JPH0259291A - Detecting method for collision of robot arm - Google Patents

Abstract

PURPOSE:To realize the detection of the collision of robot arms of high responsibility having no need for a sensor by directly detecting the current relating to a torque and proportion by the collision detecting part of the inside of a numerical value arithmetic processer and detecting the turbulence thereof. CONSTITUTION:The waveform of the current flowed in the AC servo motor 13 which drives a robot arm is read in the collision detecting part 16 of the numerical value arithmetic processer 18 inside. The collision detecting part 16 detects the turbulence of the read current waveform, deciding the presence of the collision of the robot arms from the turbulence of the detected current waveform and in the case of deciding that the robot arms are collided, outputting the stop signal of the robot arm to a main side 4. Due to the collision being decided by detecting the current by the collision detection part 16, the need for a sensor for detecting collision is eliminated and also the collision detection from all directions can be done. Moreover, the torque sensitive to impact, i.e., the current is detected and processed softly, so the responsibility from detection to the stoppage of the robot arm can be quickened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a robot arm collision detection method for determining whether or not a collision has occurred by detecting disturbances in current waveforms when a robot arm collides.

Conventional technology ROBONO 1 - A method for detecting a collision of the arm and stopping the robot arm is to install a curtain sensor in front of the place where the robot arm 2 of the robot 1 is expected to collide, as shown in FIG. 3 is installed, and when the curtain sensor 3 detects an obstacle, the robot arm 2 is stopped to prevent a collision.

Problems to be Solved by the Invention However, in the conventional method using the curtain sensor 3, (1) the curtain sensor 3 must be installed around the robot 1 because the location where the robot arm 2 collides cannot be specified;

(2) During maintenance, it is necessary to turn off the curtain sensor 3, which is inconvenient in terms of operation and poses a problem in terms of safety.

(Mari: The response until the robot arm 2 stops, as detected by the curtain sensor 3, is poor.

It has the following problems.

The purpose of the present invention is to directly detect the current that is proportional to the torque in the collision detection section in the numerical processing processor (hereinafter referred to as DSP), and detect its disturbance, thereby providing a response that does not require a sensor. The present invention provides a method for realizing highly accurate collision detection.

Means for Solving the Problems In order to solve the above problems, in the robot arm collision detection method of the present invention, in the processing of the collision detection section in the DSP, the waveform of the current flowing through the AC servo motor is sent to the collision detection section. A process of reading, a process of detecting disturbances in the read current waveform, a process of determining whether there is a collision of the robot arm from the disturbance of the detected current waveform, and a stop signal of the robot arm when it is determined that the robot arm has collided. It has a process to output.

In the present invention, in the collision detection section in the DSP, a current proportional to torque is directly detected and the presence or absence of a collision of the robot arm is determined. It becomes possible to stop the robot arm with a quick response without using the robot arm.

EXAMPLE An example of the present invention will be described below. FIG. 1 shows an embodiment of the present invention, which has an AC servo motor that drives a robot arm 2, and a microcomputer and a DSP.
2 is a block diagram of a device that performs position loop control, velocity loop control, and current loop control using the robot arm 2 and detects a collision of the robot arm 2. FIG. 4 controls robot 3,
This is the main section that gives position commands to the position/'-pu control section. 6 is a position loop control section sb which outputs a speed command from a position command and a feedback position signal; 6 is a transfer function GP of the position loop control section 6; 9 is a speed loop control that outputs a current command from a speed command and a fed-back speed signal, 8 is a transfer function Gs of the speed loop control section 7, and 9 is a differentiation for determining a speed signal from a position signal. 1° is a current control unit that outputs a voltage signal from the current command and the fed-back current signal to the AC servo motor, and 11 is a transfer function G of the current loop control unit 10.
, is. 12 is 'I for moving the AC servo motor
This is the part that performs pulse width conversion (PWM) on the E pressure signal, and 1
3 is an AC servo motor for driving the robot arm 2. 14 is an A/D converter ag for inputting the current flowing through the AC servo motor 13 into the DSP, and 15 is an encoder that provides a position signal from the rotation of the AC servo motor 13. Reference numeral 16 denotes a collision detection section which detects a current signal, determines whether there is a disturbance in the current or a collision, and outputs a stop signal to the main side 4 when it is determined that a collision has occurred.

