JP2022131424A - Robot control device - Google Patents

Abstract

To use a robot safely in a limited space without wastefully limiting performance of the robot.SOLUTION: A robot control device comprises: a drive part which performs an emergency stop of a robot when a stop command is received; a first estimation processing part for estimating a first estimated stop position on the basis of current attitude and speed of the robot; a second estimation processing part for estimating a second estimated stop position which is adjusted to be further ahead of the first estimated stop position; and a monitoring processing part which can perform a first monitoring processing of issuing the stop command to the drive part when it is determined that the first estimated stop position enters a previously set designated area and a second monitoring processing of issuing, to a control processing part, a deceleration command for decelerating the speed of the robot from its current speed when it is determined that the second estimated stop position enters the designated area.SELECTED DRAWING: Figure 1

Description

This embodiment relates to a robot control device.

For example, in order to use an articulated robot in a limited space, there are cases where a person or the like is allowed to enter the movable range of the robot. In such a case, in the conventional configuration, in order to prevent the robot from coming into contact with a person or the like, an area where the intrusion of a person or the like is prohibited and an area where the intrusion of the person or the like is permitted are divided within the movable range of the robot. Fences are provided between the areas. In the following description, an area in which human entry is prohibited is referred to as a robot operation area, and an area in which a person or the like can enter is referred to as a designated area.

Such a fence is designed so that even in the event that the robot runs out of control and collides with the fence, the robot will not come into contact with and harm a person outside the fence, i.e., within the designated area. Since it is necessary to be strong enough to withstand high pressure, it tends to be large-scale. Moreover, since the fence is sturdy, the robot itself may be damaged if it collides with the fence. Under these circumstances, there is a demand for a configuration in which the robot can be used safely without using a sturdy and large-scale fence as described above.

Here, as a method of not using a fence as described above when allowing a person or the like to enter the movable range of the robot, instead of physically preventing a collision between the robot and the person or the like with a fence or the like, for example, a so-called It is conceivable to limit the operating area by software control like software limit. In this case, for example, the robot control device sets the motion area within the movable range of the robot. Then, the robot controller monitors whether the robot has left the operating area, that is, whether the robot has entered the specified area, and issues a stop command when it detects that the robot has entered the specified area. to stop the robot.

However, in such a conventional control method, there is a time lag between when the robot control device issues a stop command and when the robot actually stops due to the time lag in signal transmission, the time it takes for the motor to stop, and the like. The difference causes the robot to slide. When the robot moves at high speed, if the robot control device detects that the robot has entered the specified area and then issues a stop command to start stopping the robot, the robot will not enter the specified area due to the sliding of the robot. It is difficult to ensure the safety of people and the like. Therefore, it is desirable to consider the sliding of the robot, predict in advance that the robot will enter the specified area, and issue a stop command to start stopping the robot before the robot enters the specified area.

On the other hand, the distance traveled by sliding is affected by the performance, individual differences, deterioration, etc. of the motors of the robots. For this reason, as described above, in the case of predicting in advance that the robot will enter the specified area and issuing a stop command before the robot enters the specified area to start stopping the robot, safety is improved. In order to guarantee this, it is necessary to make a prediction with a margin assuming the worst conditions. As a result, the robot is frequently stopped even though it is not actually necessary to stop the robot. As a result, the performance of the robot is unnecessarily restricted, and the teaching becomes difficult and the teaching time is extended, resulting in a decrease in convenience.

Japanese Patent No. 5365524

The present embodiment has been made in view of the circumstances described above, and its object is to provide a robot control apparatus that can safely use a robot in a limited space without unnecessarily limiting the performance of the robot. is to provide

The robot control device of this embodiment is a robot control device that drives and controls an articulated robot. The robot control device includes a drive unit that receives an operation command for commanding the operation of the robot, operates the robot based on the operation command, and makes an emergency stop of the robot when a stop command is received; A control processing unit capable of executing control processing for issuing an action command, a calculation processing unit capable of executing calculation processing for calculating the current posture and speed of the robot, and based on the current posture and speed of the robot, a first prediction processing unit capable of executing a first prediction process of predicting a first predicted stop position, which is a position where the robot will stop when the stop command is issued at the current position of the robot; a second prediction processing unit capable of executing a second prediction process of predicting a second predicted stop position adjusted to be ahead of the predicted position; a first monitoring process for issuing the stop command to the driving unit when it is determined that the position will enter; a second monitoring process for issuing a deceleration command for decelerating from the vehicle to the control processing unit;

According to this, while the robot is operating, the robot controller monitors the first predicted stop position, which serves as a reference for emergency stopping, and monitors the second predicted stop position, which serves as a reference for deceleration. do. The second predicted stop position is set so as to be ahead of the first predicted stop position. That is, the second predicted stop position is set with a sufficient distance from the first predicted stop position until the robot stops. Therefore, at the second predicted stop position, entry into the specified area is detected earlier than at the first predicted stop position. When the robot controller determines that the second predicted stop position will enter the specified area, the robot controller decelerates the robot instead of stopping it.

By decelerating the robot in this way, it is possible to shorten the distance traveled by sliding when the robot is brought to an emergency stop, and as a result, it is possible to reduce the risk of the robot entering the specified area. As a result, even the first predicted stop position can be prevented from entering the specified area and issuing a stop command. As a result, it is possible to prevent the movement speed of the robot from being unnecessarily limited or to stop it unnecessarily, so that the robot can continue to operate. On the other hand, if it is determined that the first predicted stop position will enter the specified area even though the robot is decelerated, a stop signal is issued to bring the robot to an emergency stop. As a result, the robot can be used safely even in a limited and narrow space without unnecessarily restricting the performance of the robot.

