JPH07223190A - Robot control device - Google Patents

Abstract

PURPOSE:To accurately and quickly detect the abnormality of a robot by providing an action monitor section inspecting whether the sensor data fall within the allowable range of a predicted value, reporting to an orbit generation section when the sensor data deviate from the allowable range, and taking a necessary action. CONSTITUTION:An action monitor section 6 has a sensor data inspection table. The predicted value of the sensor data is calculated together with the target value to be instructed to a servo controller 4, and it is repeatedly updated during the operation of a robot 7. The action monitor section 6 receives the sensor information from a sensor input section 5 and inspects the deviation from the allowable range according to this table. When the allowable range is exceeded, the abnormality is reported to an orbit generation section 3, and the orbit generation section 3 stops the robot 7 and reports the failure of the basic action to an action plan section 2. The abnormality is detected, and the work action can be re-planned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller having a function of detecting abnormality in robot operation by monitoring sensor information.

[0002]

2. Description of the Related Art A conventional robot controller is shown in FIG.
A robot controller 1 is a robot language interpreter 1 for decoding an operation program 11 in a robot language.
0, a trajectory generation unit 3 that generates a trajectory of each joint necessary for a basic operation from the decoding result, a servo control unit 4 that drives a joint by receiving a target angle of each joint, and a sensor input unit 5 The robot is controlled by feeding back information from the force sensor 9 of FIG. 7 and a position detector (not shown) attached to each joint. When detecting a robot operation abnormality from the output of the sensor, the robot operation program captures the sensor information and determines whether or not the value is within a preset range.

[0003]

However, there is a problem that the output of the force sensor greatly changes according to the change of the hand posture of the robot. If the output of the force sensor greatly changes according to the change in the hand posture, it is not abnormal. Therefore, if the value is set to be within the normal range, the abnormality during normal work will be overlooked. On the other hand, JP-A-3-
Japanese Patent No. 79293 discloses a table that holds a table of the maximum allowable droop amount corresponding to a speed command value and detects a robot abnormality from a deviation amount (droop amount). Since it is detected, it cannot be applied to the case where no positional deviation occurs (for example, when the force is controlled at a constant position). Therefore, an object of the present invention is to provide a robot control device capable of monitoring a robot abnormality by using a predicted value of force sensor information that dynamically changes during robot operation and data of an allowable range.

[0004]

In order to solve the above-mentioned problems, a plurality of sensor data created by a trajectory generation unit has a sensor data inspection table for storing predicted values and allowable ranges of each sensor data to be monitored. If the predicted value and the allowable range are input and stored in the sensor data inspection table, and the corresponding sensor data is input from the sensor input section to check whether it is within the allowable range of the predicted value Is provided with an operation monitoring unit characterized by notifying the trajectory generating unit and taking necessary measures. Further, the sensor data inspection table has an item of a time constant for averaging the sensor input cycle and the sensor input data, input the sensor data at the set cycle, and after averaging the sensor data at the time constant, It is characterized by inspecting the predicted value and deviation from the allowable range.

[0005]

[Operation] By using the predicted value of the sensor data set in time series by the trajectory generation unit and the data of the allowable range, the input sensor data is inspected to detect the sensor data whose predicted value changes during the robot operation. It becomes possible to monitor.

[0006]

EXAMPLES The present invention will be specifically described below based on examples. In FIG. 1, reference numeral 1 is a robot controller. The motion planning unit 2 plans a sequence of basic motions such as movement and grip required for work, and transfers the sequence to the trajectory generation unit 3.
The trajectory generation unit 3 generates the trajectory of each joint required for the basic motion, and the target joint angle is passed to the servo control unit 4. In the servo control unit 4, the robot is controlled by feeding back the information of the force sensor 9 of the robot 7 and the position detector (not shown) attached to each joint from the sensor input unit 5. The present invention is particularly effective for compliance control (impedance control), but can also be applied to a simple method of force control in which a force loop is added in normal position control.

