Robot control system provided with function of changing criterion for communication quality in accordance with distance between machine and portable wireless operation panel

Abstract

A robot control system of the present invention includes: a control device for controlling a machine; a portable wireless operation panel that can perform wireless communication with the control device to control the machine; a distance measuring unit that measures the distance between the machine and the portable wireless operation panel; a communication monitoring unit that monitors the communication quality of wireless communication between the control device and the portable wireless operation panel; a warning generator that emits a warning to the operator or stops the machine when the communication quality becomes lower than a predetermined criterion; and, a criterion changing unit that changes the predetermined criterion in accordance with the distance between the machine and the portable wireless operation panel.

Claims

1. A robot control system comprising: a control device for controlling a machine; a portable wireless operation panel for performing wireless communication with the control device to control the machine; a distance measuring unit for measuring the distance between the machine and the portable wireless operation panel; a communication monitoring unit for monitoring the communication quality of wireless communication between the control device and the portable wireless operation panel; a warning generator for emitting a warning to the operator or stopping the machine when the communication quality becomes lower than a predetermined criterion; and a criterion changing unit for changing the predetermined criterion in accordance with the distance between the machine and the portable wireless operation panel.

2. The robot control system according to claim 1, wherein the communication quality is monitored by measuring an exchanging interval of live data for confirming establishment of the wireless communication.

3. The robot control system according to claim 1, wherein the communication quality is monitored by measuring an exchanging interval of safety signals that are exchanged between the control device and the portable wireless operation panel to indicate whether or not the machine should be stopped.

4. The robot control system according to claim 1, wherein the communication quality is monitored by measuring the interval at which data with an error-detecting code or an error-correcting code that is exchanged between the control device and the portable wireless operation panel is exchanged in an error free condition or by measuring the frequency of errors.

5. The robot control system according to claim 1, wherein the communication quality is monitored by measuring radio wave intensity of the wireless communication.

6. The robot control system according to claim 1, wherein the distance between the machine and the portable wireless operation panel is measured by a sensor including, at least, one of a laser sensor, a pressure sensor, an infrared sensor and a light curtain, arranged near the machine.

7. The robot control system according to claim 1, wherein the distance between the machine and the portable wireless operation panel is measured by analyzing an image of surroundings of the machine taken by a fixed camera.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The object, features and advantages of the present invention will be better understood by reading the following description of the embodiments, taken together with the drawings wherein:

(2) FIG. 1 is a configurational diagram showing a conventional automated machine system;

(3) FIG. 2 is a configurational diagram showing a robot control system according to a first embodiment of the present invention;

(4) FIG. 3 is a timing chart of signals in a robot control system according to a second embodiment of the present invention;

(5) FIG. 4 is a timing chart of signals in a robot control system according to a third embodiment of the present invention;

(6) FIG. 5 shows signal waveforms in a robot control system according to a fourth embodiment of the present invention;

(7) FIG. 6 is a configurational diagram of a robot control system according to a fifth embodiment of the present invention; and,

(8) FIG. 7 is a configurational diagram showing a robot control system according to a modified example of the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(9) Referring now to the drawings, robot control systems according to the present invention will be described.

First Embodiment

(10) A robot control system according to a first embodiment of the present invention will be described. FIG. 2 shows a configurational diagram showing a robot control system according to the first embodiment of the present invention. The robot control system 101 according to the first embodiment of the present invention includes a control device 2 for controlling a machine, i.e., a robot 1; a portable wireless operation panel 4 that can wirelessly communicate with the control device 2 to control the robot 1; a distance measuring unit 6 for measuring the distance between the robot 1 and the portable wireless operation panel 4; a communication monitoring unit 7 for monitoring the communication quality of wireless communication between the control device 2 and the portable wireless operation panel 4; a warning generator 8 for emitting a warning to the operator or stopping the robot 1 when the communication quality becomes lower than a predetermined criterion; and a criterion changing unit 10 for changing the predetermined criterion in accordance with the distance between the robot 1 and the portable wireless operation panel 4. Though the distance measuring unit 6, communication monitoring unit 7, warning generator 8 and criterion changing unit 10 are provided in the control device 2 in FIG. 2, the distance measuring device 6, communication monitoring unit 7, warning generator 8 and criterion changing unit 10 may be provided in the portable wireless operation panel 4 or may be provided in both the control device 2 and the portable wireless operation panel 4.

(11) As shown in FIG. 2, the portable wireless operation panel 4 has a transceiver 41 to transmit commands for controlling the robot 1 wirelessly to a transceiver 21 on the control device side provided for the control device 2. The control device 2 controls the robot 1 based on the received commands.

