Control devices for industrial robots, methods for controlling industrial robots

Abstract

This invention provides a control device and a control method for industrial robots that can achieve both reduced power consumption and prevention of trajectory deviation during automatic setting operation. [Solution] The control method of the embodiment includes the steps of: determining the motor output of each axis using a uniform acceleration reduction rate and speed reduction rate, where the parameter for reducing the acceleration limit during automatic setting operation is the acceleration reduction rate and the parameter for reducing the speed limit is the speed reduction rate; determining the power supplied to the industrial robot as a function that includes the acceleration reduction rate and speed reduction rate; solving the function to determine the acceleration reduction rate and speed reduction rate such that the power supplied does not exceed a predetermined upper limit; and reducing the acceleration limit and speed limit during automatic setting operation using the determined acceleration reduction rate and speed reduction rate.

Description

Technical Field

[0001] The present disclosure relates to a control device for an industrial robot and a control method for an industrial robot.

Background Art

[0002] As described in Patent Document 1, for example, an industrial robot controls its posture and movement by driving a motor using electric power supplied from a power source. At this time, a so-called commercial power source is generally used to supply sufficient electric power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, an industrial robot may be used as a so-called collaborative robot that collaborates with a human, or may be mounted on an automatic guided vehicle (AGV) to perform work at a destination. In this case, in order to comply with safety standards, it is necessary to use a power source with a lower power supply voltage than a commercial power source, or to use a power source with a small power supply capacity for battery driving.

[0005] However, when an industrial robot has a motor with the same output as before, when the power supply voltage decreases, a relatively large current is required and the power consumption increases. Also, when the power supply voltage becomes, for example, half of the conventional voltage, the joule loss increases by a factor of 4, and the voltage drop in the connection cable connecting to the motor driver also increases, resulting in an increase in losses. Further, when the power supply capacity becomes small, the power becomes insufficient with respect to the peak power on the industrial robot side, and it may not be possible to maintain a constant voltage, resulting in an excessive position deviation during operation.

[0006] Furthermore, during automatic setting operation, when the motor's acceleration and speed limits are automatically set, it is anticipated that malfunctions such as voltage drops due to attempting to draw power exceeding the power supply capacity, or track deviations due to inability to supply the necessary power, are more likely to occur.

[0007] This disclosure has been made in view of the circumstances described above, and its purpose is to provide a control device for an industrial robot and a control method for an industrial robot that can achieve both reduced power consumption and prevention of track deviation during automatic setting operation. [Means for solving the problem]

[0008] A control method for an industrial robot according to one aspect of the present disclosure includes the following steps: In automatic setting operation, where the motor acceleration limit and speed limit are automatically set, the parameter for reducing the acceleration limit is the acceleration reduction rate, and the parameter for reducing the speed limit is the speed reduction rate, and the motor output of each axis is determined from the speed and torque when the acceleration reduction rate and speed reduction rate are applied, using a uniform acceleration reduction rate and speed reduction rate for each axis; the power supplied to the industrial robot is determined as a function that includes the acceleration reduction rate and speed reduction rate, as the sum of the losses that occur between the motor and the motor driver that drives the motor, the total driver loss which is the sum of the losses that occur between the motor driver and the motor of each axis, and the total motor output which is the sum of the motor outputs of each axis; the function is solved to find a combination of acceleration reduction rate and speed reduction rate such that the power supplied does not exceed a predetermined upper limit power; and the acceleration limit and speed limit during automatic setting operation are reduced using the determined acceleration reduction rate and speed reduction rate.

[0009] A control device for an industrial robot according to one aspect of the present disclosure includes, in automatic setting operation where the motor acceleration limit and speed limit are automatically set, an axis calculation unit that calculates the motor output of each axis from the speed and torque when the acceleration reduction rate and speed reduction rate are applied, using a uniform acceleration reduction rate and speed reduction rate for each axis; an overall calculation unit that calculates the power supplied to the industrial robot as a function that includes the acceleration reduction rate and speed reduction rate, as the sum of the losses that occur between the motor and the motor driver that drives the motor, the losses that occur between the motor driver and the motor of each axis, and the total motor output obtained by summing the motor outputs of each axis; a parameter calculation unit that solves the function to find a combination of acceleration reduction rate and speed reduction rate such that the supplied power does not exceed a predetermined upper limit power; and a reduction unit that reduces the acceleration limit and speed limit during automatic setting operation using the calculated acceleration reduction rate and speed reduction rate. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing the configuration of the control device according to the embodiment. [Figure 2] A schematic diagram illustrating examples of electrical connections and power supply methods. [Figure 3] This diagram shows the process flow for determining the acceleration reduction rate and velocity reduction rate. [Figure 4] Figure 1 shows the mathematical formulas used in parameter calculations. [Figure 5] Figure 2 shows the mathematical formulas used in parameter calculations. [Figure 6] A schematic diagram illustrating a method for identifying parameters. [Figure 7] This diagram schematically shows an example of verification results demonstrating the validity of an algorithm. [Modes for carrying out the invention]

