JPS62239204A - Method for positioning origin of robot - Google Patents

Abstract

PURPOSE:To eliminate a limit switch and to reduce cost by detecting an increase current flowing in a motor which drives an axis so as to decide the origin of the axis when the axis reaches a mechanical end and intends to move further. CONSTITUTION:When the axis in a position P is shifted to the mechanical end side and reaches the mechanical end by the rotation of the motor, the mechanical end becomes an obstacle and the rotary torque of the motor increases. As a result, a current flowing in the motor increases. When the current exceeds a present threshold, a current detection circuit 17 outputs a signal PS. The signal PS is supplied as a reversely driving signal of the motor, whereby the motor is driven reversely and the axis is reversed. A Z signal is generated from an incremental encoder when the axis makes at least one turn. A clear pulse from an AND circuit 11 is supplied to a clear input CLR in an up/down counter 13 and said counter 13 is cleared, whereby the origin is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of application for limb rotation] This article 6 relates to an origin positioning method for determining the origin position with respect to the L degree of freedom of a robot having the RID degree of freedom.

[Prior art]

As is well known, a robot with a strong degree of freedom consists of a robot arm that has a vertical axis so that it can move freely in three-dimensional space, an electric motor that moves this arm axis, and a robot arm that can move freely in three-dimensional space. It is equipped with a servo machine that drives and controls the electric motor and determines the position of the arm.

By the way, in the servomechanism, the position detector of the robot is often used to match the # of the bite type encoder and the uptown counter from the point of view of cost and accuracy. It is counted by an up-down counter and used as position information. However,'v
! When LuR is turned off, the contents of the counter disappear,
Power on! The position information shown by the counter is random information that has no relation to the robot position. Therefore, normally, each axis of the robot is returned to its original position, and the absolute position data is recorded by counting pulses from this original position. Since the robot is controlled based on absolute position data, this origin alignment is essential.

Next, the conventional method of locating the origin position 1q
No. 17) will be explained with reference to the accompanying drawings.

FIG. 3 is an illustrative diagram of a conventional method for determining the origin position, and FIG. 9 is a block diagram of an intoxication circuit used when this method is applied.

In FIG. 3, what is conceptually indicated by a straight line 4 is an operating region corresponding to one degree of freedom of a robot having a large number of degrees of freedom. In this operating range, the range between A and B is the range that can be controlled by the control/arithmetic means built in the control panel of the robot, such as microcomputer software, that is, the operating range during playback. Further, a normal rotation operation limit LS is provided at both ends of the operation region as an operation limit switch means.
(Limit switch) 2. Reverse operation limit LS8 is installed. Then, when LS2 or LS3 is turned on by a dog or the like, the drive unit, for example, the electric motor, is instantly turned off.

5 to 9 are time axes, which correspond to 12 m4 of spatial movement orders. The time axis 5 shows a pigeon frequency pulse signal outputted from an incremental encoder (not shown), and the time axis 6 shows the pulse signal of the pigeon frequency outputted from the n encoder which outputs one at nIls@ (or t rotation port) of this pulse signal. This is the Z signal of time +ll
l7 indicates the output signal of the reverse operation limit LS8, and the time axis 8
corresponds to the Q output of the D-type clip-flop lO as a storage means shown in FIG. And time axis 9
corresponds to the output of the AND circuit 11 in FIG.

In FIG. 9, 12 is a pulse separation circuit into which read signals and lag signals corresponding to forward and reverse rotation of the 1-minute encoder are input, and 18 is an up/down counter that receives pulse signals from this pulse separation circuit, and outputs Each bit line is connected to the data bus of the microcomputer. The output of the AND circuit [l is applied to the terminal for clearing each bit of the up/down counter 18 (all zeros). A high level signal H is always given to the data input of the flip-flop IO, and its clock input GK is
The output of the reverse operation limit LSi3 is determined by human power. That is,
This flip-flop 10 is set when the reverse rotation limit LS8 rises from off to on, and outputs a high level signal from the Q output. Note that the output of the AND circuit [l is connected to the clear input of the flip-flop 10 via the delay circuit 14.

A method for centering the robot's origin position will be explained with reference to FIGS. 3 and 9. First, put the IVL into the robot and set it to the origin alignment mode, and the origin alignment will start.

The shaft located at position P (or other than range AB, for example, position 1effi P') is moved in the direction of reverse rotation limit LS8 by a remote control box or manually (so-called die-cut operation). When LS8 is actuated by the dog of the axis and turned on, the movement of this axis is temporarily stopped. At the same time, as shown in the circuit diagram of Fig.
qyu, P-+yノ1ノ^n, j-nJJLmuJ Yuyusa nru9, Shikashi, since no Z signal enters the AND circuit 11, AND IL! The first line must remain off.