FIG. 2 is a block diagram conceptually showing an example of functional blocks of the robot control device according to the first embodiment; FIG. 3 is a diagram showing an example of a robot movable range, a designated area, and an operation area in the robot control device according to the first embodiment; FIG. 2 is a diagram conceptually showing an example of a calculation method of a first predicted stop position and a second predicted stop position for the robot control device according to the first embodiment; 3 is a flow chart showing an example of control contents executed by a normal control unit in the robot control device according to the first embodiment; 3 is a flow chart showing an example of control contents executed by a safety monitoring unit in the robot control device according to the first embodiment; Regarding the robot control device according to the first embodiment, both the first predicted stop position and the second predicted stop position do not enter the specified area, and (A) shows the relationship between the elapsed time and the position of the robot. , (B) shows the relationship between the elapsed time and the speed of the robot Regarding the robot control device according to the first embodiment, it shows a case where the second predicted stop position enters the designated area and the first predicted stop position does not enter the designated area. , and (B) shows the relationship between the elapsed time and the speed of the robot Regarding the robot control device according to the first embodiment, both the first predicted stop position and the second predicted stop position enter the designated area, and (A) shows the relationship between the elapsed time and the position of the robot. , (B) shows the relationship between the elapsed time and the speed of the robot FIG. 4 is a block diagram conceptually showing an example of functional blocks of a robot control device according to a second embodiment;

A plurality of embodiments will be described below with reference to the drawings. In addition, in each embodiment, the same code|symbol is attached|subjected to the same structure, and description is abbreviate|omitted.

(First embodiment)
The first embodiment will be described below with reference to FIGS. 1 to 8. FIG. A robot control device 20 shown in FIG. 1 is for controlling the driving of an articulated robot 10 shown in FIG. 2, for example. The robot 10 can be a vertically articulated robot having a multi-joint or multi-axis arm 11 and is controlled by a robot controller 20 . The robot 10 can also be configured by, for example, a horizontal multi-joint type robot, a parallel link side robot, an orthogonal type robot, or the like.

The robot 10 has a multi-axis arm 11 having a plurality of joints shown in FIG. 2, as well as a plurality of motors 12 and position sensors 13 as shown in FIG. The number of motors 12 and position sensors 13 varies depending on the number of joints of arm 11 . Note that FIG. 1 shows only one motor 12 and one position sensor 13 for the sake of simplicity. Each motor 12 is for operating each joint of the arm 11 and is driven and controlled by the robot controller 20 . Each position sensor 13 is for detecting the angular position of each joint of the arm 11 , and can be composed of, for example, a rotary encoder attached to a motor shaft (not shown) of each motor 12 . In addition, the robot 10 can have a tool 90 such as a chuck attached to its hand.

The robot control device 20 includes, for example, a CPU 201 and a storage area 202, as shown in FIG. A storage area 202 stores a program for controlling the driving of the robot 10 . The robot controller 20 causes the CPU 201 to execute a program stored in the storage area 202 to control each motor 12 so that the arm 11 automatically performs a predetermined operation. The robot control device 20 can also be configured by combining, for example, a processing device specialized for controlling the robot 10 called a robot controller and a general-purpose processing device such as a personal computer.

The robot control device 20 is configured to be connectable to an external device such as a teaching pendant (not shown), a personal computer, a smart phone, or a tablet terminal. In this case, the robot control device 20 uses an external device connected to the robot control device 20 as an input device for inputting various settings and the like to the robot control device 20 and various data transmitted from the robot control device 20 . It can function as an output device for outputting information.

The robot control device 20 includes a driving section 21, a setting processing section 22, a calculation processing section 23, a safety monitoring section 24, and a normal control section 25, as shown in FIG. The driving unit 21 includes a driving circuit such as an inverter circuit, for example. The drive unit 21 has a function of receiving an operation command issued by the normal control unit 25 and operating the robot 10 by driving each motor 12 based on the operation command. The motion command is related to the motion of the robot 10, and includes, for example, a command related to the position of the movement destination of a specific part of the robot 10, that is, the target position and the motion speed. The drive unit 21 also has a function of stopping the motors 12 to stop the operation of the robot 10 in an emergency upon receiving a stop command issued by the safety monitoring unit 24 .

The setting processing unit 22 can execute setting processing. The setting process includes a process of setting the specified area A1 in advance and storing it in the storage area 202 prior to the operation of the robot 10 . As shown in FIG. 2, the designated area A1 is within the movable range A0 of the specific portion of the robot 10 and is an area in which entry of a person or the like is permitted, that is, an area in which the robot 10 is prohibited from entering. The specific part of the robot 10 for determining the movable range A0 can be set to any part that is dangerous, for example, when it comes into contact with a person. For example, the specific part R of the robot can be set at the tip when the arm 11 is extended to the maximum, as shown in FIG. In this case, for example, when a tool is attached to the hand of the robot 10, the tip part including the tool 90 can be set as the specific part R. That is, the movable range A0 of the robot 10 can be considered including the tool 90 .

