JP3287151B2 - Force control device for assembly robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force control device for an assembling robot, and more particularly to a device suitable for assembling a flexible object such as a resin molded product.

[0002]

2. Description of the Related Art In general, flexible articles such as resin molded articles have a large difference in solids after production, and there is a variation in precision of parts. When assembling, it is necessary to work with the same feeling as a human being, that is, while feeling the degree of force applied to the hand (hand). It is very important to work while controlling.

Therefore, conventionally, a force sensor is mounted on the wrist of a robot hand to directly detect a reaction force or a moment (force information) acting on the hand, and to perform feedback to perform force control of an assembly operation. Attempted.

In this case, as a conventional general method of feedback of force sense, the sensor value is constantly monitored, and when the sensor value exceeds a preset threshold value (allowable range), the robot is stopped (or returned). Since the method and the operating position that may give a value exceeding the threshold value are known in advance, for example, "A kg force is applied in the X direction, B kg force in the Y direction, and C kg force in the Z direction. In some cases, move the robot by αmm in the X direction, βmm in the Y direction, and γmm in the Z direction. ” Have been.

[0005]

However, in the first force feedback method, the robot is only stopped (or returned) when the sensor value exceeds the threshold value, and the work is damaged. However, since it does not cause the robot to perform the correcting operation, the assembling work may not be completed in the first place.

In the second force feedback method, the amount of movement correction for the detection value of the force sensor is tabulated in advance as described above, and the force applied to the hand can be reduced by moving according to the table. However, in the case of force control, unlike the case of position control in which the deviation between the detected position data and the target value is simply used as the correction amount, the optimal position information of the robot is obtained from the force sense information. Is very difficult to determine, so it is not known exactly how much to move the obtained sensor value, and the correction amount should not be constant. Therefore,
There is a certain limit in the accuracy of the correction by this method in which a predetermined correction amount is determined in advance for the sensor value, and there is a possibility that the assembly operation by the robot may be NG.

In this method, it is necessary to determine the amount of correction with respect to the detection value of the force sensor when tabulating the amount of correction. Due to problems, it is a difficult and difficult task.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to reliably and easily perform the work of assembling a flexible object, which has been extremely difficult in the past, with high accuracy. An object of the present invention is to provide a force control device for an assembling robot.

[0009]

According to a first aspect of the present invention, there is provided a force control apparatus for an assembling robot according to the present invention. A force control device for controlling the operation of the assembling robot; a force information detecting means for detecting force information relating to the assembling operation of the assembling robot; Storage means for storing a detection result of the force information detecting means at the time of a working state as a target value in a predetermined format, and storing current force information detected by the force information detecting means in the storage means. Comparing means for comparing with the target value of the corresponding step, and when the current force information does not match the target value of the corresponding step as a comparison result of the comparing means, match them. Issued create a correction signal for operating the assembly robot in direction, and correction means for outputting to said robot control means, the target value stored in the storage means,
The reproduced when working state of the assembling robot, characterized by having a a stopping means for temporarily stopping the reproduction by the correction signal from the correction means.

According to a second aspect of the present invention, there is provided a force control device for an assembling robot which performs an assembling operation of parts using force control based on a force sense. Robot force control means, force information detection means for detecting force information on the assembling operation of the assembling robot, and a detection result of the force information detection means in a working state in a normal assembly operation in advance. Storage means for storing the target value in a predetermined format, and comparing the current force information detected by the force information detection means with the target value of a corresponding stage stored in the storage means, And an assembling robot in a direction to keep the error within an allowable range when the error obtained by the comparing unit is not within a predetermined allowable range. Issued create a correction signal for operating a correction means for outputting to said robot control means, said storage Hand
The target value stored in the row is
It is reproduced at the time of business state, and by the correction signal from the correction means
It characterized by having a a stopping means for temporarily stopping the reproduction.

According to a third aspect of the present invention, there is provided a force control apparatus for an assembling robot according to the first or second aspect, wherein the force sense information detecting means is provided on a wrist of the assembling robot. It is a mounted six-axis force sensor.