(12) The distance measuring unit 6 measures the distance between the robot 1 and the portable wireless operation panel 4. For example, the distance can be measured based on the intensity of the radio waves exchanged between the control device 2 and the portable wireless operation panel 4.

(13) The communication monitoring unit 7 monitors the communication quality of wireless communication between the control device 2 and the portable wireless operation panel 4. The warning generator 8 determines whether or not the communication quality monitored by the communication monitoring unit 7 is equal to or higher than a predetermined criterion. The warning generator 8 emits a warning to the operator or stops the robot 1 when the communication quality is lower than the predetermined criterion.

(14) The present invention is characterized in that the criterion changing unit 10 changes the aforementioned predetermined criterion in accordance with the distance between the robot 1 and the portable wireless operation panel 4.

(15) For example, when the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance, the criterion for judging communication quality is made stricter to ensure safety. On the other hand, when the distance between the robot 1 and the portable wireless operation panel 4 is further than the predetermined distance, the time taken to stop the robot when the communication quality degrades is made longer. However, since there is a large distance between the operator and the robot, the two will not interfere with each other, and therefore it is possible to ensure safety, avoid unnecessary stoppages, hence secure convenience.

(16) For example, as a method of monitoring the communication quality between the control device 2 and the portable wireless operation panel 4, measurement of the exchanging interval of live data for confirming establishment of wireless communication can be used. Referring now to FIG. 2, how a warning is generated or how the robot is stopped based on communication quality will be described for each of the cases when the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance and when the distance is further than the predetermined distance.

(17) Live data d.sub.L is the data to be used to confirm whether or not wireless communication is performed normally, every predetermined period of time. Accordingly, when the live data d.sub.L cannot be received, it is determined that wireless communication is not performed normally. For example, FIG. 2 shows received waveforms when the transceiver 41 of the portable wireless operation panel 4 or the control device side transceiver 21 of the control device 2 transmits live data d.sub.L at t.sub.4, t.sub.5 and t.sub.6.

(18) When the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance (which will be simply referred to hereinbelow as short distance case), the time interval at which live data d.sub.L has to be received is set short. In the example shown in FIG. 2, this interval is set to be the time period from time t.sub.4 to t.sub.5. In this case, when live data d.sub.L can be received at time t.sub.4 but cannot be received at time t.sub.5, the warning generator 8 emits a warning or stops the robot 1.

(19) In contrast, when the distance between the robot 1 and the portable wireless operation panel 4 is further than the predetermined distance (which will be simply referred to hereinbelow as long distance case), the interval at which live data d.sub.L has to be received is set long. In the example shown in FIG. 2, this interval is set to be a time period longer than the time period from t.sub.4 to t.sub.6. In this case, even if live data d.sub.L cannot be received at the same interval as in short distance case or cannot be received at time t.sub.5, the warning generator 8 will not emit a warning or stop the robot 1.

(20) Further, when live data d.sub.L can be received within the time interval set for the long distance case, or, for example at time t.sub.6, the warning generator 8 will not emit a warning or stop the robot 1.

(21) It is also possible to provide such a system configuration that a warning is generated when the time period in which no live data has been received comes close to the predetermined criterion and the robot is stopped when the time period exceeds the predetermined criterion.

(22) As described above, according to the robot control system of the first embodiment of the present invention, since the distance between the robot and the portable wireless operation panel is measured so as to change the criterion for communication quality of wireless communication, i.e., the interval at which the live data should be received, in accordance with the distance, it is possible to improve convenience without losing safety.

Second Embodiment

(23) Next, a robot control system according to a second embodiment of the present invention will be described. FIG. 3 shows the relationship between the signal waveform and the interval at which reception of safety signals are required when the distance between the robot and the portable wireless operation panel is shorter than the predetermined distance and when the distance is longer than the predetermined distance, in the robot control system according to the second embodiment of the present invention. The robot control system according to the second embodiment is different from the robot control system of the first embodiment in that communication quality is monitored by measuring the exchanging interval of safety signals that are exchanged between the control device and the portable wireless operation panel to indicate whether or not the machine or robot should be stopped. The other configurations according to the second embodiment are the same as those in the robot control system according to the first embodiment, so a detailed description is omitted.

(24) The standards specify that the maximum moving distance of the robot from when the operator performs an action of inputting an emergency stop signal (pushing a bottom or the like) for stopping the robot up to the robot stopping, must be clearly provided. Therefore, the emergency stop signal is transmitted as a safety signal to be definitely confirmed within a certain period of time.

(25) When the distance is short, the interval at which the safety signals should be confirmed is made short so as to promptly stop the robot and thereby ensure safety. On the other hand, when the distance is long, the interval at which the safety signals should be confirmed is made long so as to ensure convenience.