[0011] The embodiments will now be described with reference to the drawings. As shown in Figure 1, the control device 1 of this embodiment controls the industrial robot 4 by supplying power from the power supply 2 to the industrial robot 4 via the connecting cable 3. The industrial robot 4 is a so-called vertical articulated 6-axis robot equipped with six axes: the first axis (J1), the second axis (J2), the third axis (J3), the fourth axis (J4), the fifth axis (J5), and the sixth axis (J6).

[0012] The configuration of the industrial robot 4 is the same as that of a typical 6-axis robot, so a detailed explanation will be omitted. However, as shown in Figure 2(a) as an example of connections, the industrial robot 4 is equipped with motors 5a, 5b, 5c, 5d, 5e, and 5f on the corresponding axes (J1 to J6). The industrial robot 4 is also equipped with a motor driver 6, which is made up of electrical components such as FETs and drives motors 5a to 5f. Hereafter, when describing each of the motors 5a to 5f in common, they will simply be referred to as motor 5.

[0013] The control device 1 includes a control unit 10, which is composed of a computer having a CPU (not shown). The control device 1 also includes a storage unit (not shown) for storing various programs and data. The control unit 10 performs various processes for controlling the control device 1 itself and the industrial robot 4. In addition, the control unit 10 is provided with an axis calculation unit 11, an overall calculation unit 12, a parameter calculation unit 13, and a reduction unit 14 in relation to this embodiment. These axis calculation units 11, overall calculation unit 12, parameter calculation unit 13, and reduction unit 14 are implemented as software by the execution of programs in the control unit 10. Although not shown, the control unit 10 also performs other processes.

[0014] Although details will be described later, as shown in Fig. 2(b) as an example of power supply, each axis calculation unit 11 calculates the motor output (Wmj; where j = 1 to 6) of the motor 5 of each axis connected via the internal wiring 20 from the motor driver 6. In the case of this embodiment, the each axis calculation unit 11 calculates the motor output (Wm1) of the motor 5a provided on the first axis (J1), the motor output (Wm2) of the motor 5b provided on the second axis, the motor output (Wm3) of the motor 5c provided on the third axis, the motor output (Wm4) of the motor 5d provided on the fourth axis, the motor output (Wm5) of the motor 5e provided on the fifth axis, and the motor output (Wm6) of the motor 5f provided on the sixth axis.

[0015] Although details will be described later, the overall calculation unit 12 obtains the supply power (W) supplied to the industrial robot 4 as the sum of the bus loss (Wbus) generated between the control device 1 and the motor driver 6, the total driver loss (Wd) which is the sum of the axis losses (Wdj; where j = 1 to 6) generated between the motor driver 6 and the motors 5 of each axis, and the total motor output (Wm) which is the sum of the motor outputs (Wmj) of each axis.

[0016] When expressed by an equation, the supply power (W) is as follows. W = Wbus + Wd + Wm = Wbus + Wd1 + Wd2 + Wd3 + Wd4 + Wd5 + Wd6 + Wm1 + Wm2 + Wm3 + Wm4 + Wm5 + Wm6

[0017] In this embodiment, since the control device 1 and the industrial robot 4 are connected by the connection cable 3, the bus loss (Wbus) is defined as the loss generated between the control device 1 and the motor driver 6. However, if the connection mode is different, the bus loss (Wbus) may be defined according to the connection mode.

[0018] Also, in the present embodiment, as will be described later, the supplied power (W) is used as the power supply capacity (Wp). However, when a part of the power from the power supply 2 is consumed in, for example, the control unit 10 or the power circuit in the control device 1, a predetermined upper limit power (Wmax) obtained by subtracting the power consumed in the control device 1 from the power supply capacity (Wp) may be used as the supplied power (W).

[0019] Although details will be described later, the parameter calculation unit 13 calculates parameters for suppressing power consumption during automatic setting operation, that is, parameters for ensuring that the supplied power (W) during automatic setting operation does not exceed the upper limit. Note that the automatic setting operation is an operation mode in which, among various operation modes provided in the industrial robot 4, the acceleration upper limit and the speed upper limit of the motor 5 for each axis are automatically set according to the specifications of the motor 5 and the posture of the industrial robot 4.