According to a fourth aspect of the present invention, in the force control apparatus for an assembling robot according to the first or second aspect, the force sense information detecting means stored in the storage means. Is characterized by being stored in relation to time.

According to a fifth aspect of the present invention, there is provided the force control apparatus for an assembling robot according to the first or second aspect, wherein the force sense information detecting means stored in the storage means. Is stored in relation to the teaching point.

[0014]

In the force control apparatus for an assembling robot according to claim 1, the robot control means controls the operation of the assembling robot, and the force sense information detecting means controls the operation of the assembling robot. Detects haptic information related to the assembling operation.
The storage unit stores in advance a detection result of the force sense information detection unit during a normal assembly operation as a target value in a predetermined format. At the time of an actual assembling operation, target values corresponding to each stage of the assembling operation are sequentially reproduced from the storage means and input to the comparing means. The comparing unit compares the current haptic information detected by the haptic information detecting unit with a target value of a corresponding stage input from the storage unit, and the correcting unit includes:
When the current force sense information does not match the target value of the corresponding stage as a result of the comparison, a correction signal for operating the assembling robot in a direction for matching the force information is generated and output to the robot control means. Accordingly, the assembling robot performs the correction operation until the detected current force information matches the target value of the corresponding stage. During this correction operation, the stopping means temporarily stops the reproduction of the target value stored in the storage means. When the correction operation is completed, the storage means starts reproducing the target value again. That is, force information at the time of normal operation is stored in advance, and the assembling work is performed while controlling the operation so as to match the force sense information. Can be made. In addition, since the operation is controlled based on the result of the comparison between the current value and the target value of the force information, it is only necessary to previously store force information at the time of normal operation, and setting and changing are relatively easy. .

According to a second aspect of the present invention, in the force control device for an assembling robot, the robot control means controls the operation of the assembling robot, and the force information detecting means detects a force sense relating to the assembling operation of the assembling robot. Detect information. The storage unit stores in advance a detection result of the force sense information detection unit during a normal assembly operation as a target value in a predetermined format. At the time of an actual assembling operation, target values corresponding to each stage of the assembling operation are sequentially reproduced from the storage means and input to the comparing means. The comparing means compares the current haptic information detected by the haptic information detecting means with a target value of a corresponding stage input from the storage means, and obtains an error therebetween.
The correcting means generates a correction signal for operating the assembling robot in a direction to keep the deviation within the allowable range when the error obtained by the comparing means is not within the preset allowable range, Output to Thereby, the assembling robot performs the correcting operation until the error falls within the allowable range. During this correction operation, the stopping means temporarily stops the reproduction of the target value stored in the storage means. When the correction operation is completed, the storage means starts reproducing the target value again. In other words, force information at the time of normal operation is stored in advance, and the assembling work is performed while controlling the operation so as to follow the force sense information. Therefore, the assembling work such as the assembling work of the flexible object is reliably performed with high accuracy. be able to. In addition, since the operation is controlled based on the result of the comparison between the current value and the target value of the force information, it is only necessary to previously store force information at the time of normal operation, and setting and changing are relatively easy. .

In the force control device for an assembling robot according to the third aspect of the present invention, the six-axis force sensor is mounted on the wrist of the assembling robot. Six-dimensional information can be detected, and by performing feedback, delicate force control becomes possible, and the accuracy of assembly work is improved.

Further, in the force control device for an assembling robot according to the fourth aspect, the detection result of the force sense information detecting means is stored in the storage means in relation to time, so that the target value is set in units of time resolution. A correction operation by reproduction and comparison can be performed, and finer control can be performed.

