (e.g., a command to move to taught points P1, P2, etc.) and a speed command (e.g., a speed command (100 mm / sec) for the actuator 17 or the tip of the machine 10). As shown in Fig. 2, the control device 20 acquires a detected temperature, calculates the viscous friction force generated in the actuator 17 at the detected temperature and a reference temperature, and imposes operation restrictions on the machine 10 based on the viscous friction force so as not to exceed the capacity of the actuator 17 (e.g., an electric motor, particularly a servo motor).

[0023] Referring again to FIG. 1, the control device 20 sets various coordinate systems, such as a world coordinate system, a machine coordinate system, a flange coordinate system, a tool coordinate system, a camera coordinate system, and a user coordinate system. These coordinate systems may be, for example, Cartesian coordinate systems. For ease of explanation, in this embodiment, it is assumed that the control device 20 sets a machine coordinate system C1 and a tool coordinate system C2. The machine coordinate system C1 is fixed to a reference position (e.g., the base) of the machine 10, and the tool coordinate system C2 is fixed to a reference position (e.g., the TCP (tool center point)) of the tool 16.

[0024] As shown in Fig. 1, the teaching device 30 is configured as a teaching operation panel, but is not limited to this and may be configured as a teach pendant, other computer devices, etc. in other embodiments. As shown in Fig. 2 and Fig. 3, the teaching device 30 includes an input unit 31 for inputting various information and a display unit 32 for displaying various information. The input unit 31 is configured as, for example, a keyboard, and the display unit 32 is configured as, for example, a display.

[0025] 3, the teaching device 30 displays an editing window 33 for an operation program 35 of the machine 10 on a display unit 32, and various operation commands 36 such as position commands and speed commands are specified by an input unit 31. The teaching device 30 transfers the edited or created operation program 35 to the control device 20. The control device 20 controls the operation of the actuator 17 in accordance with the operation commands 36 in the operation program 35.

[0026] In the machine system 1 configured as described above, if the machine 10 is left in a low-temperature environment for a certain period of time, the kinetic viscosity of the lubricant that lubricates the actuator 17 of the machine 10 increases. When the cooled machine 10 begins to operate, the increased viscous frictional force generated in the actuator 17 may cause an operation command 36 that exceeds the capabilities of the actuator 17 to be input. This increases the deviation between the commanded position and the actual position, causing the position error to exceed a specified value and triggering an excessive error alarm. Therefore, the control device 20 is equipped with a function to deal with changes in viscous frictional force. In a low-temperature environment, the control device 20 strengthens operational limitations on the speed, acceleration, etc. of the actuator 17 or the machine 10, and controls the machine 10 to start operating relatively slowly.

[0027] On the other hand, when the machine 10 is in a high temperature environment, the kinetic viscosity of the lubricant decreases, reducing the viscous frictional force generated in the actuator 17, so the position error does not exceed the specified value and an error escalation alarm is not generated. However, in a high temperature environment, the control device 20 relaxes operational limitations on the speed, acceleration, etc. of the actuator 17 or the machine 10 that were imposed at the reference temperature, and performs control to operate the machine 10 at a relatively high speed.

[0028] As shown in FIG. 2, the control device 20 includes a temperature acquisition unit 21 that acquires the detected temperature from the temperature sensor 18, a friction force calculation unit 27 that calculates the viscous friction force generated in the actuator 17 of the machine 10 at the detected temperature and a reference temperature, and a control unit 28 that imposes operational restrictions on the machine 10 based on the viscous friction force so as not to exceed the capacity of the actuator 17.

[0029] The control device 20 may also include a storage unit 25 that stores various information. The storage unit 25 is configured with memories such as RAM and ROM. The storage unit 25 stores a threshold value for the detected temperature, a threshold value for the stop time before the machine 10 starts operating, a threshold value for the operating time after the machine 10 starts operating, a viscous friction force estimation formula, etc.

[0030] The components of the control device 20 other than the storage unit 25 are configured in part or in whole by a computer program, but are not limited to this, and in other embodiments may be configured in part or in whole by an electric circuit, a semiconductor integrated circuit, etc. Furthermore, in other embodiments, the components other than the control unit 28 may be arranged in a host computer device that can be connected to the control device 20 by wire or wirelessly.