[0020] In the present embodiment, two parameters are defined as the acceleration reduction rate (α), which is a parameter for reducing the acceleration upper limit, and the speed reduction rate (β), which is a parameter for reducing the speed upper limit. These acceleration reduction rate (α) and speed reduction rate (β) are numerical values in the range of 0 to 1. When the value is 0, the acceleration upper limit or the speed upper limit is reduced by 100%. When the value is 1, the acceleration upper limit or the speed upper limit is not reduced.

[0021] Although details will be described later, the reduction unit 14 uses the obtained acceleration reduction rate (α) and speed reduction rate (β) to reduce the acceleration upper limit and the speed upper limit during automatic setting operation. The reduced acceleration upper limit and speed upper limit are used for controlling the industrial robot 4 by the control unit 10.

[0022] Next, the operations and effects of the above-described configuration will be described. During automatic setting operation, as described above, the acceleration upper limit and the speed upper limit are automatically set. Therefore, if the power supply capacity is lower in voltage than the commercial power supply or the power supply capacity is small, there is a high possibility that problems will be induced due to power shortage. In this case, in order to suppress the occurrence of problems, first, it is necessary to reduce the power consumption during automatic setting operation.

[0023] Now, there are several ways to reduce power consumption: lowering only the acceleration limit, lowering only the velocity limit, or lowering both the acceleration limit and the velocity limit. However, lowering only the acceleration limit may result in a higher velocity and thus exceeding the power consumption limit, and lowering only the velocity limit may result in a higher acceleration and thus exceeding the power consumption limit.

[0024] In other words, if only one of the acceleration or velocity limits is reduced, there may be cases where power consumption does not exceed the limit, but there may also be cases where power consumption exceeds the limit. Therefore, in order to ensure that power consumption does not exceed the limit, it is necessary to reduce both the acceleration and velocity limits.

[0025] Furthermore, when reducing the acceleration and velocity limits, not only how much to reduce them, but also how to reduce them is extremely important. For example, motor 5a, which drives the entire arm, is likely to have a higher output than motor 5f. Therefore, when both motor 5a and motor 5f are driven, if the power consumption of motor 5a is reduced by 10%, the total power consumption may not exceed the limit even if the power consumption of motor 5f is not reduced.

[0026] However, if the acceleration and velocity limits of each motor 5 are reduced individually, the behavior of each motor 5, such as acceleration, deceleration, and velocity, will differ, which could cause the industrial robot 4's trajectory to deviate from the correct trajectory. In other words, in order to prevent the trajectory from deviating, the behavior of each motor 5 must be made common.

[0027] Therefore, in this embodiment, by performing the process shown in Figure 3, both reduction of power consumption during automatic setting operation and prevention of track deviation are achieved. Figure 3 shows the parts of the process performed by the control device 1 that are relevant to this embodiment. Each process is executed by the individual axis calculation unit 11, the overall calculation unit 12, the parameter calculation unit 13, and the reduction unit 14, etc., but the following explanation will mainly focus on the control device 1.

[0028] First, the control device 1 acquires the acceleration limit and speed limit (S1), and acquires the speed (Vj, where j=1 to 6) of each shaft's motor 5 (S2). The acceleration limit and speed limit can be acquired as calculation results during automatic setting operation. The speed of the motor 5 can also be acquired by calculation from the detected value of an encoder (not shown) provided on the motor 5. Steps S1 and S2 can be performed in any order.

[0029] Next, the control device 1 performs a first-order reduction calculation (S3). This first-order reduction calculation is a process that determines the acceleration reduction rate (α) and the velocity reduction rate (β) while excluding the torque component caused by the Coriolis force.

[0030] Motor output can be determined by multiplying the speed (Vj, where j=1 to 6) of motor 5 on each axis by the torque (Tj, where j=1 to 6). This motor output includes kinetic energy, gravitational potential energy, friction, and gearbox transmission efficiency.

[0031] The torque on each axis (Tj, where j=1 to 6) can be calculated as the sum of its torque components: Tj = Ta + Tv + Tc + Tg. Of the torque components, Ta is the inertial torque component, Tv is the viscous friction torque component, Tc is the torque component due to the Coriolis force, and Tg is the fixed term torque component due to gravity and Coulomb force. Furthermore, the inertial torque component (Ta) is proportional to acceleration, the viscous friction torque component (Tv) is proportional to velocity, the torque component due to the Coriolis force (Tc) is proportional to the square of the velocity, and the fixed term torque component is independent of acceleration and velocity.