In the force control device for an assembling robot according to the fifth aspect, the detection result of the force sense information detecting means is stored in the storage means in relation to the teaching point, so that the number of comparisons is reduced. Since the entire processing time is shortened, the time required for the assembly operation by the robot is shortened.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall view showing an example of an assembly robot controlled by the force control device of the present invention. The assembling robot 1 has, for example, two arms (arms) like a human.
It consists of a playback type dual arm robot with
The operation for attaching the resin duct 5 to the resin instrument panel 4 fixed on the work table 2 by a predetermined jig 3 is performed. Each arm of the double-arm robot 1 is a multi-joint arm by a servo motor direct drive system, and can be independently taught, and force sense information is detected on a wrist which is a joint between the arm 6 and the hand (hand) 7. A force sensor 8 as means is mounted (see FIG. 2). When the duct 5 is actually assembled to the instrument panel 4, the duct 5 is gripped at two predetermined positions by the double-arm robot 1, and a projection (not shown) provided on the duct 5 is provided inside the instrument panel 4. Into the outlet. As described above, when both the assembly (duct 5) and the assembly (instrument panel 4) are flexible materials such as resin molded products, there is a large difference between solids. It is necessary to correct the operation and work properly.

The force sensor 8 mounted on the wrist of each arm of the dual-arm robot 1 is, for example, a six-axis force sensor that handles six-dimensional information, and is a force or moment (force) applied to the hand. Information) is detected directly. Force sensor 8
Since the structure itself is well known, its description is omitted. As described later, the force information (force signal) from the force sensor 8 is fed back to the force control, so that the work such as the assembling work of the flexible objects can be performed while delicately controlling the force of the arm portion. Can be done.

FIG. 3 is a block diagram showing an example of the configuration of a force control device for an assembling robot according to the present invention. As shown in the figure, the dual-arm robot 1 for assembly is integrally controlled by a robot controller 10. The robot controller 10 includes a central control unit 11 and a servo amplifier 12 that supplies driving power to servo motors (hereinafter simply referred to as “axis motors”) of respective drive axes of the dual-arm robot 1.
And a power supply unit 13 for supplying predetermined power to each unit. The control unit 11 inputs a robot control unit 14 as robot control means for controlling the operation of the double-arm robot 1 and force sensors from force sensors 8a and 8b mounted on each arm of the double-arm robot 1. A correction unit 15 for generating a correction signal. Although not shown, the robot control unit 14 includes a robot control CPU, various input / output interfaces, and the like, and the correction unit 15 includes a model CPU and an interface for the force sensor 8 described later. The robot controller 14 visually detects various kinds of sensors 16 such as a limit switch for detecting that a work (instrument panel 4 and duct 5) has been carried in and out of the work table 2 and the movement of the double-arm robot 1. An image processing device 18 that receives a signal from a camera 17 that is captured in a targeted manner and performs image processing to generate image information (visual information)
And a teaching board 19 for storing required work in each arm of the dual-arm robot 1 are connected to each other. In addition, a robot signal (for example, a data warning signal or disconnection detection) related to the dual-arm robot 1 is also input / output to / from the robot controller 14.

The control of the basic operation of the dual-arm robot 1 is the same as that of a normal playback robot. First, the manipulator is moved by a human operation on the teaching board 19 in advance to teach the actual work. Thereby, the order, position, and other information of the work are stored in a predetermined memory in the robot controller 14. This teaching operation is performed for both arms. In the actual operation, information such as the taught order and position is read out as necessary, and the axis motor control and the brake control are performed via the servo amplifier 12 to operate according to the preset order, condition and position. Each stage of the procedure is carried out sequentially.

FIG. 4 is a block diagram showing functions of the control unit 11 of FIG. As shown in the figure, the correction unit 15 functionally includes an interface 20 that inputs and processes signals from the force sensors 8a and 8b, and a detection value of the force sensor 8 during a normal assembly operation. A model generation unit 21 captured via the interface 20, and six-dimensional force information captured by the model generation unit 21 (for example,
The model storage unit 22 stores the XYZ load and moment in the respective axial directions in a predetermined format, and the values of the force sense information during normal operation stored in the model storage unit 22 are described below. A model reproducing unit 23 for outputting to the comparing unit;
A comparing unit for comparing the current detection value of the force sensor 8 input via the interface 20 with the value (target value) of force information during normal operation input via the model reproducing unit 23 to obtain an error therebetween. 24, a determining unit 25 for determining whether the error obtained by the comparing unit 24 is within a preset allowable range, and a signal for correcting the operation of each arm of the double-arm robot 1 based on the determination result of the determining unit 25. And a correction signal generation unit 26 for generating the correction signal. The storage means is constituted by the model storage section 22, the comparison means is constituted by the comparison section 24, the correction means is constituted by the correction signal generation section 26, and the stop means is constituted by the model reproduction section 23.

