JPH0460171B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a slow start position that can soften the shock at start-up in positioning control of work equipment such as booms, arms, and buckets of construction machines such as hydraulic excavators. This relates to a control device.

(Prior art) In position control, which positions a work equipment, etc. to a target position at a speed according to the deviation between a set value and a detected value of the current position, if the work equipment is driven with the given speed command as it is, the work equipment suddenly moves. This may cause an unpleasant shock to the operator or cause the dirt in the bucket to fall.

Conventionally, as shown in Japanese Patent Application Laid-open No. 55-7335, a method to reduce this impact is to change the set value of the target position by changing the relative movement amount from the current position to the set value via a temporary delay element. A soft start control device for a work machine is known in which the deviation from the detected value of the current position gradually increases from 0.

In addition, in order to improve positioning accuracy, it is necessary to increase the feedback gain in feedback control, and increasing this feedback gain increases the change in speed command to the drive system, which causes shock when the work equipment moves. This is particularly noticeable when the target position is far away.

In order to avoid this, in the conventional soft start control device disclosed in the above publication, the value of the feedback gain is uniformly switched in two stages in accordance with the magnitude of the deviation using a compensator.

However, setting the deviation so that it gradually increases from 0 at the initial stage of startup and driving with the corresponding speed command to perform slow startup control takes extra operating time, and it is difficult to shorten the operating time and position Even in compensators designed to improve accuracy, the operating time becomes longer due to the use of a smaller feedback gain.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention is capable of performing slow start control that does not give an unpleasant shock to the operator when driving a working machine in a construction machine, and also enables the target position to be quickly reached with high precision. The object of the present invention is to provide a slow start position control device that can perform position control.

(Structure of the Invention) The present invention provides a position control device for a working machine in a construction machine that moves a controlled object at a speed according to a deviation between a target position and a detected position. a calculation means that calculates a speed command by inputting the detected value of the work machine position at the time of control start and multiplying these deviations by a preset feedback gain; Find the change value between the speed command based on the deviation at the position and the speed command based on the deviation at the previous position, compare this change value with the maximum allowable value set in advance, and if the change value is less than the maximum allowable value, the current position The speed command calculated based on the deviation of is used as the corrected speed command at the current position, and if the above change value is greater than the maximum allowable value, the value obtained by adding the maximum allowable value to the speed command at the previous position is used as the corrected speed at the current position. The present invention is characterized in that it has a calculation means for calculating as a command, and the calculation means and drive means are connected so that the working machine can be started based on the modified speed command.

In the above configuration, the change value of the speed command for each target position in driving the work equipment, that is, the increase can be regulated to be below the maximum allowable value in practice without giving an unpleasant shock to the operator, and the maximum allowable value The work equipment can be moved based on a modified speed command that makes maximum use of the range of speed changes up to The working machine can be started slowly based on the command, and the positioning can be performed with high accuracy and delays in reaching the target position can be avoided.

(Embodiment) Fig. 1 shows a basic embodiment of the slow start position control device of the present invention, where 1 is a control start command generating means such as a switch, and 2 is a control start command generating means such as a switch, and 2 is a control start command generating means for controlling a target position (set value) by manual operation. Reference numeral 3 indicates an electrical setting means, numeral 3 indicates a current position detector of the working machine, numeral 4 indicates an arithmetic processing unit, and numeral 5 indicates a driving means for the working machine.

This slow start position control device connects a control start command generating means 1, a target position setting means 2, and a current position detector 3 to an arithmetic processing device 4 so that a control start command, a set value, and a detected value can be input, respectively. Based on the corrected speed command output from the processing unit 4, the drive means 5 starts the working machine and moves it in the direction of the target position, and then the processing unit 4 and the drive means 5 start the work machine again based on the detected value of the moved position. The work machine is moved and these steps are repeated until the target position is reached.

