JPS62274309A - Servo system - Google Patents

Abstract

PURPOSE:To hold an operation path for multiple axis contour control and to limit torque by increasing or decreasing the driving speed of each unit when the output torque value of one of servo drive units deviates from a specific limit range. CONSTITUTION:A high-priority controller 2 sets a high-level torque limit value -VT to uninverted input terminals of comparators 5 of respective servo drive units 11-13 through a control bus 3 previously and sets a low-level torque limit value -VT to inverted input terminals of comparators 6. Output torque values V which are detected in the units 11-13 during operation are inputted to the inverted input terminals of the comparators 5 and uninverted input terminals of the comparators 6. Then, the detected torque values V are compared with the high or low torque limit value +VT or -VT at any time to obtain a plus or minus saturated output value according to their large/small relation.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a servo system used in NC devices, robots, and the like.

(Prior art) Conventionally, in this type of servo system, a torque limiting circuit is installed in each servo drive unit.
Torque limitations were applied to each axis independently of each other. FIG. 3 is a diagram showing an example of a conventional torque limiting circuit for one axis, and FIG. 4 is a graph showing the relationship between the output torque value detected by the circuit of FIG. 3 and the operating range.

The high torque limit value +V is input manually to the non-inverting input terminal of the voltage follower 5, and the output torque value V of the servo drive unit detected on the resistor R is compared with the high torque limit value +V through the diode 7. . Similarly, the low torque limit value -v is input to the non-inverting input terminal of the voltage follower 6, and the output torque value V is compared with the low torque limit -v through the diode 8. In other words, the voltage followers 5 and 6 operate as torque limiters, and when the output torque value V of the unit deviates from the set range of +Vτ~v, the output torque V is adjusted to the normal operating range +Vτ~ by accelerating or decelerating the drive speed. It was stored in a V-cho.

[Problem that the invention seeks to solve]

In the conventional servo system described above, the output torque limiter performs limiting operations on each axis independently of each other, so when performing multi-axis contour control, if the torque limiter operates on the negative axis as well, the overall operation will be affected. There is a drawback that the route changes.

[Means for solving problems]

The servo system of the present invention includes a comparison means that is installed in each of the plurality of servo drive units and compares the output torque value with set high and low torque limit values, and sets the high and low torque limit values in each servo drive unit. By the output of the setting means and the comparison means,
detecting means for detecting that the output torque value of at least one servo drive unit has increased beyond the high torque limit value or decreased beyond the low torque limit value; The servo drive unit includes speed command means for outputting a speed command value for decelerating or accelerating the speed of all servo drive units at a common ratio until the output value exceeding the torque limit value falls within the torque limit value.

(Function) In this way, while the servo system is operating, the output torque values of all servo drive units are monitored, and any
If the limit range is exceeded at any time, the drive speed of all units is accelerated or decelerated at a common ratio to bring the exceeded output torque value within the specified limit range without changing the overall operating path. can.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the servo system of the present invention, and FIG. 2 shows each servo drive unit 1 of the embodiment of FIG. 13 is a torque comparison circuit diagram.

Multiple servo drive units1. ．． Reference numerals 12 and 13 denote units for driving each axis of the mechanical device, each having a torque comparison circuit composed of a first comparator 5 and a second comparator 6, as shown in FIG. There is. The host controller 2 has an arithmetic circuit, and is a controller that commands the torque limit value of each servo drive unit 11 to 13 and the drive speed of the entire device, and controls each servo drive unit II to 12 via a control bus 3.4.
13.

Next, the operation of this embodiment will be explained.

The host controller 2 previously controls each servo drive unit 1 via the control bus 3. ~13, the respective high torque flTI is applied to the non-inverting input terminal of the first comparator 5.
J limit value +vT is set, and each low torque fI11 limit value -■T is set to the inverting input terminal of the second comparator 6. Since the output torque value V detected inside each of the servo drive units II to 13 is input to the inverting input terminal of the first comparator 5 and the non-inverting input terminal of the second comparator 6 during operation, , this detected torque value V and the higher or lower torque limit value + V7
．． -VT is always compared, and the output shown in Table 1 below can be obtained.

The values in Table 1 output from the first and second comparators 5 and 6 are reported to the higher-level controller 2 via the control bus 4, and the higher-level controller 2 monitors and detects the reported values with its arithmetic circuit. When the torque value V exceeds the range of high torque limit value + 7 to low torque limit - 1, the speed command value being set to all servo drive units II to 13 is set to a common ratio via the control bus 3. Adjust. As a result, the output torque value V can be kept within the above range, over-torque or under-torque can be eliminated, and the operating path of contour control can be prevented from changing.

(Effects of the Invention) As described above, the present invention provides a comparison means for comparing an output torque value and a torque limit value in each servo drive unit, and a setting means for setting a torque limit value in a host controller, and a setting means for setting a torque limit value, and an output torque A detection means for detecting that the value exceeds the limit range, and a speed command means for accelerating or decelerating the speed of all servo drive units at a common ratio according to the output of the detection means, and even if any one of the servo drive units When the output torque value deviates from the predetermined limit range, the drive speeds of all units are accelerated or decelerated without breaking the mutual relationship4, so that the operating path does not overlap for multi-axis contour control. This has the effect of limiting torque.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the servo system of the present invention, Fig. 2 is a torque comparison circuit diagram of each servo drive unit 11 to 13 of the embodiment of Fig. 1, and Fig. 3 is a diagram of a conventional single axis. 4th diagram showing an example of the torque limiting circuit of
The figure is a graph showing the relationship between the output torque value detected by the circuit of FIG. 3 and the operating range. 11-13-----Servo drive unit, 2
・−・−−−−− Upper controller, 3.4−−−−−
-Control bus, 5.6...Comparator, V ----・----Output torque value, +v t...
...High torque limit value, -V--...Low torque limit value.

Claims (1)

[Claims] In a servo system such as an NC device or a robot, it is installed in each of a plurality of servo drive units,
a comparison means for comparing an output torque value with set high and low torque limit values; a setting means for setting the high and low torque limit values in each servo drive unit; and at least one servo drive unit based on the output of the comparison means. detecting means for detecting that the output torque value of the output torque increases beyond the high torque limit value or decreases beyond the low torque limit value; 1. A servo system comprising a speed command means for outputting a speed command value for decelerating or accelerating the speed of all servo drive units at a common ratio until the torque output value falls within the torque limit value.