Next, rotate the shaft in the forward direction. Two signals are output from the incremental encoder with a pulse signal, but from the point where the axis is stopped, the encoder is at least /[gI4i
Then, the first Z signal is output. Since these 2nd and 1st signals are high-level pulse signals, they pass through the AND circuit 11 and are outputted as clear pulses from the AND circuit [l to the clear manual input of the up/down counter 18, and are
? The flip-flop is cleared manually through circuit 14 (
output to the reset terminal). The up/down counter 18 is cleared by the clear pulse, and the flip-flop 0 is also reset by the next two signals, so the time of clearing, that is, the axis position provides the absolute home position. From this position, the counter 18 counts the pulse signals of the encoder, and the counted value gives the absolute (n+R data) of this axis.In this way, the origin alignment of 1 + iqh 9p is completed. The origin alignment is performed in the same way as above for the number of h - peaks, and the origin alignment of all axes of the robot is completed, completing the $1 song of the actual work.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional origin positioning method,
For the l-axis, which corresponds to each degree of freedom of the robot, a total of two limit switches, one at each end of the arm's limit movement range, must be installed, which not only increases costs, but also increases costs. As robots become more compact, the location of limit switches becomes a major issue.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for determining the origin position of a robot, which can determine the origin position of the robot without using a limit switch.

[Means to solve the problem]

This invention moves the axes to the mechanical end of the robot simultaneously,
When the shaft reaches the mechanical end and is about to cut further, an increased current flowing to the motor is detected, and then the shaft is reversed, and when the shaft is reversed, the n-th pulse generated from the pulse generating means is This is a method for determining the origin position of a robot, which is characterized in that the origin position of the axis is determined based on a pulse signal.

[Effect]

This invention detects the increased current flowing to the electric motor that drives the shaft when the shaft reaches the mechanical end and is about to become more effective.
This is a method of determining the origin position of the axis based on this detection result, and the origin position of the robot can be determined without using this pinching or limit switch.

〔Example〕

FIG. 1 is an illustrative diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing the electrical configuration of the same embodiment. In these figures, parts corresponding to those in FIGS. 3 and 9 are designated by the same reference numerals, and their explanations will be omitted.

In FIG. 1, 15 and 16 are time axes, which correspond to the spatial motion region 4. A time axis 15 represents the motor current flowing through the electric motor. The time axis [6 represents the output signal PS generated by the increased current detection circuit L7 shown in Figure @2. The increased current detection circuit 17 detects the current flowing through the motor, and generates a signal PS when the current flowing through the motor reaches a threshold value.

In the above configuration, when the power of the robot is turned on and the robot is set to the origin alignment mode, the origin alignment operation starts. In this origin alignment operation, first, for example, the shaft located at position P is moved toward the mechanical end side by rotation of the electric motor. When the shaft reaches the mechanical end building, the mechanical end becomes an obstacle and the rotational torque of the electric motor increases. As a result, the current flowing through the motor increases, and when the current flowing through the motor exceeds a predetermined threshold, the current detection circuit 7 outputs a signal PS. The clock of step 10 is supplied to the human power CK.

As a result, the flip-flop 10 reads the 1H' signal from the data input and outputs a high level signal from the Q output. Further, the signal P generated by the current detection circuit 17
S is also supplied as a reverse drive signal for the motor, which causes the motor to be driven in reverse so that the shaft is reversed. On the other hand, as the shaft rotates, a pulse signal (reference numeral 5 in FIG. 1) is outputted from the incremental encoder, and count data is supplied from the pulse separation circuit 12 to the up/down counter 18 in accordance with this pulse signal. Additionally, the incremental 1/coder outputs a Z signal every t rotations of the shaft.

Then, when 'ill is reversed at the mechanical end and rotates at least once and -pc, a Z signal is generated from the incremental encoder IL, and this Z signal is supplied to the AND circuit E[. And Ir! When this Z(i) and the output signal of the flip-flop [0 are both supplied to the first path 11, the AND circuit 11 outputs a clear pulse.

This clear pulse is supplied to the clear input CLH of the up/down counter 18, and the up/down counter 13 is cleared. In other words, the jix point crying 1c point should be done. Well, clear pulse is a! The reset power CLR of the flip-flop lO is supplied via the extension circuit 14, and the flip-flop 70 is reset.

In the above embodiment, the origin position is determined by the first Z signal generated after the axis is reversed.
2.8.4 after axis reversal. ..., the origin position may be determined using any nth Z signal.

〔Effect of the invention〕

As described above, according to the present invention, when the shaft reaches the mechanical end and is about to move further, the origin position of the shaft is determined by detecting the increased current flowing through the ILF and the drive that drive the shaft. So, you can easily use a limit switch on the robot arm! The east point position and direction can be determined, resulting in cost reduction and space saving for the robot body.

[Brief explanation of drawings]

FIG. 1 is an illustrative diagram showing a method according to an embodiment of the present invention;
@Figure 2 is a block diagram showing the configuration of an electric circuit that implements the method shown in Figure 3, Figure 3 is an illustrative diagram showing the conventional origin positioning method, and Figure 19 is an electric circuit that implements the method shown in Figure 3. In the block diagram showing Hironari. 4,...Robot axis movement 1/l: area, 6.
...Z signal, 9...Clear pulse, kl
......AND circuit, 15...Motor rt
t current, 16... 噌) In current detection control PS, 1
7...Increase supercurrent habituation circuit.

Claims (1)

[Scope of Claims] A robot equipped with a plurality of axes, an electric motor that drives the axes, and a pulse generation means that generates a pulse signal every rotation of the axes, wherein the axes are rotated toward a mechanical end of the robot. When the shaft reaches the mechanical end and is about to move further, it produces an increased current flowing through the electric motor, and then the shaft is reversed, and when the shaft is reversed, the pulse generating means generates n. A method for positioning the origin of a robot, characterized in that the origin of the axis is determined based on the (n=positive integer)th pulse signal.