Reference numeral 17 denotes a microcomputer that performs processing of the position loop control section 5 and the velocity loop control section 7. 18 is a numerical processor (DSP) that performs processing of the current loop control section 10 and the collision detection section 16;

FIG. 2 is an example of a flowchart of a processing algorithm in the collision detection unit 16. The flow will be explained in conjunction with the enlarged view of the current waveform in FIG. At step 19 in FIG. 2, a sample point 20 obtained by A/D converting the current '1π flow signal shown in FIG. 3 is input into the DSP 18. In step 21, the current sample point 2o and the sample point 2 one time ago stored in the memory are
2, the current slope data (change in current) is approximately calculated. In step 23, the current slope data obtained in step 21 is compared with the maximum MAX data among the slope data within a certain time T shown in FIG. 3, and if the current slope data is large, step 24 So, M.A.
Substitute the current slope data into the X slope data. In step 25, the current slope data is compared with the minimum MIN slope data among the slope data within a certain period of time T. If the current slope data is small, in step 26, the minimum MIN slope data is compared.
Substitute the current slope data into the N slope data. In step 27, as shown in FIG.
Calculate the angle α formed by the N slope data. In step 28, the absolute value of the angle α obtained in step 27 is compared with a certain threshold value, and if 1α] is small, a stop signal for the robot arm 2 is output in step 29. In step 3o, in order to store the time series data for a certain period of time T in memory, the data of the oldest sample point 31 is deleted, the data of the current sample point 21 is registered, and the data of the oldest sample point 31 is deleted. If the slope data is MAX slope data or M
In the case of IN slope data, the second largest or smallest slope data is replaced with MAX slope data or MIN slope data.

Normally, the current waveform when driving the robot arm 2 is as shown by the solid line 32 in Figure 4, and when a collision is detected, it is as shown by the broken line 33 in the figure, and the current waveform is approximately zero from the collision. ．．
At 3m5ec, the robot arm 2 stops.

In this embodiment, in the block diagram of FIG. 1, the processing of the velocity loop control section 5 and the position loop control section 7 is performed by the microcomputer 17. Processing may be performed.

In addition, the stop signal for the robot arm 2 is output to the main side 4, but it is also output to the microcomputer 17 and the DSP1.
A stop signal may be issued to a, and the stop processing may be performed.

Regarding the collision detection algorithm, Fig. 2 shows one example, and it is not necessary to use this algorithm.
It is assumed that any collision determination algorithm can be used, including the case of using I or the like.

Effects of the Invention According to the present invention, the collision detection section of the DSP detects the current,
Since a collision is determined, a sensor for collision detection is not required, and a collision can be detected from any direction.

Furthermore, since torque (current), which is sensitive to impact, can be detected and processed by software, the response from collision detection to stopping the robot arm is quick.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a collision detection device for a robot arm according to an embodiment of the present invention, Fig. 2 is a flowchart of a collision detection algorithm, and Fig. 3 is an explanatory diagram showing a method for determining a collision from a current waveform. , FIG. 4 is an explanatory diagram showing a current waveform with respect to time. FIG. 5 is a perspective view of a detection device for a robot arm using a conventional curtain sensor. 4...Main section, 6...Position loop control section, 7...Velocity loop control section, 10...
... Current loop control section, 13 ... AC servo motor, 16 ... Collision detection section, 17 ...
Microcomputer, 18... Numerical calculation processor. Name of agent: Patent attorney Shigetaka Awano and 1 other person H+

Claims (1)

[Claims] A method for detecting a collision of a robot arm by using a robot equipped with an AC servo motor that drives the robot arm, performing position loop control, speed loop control, and current loop control using a microcomputer and a numerical processor, a step of reading the waveform of the flowing current with a collision detection section in the numerical processor;
A process of detecting disturbances in the current waveform read by the collision detection unit, a process of determining whether there is a collision of the robot arm from the disturbance of the detected current waveform, and a process of generating a stop signal for the robot arm when it is determined that the robot arm has collided. A method for detecting a collision of a robot arm, comprising: a step of outputting a collision detection method for a robot arm.