[0031] The temperature acquisition unit 21 multiplies the A / D converted output value (e.g., voltage value) of the temperature sensor 18 by a temperature coefficient to convert it into the temperature of the actuator 17 (e.g., the windings or stator core of the electric motor), and acquires the detected temperature. In other words, even if the temperature sensor 18 outputs the temperature of the lubricant or the ambient temperature inside or outside the machine 10, the temperature acquisition unit 21 acquires the temperature of the actuator 17. The temperature coefficient for converting the output value of the temperature sensor 18 into the temperature of the actuator 17 may be stored in the storage unit 25, or may be defined within a program.

[0032] The friction force calculation unit 27 calculates the viscous friction force τ generated in the actuator 17 at the detected temperature. d and the viscous friction force τ generated in the actuator 17 at the reference temperature. r As a result, the control unit 28 calculates the amount of change Δτ (=τ d -τ r ) based on which an operation limit can be imposed on the machine 10. The viscous friction force τ can be calculated, for example, from the following viscous friction force estimation formula.

[0033]

number

[0034] In the viscous friction force estimation formula (Formula 1), μ is the viscous friction coefficient, ν is the kinematic viscosity of the lubricant, s is the speed (e.g., rotational speed) of the actuator 17, and n is a power of a constant. The kinematic viscosity ν in Formula 1 can be calculated from the following kinematic viscosity estimation formula based on the well-known Andrade viscosity calculation formula and the definition of kinematic viscosity.

[0035]

number

[0036] In the kinematic viscosity estimation equation (Equation 2), f and e are constants, and T is the temperature of the lubricant (for example, absolute temperature). As described above, the temperature acquisition unit 21 acquires the detected temperature of the actuator 17 (for example, the windings, stator core, bearings, etc. of the electric motor), and the frictional force calculation unit 27 estimates the temperature T of the lubricant based on the detected temperature of the actuator 17. The constants f and e are determined in advance based on data such as the temperature, viscosity, and density of the lubricant used in the actuator 17. The constants f and e may be stored in the storage unit 25 or may be defined within a program.

[0037] The viscous friction coefficient μ in the viscous friction force estimation formula (Formula 1) is determined in advance by performing experiments in which the machine 10 is made to perform standard operations in various temperature environments (low temperature environment, reference temperature, high temperature environment, etc.) and identifying the viscous friction coefficient μ from Formula 1 based on the command values ​​(speed command value, torque command value, etc.) of the actuator 17, the detected values ​​(detected speed value, detected torque value, etc.), the temperature, etc. The viscous friction coefficient μ may be stored in the storage unit 25 as a database in association with various temperatures, or may be defined within the program.

[0038] Alternatively, as shown in FIG. 2, the control device 20 may calculate the viscous friction coefficient μ d and the viscous friction coefficient μ at the reference temperature r The friction coefficient calculation unit 26 causes the machine 10 to perform a standard operation at the detected temperature and the reference temperature, and calculates the viscous friction coefficient μ based on the command values ​​(speed command value, torque command value, etc.) of the actuator 17, the detected values ​​(detected speed value, detected torque value, etc.), the detected temperature, the reference temperature, etc. d , μ r Calculate the viscous friction coefficient μ at the detected temperature and the reference temperature. d , μ r may be stored in the storage unit 25 or may be defined within the program.

[0039] Alternatively, the friction force calculation unit 27 performs an experiment to identify the relationship between temperature and viscous friction force without using the viscous friction coefficient μ, predetermines a temperature-friction force database, and calculates the viscous friction force τ at the detected temperature and the reference temperature based on the temperature-friction force database. d , τ r The temperature-frictional force database may be stored in advance in the storage unit 25 or may be defined within the program.

[0040] In addition, the speed s of the actuator 17 in the viscous friction force estimation formula (Formula 1) is set to the maximum speed s in the specifications of the actuator 17 at the reference temperature so that the operational restrictions imposed on the machine 10 at the detected temperature are not too strong. max (e.g., maximum rotation speed) is used. max may be stored in advance in the storage unit 25 or may be defined within the program.

