CN100371122C - Electronic differential speed automatic tracking welding trolley drive control device - Google Patents

Abstract

The utility model relates to a driving control device of an electronic differential speed automatic tracking welding trolley. It mainly solves the technical problems such as complex structure of the control system, low control precision and high cost when the existing welding trolley is automatically tracked. The main points of its technical solution are: it includes a welding trolley driven by left and right wheels, the left and right driving wheels of the welding trolley are respectively driven by stepping motors, and a differential speed controller connected with a sensor that characterizes the relative position characteristics of the welding torch and the welding seam Connect the differential speed ratio to the PWM circuit, and connect to the stepper motors of the left and right driving wheels of the welding trolley. It adopts single-chip microcomputer and differential speed proportioner circuit, combined with PWM control technology, the single-chip microcomputer controller outputs welding seam deviation information in real time, and then optimizes and matches the speed of the two driving wheels through the differential speed proportioner circuit, and adjusts the speed of the left and right wheels in a timely manner. Realize seam tracking. The structure of the welding seam tracking process control system of the welding trolley is simple, the control precision is high, the tracking effect is good, the operation is stable and reliable, and the practicability is strong.

Description

Electronic differential speed automatic tracking welding trolley drive control device

technical field

The invention relates to an electronic differential drive device for automatic tracking of a welding trolley.

Background technique

During the welding process, in addition to requiring the welding torch to track the weld seam in real time, it should also ensure that the tangential speed of the welding torch along the weld seam remains constant to stabilize the welding specification. The requirements for the automatic tracking welding trolley, in addition to realizing general straight-line walking, should also be able to adjust the speed of the wheels in a timely manner according to the deflection of the weld seam, and a certain proportional relationship should be maintained.

At present, for the two-wheel drive welding trolley, the methods to realize these functions include: limit control turning method, mathematical model method, real-time adjustment turning radius method and fuzzy control method. The principle of the limit control turning method is that when the horizontal tracking slider reaches a specific position, the welding trolley is controlled to turn in the corresponding direction with a fixed radius; the mathematical model method calculates the trajectory of the welding bead based on the detected data and controls the welding trolley. Movement; the principle of real-time adjustment of the turning radius method is: the control system detects and analyzes the model parameters that reflect the relationship between the weld trajectory and the position of the welding trolley at a fixed frequency, and determines the turning radius according to a certain adjustment rule according to the parameters; the principle of the fuzzy control method It can be described as: According to the position and movement trend of the horizontal adjustment slider, judge the relative positional relationship between the current weld seam and the welding trolley, and then determine the change of the turning degree of the welding trolley.

Among the above four methods, the limit control turning method and the mathematical model method have a long and unstable adjustment period, and the tracking accuracy is not easy to guarantee; although the real-time adjustment turning radius method has a slightly smaller error, the calculation workload is relatively large, and the implementation is relatively complicated. It is also not suitable for automatic seam tracking. In view of the above contradictions, we use a single-chip microcomputer and external hardware circuits, combined with PWM control technology, to design an electronic differential, which can adjust the speed of the left and right wheels in a timely manner according to the welding seam deviation information to achieve tracking.

Contents of the invention

The purpose of the present invention is to provide a drive control device for an electronic differential automatic tracking welding trolley with simple circuit, low cost, high sensitivity and precision, and good reliability.

The technical solution adopted by the present invention to solve the technical problem is: it includes a welding trolley driven by left and right wheels, and the left and right driving wheels of the welding trolley are respectively driven by stepping motors, and its feature is: opposite to the welding torch and the welding seam The differential speed controller connected to the arc sensor of the position characteristic is connected to the differential speed proportioner to the PWM circuit, and connected to the stepper motors of the left and right driving wheels of the welding trolley. The differential speed controller outputs a welding seam deviation signal through a D/A chip. The welding trolley adopts a double rear wheel drive welding trolley without guide rails. The differential speed controller is composed of MCS-51 series single-chip microcomputer or 196 series single-chip microcomputer. The differential speed proportioner is composed of a selection circuit composed of an electronic switch connected to an operation comparison circuit composed of two operational amplifiers connected to an output terminal of an amplifying circuit composed of an operational amplifier connected to a PWM circuit.