Here, the area other than the specified area A1 in the movable range A0, in this case, the area inside the specified area A1 becomes the operation area A2 of the robot . The operation area A2 is an area in which the robot 10 is permitted to operate, that is, an area in which entry of people or the like is prohibited. In other words, the operating area A2 is an area in which it is necessary to prevent intrusion of people or the like. In this case, the setting process may be configured such that, for example, the operator directly specifies the specified area A1, or, for example, the operator indirectly specifies the specified area A1 by specifying the operation area A2. Further, the setting process can be configured such that setting information is input to the robot control device 20 by the operator operating an external device (not shown) connected to the robot control device 20, for example.

Note that the boundary line Plim shown in FIG. 2 indicates the boundary between the designated area A1 and the operation area A2. In this case, on the boundary between the designated area A1 and the operation area A2, that is, on the boundary line Plim, although not shown in FIG. is preferred. The fence provided in this case is mainly intended to prevent entry of people, etc., and since the robot 10 does not collide at high speed, it does not require strength for protecting people, etc. from collision.

The calculation processing unit 23 can receive position information of each joint of the arm 11 from the position sensor 13 of the robot 10 and execute calculation processing. The calculation process calculates the current posture and position of the robot 10 and the current movement speed from the current angular positions of the joints of the arm 11 detected by the position sensor 13, for example. It includes processing for calculating the position of the part R and the motion speed of each joint. The calculation processing unit 23 transfers the current posture of the robot 10 and the position and movement speed of the specific part R calculated by the calculation processing to the safety monitoring unit 24 and the normal control unit 25 . Note that the calculation processing unit 23 may be incorporated in the safety monitoring unit 24 or the normal control unit 25, for example.

The safety monitoring unit 24 monitors the operation of the robot 10 by executing the operation program stored in the storage area 202, for example, and detects that the specific part R of the robot 10 enters the designated area A1 during the operation of the robot 10. It has a function of issuing a stop command to the drive unit 21 when there is a possibility that it will stop. Upon receiving a stop command from the safety monitoring unit 24 , the driving unit 21 stops the motor 12 to emergency stop the operation of the arm 11 , that is, the operation of the robot 10 . In this case, the drive unit 21 gives top priority to the stop command. That is, when receiving, for example, an operation command at the same time as a stop command, the drive unit 21 gives priority to the stop command over the operation command, and causes the robot 10 to stop urgently.

In the case of this embodiment, the safety monitoring unit 24 has a first prediction processing unit 241 and a first monitoring processing unit 242 as a monitoring processing unit. In this case, the safety monitoring unit 24 may have a CPU (not shown) different from the CPU 201 . The first prediction processing unit 241 and the first monitoring processing unit 242 may be virtually realized by software by executing a predetermined program in a CPU (not shown) of the safety monitoring unit 24, or may be implemented by an integrated circuit or the like. may be implemented in hardware by

The first prediction processing unit 241 receives the current posture of the robot 10 and the position and movement speed of the specific part R from the calculation processing unit 23 . And the 1st prediction process part 241 can perform a 1st prediction process. The first prediction process includes a process of predicting the first predicted stop position Ps1 shown in FIG. .

The first predicted stop position Ps1 is the predicted position of the specific part R of the robot 10 when the robot 10 is completely stopped when a stop command is issued at the current position, that is, at the present time. In other words, the first predicted stop position Ps1 is a position that considers the free running time and the sliding time. In this embodiment, the idle running time means the time from when the stop command is issued to when the motor 12 starts the operation for stopping. Also, the sliding time means the time from when the motor 12 starts decelerating for stopping to when it stops completely.

Further, in the present embodiment, idle running means that the robot 10 operates during the idle running time. The idling distance means the distance traveled by the robot 10 by idling, that is, the distance traveled by the robot 10 during the idling time. Moreover, sliding means that the robot 10 operates during the sliding time. The sliding distance means the distance that the robot 10 moves by sliding, that is, the distance that the robot 10 moves during the sliding time.

For example, when the specific part R of the robot 10 is set to the tip of the tool 90, the first predicted stop position Ps1 is the position where the tip of the tool 90 is predicted to exist when the robot 10 stops completely. Become. The first prediction processing unit 241 transfers the calculated first predicted stop position Ps1 to the first monitoring processing unit 242 .

The first monitoring processing unit 242 constitutes a monitoring processing unit, and can execute a first monitoring process. The first monitoring process includes a process of issuing a stop command to the drive unit 21 when it is determined that the first predicted stop position Ps1 will enter the designated area A1 preset by the setting process. That is, the first monitoring processing unit 242 constantly monitors the first predicted stop position Ps1 while the robot 10 is operating. Then, when the first monitoring processing unit 242 detects that the first predicted stop position Ps1 enters the specified area A1, it issues a stop command to the driving unit 21 .

The normal control unit 25 has a function of controlling the normal operation of the robot 10, that is, the operation when the specific portion R of the robot 10 does not enter the designated area A1. In addition, the normal control unit 25 monitors the operation of the robot 10, and if there is a possibility that the specific part R of the robot 10 may enter the designated area A1 during the operation of the robot 10, the safety monitoring unit 24 stops. It has the function of decelerating the operating speed of the robot 10, that is, the speed of the motor 12, before issuing a command.