[0041] The viscous friction force τ at the detected temperature and the reference temperature calculated as above d , τ r Based on this, the control unit 28 imposes operational limitations on the machine 10 so as not to exceed the capacity of the actuator 17. The control unit 28 includes an upper limit calculation unit 28a that calculates an upper limit value for the operation of the actuator 17 or the machine 10, a command limiting unit 28b that limits an operation command 36 for the actuator 17 or the machine 10 based on the upper limit value, and a drive control unit 28c that drives and controls the actuator 17 based on the operation command 36 with the operational limitations imposed.

[0042] The upper limit calculation unit 28a calculates the amount of change Δτ (=τ d -τ r ) is used to calculate the upper limit value of at least one of the speed and acceleration of the actuator 17. lim is calculated, for example, from the following formula:

[0043]

number

[0044] In Equation 3, τ d is the viscous friction force at the detected temperature, Δτ is the amount of change in the viscous friction force between the detected temperature and the reference temperature, and μ d is the viscous friction coefficient at the detected temperature. In other words, the upper limit calculation unit 28a calculates the upper limit value s of the speed by the amount of change Δτ of the viscous friction force between the detected temperature and the reference temperature. lim This will strengthen or ease the

[0045] On the other hand, the upper limit value a of the acceleration of the actuator 17 lim is calculated, for example, from the following formula:

[0046]

number

[0047] In Equation 4, a max is the maximum acceleration of the actuator 17, and J m is the moment of inertia (for example, rotor inertia), and Δτ is the amount of change in viscous friction force between the detected temperature and the reference temperature. In other words, the upper limit calculation unit 28a calculates the upper limit value a of the acceleration by the amount of change Δτ in viscous friction force between the detected temperature and the reference temperature. lim This will strengthen or ease the

[0048] The command limiting unit 28b sets the upper limit s of the speed of the actuator 17. lim and upper limit of acceleration a lim In other words, the command limiting unit 28b limits at least one of the velocity command and the acceleration command of the actuator 17 in the operation program 35.

[0049] Alternatively, in another embodiment, the command limiting unit 28b sets upper limit values ​​s of the velocities and accelerations of n actuators 17 (n is an integer of 1 or more).lim1 ~s limn , a lim1 ~a limn At least one of the velocity command and the acceleration command of the machine 10 may be limited so as not to exceed

[0050] The velocity and acceleration of the machine 10 are the velocity and acceleration of the tip of the machine 10 (for example, the origin of the tool coordinate system C2). In addition, since the machine 10 is equipped with n actuators 17, the command limiting unit 28b sets upper limit values ​​s of at least one of the velocity and acceleration of each of the n actuators 17 based on forward kinematics. lim1 ~s limn , a lim1 ~a limn The upper limit value S of at least one of the speed and acceleration of the tip of the machine 10 lim , A lim Convert to.

[0051] The upper limit value s of the speed of each of the n actuators 17 lim1 ~s limn are the positions q1 to q of the actuator 17. n (For example, the rotation angle in the case of a rotary actuator, or the linear position in the case of a linear actuator) is expressed as the derivative of the time t. On the other hand, the upper limit S lim is expressed as the position and orientation (x, y, z, ω, p, r) of the machine 10 (for example, the position and orientation of the tool coordinate system C2 in the reference coordinate system C1) differentiated with respect to time t. Therefore, the upper limit value S of the speed of the tip of the machine 10 lim is calculated by forward kinematics, for example, by the following equation:

[0052]

number

[0053] In Equation 5, J is a Jacobian matrix, which is determined in advance according to the machine 10 (length of the link, movable range of the link, etc.), and is stored in the storage unit 25 or defined within the program.

[0054] On the other hand, the upper limit A of the acceleration at the tip of the machine 10 lim is the upper limit S of the tip speed of the machine 10. lim is obtained by differentiating with respect to time t, or by forward kinematics, the upper limit value a of the acceleration of the actuator 17 is obtained. lim1 ~a limn It may also be found from

[0055] The command limiting unit 28b limits the upper limit S of at least one of the speed and acceleration of the tip of the machine 10. lim , A lim That is, the command limiting unit 28b limits at least one of the speed command and the acceleration command of the machine 10 in the operation program 35.

[0056] As a result, even if the viscous friction force increases due to a low temperature environment, the control device 20 strengthens the operational restrictions of the machine 10 so as not to exceed the capacity of the actuator 17, thereby preventing the generation of an excessive position error alarm and ultimately allowing the machine 10 to continue operating.