The fetching of the haptic information into the model generating section 21 and the storing processing of the haptic information in the model storing section 22 are performed in advance, for example, at the time of teaching. The force information from the force sensor 8 at this time is a detection value when the assembly work is actually performed successfully, that is, a value when a normal assembly operation is performed. The model storage unit 22 stores the detection value of the force sensor 8 at the time of such a normal assembly operation, for example, in relation to time as shown in FIG. 6 (hereinafter, stored in the model storage unit 22). The data of the force sensor detected value during the normal operation with respect to the time during which it is present is called a model. Actually, since the detection value of the force sensor 8 is six-dimensional, the model has a load in the X-axis direction, a load in the Y-axis direction, and a load in the Z-axis direction for each of the force sensors 8a and 8b. , X-axis direction moment, Y-axis direction moment, and Z-axis direction moment are stored in relation to time. Since this model is force information when the work (instrument panel 4 and duct 5) is completely assembled, when the robot 1 actually performs the assembling work, it is sequentially reproduced with the target value as the target value. Then, by comparing with the force sensor detection value (unattached state) at the stage of the corresponding assembling operation at that time and making correction so as to follow the model, assembling work can be performed reliably Becomes It should be noted that model creation is sufficient if it is necessary to consider at least the stage in which the work needs to be performed while delicately controlling the force of the arm portion, and it is not necessary to carry out the intermediate transfer stage.

The reproduction of the model stored in the model storage section 22 must be reproduced in synchronization with the assembly operation by the robot arm. Therefore, the reproduction of the model is started by the work start signal output from the robot control unit 14 and ends by the work end signal, and is further temporarily stopped by the reproduction stop signal output from the correction signal generation unit 26 during the correction operation. It is to be stopped. The work start signal, the work end signal, and the reproduction stop signal are input to the model reproducing unit 23, which controls the output of the reproduced model to the comparing unit 24. The output timings of the work start signal and the work end signal are respectively at the time of starting the assembling work (teaching point) and at the time of finishing the assembling work (teaching point).
Is set in advance so as to be output. The work end signal is also output when an abnormal stop is applied. The reproduction stop signal is output when the error obtained by the comparing section 24 as a result of the determination by the determining section 25 is not within the allowable range, and is stopped when the error falls within the allowable range. . Correction signal generator 2
When the output of the reproduction stop signal from 6 stops, the reproduction of the model is started.

The model may be stored in terms of a point, for example, a teaching point of an operation, in addition to the above-described format in which the model is stored in relation to time. In this case, the information is stored in relation to the axis parameters for each drive axis.

The correction signal generating section 26 generates a signal for correcting the operation of each arm of the double-arm robot 1 based on the result of the determination by the determining section 25 as described above. More specifically,
When the error determined by the comparing unit 24 as a result of the determination by the determining unit 25 is not within the allowable range, a command signal for moving the robot 1 in a direction to keep the error within the allowable range is generated and output to the robot control unit 14. I do. For example, if the load error in the X-axis direction exceeds the allowable range and is in a plus (+) state, the robot 1 is moved in a direction to keep it within the allowable range, that is, in the minus (-) direction of the X-axis. I do. The robot control unit 14 moves the robot 1 in the direction instructed by the correction signal generation unit 26, and delicately controls the degree of the applied force. This control is repeated until the actual detected value matches the value (target value) of the force information during normal operation within an allowable range.