[0032] In the first-order reduction calculation, the control device 1 first determines the motor output (Wmj, where j=1 to 6) under conditions where the acceleration reduction rate (α) and velocity reduction rate (β) are applied. At this time, the control device 1 uniformly applies the acceleration reduction rate (α) and velocity reduction rate (β) to each axis. This ensures that the reduction rate is common to all axes, preventing different behaviors for each axis and suppressing deviations from the trajectory.

[0033] This motor output (Wmj) can be calculated as shown in equation (1) in Figure 4. In this way, the control device 1 calculates the motor output (Wmj) of each axis from the speed (Vj) and torque (Tj) under the assumption that the acceleration upper limit is reduced by the acceleration reduction rate (α) and the speed upper limit is reduced by the speed reduction rate (β).

[0034] Furthermore, the control device 1 calculates the loss for each axis (Wdj, where j=1 to 6) by multiplying the resistance of the wiring path for each axis (Rdriver) by the square of the current (Ij) for each axis. Note that Rdiver is the sum of the switching loss and on-resistance of the FET of the motor driver 6, the resistance of the internal wiring 20, and the windings and circuit patterns of the motor 5.

[0035] The loss in each axis (Wdj) can be calculated as shown in equation (2) of Figure 4, by expressing the current (Ij) in terms of torque (Tj) and torque coefficient (K). The control device 1 then calculates the total energy (Wmdj) from the motor driver 6 onwards in each axis as a function that includes the acceleration reduction rate (α) and the speed reduction rate (β), as shown in equation (3) of Figure 4, by summing the motor output (Wmj) and the loss in each axis (Wdj).

[0036] Furthermore, the control device 1 calculates the total energy (Wmd) from the motor driver 6 onwards for all axes as the sum of the total driver loss (Wd) and the total motor output (Wm), as shown in equation (4) of Figure 4, that is, the sum of the total energy (Wmdj, where j=1 to 6) from the motor driver 6 onwards for each axis. This total energy (Wmd) is a function that includes the acceleration reduction rate (α) and the velocity reduction rate (β), although the expanded form of equation (4) is not shown in the figure. Hereafter, the function representing the total energy (Wmd) will be denoted as f(α,β).

[0037] Furthermore, the control device 1 calculates the bus loss (Wbus) occurring between the control device and the motor driver 6 according to Ohm's law, using equation (5) in Figure 4, where Rbus is the resistance of the wiring path to the motor driver 6 and E is the power supply voltage.

[0038] Now, the power supply (W) that should be supplied to the industrial robot 4 after reduction by the acceleration reduction rate (α) and the velocity reduction rate (β) is the sum of the total energy (Wmd) and the bus loss (Wbus), and is expressed by equation (6) in Figure 4. Furthermore, in this embodiment, since the upper limit power (Wmax) = power supply capacity (Wp), this equation (6) can be expressed as equation (7) in Figure 5. This equation (7) represents the state in which maximum power is supplied to the industrial robot 4 while reducing power consumption, that is, the state in which the industrial robot 4 can perform at its maximum performance.

[0039] Solving equation (7) for total energy (Wmd) yields equation (8). As mentioned above, total energy (Wmd) is expressed as f(α,β), which is a function of acceleration reduction rate (α) and velocity reduction rate (β). Therefore, by finding the acceleration reduction rate (α) and velocity reduction rate (β) that satisfy equation (8), it can be seen that the supplied power (W) becomes the power supply capacity (Wp). In other words, by using the acceleration reduction rate (α) and velocity reduction rate (β) obtained by this algorithm, power can be supplied to the industrial robot 4 in a state that allows it to perform at maximum performance while reducing power consumption.

[0040] As mentioned above, the first-order reduction calculation is a process that determines the acceleration reduction rate (α) and the velocity reduction rate (β) by removing the torque component caused by the Coriolis force. If the Coriolis force is sufficiently small and the torque component caused by the Coriolis force can be ignored, then Tc=0 in equation (3) of Figure 4, and the calculation can be simplified. In other words, by performing a first-order reduction calculation, the processing speed for determining the acceleration reduction rate (α) and the velocity reduction rate (β) can be improved.

[0041] Furthermore, when Tc=0, it can be mathematically understood that the solution space of f(α,β) becomes hyperbolic. Figure 6 shows a line segment (L1) representing the solution space in the αβ plane, where the acceleration reduction rate (α) is the first axis and the velocity reduction rate (β) is the second axis. The coordinates of a point on the line segment (L1) representing the solution space correspond to the combination of acceleration reduction rate (α) and velocity reduction rate (β) that gives the solution of the function, i.e., the supplied power (W) = power supply capacity (Wp). Therefore, by identifying a point on the line segment (L1), it is possible to identify the acceleration reduction rate (α) and velocity reduction rate (β) that give the supplied power (W) = power supply capacity (Wp).