[0057] On the other hand, when the viscous friction force decreases due to a high temperature environment, the control device 20 relaxes the operational restrictions of the machine 10 so as not to exceed the capacity of the actuator 17, allowing the machine 10 to perform operations at a relatively high speed.

[0058] The command limiting unit 28b also sends a display command to the display unit 32 to highlight the operation command 36 of the actuator 17 or machine 10 for which the operation is limited. As shown in FIG. 3, the display unit 32 may highlight the operation command 36 in an editing window 33 for the operation program 35 based on the display command. The highlighting of the operation command 36 is performed, for example, by displaying the background color of the text of the operation command 36 in red or the like. Alternatively, in other embodiments with an icon-based programming environment rather than a text-based one, the highlighting may be performed by displaying the icon of the operation command 36 in red or the like. This allows the user to visually grasp the operation command 36 of the machine 10 that is limited, and easily recognize that the machine 10 is not operating as intended.

[0059] Referring again to FIG. 2, the command limiting unit 28b sets the upper limit values ​​s of the velocity and acceleration of the actuator 17. lim1 ~s limn , a lim1 ~a limn , or an upper limit S of at least one of the speed and acceleration of the machine 10 lim , A lim 3, the display unit 32 displays the upper limit value s of the operation of the actuator 17 near the operation command 36 in the edit window 33 of the operation program 35 based on the display command. lim1 ~s limn , a lim1 ~a limn or the upper limit S of the operation of the machine 10 lim , A lim In the example of FIG. 3, since the machine 10 is in a low temperature environment, the speed command (100 mm / sec) of the actuator 17 or the machine 10 is changed to the upper limit value S lim This allows the user to visually understand the upper limit of the operation command for the machine 10.

[0060] 2 again, the drive control unit 28c drives and controls the actuators 17 based on the operation commands of the actuators 17 with the operation restrictions imposed. Alternatively, in another embodiment, the drive control unit 28c converts the operation commands 36 of the machine 10 with the operation restrictions imposed into operation commands for n actuators 17 based on inverse kinematics, and drives and controls the actuators 17 based on the converted operation commands of the actuators 17. The drive control unit 28c is configured, for example, with a motor drive control device (for example, a servo amplifier).

[0061] The control device 20 may further include a stop time calculation unit 22 that calculates the stop time before the machine 10 is put into operation, an operation time calculation unit 23 that calculates the operation time after the machine 10 is put into operation, and a temperature state determination unit 24 that determines whether the temperature state is such that an operation restriction is imposed on the machine 10 based on at least one of the detected temperature, the stop time, and the operation time.

[0062] The downtime calculation unit 22 calculates the downtime before the operation of the machine 10 by measuring the time interval from when the power is turned off (power OFF) to when the power is turned on (power ON) using the timer function of the control device 20. Alternatively, in another embodiment, the downtime calculation unit 22 may measure the time interval from when the power is turned off (power OFF) to when the operation of the machine 10 starts.

[0063] The operation time calculation unit 23 calculates the operation time after operation of the machine 10 by measuring the cumulative operation time from when the power is turned on (power ON) to the current time using the timer function of the control device 20. Alternatively, in another embodiment, the operation time calculation unit 23 may roughly calculate the operation time of the machine 10 by simply measuring the time interval from when the power is turned on (power ON) to the current time using the timer function of the control device 20.

[0064] The temperature state determination unit 24 determines whether the detected temperature T is below a threshold value (e.g., 10°C) and whether the downtime before the machine 10 is put into operation exceeds a threshold value (e.g., 9 hours), thereby determining whether the lubricant is in a low enough state to impose (strengthen) operational restrictions on the machine 10. If the downtime before the machine 10 is put into operation is short, the machine 10 is still warm, and there is a possibility that the viscous friction force at the detected temperature has not changed much compared to the viscous friction force at the reference temperature. Therefore, by taking into account the downtime before the machine 10 is put into operation, the temperature state of the lubricant can be determined more accurately.

[0065] On the other hand, the temperature state determination unit 24 determines whether the detected temperature T exceeds a threshold value (for example, 40°C) to determine whether the lubricant is in a high enough temperature state to impose (relax) operational restrictions on the machine 10. The threshold value of the detected temperature T and the threshold value of the stop time may be stored in advance in the storage unit 25 or may be defined in advance in the program.