In the case of this embodiment, the normal control unit 25 has a second prediction processing unit 251 , a second monitoring processing unit 252 as a monitoring processing unit, and a control processing unit 253 . The second prediction processing unit 251, the second monitoring processing unit 252, and the control processing unit 253 may be virtually realized by software by executing a predetermined program in the CPU (not shown) of the CPU 201 or the normal control unit 25. Alternatively, it may be realized by hardware such as an integrated circuit. The second prediction processing unit 251 receives the current posture of the robot 10 and the position and movement speed of the specific part R from the calculation processing unit 23 . Then, the second prediction processing unit 251 can execute the second prediction processing. The second prediction process includes a process of predicting the second predicted stop position Ps2 shown in FIG. .

As with the first predicted stop position Ps1, the second predicted stop position Ps2 is a position that takes into consideration the free running time and the sliding time. The parameters of the second predicted stop position Ps2 are adjusted so as to be ahead of the first predicted stop position Ps1. The second predicted stop position Ps2 is the predicted position of the specific part R of the robot 10 when the robot 10 is completely stopped when a stop command is issued at the current position, that is, at the present time. Either or both of the idling time and the sliding time are given a margin from the one-stop predicted position Ps1. That is, the second predicted stop position Ps2 takes into account a longer idle or skid than the first predicted stop position Ps1. The second prediction processing unit 251 transfers the calculated second predicted stop position Ps2 to the second monitoring processing unit 252 .

The second monitoring processing unit 252 constitutes a monitoring processing unit, and can execute a second monitoring process. The second monitoring process issues a deceleration command to the control processing unit 253 when it is determined that the second predicted stop position Ps2 will enter the specified area A1 set in advance by the setting process. That is, the second monitoring processor 252 constantly monitors the second predicted stop position Ps2 while the robot 10 is operating. Then, when detecting that the second predicted stop position Ps2 enters the designated area A1, the second monitoring processing unit 252 issues a deceleration command to the control processing unit 253 . The deceleration command is a command for decelerating the motion speed of the robot 10 from the current motion speed.

The control processing unit 253 can execute control processing. The control processing includes processing for issuing an operation command to the drive unit 21 . When the control processing unit 253 has not received a deceleration command, it issues an operation command for operating the robot 10 at a normal operating speed, that is, at a preset operating speed. On the other hand, when the control processing unit 253 receives the deceleration command, it issues a motion command for decelerating the robot 10 from the current motion speed. In this case, when receiving an operation command for decelerating the robot 10 from the current operating speed, the drive unit 21 reduces the operating speed of the robot 10 from the current operating speed.

In the case of this embodiment, the safety monitoring unit 24 satisfies the standard regarding functional safety, while the normal control unit 25 does not satisfy the standard regarding functional safety. That is, in the case of this embodiment, the first prediction processing unit 241 and the first monitoring processing unit 242 satisfy the standard regarding functional safety. On the other hand, the second prediction processing unit 251 and the second monitoring processing unit 252 may not satisfy the standard regarding functional safety. In this case, the safety monitoring unit 24 satisfying functional safety can be called a safety system, and the normal control unit 25 not satisfying functional safety can be called a non-safety system.

Standards relating to functional safety required for the safety monitoring unit 24 are stipulated in ISO 10218, for example, and are based on the concept of multiplexing or multiple safety. The safety monitoring unit 24 can satisfy the standard regarding functional safety by having, for example, a plurality of systems of the first prediction processing unit 241 and the first monitoring processing unit 242 . As a result, even if the first prediction processing unit 241 and the first monitoring processing unit 242 of one system do not sufficiently function due to a failure or the like, the safety monitoring unit 24 can prevent the robot 10 from It is configured to be able to issue monitoring and stop commands.

Next, an example of the first prediction process and the second prediction process, that is, an example of a method of calculating the first predicted stop position Ps1 and the second predicted stop position Ps2 will be described. The graph shown in FIG. 3 conceptually shows the change in the position P of the specific part R of the robot 10 with respect to the passage of time t, with the horizontal axis representing time t and the vertical axis representing the position P of the specific part R of the robot 10 . is. In this case, the current time t0 indicates the current time. The left side of the current time t0 indicates the past, that is, the measured value, and the right side of the current time t0 indicates the future, that is, the predicted value. In this case, the current position P0 is the position of the specific part R of the robot 10 at the current time t0, that is, the value calculated by the calculation processing unit 23. FIG. Also, the first predicted stop position Ps1 and the second predicted stop position Ps2 are predicted values calculated by the first prediction processing section 241 and the second prediction processing section 251, respectively.

First, the first prediction process will be described. In this embodiment, the first prediction process includes a process of predicting the first predicted stop position Ps1 assuming that deceleration for stopping the robot 10 will start after the first predicted idle running time tr1 has elapsed from the current time t0. there is The first prediction processing unit 241 uses the current position P0 of the robot 10, the current speed V0 of the robot 10, the first predicted free running time tr1, and the deceleration prediction function S to perform the first prediction processing, thereby obtaining the first A predicted stop position Ps1 can be calculated. The current position P<b>0 and current velocity V<b>0 of the robot 10 are calculated by the calculation processing unit 23 , that is, based on actual measurement values of the position sensor 13 . The first predicted idle running time tr1 is the idle running time used when predicting the first predicted stop position Ps1. The first predicted idling time tr1 assumes the time difference from when the stop command is issued to when the motor 12 starts decelerating for stopping, and is sometimes referred to as reaction time or reaction time.