[0042] Points on line segment (L1) can be easily identified as intersections of line segment (L1) in the solution space with monotonically increasing line segments (L11, L12, L13, L14) in the αβ plane. In this case, the intersection point (αx, βx) can be quickly and reliably determined by using a linear line segment (L11) where acceleration reduction rate (α) = velocity reduction rate (β). Note that this method is excluded when acceleration reduction rate (α) = velocity reduction rate (β) = 0, which leads to a breakdown.

[0043] Incidentally, in the case of the industrial robot 4, which is a 6-axis robot, it is often considered that the torque component due to the Coriolis force cannot be ignored. Therefore, as shown in Figure 3, the control device 1 performs a second-order reduction calculation that takes into account the torque component due to the Coriolis force after performing a first-order reduction calculation (S4). Hereafter, the acceleration reduction rate (α) and velocity reduction rate (β) obtained in the first-order reduction calculation will be conveniently referred to as the first-order acceleration reduction rate (α1) and the first-order velocity reduction rate (β1).

[0044] In the second-order reduction calculation, the control device 1 calculates the acceleration reduction rate (α) = velocity reduction rate (β) while including the torque component (Tc) caused by the Coriolis force. As mentioned above, this torque component (Tc) is proportional to the square of the velocity and is unrelated to acceleration. Therefore, when calculating power consumption while considering the torque component (Tc), the calculation can be simplified by setting the acceleration reduction rate (α) = 1.

[0045] In equation (3) in Figure 4, if the acceleration reduction rate (α) = 1, then Wmd = f(α,β) becomes a fourth-degree equation for the velocity reduction rate (β). Although the intermediate calculations are omitted from the diagram, if we group the constant terms of each order as B, f(α,β) can be expressed as shown in equation (9) in Figure 5. By solving this equation (9), we can find the velocity reduction rate (β) in a state that includes the torque component (Tc) due to the Coriolis force. Hereafter, the velocity reduction rate (β) obtained by this second-order reduction calculation will be referred to as the second-order velocity reduction rate (β2).

[0046] Incidentally, considering the effort and calculation speed required to implement the formula for solving quartic equations, it is possible to reduce power quickly and reduce implementation effort by using the secondary velocity reduction rate (β2) on the left side obtained by setting β2=1 on the right side of equation (10) in Figure 5, which is a transformation of equation (9). However, with this method, there is a possibility of excessive reduction when the Coriolis force is large. In other words, there is a possibility that the solution will yield a secondary velocity reduction rate (β2) that excessively reduces the upper limit of the speed.

[0047] Therefore, in order to find a more optimal secondary velocity reduction rate (β2), it is conceivable to limit the range of the secondary velocity reduction rate (β2). Specifically, since the secondary velocity reduction rate (β2) is in the range of 0 to 1, if we set β2 = 1 on the right side of equation (10), we can find the lower limit (βmin) of the secondary velocity reduction rate (β2) as shown in equation (11). Then, by setting the search range when finding the solution to βmin ≤ β2 ≤ 1, we can find the optimal secondary velocity reduction rate (β2) as the solution and prevent excessive reduction of the velocity upper limit.

[0048] The control device 1 determines the acceleration reduction rate (α) and the velocity reduction rate (β) using this algorithm. Next, as shown in Figure 3, the control device 1 reduces the acceleration upper limit and the velocity upper limit by the acceleration reduction rate (α) and the velocity reduction rate (β), respectively (S5). At this time, the control device 1 determines the reduced acceleration upper limit by multiplying the acceleration upper limit determined in step S1 by the acceleration reduction rate (α). The control device 1 also determines the reduced velocity upper limit by multiplying the velocity upper limit determined in step S1 by the final velocity reduction rate (βfin), which is obtained by multiplying the primary acceleration reduction rate (β1) and the secondary velocity reduction rate (β2).

[0049] Then, the control device 1 controls the industrial robot 4 using the reduced acceleration limit and reduced speed limit as control parameters (S6). At this time, the control device 1 controls the industrial robot 4 by generating and outputting position command values ​​corresponding to the reduced acceleration limit and reduced speed limit. In other words, the algorithm described above is not only a way to reduce power consumption, but also a trajectory correction algorithm that can prevent the trajectory of the industrial robot 4 from deviating when the acceleration limit and speed limit are reduced.