[0066] When the detected temperature T deviates from the threshold value (for example, 10°C < T < 40°C) (that is, when it is determined that the lubricant is in a low-temperature state or a high-temperature state), the temperature state determination unit 24 sends a friction coefficient calculation command to the friction coefficient calculation unit 26 or sends a frictional force calculation command to the frictional force calculation unit 27.

[0067] As described above, the friction coefficient calculation unit 26 calculates the viscous friction coefficients μ d , μ r at the detected temperature and the reference temperature respectively, and sends the calculated viscous friction coefficients μ d , μ r to the frictional force calculation unit 27. The frictional force calculation unit 27 calculates the viscous frictional forces τ d , τ r at the detected temperature and the reference temperature respectively, and sends them to the control unit 28. As described above, the control unit 28 places an operation limit on the machine 10 so as not to exceed the capacity of the actuator 17 based on the change amount Δτ of the viscous frictional force between the detected temperature and the reference temperature.

[0068] In addition, when the temperature state determination unit 24 determines that the lubricant is in a low-temperature state and determines that the operation time after the operation of the machine 10 exceeds the threshold value (for example, 10 minutes), since the lubricant has already warmed up, the temperature state determination unit 24 may send a command to release the operation limit (strengthening) of the machine 10 to the command restriction unit 28b, and the command restriction unit 28b releases the operation limit (strengthening) of the machine 10 based on the release command. Alternatively, in another embodiment, when the temperature state determination unit 24 determines that it is a low-temperature environment, and the operation time after the operation of the machine 10 exceeds the threshold value (for example, 10 minutes) and the detected temperature T at that time exceeds the threshold value (for example, 10°C), the temperature state determination unit 24 may send a command to release the operation limit (strengthening) of the machine 10 to the command restriction unit 28b. Thereby, the temperature state of the lubricant can be determined more accurately.

[0069] On the other hand, when the temperature state determination unit 24 determines that the lubricant is in a high temperature state, if it determines that the detected temperature T exceeds a maximum allowable threshold (for example, 90°C), it sends a command to the command limiting unit 28b to cancel the operation restriction (relaxation) of the machine 10. Here, the maximum allowable threshold of the detected temperature T means the maximum allowable temperature in the specifications of the actuator 17 (for example, an electric motor). For example, if the actuator 17 exceeds the maximum allowable temperature of 90°C, the actuator 17 will overheat, and therefore the relaxation of the operation restriction of the machine 10 must be canceled.

[0070] Furthermore, when the temperature state determination unit 24 determines that the lubricant is in a temperature state that will impose operational restrictions on the machine 10, it may send a display command to the display unit 32 to display a warning message 34 indicating that the lubricant is in a low or high temperature state. In the example of Fig. 3, the display unit 32 displays the warning message 34 indicating that the lubricant is in a low temperature state based on the display command. This allows the user to visually understand that the lubricant is in a temperature state that will impose operational restrictions (strengthening or relaxing) on ​​the machine 10.

[0071] 2 again, the mechanical system 1 may further include an input unit 31 that allows the user to input a designated temperature instead of acquiring the detected temperature from the temperature sensor 18. The control device 20 calculates the viscous friction force from the viscous friction force estimation formula (Formula 1) without using the detected values ​​(detected torque value, detected speed value) of the actuator 17 at the detected temperature, and therefore can calculate the viscous friction force even at a designated temperature other than the detected temperature.

[0072] This allows the user to simulate the operational limitations of the machine 10 due to viscous frictional forces at the specified temperature that the user inputs. In other words, when the specified temperature is low, the operational speed and operation execution time of the machine 10 can be simulated when the operational limitations are strengthened, and when the specified temperature is high, the operational speed and operation execution time of the machine 10 can be simulated when the operational limitations are relaxed.