The current position detector 3 uses, for example, an encoder, a potentiometer, etc., and connects them to an arm, boom,
It is provided at each hinge of a working machine such as a bucket cart, electrically detects the current position of the working machine, and is connected to the arithmetic processing unit 4 via an A/D (analog/digital) converter or the like.

The drive means 5 includes a control valve drive amplifier 6, a control valve 7, a work machine cylinder 8, etc., and receives a speed command signal from the arithmetic processing unit 4, and receives a speed command signal from the control valve drive amplifier 6 to determine the switching direction of hydraulic oil, the pressure, and the like. Control signals are issued to various control valves 7 that control flow rates, etc.
Hydraulic oil flows into and out of the working machine cylinder 8, and the working machine cylinder 8 expands and contracts, thereby moving each working machine in the direction of the target position.

Next, the processing procedure of the arithmetic processing unit 4 will be explained with reference to the flowchart shown in FIG.

When starting the arithmetic processing unit 4 and starting the slow start position control, in step _S1 , zero is set as the initial value of the pre-position speed command value _V0 used in the arithmetic processing step.

In step _S2 , the control start command signal, the set value θr of the target position, and the detected value θ of the current position are input from the control start command generation means 1, the target position setting means 2, and the current position detector 3, and the process proceeds to step _S3 . determine whether or not to start control based on the control start command signal,
If YES, proceed to the next step.

In the next step, step _S4 , a deviation E is calculated as the difference in relative movement amount from the input setting value θr and the detected value θ, and this deviation E and the feedback gain K set in step _S5 are calculated. The speed command value V at the current position is calculated in step _S6 .

In step _S7 , the speed change is calculated as the difference between the speed command value V calculated in step _S6 and the speed command _V0 at the previous position input as the initial value or the speed command _V0 set in step _S12 described later. A value ΔV is calculated, and this speed change value ΔV is compared in magnitude with the maximum permissible speed change value ΔVmax set in step _S8 in step _S9 .

Here, as the maximum allowable value ΔVmax, the maximum value is adopted among the speed changes corresponding to the impact that does not give a shock to the operator, among the shocks that occur with the speed change in driving the work machine.

If the speed change value ΔV when driving from the current position is smaller than the maximum allowable value ΔVmax in step S ₉ , then in step S ₁₀ the corrected speed command value is set to drive the work equipment using the speed command value V at the current position.
Vs, and conversely, when the speed change value ΔV at the current position is larger than the maximum allowable value ΔVmax, in step _S11 , the value obtained by adding the maximum allowable value ΔVmax to the speed command value V ₀ at the previous position is corrected at the current position. Let the speed command value be Vs.

Then, when repeating the calculation process of the corrected speed command value again based on the work equipment position after moving according to this corrected speed command, the speed command value at the previous position (i.e. current position) used for this process
In step _S12 , the corrected speed command value Vs at the current position is replaced as _V0 , and in step _S13 , the corrected speed command value Vs is outputted as an electric signal to the driving means 5.
Return to step S ₂ again, and proceed from step S ₂ .
Step S ₄ , step S ₆ , step S ₇ , step S ₉ to step S ₁₃ are repeated to output the corrected speed command value at the next working machine position.

Here, once the maximum permissible speed change value ΔVmax in step _S8 is set once, there is no need to set it again unless it is changed later.

These calculation processes end when the control start command is NO in step _S3 .

In this way, the arithmetic processing unit 4 controls the position control of the work equipment by keeping the change in the speed command between the front position and the current position within a range that does not cause an unpleasant shock to the operator, and keeping the speed change from zero. Instead of increasing the speed gradually, the speed change up to the maximum speed change value in the above range is allowed from the beginning of startup, and a modified speed command is output that effectively uses the maximum speed change within the maximum allowable value. ing.

By driving the working machine based on this modified speed command signal, position control can be performed such that the working machine can reach the target position in a short time under substantial slow start control.

FIG. 3 shows the relationship between the movement speed command value of the working machine and time, and the change in movement speed over time due to the corrected speed command in the present invention is shown by a solid line.