[0050] Here, we verify the validity of the algorithm for determining the acceleration reduction rate (α) and the velocity reduction rate (β). Figure 7 shows the changes in estimated power consumption estimated based on position command values, calculated power consumption calculated from encoder detection values ​​when the industrial robot 4 was actually operated, and measured power consumption measured by a measuring instrument. Note that if the upper limit of the supplied power (W) is set to the upper limit power (Wmax) rather than the power supply capacity (Wp), then "Wp" should be read as "Wmax". Also, the horizontal axis in Figure 7 is time, and the vertical axis is power.

[0051] Figure 7(a) shows the verification results when the algorithm described above is applied. The estimated power (G1) is the command value when the acceleration limit and speed limit are reduced using the acceleration reduction rate (α) and speed reduction rate (β), which are calculated using the power supply capacity (Wp) as the upper limit of the supplied power (W). The calculated power (G2) is the supplied power (W), and the hatched area R1 shows the calculated value of the total motor output (Wm), the area with a different hatch R2 shows the calculated value of the total driver loss (Wd), and the area with yet another different hatch R3 shows the calculated value of the bus loss (Wbus). The measured power (G3) was measured at the end of the connecting cable 3 on the control device 1 side.

[0052] Figure 7(a) shows that neither the estimated power (G1) nor the calculated power (G2) exceeds the power supply capacity (Wp) set as the upper limit. This confirms that by using the algorithm described above, the peak power consumption can be kept below the power supply capacity (Wp) set as the upper limit of the supplied power (W). Note that the measured power (G3) fluctuates significantly up and down in some parts because regenerative braking occurs when power is returned to power supply 2 during deceleration.

[0053] Furthermore, it can be seen that the calculated power (G2) follows the estimated power (G1) based on the position command value. From this, it can be confirmed that the industrial robot 4 is operating along the correct trajectory.

[0054] In contrast, Figure 7(b) is a comparative example showing the changes in estimated power (G11), calculated power (G12), and measured power (G13) when the above-described algorithm is not applied. From Figure 7(b), it can be seen that when the above-described algorithm is not applied, both the estimated power (G11) and calculated power (G12) exceed the power supply capacity (Wp) set as the upper limit. This confirms the validity of the above-described algorithm. Note that region R11 represents the calculated value of total motor output (Wm), region R12 represents the calculated value of total driver loss (Wd), and region R13 represents the calculated value of bus loss (Wbus).

[0055] Thus, the control device 1 can be controlled based on the algorithm described above, within a range where power consumption does not exceed a predetermined upper limit. In other words, the validity and effectiveness of the algorithm for determining the acceleration reduction rate (α) and the speed reduction rate (β) were verified using the data shown in Figure 7.

[0056] According to the embodiments described above, the following effects can be obtained. In the control method according to this embodiment, during automatic setting operation where the acceleration upper limit and speed upper limit of the motor 5 are automatically set, the parameter that reduces the acceleration upper limit is the acceleration reduction rate (α), and the parameter that reduces the speed upper limit is the speed reduction rate (β). Using a uniform acceleration reduction rate (α) and speed reduction rate (β) for each axis (j), the motor output (Wmj) of each axis (j) is determined from the speed (Vj) and torque (Tj) when the acceleration reduction rate (α) and speed reduction rate (β) are applied, respectively. The power to be supplied from the power supply 2 is generated between the motor driver 6 that drives the motor 5 and the motor driver 6. The process includes: calculating the total driver loss (Wd), which is the sum of the losses incurred (Wbus), the losses incurred between the motor driver 6 and the motors 5 of each axis (Wdj), and the total motor output (Wm), which is the sum of the motor outputs (Wmj) of each axis, as a function that includes an acceleration reduction rate (α) and a speed reduction rate (β); solving the function to find a combination of acceleration reduction rate (α) and speed reduction rate (β) such that the supplied power (W) does not exceed a predetermined upper limit power (Wmax); and reducing the upper limit of acceleration and the upper limit of speed during automatic setting operation using the calculated acceleration reduction rate (α) and speed reduction rate (β).

[0057] By using this control method, the upper limits of acceleration and speed during automatic setting operation can be reduced, thereby suppressing power consumption. Furthermore, since the reduction is applied uniformly to each axis, it becomes possible to make the behavior of each axis consistent, thus preventing deviation from the track. In other words, the algorithm described above makes it possible to achieve both a reduction in power consumption and prevention of track deviation during automatic setting operation.