[0073] An example of the operation of the machine system 1 of this embodiment will be described in detail below. FIG. 4 is a flowchart of the machine system 1 of this embodiment in a low-temperature state. First, in step S1, a threshold for the detected temperature, a threshold for the stop time, and a threshold for the operating time after the machine 10 has been started are set in advance. The threshold for the detected temperature, the threshold for the stop time, and the threshold for the operating time after the machine 10 has been started are stored in the memory unit 25 of the control device 20 or in a memory unit of an external device, but in other embodiments, they may be input from the input unit 31 of the teaching device 30. In step S2, when the control device 20 is powered on, the temperature acquisition unit 21 acquires the detected temperature, while the stop time calculation unit 22 calculates the stop time before the machine 10 is started, and the operating time calculation unit 23 calculates the operating time after the machine 10 has been started.

[0074] In step S3, the temperature state determination unit 24 determines whether the detected temperature T is below a threshold value (e.g., 10°C) and whether the stop time before the operation of the machine 10 exceeds a threshold value (e.g., 9 hours), thereby determining whether the lubricant is in a low enough state to impose (strengthen) an operation restriction on the machine 10. If the temperature state determination unit 24 determines that the detected temperature T is equal to or higher than the threshold value (e.g., 10°C) or that the stop time does not exceed the threshold value (e.g., 9 hours) (NO in step S3), in step S4, the command limiting unit 28b cancels the already imposed restriction (strengthening) on ​​the operation command of the actuator 17 or the machine 10, and terminates the function of dealing with changes in viscous friction.

[0075] On the other hand, if the temperature state determination unit 24 determines that the detected temperature T is below a threshold value (e.g., 10°C) and that the stop time exceeds a threshold value (e.g., 9 hours) (YES in step S3), it may cause the display unit 32 to display a warning message 34 warning that the lubricant is in a low temperature state in which the operational restrictions of the machine 10 are tightened.

[0076] In addition, in order to impose (strengthen) an operation restriction on the machine 10, in step S5, the friction force calculation unit 27 calculates the viscous friction force τ at the detected temperature and the reference temperature based on the viscous friction force estimation formula (Formula 1). d , τ rThe viscous friction coefficient is calculated by previously conducting an experiment and storing it in the storage unit 25 or the storage unit of an external device, or by calculating the viscous friction coefficient μ at the detected temperature and the reference temperature by the friction coefficient calculation unit 26. d , μ r Alternatively, the friction force calculation unit 27 calculates the viscous friction coefficient μ d , μ r Without using the temperature-friction force database, the viscous friction force τ at the detected temperature and the reference temperature is calculated. d , τ r may be calculated separately.

[0077] In step S6, the upper limit calculation unit 28a calculates the viscous friction force τ d , τ r The upper limit value s of the operation of the actuator 17 is set so as not to exceed the capacity of the actuator 17 based on lim1 ~s limn , a lim1 ~a limn or the upper limit S of the operation of the machine 10 lim , A lim In step S7, the command limiting unit 28b limits (strengthens) the operation command 36 for the actuator 17 or the machine 10 based on the upper limit value.

[0078] In step S8, the command limiting unit 28b may highlight the restricted (strengthened) operation command 36 on the display unit 32. Furthermore, the command limiting unit 28b may display the upper limit value s of the operation in the vicinity of the restricted operation command 36. lim1 ~s limn , a lim1 ~a limn or S lim , A lim It is advisable to display this on the display unit 32.

[0079] In a low temperature state where operational restrictions on the machine 10 are strengthened, in step S9, the temperature state determination unit 24 determines whether the operating time of the machine 10 exceeds a threshold value (e.g., 10 minutes). If the temperature state determination unit 24 determines that the operating time of the machine 10 does not exceed the threshold value (e.g., 10 minutes) (NO in step S9), it determines that the lubricant is still in a low temperature state, and repeats the determination in step S9 until the operating time exceeds the threshold value (e.g., 10 minutes).

[0080] On the other hand, if the temperature state determination unit 24 determines that the operating time of the machine 10 has exceeded a threshold value (e.g., 10 minutes) in a low-temperature state in which the operational restrictions of the machine 10 are strengthened (YES in step S9), it determines that the lubricant has left the low-temperature state, and in step S4, the command restriction unit 28b releases the restriction (strengthening) on ​​the operational command of the actuator 17 or the machine 10, and terminates the function of dealing with changes in viscous friction.