The operation monitoring unit 6, which is a feature of the present invention, has a sensor data inspection table shown in FIG. The sensor data inspection table has items of a predicted value of force sensor data to be monitored, an allowable range, an input cycle, and an averaging time constant for each sensor information, and these items are asynchronously set by the trajectory generation unit 3. In particular, the predicted value of the sensor data is calculated together with the target value commanded to the servo control unit, and is repeatedly updated during the operation of the robot. The operation monitoring unit inputs the sensor information from the sensor input unit according to this table, and inspects the deviation from the allowable range. When the allowable range is exceeded, the trajectory generator 3 is notified of the abnormality, and the trajectory generator 3 makes the robot stand still and notifies the motion planner 2 that the basic motion has failed. Therefore, it becomes possible to detect an abnormality and re-plan the work operation.

FIG. 4 shows a concrete example of sensor data monitoring in this embodiment. This is an example in which a gripper of a robot grips an object and moves from A to B. At this time, the moving object may come into contact with another obstacle or drop the grasped object. In order to detect such an abnormality, force information may be monitored by a force sensor provided on the wrist of the robot. However, due to the influence of the gravity of the object to be grasped, the force sensor output greatly changes according to the change in the robot hand posture, and therefore it is not possible to detect the abnormality simply by setting the threshold of the input level. In this embodiment, a basic motion command “move_obj” shown in FIG. 4 is given from the motion planning unit 2 to the trajectory generation unit 3. The target movement position Xd, target speed Vd, gripping target object weight M, and center of gravity position Xg of the gripping target object in the wrist coordinate system are passed as arguments. The trajectory generator generates a desired trajectory for the required joint position from Xd and Vd and sends it to the servo controller 4. The posture of the robot wrist is calculated from the target joint position at this time, and the forces in the x, y, and z axis directions of the force sensor, which are predicted from the weight and the center of gravity of the object, and the moments around the axes are calculated by the operation monitoring unit. Set in the corresponding sensor data inspection table. Here, it is assumed that the other items of the sensor data inspection table are set to appropriate values at the time of initialization of the basic operation command.

The operation monitoring unit 6 collects the actual data of the force sensor at a designated input cycle, averages the measured data at a designated time constant, and compares it with a predicted value updated according to the posture of the robot. Do. When it deviates from the allowable range, the content is notified to the trajectory generation unit 2. A first-order lag filter or the like is used for averaging the sensor data to remove the influence of noise. In this way, it becomes possible to accurately and promptly detect and cope with abnormalities in robot operation.

[0010]

As described above, according to the present invention, even if there is a change in the output of the force sensor due to a change in the hand posture during the operation of the robot, it is easy to deviate from the predicted value of the force sensor information. There is an effect that the robot can be monitored and abnormality of the robot can be detected accurately and quickly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a specific embodiment of the present invention.

FIG. 2 is a block diagram of a conventional robot controller.

FIG. 3 is a diagram showing the contents of a sensor data inspection table according to the embodiment.

FIG. 4 is a diagram for explaining a specific example of force sensor monitoring during movement of a grasped object.

[Explanation of symbols]

 1 Robot control device 2 Motion planning unit 3 Trajectory generation unit 4 Servo control unit 5 Sensor input unit 6 Motion monitoring unit 7 Robot 8 Object 9 Force sensor 10 Robot language interpreter 11 Motion program

Claims (2)

[Claims] 1. A motion planning unit for planning a sequence of basic motions such as movement and grip required for work, and trajectory of each joint required for basic motion is generated from the output of the motion planning unit, and a target joint angle thereof. The robot by feeding back the trajectory generation unit that outputs the data, the sensor input unit that inputs the detection data of the force sensor attached to the wrist or arm of the robot, and the information of the joint angle sensor and the force sensor of the robot from the sensor input unit. In a robot control device configured by a servo control unit for controlling, the sensor data obtained from the sensor input unit generates an allowable range of the predicted value of the detection data of the force sensor corresponding to the output of the trajectory generation unit. , Check whether the predicted value is within the allowable range, and notify the trajectory generation unit if the allowable range is deviated, and take necessary measures. Robot control apparatus characterized in that a work monitoring unit. 2. In the inspection, after a sensor input cycle and a time constant for averaging the sensor input data are set, the sensor data is input at the set cycle, and the sensor data is averaged at the time constant. The robot controller according to claim 1, wherein the predicted value and a deviation from the allowable range are inspected.