The present invention uses a single-chip microcomputer to process the characteristic parameters representing the relative position of the welding torch and the welding seam to obtain the welding seam deviation information, and uses a differential speed proportioner circuit to compare and calculate the welding seam deviation information to realize the readjustment of the speed of the left and right wheels. Distribution, to ensure that the controlled voltage signal is output according to the deviation information when the trolley turns and walks in a straight line. The PWM circuit is used to output the corresponding pulse rectangular wave according to the voltage signal output by the differential speed proportioner, so as to optimize the matching of the speed of the two driving wheels, so that The welding seam tracking process control system of the welding trolley has simple structure and high control precision. It mainly solves the technical problems such as complex structure of the control system, low control precision and high cost when the existing welding trolley is automatically tracked. The actual welding process test proves that the tracking effect of the welding trolley is good, the operation is stable and reliable, and the practicability is strong.

Description of drawings

Fig. 1 is a schematic diagram of the basic structure of the present invention.

Fig. 2 is a schematic circuit diagram of the differential speed distributor of the present invention.

Detailed ways

The invention includes a welding trolley driven by left and right wheels, the left and right driving wheels of the welding trolley are respectively driven by stepping motors, and the differential speed controller connected with the sensor representing the relative position characteristics of the welding torch and the welding seam is connected with a differential speed proportioner The PWM circuit is connected, and the stepping motors of the left and right driving wheels of the welding trolley are connected. The welding trolley can be driven by double rear wheels without guide rails. Its basic structure can be divided into three parts: differential speed controller, differential speed proportioner and PWM generating circuit. The sensor can be an arc sensor or a swing arc sensor. Now refer to Fig. 1 to describe the working principle of this device in detail:

The differential speed controller can be composed of a single-chip computer with a CPU of 89C51. It performs software processing on the current signal sampled by the arc sensor to obtain the weld seam deviation signal, including the deflection direction and the size of the weld seam deflection. Control whether the car is turning or not through two ports P1.4 and P1.5: P1.4 controls whether the car needs to turn, and P1.5 controls the direction when turning. Its logical function table is as follows:

serial number P1.4 P1.5 working status 1 1 x The car goes straight 2 0 0 turn left 3 0 1 turn right

The D/A output uses a common DAC0832 chip, which can output a voltage U _bias that is linearly related to the magnitude of the weld deflection angle signal, that is: U _bias = k ₀ (θ).

When the welding seam deviation signal is within a certain range, P1.4 is set to high level, U _bias has no output, and the trolley moves forward in a straight line; when the welding seam deviation signal is greater than the set range, P1.4 is set to low level, U _{The bias} can be output to the differential proportioner; at the same time, P1.5 outputs high and low levels to control the turning direction of the trolley.

The differential speed proportioner (refer to attached picture 2) outputs the voltage signals of different walking states of the welding trolley according to the P1.4, P1.5 and U- _bias signals output by the single-chip microcomputer, and then outputs them to the PWM circuit after linear amplification. Its working principle as follows:

When walking in a straight line: under the control of the high and low levels of P1.4 and P1.5, the output voltage U of the differential speed controller D/A _cannot reach the operational amplifier IC2 through the electronic switch IC1, and the input signal of the operational amplifier IC2 at this time are U ₀₁ and U ₀₂ , and U ₀₁ = U ₀₂ , U ₀₁ and U ₀₂ are the set voltage values when the welding trolley travels in a straight line at a certain welding speed, and are amplified by the linear amplifier IC3 as the input of the PWM circuit. Its transfer function is as follows:

Left wheel: U ₃ =K ₂ *U ₁ =K ₁ *K ₂ *U ₀₁

Right wheel: U ₄ ＝K ₂ *U ₂ ＝K ₁ *K ₂ *U ₀₂

(K ₁ and K ₂ are the transfer coefficients of operational amplifiers IC1 and IC2 respectively, the sizes of K ₁ and K ₂ are determined by circuit parameters, and K ₂ is adjustable)

When turning left: the speed of both wheels of the trolley should increase. We use the U _bias of the D/A output to be superimposed in proportion on the basis of the voltage signal when walking in a straight line. At this time, under the control of P1.4 and P1.5, the U _bias can reach IC2 through IC1, and be distributed to the reverse end of IC2 in proportion, and U ₀₁ and U ₀₂ when walking in a straight line are used as the input of IC2, and then through IC3 is amplified as the input of PWM circuit. Its transfer function is as follows:

Left wheel: U ₃ ＝K ₂ *U ₁ ＝K ₁ *K ₂ *(U ₀₁ +K ₃ U _bias )

Right wheel: U ₄ ＝K ₂ *K ₁ *K ₂ *(U ₀₁ +K ₁ U _bias )

(K ₃ and K ₄ are the deviation distribution coefficients when turning left, and their size is determined by circuit parameters, and both are adjustable)

When turning right: the left and right wheels need to slow down, and the U _-bias output by D/A is proportionally subtracted on the basis of straight-line walking. Under the control of P1.4 and P1.5, the U _deviation can reach IC2 via IC1, and be distributed to the same direction end of IC2 in proportion, and then it is similar to turning left. Its transfer function is as follows:

Left wheel: U ₃ ＝K ₂ *U ₁ ＝K ₁ *K ₂ *(U ₀₁ -K ₅ U _bias )

Right wheel: U ₄ ＝K ₂ *U ₂ ＝K ₁ *K ₂ *(U ₀₁ -K ₆ U _bias )

(K ₅ and K ₆ are the deviation distribution coefficients when turning right, and their size is determined by circuit parameters, and both are adjustable)

The PWM circuit outputs the corresponding pulse rectangular wave according to the voltage signal output by the differential speed proportioner, and controls the drive module of the stepping motor of the left and right wheels, so that the speed of the left and right wheels is different, thereby completing the turning control of the car.

The present invention adopts the single-chip microcomputer and the differential speed proportioner circuit, combined with the PWM control technology, the single-chip microcomputer controller outputs the welding seam deviation information in real time, and then optimizes and matches the speed of the two driving wheels through the differential speed proportioner circuit, and timely adjusts the speed of the left and right wheels for seam tracking. The structure of the welding seam tracking process control system of the welding trolley is simple, the control precision is high, the tracking effect is good, the operation is stable and reliable, and the practicability is strong.

Claims (5)

1. an electronic differential formula is followed the tracks of the driving control device of welding tractor automatically, it comprises the welding tractor by left and right sides two-wheel drive, two driving wheels are driven by stepper motor respectively about welding tractor, it is characterized in that: the differential controller that joins with the arc sensor that characterizes welding torch and weld seam relative position characteristic connects the differential proportioner and connects pwm circuit, connect welding tractor about the stepper motor of two driving wheels.

2. electronic differential formula according to claim 1 is followed the tracks of the driving control device of welding tractor automatically, it is characterized in that: described differential controller is by D/A chip output weld seam deviation signal.

3. electronic differential formula according to claim 1 is followed the tracks of the driving control device of welding tractor automatically, it is characterized in that: described welding tractor adopts no guide rail double rear wheel to drive welding tractor.

4. follow the tracks of the driving control device of welding tractor automatically according to claim 1,2 or 3 described electronic differential formulas, it is characterized in that: described differential controller is made of MCS-51 series monolithic or 196 series monolithics.

5. electronic differential formula according to claim 1 is followed the tracks of the driving control device of welding tractor automatically, it is characterized in that: the selection circuit that described differential proportioner is made of electronic switch connects the output termination pwm circuit that computing comparison circuit that the two-way operational amplifier constitutes connects the amplifying circuit that operational amplifier constitutes.

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