[0081] 5 is a flowchart of the high temperature state of the machine system 1 of this embodiment. First, in step S1, the threshold for the detected temperature, the threshold for the stop time, and the threshold for the operating time after the machine 10 is started are set in advance. The threshold for the detected temperature, the threshold for the stop time, and the threshold for the operating time after the machine 10 is started are stored in the memory unit 25 of the control device 20 or in the memory unit of an external device, but in other embodiments, they may be input from the input unit 31 of the teaching device 30. In step S2, when the control device 20 is powered on, the temperature acquisition unit 21 acquires the detected temperature, while the stop time calculation unit 22 calculates the stop time before the machine 10 is started, and the operating time calculation unit 23 calculates the operating time after the machine 10 is started.

[0082] In step S3a, the temperature state determination unit 24 determines whether the detected temperature T is equal to or higher than a threshold value (e.g., 40°C), thereby determining whether the lubricant is in a high enough temperature state to impose (relax) operational restrictions on the machine 10. If the temperature state determination unit 24 determines that the detected temperature T is lower than the threshold value (e.g., 40°C) (NO in step S3a), in step S4, the command limiting unit 28b cancels the already imposed restriction (strengthening) on ​​the operational command of the actuator 17 or the machine 10, and terminates the function of dealing with changes in viscous friction.

[0083] On the other hand, if the temperature state determination unit 24 determines that the detected temperature T is equal to or higher than a threshold value (e.g., 40°C) (YES in step S3a), it may cause the display unit 32 to display a warning message 34 warning that the lubricant is in a high temperature state at which the operational restrictions of the machine 10 are relaxed.

[0084] In addition, in order to impose (relax) an operation restriction on the machine 10, in step S5, the friction force calculation unit 27 calculates the viscous friction force τ at the detected temperature and the reference temperature based on the viscous friction force estimation formula (Formula 1). d , τ r The viscous friction coefficient is calculated by previously conducting an experiment and storing it in the storage unit 25 or the storage unit of an external device, or by calculating the viscous friction coefficient μ at the detected temperature and the reference temperature by the friction coefficient calculation unit 26. d , μ r Alternatively, the friction force calculation unit 27 calculates the viscous friction coefficient μ d , μ r Without using the temperature-friction force database, the viscous friction force τ at the detected temperature and the reference temperature is calculated. d , τ r may be calculated separately.

[0085] In step S6, the upper limit calculation unit 28a calculates the viscous friction force τ d , τ r The upper limit value s of the operation of the actuator 17 is set so as not to exceed the capacity of the actuator 17 based on lim1 ~s limn , a lim1 ~a limnor the upper limit S of the operation of the machine 10 lim , A lim In step S7, the command limiting unit 28b limits (relaxes) the operation command 36 for the actuator 17 or the machine 10 based on the upper limit value.

[0086] In step S8, the command limiting unit 28b may highlight the restricted (relaxed) operation command 36 on the display unit 32. Furthermore, the command limiting unit 28b may display the upper limit value s of the operation in the vicinity of the restricted operation command 36. lim1 ~s limn , a lim1 ~a limn or S lim , A lim It is advisable to display this on the display unit 32.

[0087] In a high temperature state in which the operational restrictions of the machine 10 are relaxed, in step S9a, the temperature state determination unit 24 determines whether the detected temperature T is equal to or greater than a maximum allowable threshold value (e.g., 90°C) in order to prevent overheating of the actuator 17. If the temperature state determination unit 24 determines that the detected temperature T is less than the maximum allowable threshold value (e.g., 90°C) (NO in step S9a), it determines that the detected temperature T is within a margin relative to the maximum allowable temperature in the specifications of the actuator 17, and repeats the determination in step S9a until the detected temperature T becomes equal to or greater than the maximum allowable threshold value (e.g., 90°C).

[0088] On the other hand, if the temperature state determination unit 24 determines that the detected temperature T is equal to or higher than the maximum allowable threshold (e.g., 90°C) in a high temperature state where the operational restrictions of the machine 10 are relaxed (YES in step S9a), it determines that the detected temperature T has risen to near the maximum allowable temperature in the specifications of the actuator 17, and in step S4, the command restriction unit 28b releases the restriction (relaxation) on the operational command of the actuator 17 or the machine 10, and terminates the function of dealing with changes in viscous friction.