FIG. 5 is a flowchart showing the operation of the control unit 11. Here, a flowchart in the case where the work (instrument panel 4, duct 5) is assembled by the double-armed robot 1 after a predetermined teaching operation is completed is shown. When the robot 1 reaches the assembly work start position and a work start signal is input from the robot control unit 14 to the model reproduction unit 23 (step S1), reproduction of the model stored in the model storage unit 22 is started. ,
The model is reproduced while synchronizing with the movement of the robot 1, and the value of the force information corresponding to each stage of the assembling operation is sequentially output to the comparing unit 24 as a target value (step S).
2).

At the same time, the comparing section 24 inputs the six-dimensional force signal (force information) from each of the force sensors 8a and 8b via the interface 20 (step S3), and inputs the current force. The sensation information value is compared with the target value of the corresponding stage input in step S2, an error between them is obtained, and the result is output to the determination unit 25 (step S4).

Then, the determination section 25 determines whether or not the error obtained in step S4 is within a predetermined allowable range (step S5). If the error is within the allowable range as a result of this determination, Unless a work end signal has been input to the model reproducing unit 23, that is, unless the robot 1 has reached the work end position or has not stopped abnormally (step S10), the process returns to step S2 to continue model reproduction. Then, continue the assembly work.

On the other hand, if the result of the determination in step S5 is that the error is not within the allowable range, the correction signal generation unit 26 determines that the assembly is not successful and starts the correction operation so as to start the correction operation. And a reproduction stop signal is output to temporarily stop the reproduction of the model (step S6).
A command signal (correction signal) for moving the robot 1 in a direction to keep the error obtained in step S4 within an allowable range is generated (step S7), and this signal is fed back to the robot control unit 14 (step S8). Robot controller 1
4 causes the dual-arm robot 1 to execute a correction operation for moving the robot 1 in the commanded direction, delicately controls the degree of force applied (step S9), and returns to step S3. That is, this correction operation is repeated until the actual detected value matches the value (target value) of the force sense information in the normal operation within the allowable range.

By repeating the above control, as shown in FIG. 7, the change (solid line P) of the force sense information in the actual assembling work (actual operation) follows the model (dashed line Q), and it is ensured. The work (instrument panel 4, duct 5) can be assembled to the work. Note that the above force control based on the force sense information is executed independently for each arm of the dual arm robot 1.

Therefore, according to the present embodiment, force sense information during normal operation is stored in the model storage unit 22 as a model (see FIG. 6) in advance, and the relationship between the operating position of the robot 1 and the force sense is determined. Since the assembling work is performed while controlling the operation so as to follow the model, the assembling work of a flexible article such as a resin molded product (instrument panel 4, duct 5) can be performed with high accuracy.

In this embodiment, since the operation is controlled based on the result of comparison between the current value of the force information and the model (target value), force information during normal operation is sensed and stored in advance. Since it requires only time and effort, and it is not necessary to create a table as in the related art, setting and changing the table are simple.

In this embodiment, the double-arm robot 1 is shown as an assembling robot. However, the present invention is not limited to this. INDUSTRIAL APPLICABILITY The present invention is widely applied to a case in which a normal robot having one arm performs work while delicately controlling the force, for example, assembling flexible objects or fitting a flexible object into a hole. It is possible.

[0036]

As described above, according to the force control device for an assembling robot according to the first aspect of the present invention, force sense information in a normal operation is stored in advance, and the force sense information is set to match the force sense information. Since the assembling work is performed while controlling the operation, for example, the assembling work such as the assembling work of the flexible object can be performed with high accuracy. Further, since the operation is controlled based on the result of comparison between the current value of the force information and the target value, it is only necessary to previously store force information at the time of normal operation, and setting and changing are easy.

According to the force control device for an assembling robot according to the second aspect, the force sense information in a normal operation is stored in advance, and the assembling work is performed while controlling the operation to follow the force sense information. For example, an assembling operation such as an assembling operation of a flexible object can be reliably performed with high accuracy. Further, since the operation is controlled based on the result of comparison between the current value of the force information and the target value, it is only necessary to previously store force information at the time of normal operation, and setting and changing are easy.