The first predicted idle running time tr1 is set in advance by, for example, a user or the like, and is appropriately set according to the characteristics of the robot 10 . In this case, the first predicted idling time tr1 is set to be longer than the reaction time of the motor 12 when the robot 10 is momentarily stopped, that is, the shortest reaction time that is the performance limit of the robot 10. .

The deceleration prediction function S is a function for calculating the moving distance of the robot 10 in the period from when the motor 12 starts decelerating for stopping until it completely stops, and the position and speed of the robot 10 are input values. becomes. The deceleration prediction function S can be realized by solving the equation of motion of the robot 10 with the attitude and speed of the robot 10 as inputs, finding the acceleration during the emergency stop period, and integrating the acceleration. The deceleration prediction function S is appropriately set according to, for example, the number of joints of the robot 10, the length of the arm 11, and the like.

First, the first prediction processing unit 241 uses the current position P0, the first predicted free running time tr1, and the current speed V0 to obtain the first predicted deceleration start position Pr1 according to Equation 1 below. The first predicted deceleration start position Pr1 is a predicted position of the robot 10 when the first predicted idle running time tr1 has elapsed from the current time t0.
Pr1=P0+tr1×V0 (Formula 1)

Next, the first prediction processing unit 241 uses the deceleration prediction function S, the current speed V0, and the first predicted deceleration start position Pr1 calculated by the above formula 1 to calculate the first predicted stop position Ps1 according to the following formula 2. calculate. In this case, since the robot 10 does not decelerate or accelerate until the first predicted idle running time tr1 elapses from the current time t0, the speed of the robot 10 when the first predicted idle running time tr1 elapses from the current time t0 is It can be treated as equal to the current velocity V0.
Ps1=Pr1+S(Pr1, V0) (Formula 2)

Next, the second prediction process will be explained. In the present embodiment, the second prediction process starts deceleration for stopping the robot 10 after a second predicted idle running time tr2 set longer than the first predicted idle running time tr1 elapses from the current time t0. This includes the process of predicting the second predicted stop position Ps2. That is, the second prediction processing unit 251 executes the second prediction processing using the current position P0 of the robot 10, the current speed V0 of the robot 10, the second predicted free running time tr2, and the deceleration prediction function S, A second predicted stop position Ps2 can be calculated. In the case of this embodiment, the second prediction process can use the same deceleration prediction function S as the deceleration prediction function S used in the first prediction process. In this case, only the predicted deceleration start positions Pr1 and Pr2 to be input to the deceleration prediction function S are different between the first prediction process and the second prediction process.

The second predicted idle running time tr2 is the idle running time used when predicting the second predicted stop position Ps2. Like the first predicted idle running time tr1, the second predicted idle running time tr2 is a time that assumes a time difference from when the stop command is issued until the motor 12 starts decelerating for stopping. Sometimes called time or reaction time. The second predicted idle running time tr2 is also preset. For example, the setting processing unit 22 automatically sets the second predicted idle running time tr2 according to the value of the first predicted idle running time tr1. In this case, the setting processing unit 22 sets the second predicted idle running time tr2 longer than the first predicted idle running time tr1. For example, the second predicted idle running time tr2 is set to be at least twice as long as the first predicted idle running time tr1. As a result, the second predicted stop position Ps2 is adjusted to be ahead of the first predicted stop position Ps1.

The second prediction processing unit 251 first uses the current position P0, the second predicted free running time tr2, and the current speed V0 to obtain the second predicted deceleration start position Pr2 according to Equation 3 below. The second predicted deceleration start position Pr2 indicates the position of the robot 10 when the second predicted free running time tr2 has elapsed from the current time t0.
Pr2=P0+tr2×V0 (Formula 3)

Next, the second prediction processing unit 251 uses the deceleration prediction function S, the current speed V0, and the second predicted deceleration start position Pr2 calculated by the above formula 3 to calculate the second predicted stop position Ps2 according to the following formula 4. calculate. In this case, as in the first prediction process, since the robot 10 does not decelerate or accelerate until the second predicted idle running time tr2 has elapsed from the current time t0, the second predicted idle running time tr2 has elapsed from the current time t0. The velocity of the robot 10 at the moment can be treated as being equal to the current velocity V0.
Ps2=Pr2+S(Pr2, V0) (Formula 4)

Next, the control flow executed by the safety monitoring unit 24 and the normal control unit 25 will be described with reference to FIGS. 4 to 8 as well. In the graphs shown in FIGS. 6 to 8A, similarly to the graph shown in FIG. 3, the horizontal axis is the time t and the vertical axis is the position P of the specific part R of the robot 10. 1 conceptually shows a change in the position P of the specific part R of the robot 10 with respect to the . In this case, the boundary line Plim shown in (A) of FIGS. 6 to 8 indicates the boundary line between the specified area A1 and the operation area A2 shown in FIG. 6 to 8A, the specified area A1 is above the boundary line Plim, and the operation area A2 is below the boundary line Plim.

In the graphs shown in FIGS. 6 to 8B, the horizontal axis is time t and the vertical axis is the movement speed V of the specific part R of the robot 10. This diagram conceptually shows changes in the operating speed V. FIG. 7B conceptually shows the actual speed of the specific part R of the robot 10 when neither the deceleration command nor the stop command is issued. be.