[0058] Furthermore, the control method uses acceleration reduction rate (α) and speed reduction rate (β), obtained while excluding the torque component caused by the Coriolis force, to reduce the upper limits of acceleration and speed during automatic setting operation, respectively. This reduces the load required for calculations and improves the calculation speed.

[0059] Furthermore, the control method involves using the acceleration reduction rate (α) and velocity reduction rate (β), obtained by excluding the torque component caused by the Coriolis force, as the primary acceleration reduction rate (α1) and primary velocity reduction rate (β1), respectively. The velocity reduction rate (β), obtained by including the torque component caused by the Coriolis force with the acceleration reduction rate (α) set to 1, is then used as the secondary velocity reduction rate (β2). The acceleration upper limit and velocity upper limit during automatic setting operation are then reduced using the primary acceleration reduction rate (α1) and the final velocity reduction rate (βf), which is obtained by multiplying the primary velocity reduction rate (β1) by the secondary velocity reduction rate (β2). As a result, the primary and secondary reduction calculations are simplified, reducing the load required to determine the final reduction rate and shortening the calculation time, thus enabling rapid control of the industrial robot 4.

[0060] Furthermore, the control method involves determining the acceleration reduction rate (α) and the speed reduction rate (β) during automatic setting operation by finding the intersection points of the line segment representing the solution space and the monotonically increasing line segments (L11~L14) in the αβ plane, where the acceleration reduction rate (α) is the first axis and the speed reduction rate (β) is the second axis. This makes it easy to determine the acceleration reduction rate (α) and speed reduction rate (β) that are solutions to the function.

[0061] Furthermore, the control method involves determining the acceleration reduction rate (α) and the speed reduction rate (β) during automatic setting operation by finding the intersection point between a line segment representing the solution space in the αβ plane and a monotonically increasing linear line segment (L11) where the acceleration reduction rate (α) and the speed reduction rate (β) coincide. This makes it possible to determine the acceleration reduction rate (α) and the speed reduction rate (β), which are solutions to the function, more easily and reliably.

[0062] Furthermore, in automatic setting operation, when the control device 1 automatically sets the upper limit of acceleration and the upper limit of speed of the motor 5, the parameter that reduces the upper limit of acceleration is the acceleration reduction rate (α), and the parameter that reduces the upper limit of speed is the speed reduction rate (β). The control device 11 calculates the motor output (Wmj) of each axis (j) using a uniform acceleration reduction rate (α) and speed reduction rate (β) for each axis (j), based on the speed (Vj) and torque (Tj) after applying the acceleration reduction rate (α) and speed reduction rate (β). The control device 1 also calculates the power supply (W) to be supplied to the industrial robot 4 up to the motor driver 6 that drives the motor 5. The system includes: an overall calculation unit 12 that calculates the total motor output (Wm), which is the sum of the losses (Wbus) that occur in the system, the losses (Wd) that occur between the motor driver 6 and the motors 5 of each axis, and the motor output (Wj) of each axis, as a function that includes an acceleration reduction rate (α) and a speed reduction rate (β); a parameter calculation unit 13 that solves the function to find a combination of acceleration reduction rate (α) and speed reduction rate (β) such that the supplied power (W) does not exceed a predetermined upper limit power (Wmax); and a reduction unit 14 that uses the calculated acceleration reduction rate (α) and speed reduction rate (β) to reduce the upper limit of acceleration and the upper limit of speed during automatic setting operation.

[0063] With a control device 1 configured in this way, the upper limits of acceleration and speed during automatic setting operation can be reduced, thereby suppressing power consumption. Furthermore, since the reduction is applied uniformly to each axis, the behavior of each axis becomes consistent, preventing deviation from the track. Thus, the same various effects as described above can be obtained as with the control method.

[0064] In this embodiment, a configuration in which each axis calculation unit 11, the overall calculation unit 12, and the parameter calculation unit 13 are provided in the control device 1 is illustrated. However, some or all of these can be implemented in a teaching device or personal computer connected to the control device 1, for example. Furthermore, some or all of the each axis calculation unit 11, the overall calculation unit 12, the parameter calculation unit 13, and the reduction unit 14 can also be implemented in hardware.

[0065] In this embodiment, an example was shown using a so-called 6-axis robot with vertical articulation, but it can also be used for so-called 7-axis robots, so-called 4-axis robots with horizontal articulation, or linear robots.

[0066] In the embodiment, a configuration that performs both first-order and second-order reduction calculations has been illustrated. However, in structures where it is known that no Coriolis force is generated, or where its generation is negligible or does not cause problems, a configuration that uses the first-order acceleration reduction rate (α1) and first-order velocity reduction rate (β1) obtained by the first-order reduction calculation for control, that is, a configuration that does not perform second-order reduction calculations, is also possible. In this case, the control device 1 will reduce the acceleration upper limit by the first-order acceleration reduction rate (α1) and the velocity upper limit by the first-order velocity reduction rate (β1).