According to the third aspect of the present invention, a six-axis force sensor is mounted on the wrist of the assembling robot, and the force and moment of each of the axes applied to the robot hand are calculated. Since dimensional information is detected, delicate force control becomes possible by feedback, and the accuracy of assembly work is improved.

According to the force control device for an assembling robot of the present invention, the detection result of the force sense information detecting means is stored in the storage means in relation to time, so that the target value is reproduced in units of time resolution. , And a correction operation by comparison can be performed, and more detailed control can be performed.

According to the force control device for an assembling robot according to the fifth aspect, the detection result of the force sense information detection means is stored in the storage means in relation to the teaching point, so that the number of comparisons is reduced, and , The time required for the assembly operation by the robot is reduced.

[Brief description of the drawings]

FIG. 1 is an overall view showing an example of an assembly robot controlled by a force control device of the present invention.

FIG. 2 is a diagram for explaining a mounting position of a force sensor.

FIG. 3 is a block diagram showing an example of a configuration of a force control device for an assembly robot according to the present invention.

FIG. 4 is a block diagram showing functions of a control unit.

FIG. 5 is a flowchart showing the operation of the control unit.

FIG. 6 is a diagram showing an example of a model.

FIG. 7 is a diagram showing an example of an actual operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Double arm robot (assembly robot) 8 ... Force sensor (force information detection means) 10 ... Robot controller 11 ... Control unit 14 ... Robot control part (robot control means) 15 ... Correction part 19 ... Teaching board 20 ... Interface 21 Model generation unit 22 Model storage unit (storage unit) 23 Model reproduction unit (stop unit) 24 Comparison unit (comparison unit) 25 Determination unit 26 Correction signal generation unit (correction unit)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B25J 13/08 B23P 19/04

Claims (5)

(57) [Claims] 1. An assembling robot force control device for assembling parts using force control by force sense, comprising: a robot control means for controlling an operation of the assembling robot; and assembling the assembling robot. Force information detection means for detecting force information relating to the operation, storage means for storing in advance a detection result of the force information detection means in a working state during a normal assembly operation as a target value in a predetermined format, Comparing means for comparing the current haptic information detected by the haptic information detecting means with a target value of a corresponding stage stored in the storage means, and the current haptic information corresponding as a comparison result of the comparing means A correction means for generating a correction signal for operating the assembling robot in a direction in which the target values do not coincide with each other, and outputting the correction signal to the robot control means; The target value stored in the storage means, b for the assembly
It reproduced when working state of bots, the a stopping means for temporarily stopping the reproduction by the correction signal from the correction means, the force control device of the assembly robot, characterized in that it comprises a. 2. A force control device for an assembling robot for assembling parts using force control based on haptics, comprising: a robot control means for controlling an operation of the assembling robot; and assembling the assembling robot. Force information detection means for detecting force information relating to the operation, storage means for storing in advance a detection result of the force information detection means in a working state during a normal assembly operation as a target value in a predetermined format, Comparing the current haptic information detected by the haptic information detecting means with a target value of a corresponding stage stored in the storage means, and calculating the errors thereof; and an error obtained by the comparing means. When the error is not within a preset allowable range, a correction signal for operating the assembly robot in a direction to keep the error within the allowable range is generated, and the robot control is performed. And correcting means for outputting to the means, the target value stored in the storage means, b for the assembly
Reproduced when working state of bots, the a stopping means for temporarily stopping the reproduction by the correction signal from the correction means, the force control instrumentation of the assembly robot, characterized in that it comprises a
Place . 3. A force control device for an assembly robot according to claim 1, wherein the force information detection means is a six-axis force sensor mounted on a wrist of the assembly robot. . 4. The force control of an assembling robot according to claim 1, wherein the detection result of said force sense information detection means stored in said storage means is stored in relation to time. apparatus. 5. The force of the assembling robot according to claim 1, wherein the detection result of said force sense information detection means stored in said storage means is stored in relation to a taught point. Control device.