A position Px indicated by a dashed line in FIG. 7A conceptually shows how the actual position of the specific portion R of the robot 10 changes due to issuance of a deceleration command. ) conceptually shows how the actual speed of the specific portion R of the robot 10 changes due to the issuance of the deceleration command. A position Px indicated by a dashed line in FIG. 8A conceptually shows how the actual position of the specific portion R of the robot 10 changes due to issuance of a stop command, and FIG. ) conceptually shows how the actual speed of the specific portion R of the robot 10 changes due to the issuance of the stop command.

While the robot 10 is operating, the normal control unit 25 executes the processing shown in FIG. 4, and the safety monitoring unit 24 executes the processing shown in FIG. In this case, in the processing shown in FIG. 4, step S12 corresponds to second stop position prediction processing, and step S13 corresponds to second monitoring processing. Further, in the processing shown in FIG. 5, step S22 corresponds to the first stop position prediction processing, and step S23 corresponds to the first monitoring processing.

When the robot 10 starts to operate, the normal control unit 25 starts the processing shown in FIG. 4 (start). Then, in step S<b>11 , the second prediction processing unit 251 acquires the current posture of the robot 10 calculated by the calculation processing unit 23 , the position P<b>0 of the specific part R, and the current velocity V<b>0 . Next, in step S12, the second prediction processing section 251 executes the second prediction processing to calculate the second predicted stop position Ps2. After that, in step S13, the second monitoring processing unit 252 executes the second monitoring processing to determine whether or not the second predicted stop position Ps2 will enter the specified area A1.

For example, when the second monitoring processing unit 252 determines that the second predicted stop position Ps2 does not enter the designated area A1, that is, does not exceed the boundary line Plim as shown in FIG. 6 (NO in step S13 of FIG. 4), The processing is returned to step S11. Then, the normal control unit 25 re-executes step S11 and subsequent steps. In this case, the operating speed Vx of the robot 10 is maintained at a predetermined speed without being decelerated, as shown in FIG. 6B.

On the other hand, when the second monitoring processing unit 252 determines that the second predicted stop position Ps2 enters the designated area A1, that is, exceeds the boundary line Plim as shown in FIG. 6 (YES in step S13), step S14 transfer the processing to Then, the second monitoring processing unit 252 issues a deceleration command to the control processing unit 253 in step S14. Upon receiving the deceleration command, the control processing unit 253 issues an operation command for deceleration to the drive unit 21, thereby decelerating the operating speed Vx of the robot 10 as shown in FIG. 7B. be done. Then, the normal control unit 25 returns the process to step S11, and repeats the steps after step S11.

The second monitoring processing unit 252 continues to issue the deceleration command while determining that the second predicted stop position Ps2 will enter the designated area A1. As a result, while there is a danger that the specific portion R of the robot 10 will enter the specified area A1, the operating speed Vx of the robot 10 continues to decelerate (YES in step S13). Then, when the operating speed Vx of the robot 10 is sufficiently decelerated so that the second predicted stop position Ps2 does not enter the designated area A1, that is, when the graph shown in FIG. NO), the second monitoring processing unit 252 stops issuing the deceleration command, and as a result, deceleration of the robot 10 is completed as shown after deceleration end time te in FIG. 7B.

Next, the contents of control in the safety monitoring unit 24 will be described. When the robot 10 starts to operate, the safety monitoring unit 24 starts the processing shown in FIG. 5 (start). First, in step S21, the first prediction processing unit 241 acquires the current posture of the robot 10 calculated by the calculation processing unit 23 and the current position P0 and current velocity V0 of the specific part R from the calculation processing unit 23 . Next, in step S22, the first prediction processing section 241 executes the first prediction processing to calculate the first predicted stop position Ps1. Thereafter, in step S23, the first monitoring processing unit 242 executes the first monitoring processing to determine whether or not the first predicted stop position Ps1 will enter the specified area A1.

For example, as shown in FIGS. 6 and 7A, the safety monitoring unit 24 determines that the first predicted stop position Ps1 does not enter the designated area A1, that is, does not exceed the boundary line Plim (step S23 NO), the process returns to step S21, and the steps after step S21 are executed. In this case, the motion speed Vx of the robot 10 follows the content of the motion command issued from the control processing unit 253 .

On the other hand, when the first monitoring processing unit 242 determines that the first predicted stop position Ps1 enters the designated area A1, that is, exceeds the boundary line Plim as shown in FIG. 8 (YES in step S23 of FIG. 5). , the process proceeds to step S24. Then, the first monitoring processing unit 242 issues a stop command to the driving unit 21 in step S24. Upon receiving the stop command, the drive unit 21 stops the motor 12 to bring the robot 10 to an emergency stop regardless of the content of the operation command received from the control processing unit 253 . Then, the safety monitoring unit 24 notifies the user of an error, for example, although the details are not shown, and then terminates the series of controls (end).

According to the embodiment described above, the robot control device 20 is a robot control device that drives and controls the articulated robot 10 . The robot control device 20 includes a drive unit 21, a control processing unit 253, a calculation processing unit 23, a first prediction processing unit 241, a first monitoring processing unit 242, a second prediction processing unit 251, and a second monitoring unit 241. and a processing unit 252 .

The driving unit 21 has a function of receiving an operation command for instructing the operation of the robot 10, operating the robot 10 based on the operation command, and emergency stopping the robot 10 when a stop command is received. The control processing unit 253 can execute control processing for issuing an operation command to the drive unit 21 . The calculation processing unit 23 can execute calculation processing. The calculation processing includes processing for calculating the current posture, position P0, and velocity V0 of the robot 10. FIG.