Here, the section in which the speed command shows a constant value Vmax regardless of the passage of time is determined by the maximum speed limit due to the mechanical capacity of the drive means 5, and the speed command has the same value as the speed change value ΔVmax at the initial stage of startup. The drive starts from a speed command value V that is smaller than the speed change value ΔVmax, and when it reaches point a, it enters the driving state based on the above constant value Vmax, and continues in that state until the deceleration start point b, which is automatically determined by feedback control. .

Furthermore, the broken line in the same figure shows the case where the value of the feedback gain K is increased using the conventional device described above. According to this, the change in the speed command becomes large and a large shock is generated. This tendency becomes larger as the value of feedback gain K increases.

In other words, in the present invention, even if the value of the feedback gain K at step _S5 becomes large, the
In the comparison calculation process from _S9 to _S11 , the corrected speed command value Vs is determined based only on the relationship between the speed change value ΔV and the maximum allowable speed change value ΔVmax, regardless of the magnitude of the feedback gain K. This allows for highly accurate slow start position control without generating an unpleasant shock to the operator.

If a dead zone occurs in the control valve 7 due to a delay in operation, the initial value setting before the start of control in step _S1 of the arithmetic processing unit 4 in FIG. If Vd is set as shown by the dashed line in FIG. 3, the delay due to the dead zone of the control valve 7 can be eliminated, leading to a reduction in the time required to reach the target position.

(Effects of the Invention) According to the slow start position control device for a work machine in a construction machine of the present invention, the change in speed command for making the work machine reach a target position between the previous position and the current position can be controlled in a manner that does not make the operator uncomfortable. It is possible to regulate speed changes within a range that does not cause shock, and
Rather than gradually increasing the speed change from zero, the speed change is allowed from the beginning of startup to the maximum speed change value in the above range, and the speed is corrected by making full use of the speed change range up to the maximum allowable value. Work equipment can be moved based on commands.

Therefore, by driving the work equipment based on this modified speed command signal, the work equipment is effectively controlled to start slowly, compared to the conventional case where the speed change is gradually increased from zero. Position control can be performed to reach the target position in a short time.

In particular, even if the feedback gain is increased to improve positioning accuracy and shorten operation time, the work equipment must be driven based on a modified speed command that limits the speed change at startup to less than the maximum allowable value above. Even when approaching the target position from a distance, it is possible to perform high-accuracy, quick, and gradual starting position control without generating an unpleasant shock to the operator.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, Fig. 2 is a flowchart showing the processing procedure of the arithmetic processing unit shown in Fig. 1, and Fig. 3 shows the relationship between speed command value and time. FIG. DESCRIPTION OF SYMBOLS 1... Control start command generating means, 2... Target position setting means, 3... Current position detector, 4... Arithmetic processing unit, 5... Drive means, 6... Control valve drive amplifier, 7... Control Valve, 8... Work machine cylinder.

Claims (1)

[Claims] 1. In a position control device for a work equipment in a construction machine that moves a controlled object at a speed according to the deviation between the target position and the detected position, the set value of the target position and the work equipment position at the time of control start are determined based on a control start command. a calculation means for calculating a speed command by inputting detected values and multiplying these deviations by a preset feedback gain, and a speed command based on the deviation at the current position of the work equipment calculated by this calculation means. Find the change value between the speed command and the speed command based on the deviation at the previous position, compare this change value with the maximum allowable value set in advance, and if the change value is less than the maximum allowable value, the change value is calculated based on the deviation at the current position. calculation means for calculating the speed command at the previous position as a corrected speed command at the current position, and when the change value is greater than the maximum allowable value, a value obtained by adding the maximum allowable value to the speed command at the previous position as the corrected speed command at the current position; A slow start position control device for a working machine in a construction machine, characterized in that the calculating means and the driving means are connected to each other so that the working machine can be started based on the corrected speed command.