[0067] In this embodiment, a configuration was illustrated in which power supplied from power supply 2 is supplied to the industrial robot 4 via a connection cable 3 through a control device 1. However, it is also possible to configure the system to supply power directly from power supply 2 to the industrial robot 4.

[0068] This disclosure is described in accordance with embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and idea of ​​this disclosure. [Explanation of Symbols]

[0069] In the drawing, 1 is the control unit, 3 is the power supply, 4 is the industrial robot, 5a to 5f are the motors, 6 is the motor driver, 11 is the individual axis calculation unit, 12 is the overall calculation unit, 13 is the parameter calculation unit, and 14 is the reduction unit.

Claims

1. In automatic setting operation, where the motor's acceleration limit and speed limit are automatically set, if the parameter that reduces the acceleration limit is called the acceleration reduction rate, and the parameter that reduces the speed limit is called the speed reduction rate, The process involves determining the motor output of each axis using a uniform acceleration reduction rate and speed reduction rate for each axis, and calculating the speed and torque when the acceleration reduction rate and speed reduction rate are applied. A process to determine the power supplied to an industrial robot as a function that includes acceleration reduction rate and speed reduction rate, which is the sum of the losses that occur between the motor and the motor driver that drives the motor, the total driver loss which is the sum of the losses that occur between the motor driver and the motors of each axis, and the total motor output which is the sum of the motor outputs of each axis. The process involves solving the aforementioned function to find a combination of acceleration reduction rate and speed reduction rate such that the supplied power does not exceed a predetermined upper limit power, A process of reducing the upper limit of acceleration and the upper limit of speed during automatic setting operation using the calculated acceleration reduction rate and speed reduction rate, A control method for industrial robots, including [specific component / feature].

2. A control method for an industrial robot according to claim 1, wherein the acceleration reduction rate and speed reduction rate obtained while excluding the torque component caused by the Coriolis force are used to reduce the acceleration upper limit and speed upper limit during automatic setting operation, respectively.

3. The acceleration reduction rate and velocity reduction rate obtained while excluding the torque component caused by the Coriolis force are defined as the primary acceleration reduction rate and primary velocity reduction rate, respectively. The velocity reduction rate obtained by setting the acceleration reduction rate to 1 and including the torque component due to the Coriolis force is defined as the secondary velocity reduction rate. A control method for an industrial robot according to claim 1, wherein the acceleration limit and speed limit during automatic setting operation are reduced, respectively, by a primary acceleration reduction rate and a final speed reduction rate obtained by multiplying the primary speed reduction rate by a secondary speed reduction rate.

4. A control method for an industrial robot according to claim 1, wherein in an αβ plane with the acceleration reduction rate as the first axis and the velocity reduction rate as the orthogonal second axis, the intersection points of a line segment representing the solution space of the function and a monotonically increasing line segment in the αβ plane are determined as the acceleration reduction rate and velocity reduction rate during automatic setting operation.

5. The method for controlling an industrial robot according to claim 4, wherein in the αβ plane, the intersection point of a line segment representing the solution space and a linear line segment that increases monotonically while the acceleration reduction rate and velocity reduction rate are the same is determined as the acceleration reduction rate and velocity reduction rate during automatic setting operation.

6. In automatic setting operation, where the motor's acceleration limit and speed limit are automatically set, if the parameter that reduces the acceleration limit is called the acceleration reduction rate, and the parameter that reduces the speed limit is called the speed reduction rate, The motor output of each axis is calculated by using a uniform acceleration reduction rate and speed reduction rate for each axis, and the calculation unit for each axis determines the speed and torque when the acceleration reduction rate and speed reduction rate are applied. A total calculation unit calculates the power supplied to an industrial robot as a function that includes acceleration reduction rate and speed reduction rate, by summing the losses that occur between the motor and the motor driver that drives the motor, the losses that occur between the motor driver and the motors of each axis, and the total motor output obtained by summing the motor outputs of each axis. A parameter calculation unit solves the aforementioned function to find a combination of acceleration reduction rate and speed reduction rate such that the supplied power does not exceed a predetermined upper limit power, A reduction unit that reduces the upper limits of acceleration and speed during automatic setting operation using the calculated acceleration reduction rate and speed reduction rate, A control device for industrial robots equipped with [a specific feature / feature].

Images