The first prediction processing unit 241 can execute a first prediction process. In the first prediction process, based on the current posture, position P0, and velocity V0 of the robot 10, the first stop prediction is the position at which the robot 10 will stop if a stop command is issued at the current position P0 of the robot 10. It includes the process of predicting the position Ps1. The first monitoring processing unit 242 can execute a first monitoring process. The first monitoring process includes a process of issuing a stop command to the drive unit 21 when it is determined that the first predicted stop position Ps1 will enter the preset designated area A1.

The second prediction processing unit 251 can execute the second prediction processing. The second prediction process includes a process of predicting a second predicted stop position Ps2 adjusted to be ahead of the first predicted stop position Ps1. Then, the second monitoring processing unit 252 can execute the second monitoring processing. The second monitoring process includes a process of issuing a deceleration command to the control processing unit 253 to decelerate the speed of the robot 10 from the current speed V0 when it is determined that the second predicted stop position Ps2 will enter the designated area A1.

According to this, while the robot 10 is operating, the robot control device 20 monitors the first predicted stop position Ps1 that serves as a reference for an emergency stop, and also monitors the second predicted stop position Ps1 that serves as a reference for deceleration. Monitor position Ps2. The second predicted stop position Ps2 is set to be ahead of the first predicted stop position Ps1. That is, the second predicted stop position Ps2 is set with a margin in the distance until the robot 10 stops, in this case, the idle running distance, with respect to the first predicted stop position Ps1. Therefore, the second predicted stop position Ps2 is detected to enter the designated area A1 earlier than the first predicted stop position Ps1. When the robot controller 20 determines that the second predicted stop position Ps2 will enter the specified area A1, the robot controller 20 decelerates the robot 10 instead of stopping it.

By decelerating the robot 10 in this way, it is possible to shorten the moving distance due to sliding when the robot 10 is brought to an emergency stop, and as a result, it is possible to reduce the risk of the robot 10 entering the specified area A1. As a result, it is possible to prevent even the first predicted stop position Ps1 from entering the specified area A1 and issue a stop command. can be suppressed. On the other hand, if it is determined that the first predicted stop position Ps1 will enter the designated area A1 despite the deceleration of the robot 10, a stop signal is issued to bring the robot 10 to an emergency stop. . As a result, the robot 10 can be safely used even in a limited and narrow space without unnecessarily restricting the performance of the robot 10 .

Here, when the robot 10 is stopped in an emergency, for example, it is necessary for the operator or the like to confirm the safety around the robot 10 and then restore the operation of the robot 10 . Therefore, once the robot 10 is stopped in an emergency, it takes time and effort to restore the robot 10 . On the other hand, according to the present embodiment, although the robot 10 is decelerated, the robot 10 can continue to operate while avoiding an emergency stop.

Further, in the case of the present embodiment, the first prediction process is a process of predicting the first predicted stop position Ps1 assuming that deceleration for stopping the robot 10 will start after the first predicted free running time tr1 has elapsed from the current time t0. including. In the second prediction process, it is assumed that deceleration for stopping the robot 10 starts after a second predicted idle running time tr2 set longer than the first predicted idle running time tr1 elapses from the current time t0. A process of predicting the second predicted stop position Ps2 is included.

According to this, for example, the same deceleration prediction function S can be used to calculate the first predicted stop position Ps1 and the second predicted stop position Ps2. As a result, for example, most of the parameters for calculating the first predicted stop position Ps1 and the second predicted stop position Ps2 can be shared. configuration can be simplified.

Here, since the safety monitoring unit 24, that is, the first prediction processing unit 241 and the first monitoring processing unit 242 are responsible for the emergency stop of the robot 10, it is necessary to satisfy the standard regarding functional safety. In this case, the functions of the second prediction processing unit 251 and the second monitoring processing unit 252, that is, the functions of the normal control unit 25, may also be incorporated into the safety monitoring unit 24 so as to satisfy the standard regarding functional safety. That is, it is conceivable that the safety monitoring unit 24 and the normal control unit 25 are configured with the same hardware. However, if the functions of the normal control unit 25 are to be incorporated into the safety monitoring unit 24, the control processing unit 253 and the driving unit 21 must also meet the standards regarding functional safety, which complicates the configuration and increases the implementation cost. also increases.

In contrast, in this embodiment, the second prediction processing unit 251 and the second monitoring processing unit 252 are not responsible for emergency stop of the robot 10 . Further, the normal control unit 25 prevents the second predicted stop position Ps2 from entering the designated area A1 before the safety monitoring unit 24 detects that the first predicted stop position Ps1 enters the designated area A1. can be detected. Therefore, the second prediction processing unit 251 and the second monitoring processing unit 252 do not need to satisfy the standard regarding functional safety, and the second prediction processing unit 251 and the second monitoring processing unit 252 are added to the normal control unit 25 which is a non-safety system. can be incorporated.

As described above, according to the present embodiment, the robot control device 20 includes, as monitoring processing units, the first monitoring processing unit 242 capable of executing the first monitoring process and the second monitoring processing unit capable of executing the second monitoring process. and a portion 252 . In this case, the first monitoring processing unit 242 and the second monitoring processing unit 252 are configured with different hardware. The first prediction processing unit 241 and the first monitoring processing unit 242 are configured so as to satisfy the standard regarding functional safety. On the other hand, the second prediction processing unit 251 and the second monitoring processing unit 252 do not have to satisfy the standard regarding functional safety. According to this, compared with the case where the second prediction processing unit 251 and the second monitoring processing unit 252 are incorporated in the safety monitoring unit 24, the configuration can be simplified and an increase in mounting cost can be suppressed.