(26) Even when the distance is long, the moving distance of the robot at the time of inputting the emergency stop signal must not exceed the maximum moving distance. Accordingly, in the case of the above operation, when the communication quality between the robot and the portable wireless operation panel is degraded at the time of a short distance case such that the safety signal has not been confirmed for a certain period of time, the robot will stop moving in a shorter distance than the maximum moving distance. The maximum moving distance is a value set by the manufacturer, and is not the distance to assure total safety. Therefore, making the robot stop moving a shorter distance than the maximum moving distance means an improvement of safety.

(27) With reference to FIG. 3, description will be given on how a warning is generated or how the robot is stopped based on whether or not the safety signals have been received within the interval at which the safety signals should be received, for each of the cases when the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance and when further than the predetermined distance.

(28) It is judged that wireless communication is not performed normally when the safety signal d.sub.S cannot be received. For example, FIG. 3 shows received waveforms when the transceiver of the portable wireless operation panel or the control device side transceiver of the control device transmits safety data d.sub.S at t.sub.7, t.sub.8 and t.sub.9.

(29) When the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance, the interval at which safety signals d.sub.S have to be received is set short. In the example shown in FIG. 3, this interval is set to be the time period from time t.sub.7 to t.sub.8. In this case, when the safety signal d.sub.S can be received at time t.sub.7 but cannot be received at time t.sub.8, the warning generator 8 emits a warning or stops the robot 1.

(30) In contrast, when the distance between the robot 1 and the portable wireless operation panel 4 is further than the predetermined distance, the interval at which safety signals d.sub.S have to be received is set long. In the example shown in FIG. 3, this interval is set to be a time period longer than the time period from t.sub.7 to t.sub.9. In this case, even if the safety signal d.sub.S cannot be received at the same interval as in the short distance case, or cannot be received at time t.sub.8, the warning generator 8 will not emit a warning or stop the robot 1.

(31) Further, when the safety signal d.sub.S can be received within the interval set for the long distance case, or, for example at time t.sub.9, the warning generator 8 will not emit a warning or stop the robot 1.

(32) As described above, according to the robot control system of the second embodiment of the present invention, since the distance between the robot and the portable wireless operation panel is measured so as to change the criterion for communication quality of wireless communication, i.e., the interval at which the safety signals should be received, in accordance with the distance, it is possible to improve convenience without losing safety.

Third Embodiment

(33) A robot control system according to a third embodiment of the present invention will be described. FIG. 4 shows the relationship between the signal waveform and the time period within which reception of error corrected data is permitted when the distance between the robot and the portable wireless operation panel is shorter than the predetermined distance and when further than the predetermined distance, in the robot control system according to the third embodiment of the present invention. The robot control system according to the third embodiment is different from the robot control system of the first embodiment in that the communication quality is monitored by measuring the interval at which data with an error-detecting code or an error-correcting code that are exchanged between the control device 2 and the portable wireless operation panel 4 is transmitted in error free condition or by measuring frequency of errors. The other configurations according to the third embodiment are the same as those in the robot control system according to the first embodiment, and therefore a detailed description is omitted.

(34) As shown in FIG. 4, when the distance between the robot 1 and the portable wireless operation panel 4 is shorter than the predetermined distance, a warning is emitted or the robot is stopped if error d.sub.e1 is detected even once.

(35) In contrast, when the distance between the robot and the portable wireless operation panel is distant, the time period in which reception of error-corrected data is permitted is set longer or the permissible frequency of error-corrected data is set higher. For example, if errors appear sporadically like errors d.sub.e2, d.sub.e3, d.sub.e4 as shown in FIG. 4, the robot will not be stopped.

(36) It is preferable that a warning is emitted or the robot is stopped when the number of times of consecutive errors or the frequency of errors exceeds the criterion. For example, in the example shown in FIG. 4, occurrence of two consecutive errors d.sub.e5, d.sub.e6 is permitted, but when three consecutive errors d.sub.e5 to d.sub.e7 take place, a warning is emitted or the robot is stopped. The occurrence of three consecutive errors is a mere example, and the number of consecutive errors is not limited to this example.

(37) As described above, according to the robot control system of the third embodiment of the present invention, since the distance between the robot and the portable wireless operation panel is measured so as to change the criterion for communication quality of wireless communication, i.e., the number of times of errors or the frequency of errors, in accordance with the distance, it is possible to improve convenience without losing safety.