[0089] As described above, according to this embodiment, even if the viscous friction force increases due to a low-temperature environment, the operational restrictions on the machine 10 are strengthened so as not to exceed the capacity of the actuator 17, thereby preventing the generation of an excessive position error alarm and enabling the machine 10 to continue operating. On the other hand, if the viscous friction force decreases due to a high-temperature environment, the operational restrictions on the machine 10 are relaxed so as not to exceed the capacity of the actuator 17, allowing the machine 10 to operate at a relatively high speed.

[0090] Furthermore, if it is determined that the temperature condition is such that an operational restriction is imposed on the machine 10, the operation command of the actuator 17 or machine 10 that has imposed the operational restriction (strengthened or relaxed) is highlighted on the display unit 32, so that the user can visually grasp the operation command of the actuator 17 or machine 10 that has been restricted, and can easily recognize that the machine 10 is not operating as intended.

[0091] While various embodiments have been described herein, it should be recognized that the present invention is not limited to the above-described embodiments, but rather can be modified in various ways within the scope of the following claims. [Explanation of symbols]

[0092] 1 Mechanical Systems 10 machines 11. Base 12 Rotating body 13 First Arm 14 Second Arm 15 Wrist Unit 16 Tools 17 Actuators 18 Temperature Sensor 20 Control device 21 Temperature acquisition section 22 Stop time calculation unit 23 Operating time calculation unit 24 Temperature state determination unit 25 Memory section 26 Friction coefficient calculation section 27 Friction force calculation section 28 Control Unit 28a Upper limit calculation section 28b Instruction Restrictions Section 28c Drive control unit 30 Teaching device (display device) 31 Input section 32 Display section 33 Edit Window 34 Warning Messages 35 Operation Program 36 Operation command C1 Machine coordinate system C2 Tool coordinate system J1~J6 axis

Claims

1. a temperature acquisition unit that acquires a detected temperature; a friction force calculation unit that calculates a viscous friction force generated in an actuator of the machine at the detected temperature and a reference temperature; a control unit that applies an operational restriction to the machine based on a change in the viscous frictional force between the detected temperature and the reference temperature so as not to exceed the movement capacity of the actuator; Equipped with The control unit an upper limit calculation unit that calculates an upper limit value of the velocity or acceleration of the actuator or the machine based on the amount of change in the viscous friction force; a command limiting unit that limits an operation command of the actuator or the machine so that the operation of the actuator or the machine does not exceed the upper limit value, Control device.

2. The control device according to claim 1 , further comprising a friction coefficient calculation unit that calculates a viscous friction coefficient at the detected temperature and the reference temperature.

3. 3. The control device according to claim 1, further comprising a display unit that highlights the operation command of the actuator or the machine to which the operation restriction has been applied in comparison with the operation command of the actuator or the machine to which the operation restriction has not been applied, so that the operation command of the actuator or the machine to which the operation restriction has been applied can be visually recognized.

4. A control device described in any one of claims 1 to 3, further comprising a display unit that displays the upper limit value of the operation of the actuator or the machine in the vicinity of the operation command so that it can be visually confirmed that the operation command is for the actuator or the machine whose upper limit of operation has been limited by the operation restriction.

5. a stop time calculation unit that calculates a stop time before the machine is put into operation; an operation time calculation unit that calculates an operation time after the machine is started; a temperature state determination unit that determines whether or not the temperature state is such that an operation restriction is imposed on the machine based on at least one of the detected temperature, the stop time, and the operation time; The control device according to claim 1 , further comprising:

6. The control device according to claim 1 , further comprising a display unit that displays a temperature state of the lubricant in the actuator.

7. The control device according to claim 1 , further comprising an input unit through which a user inputs a designated temperature instead of the detected temperature.

8. Machines and A temperature sensor; a temperature acquisition unit that acquires a detected temperature from the temperature sensor; a friction force calculation unit that calculates a viscous friction force generated in an actuator of the machine at the detected temperature and a reference temperature; a control unit that applies an operational restriction to the machine based on a change in the viscous frictional force between the detected temperature and the reference temperature so as not to exceed the movement capacity of the actuator; Equipped with The control unit an upper limit calculation unit that calculates an upper limit value of the velocity or acceleration of the actuator or the machine based on the amount of change in the viscous friction force; a command limiting unit that limits an operation command of the actuator or the machine so that the operation of the actuator or the machine does not exceed the upper limit value, Mechanical systems.

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