(Second embodiment)
A second embodiment will be described with reference to FIG. In this embodiment, the robot control device 20 has a correction processing section 254 instead of the second prediction processing section 251 . The correction processing unit 254 can execute a second prediction process. The second prediction process of the present embodiment includes a process of predicting the second predicted stop position Ps2 by correcting the first predicted stop position Ps1 predicted by the first prediction process. The correction processing unit 254 reads the first predicted stop position Ps1 predicted by the first prediction process, and corrects the first predicted stop position Ps1 to calculate the second predicted stop position Ps2.

That is, in this embodiment, the deceleration prediction function S is calculated only by the safety monitoring unit 24, and the correction processing unit 254, that is, the normal control unit 25 does not calculate the deceleration prediction function S. In this case, the second predicted stop position Ps2 can be expressed by Equation 5 below. By substituting Equations 1 to 3 into Equation 5, the second predicted stop position Ps2 can be expressed by Equation 6 below. In this case, if the difference between the first predicted idle running time tr1 and the second predicted idle running time tr2 is sufficiently small, that is, if the difference between the first predicted deceleration start position Pr1 and the second predicted deceleration start position Pr2 is not large, A large error does not occur in the second predicted stop position Ps2.
Ps2=Pr2+S(Pr1, V0) (Formula 5)
Ps2=Ps1+Pr2-Pr1 (Formula 6)

As described above, according to the present embodiment, the correction processing unit 254 reads the first predicted stop position Ps1 predicted in the first prediction process, and corrects the first predicted stop position Ps1 to obtain the second predicted stop position. By calculating the position Ps2, the calculation amount of the correction processing unit 254 can be reduced. That is, according to the present embodiment, it is possible to suppress an increase in the load on the normal control section 25 due to the calculation of the second predicted stop position Ps2.

(Other embodiments)
The present invention is not limited to the embodiments described above and illustrated in the drawings, and can be arbitrarily modified, combined, or expanded without departing from the scope of the invention.
The numerical values and the like shown in each of the above embodiments are examples, and are not limited to them.
Further, the above embodiments can be combined as appropriate.

For example, the safety monitoring unit 24 and the normal control unit 25 are preferably configured with different hardware, but they can also be configured with the same hardware. Further, for example, in the above-described embodiment, the first prediction process and the second prediction process are performed using the deceleration prediction function S, but the first prediction process and the second prediction process may be performed without using the deceleration prediction function S. can also As a method of performing the first prediction process and the second prediction process without using the deceleration prediction function S, for example, a method of linearly predicting the acceleration under the worst conditions can be adopted. According to this, compared with the case where the deceleration prediction function S is used, although the prediction accuracy is lowered, the amount of calculation can be reduced, so the processing load can be reduced.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

DESCRIPTION OF SYMBOLS 10... Robot 20... Robot control apparatus 21... Driving part 23... Calculation processing part 241... First prediction processing part 242... First monitoring processing part 251... Second prediction processing part 252... Second monitoring Processing unit 253 Control processing unit A1 Specified area Ps1 First predicted stop position Ps2 Second predicted stop position V0 Current speed t0 Present time tr1 First predicted free running time tr2 2nd predicted free running time

Claims (4)

A robot control device for driving and controlling an articulated robot,
a driving unit that receives an operation command for commanding the operation of the robot, operates the robot based on the operation command, and makes an emergency stop of the robot when a stop command is received;
a control processing unit capable of executing control processing for issuing the operation command to the driving unit;
a calculation processing unit capable of executing calculation processing for calculating the current posture, position, and speed of the robot;
First prediction processing for predicting a first predicted stop position, which is a position at which the robot will stop if the stop command is issued at the current position of the robot, based on the current posture, position, and speed of the robot. a first prediction processing unit capable of executing
a second prediction processing unit capable of executing a second prediction process of predicting a second predicted stop position adjusted to be ahead of the first predicted stop position;
a first monitoring process for issuing the stop command to the driving unit when it is determined that the first predicted stop position will enter a preset specified area; and a second predicted stop position enters the specified area. a monitoring processing unit capable of executing a second monitoring process of issuing a deceleration command to reduce the speed of the robot from the current speed to the control processing unit when it is determined that
A robot controller comprising: The first prediction process includes a process of predicting the first predicted stop position assuming that deceleration for stopping the robot will start after a first predicted idling time has elapsed from the current time point,
The second prediction process assumes that deceleration for stopping the robot will start after a second predicted idle running time set to be longer than the first predicted idle running time elapses from the present time. Including processing to predict the predicted stop position,
The robot controller according to claim 1. a first monitoring processing unit capable of executing the first monitoring process and a second monitoring processing unit capable of executing the second monitoring process as the monitoring processing unit;
The first prediction processing unit and the first monitoring processing unit are configured to satisfy standards related to functional safety,
The second prediction processing unit and the second monitoring processing unit are configured not to satisfy the functional safety standard,
The robot controller according to claim 1 or 2. The second prediction process includes a process of predicting the second predicted stop position by correcting the first predicted stop position calculated in the first prediction process.
The robot control device according to any one of claims 1 to 3.

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