Fourth Embodiment

(38) A robot control system according to a fourth embodiment of the present invention will be described. FIG. 5 shows the relationships between the signal waveform and the permissible radio wave intensity of the wireless communication signal when the distance between the robot and the portable wireless operation panel is shorter than the predetermined distance and when further than the predetermined distance, in the robot control system according to the fourth embodiment of the present invention. The robot control system according to the fourth embodiment is different from the robot control system of the first embodiment in that the communication quality is monitored by measuring the radio wave intensity of wireless communication. The other configurations according to the fourth embodiment are the same as those in the robot control system according to the first embodiment, so a detailed description is omitted.

(39) When the distance between the robot and the portable wireless operation panel is longer than the predetermined distance, the permissible level of the radio wave intensity of wireless communication signals is set lower. For example, as shown in FIG. 5, when the distance between the robot and the portable wireless operation panel is shorter than the predetermined distance, a warning is emitted or the robot is stopped because the radio wave intensity of the wireless communication signal at time t.sub.10 is lower than P.sub.1, the warning or stopping criterion.

(40) In contrast, when the distance between the robot and the portable wireless operation panel is far, no warning will be emitted or the robot will not be stopped because the radio wave intensity of the wireless communication signal at time t.sub.11 is higher than P.sub.2, the warning or stopping criterion.

(41) As described above, according to the robot control system of the fourth embodiment of the present invention, since the criterion for the radio wave intensity of wireless communication signals to emit a warning or stop the robot is set at P.sub.2 in the long distance case, which is lower than P.sub.1 in the short distance case (P.sub.2<P.sub.1), it is possible to improve convenience without losing safety.

Fifth Embodiment

(42) A robot control system according to a fifth embodiment of the present invention will be described. FIG. 5 shows a configurational diagram of a robot control system according to the fifth embodiment of the present invention. The robot control system 105 according to the fifth embodiment is different from the robot control system 101 of the first embodiment in that the distance between the machine or robot 1 and the portable wireless operation panel 4 is measured by a sensor 16 including, at least, one of a laser sensor, a pressure sensor, an infrared sensor and a light curtain, arranged near the robot 1. The other configurations according to the fifth embodiment are the same as those in the robot control system according to the first embodiment, so a detailed description is omitted.

(43) Arrangement of the sensor 16 (a laser sensor, a pressure sensor, an infrared sensor, a light curtain and/or the like) capable of detecting entrance of an object near the robot 1 makes it possible to perceive the approach of the operator to the robot 1 when the operator carrying the portable wireless operation panel 4 enters a sensing range 160 of the sensor as indicated by an arrow in FIG. 6.

(44) It is impossible for a light curtain and the like to perceive the distance continuously. However, no problem will occur if there is no need to define a number of levels for loosening the criterion of communication quality. For example, by arranging a sensor at the boundary inside which the robot is operated, it is possible to provide such a configuration that the criterion of communication quality is made strict when the operator resides within the operation range, whereas the criterion of communication quality is loosened when the operator is out of the operation range.

(45) Further, it is not possible for the sensor alone to perceive whether or not the operator is carrying the portable wireless operation panel 4. However, when another means is used at the same time, for example, when an RFID (Radio Frequency Identifier) tag is mounted on the portable wireless operation panel, and therefore the RFID tag detector reads the tag when the portable wireless operation panel passes by the sensor, it is possible to perceive where the portable wireless operation panel 4 is, in a more reliable manner.

(46) Instead of the sensor, a fixed camera 18 for taking an image of the surroundings of the machine or robot 1 may be arranged as in a robot control system 105 as a modified example of the fifth embodiment shown in FIG. 7, and therefore the distance between the machine or robot 1 and the portable wireless operation panel 4 can be measured by analyzing the image taken by the fixed camera 18. When the fixed camera 18 is installed, and if the operator carrying the portable wireless operation panel 4 enters within the imaging area 180 of the fixed camera 18, it is possible by image recognition to perceive at which position the operator carrying the portable wireless operation panel 4 is relative to the robot 1.

(47) Determination of whether or not the operator is carrying a controllable portable wireless operation panel 4 can be realized by using an RFID tag or the like at the same time, similarly to the case of the sensor.

(48) Not limited to the above examples, the means for measuring the distance between the robot and the portable wireless operation panel can be realized by using various devices in combination, and can be selected as appropriate depending on the various usage conditions (the ambient conditions in the factory (dirt, fine particles, temperature), the number of robots and operators, the number of portable wireless operation panels, the frequency at which the installed site of the robot is moved).

(49) According to the robot control system of the embodiment of the present invention, since the distance between the robot and the portable wireless operation panel is measured so as to change the safety criterion for the quality of wireless communication, in accordance with the distance, it is possible to improve convenience without losing safety.