Steering wheel calibration method for AGV with chassis four-wheel steering drive

Abstract

The application discloses a kind of steering wheel calibration methods of steering drive axle chassis four-wheel steering AGV, it belongs to AGV wheel calibration technical field.It solves the defects of poor flexibility and poor calibration effect of the conventional AGV steering wheel calibration method in the prior art.The main structure includes the following steps:Step one: adjust the steering mechanism to return to the middle point position;Step two: position the tire direction parallel to the frame direction;Step three: position the left and right tires parallel;Step four: position the front and rear tires on the same side parallel;Step five: reset the encoder zero point;Step six: test the fine-tuning encoder connecting rod;Step seven: adjust the limit.The present application is mainly used for AGV steering wheel calibration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of AGV wheel calibration, in particular, relates to a steering wheel calibration method for a steering drive axle chassis four-wheel steering AGV. BACKGROUND

[0002] In the prior art, the four-wheel positioning of an automobile is performed by using a 3D four-wheel positioning instrument to position the tires. The measurement principle is that four target reflectors are installed on the four wheel rims of the vehicle, the wheels are rolled, and the camera continuously photographs the geometric figures on the target reflectors. The corresponding positioning parameters of the wheels and chassis are obtained by analyzing and calculating the changes of the geometric figures by a computer, and are displayed on a display screen.

[0003] The existing problems of the prior art are: 1. It is heavy and not flexible. The deployment of the lifting machine and the four-wheel positioning instrument occupies a fixed space, and it does not have the possibility of being implemented anytime and anywhere; 2. The size of the lifting machine is fixed, and it is difficult to consider AGV products with different wheelbase and track; 3. The engineering machinery bridge only needs to adjust the initial turning angle, and does not need to adjust the inclination angle and the beam angle. There is a lot of functional redundancy in using the 3D four-wheel positioning instrument. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a steering wheel calibration method for a steering drive axle chassis four-wheel steering AGV. The method has less required tools, can be implemented anytime, is convenient to maintain, and can be recalibrated on site when a customer needs maintenance, without the need to ship other equipment.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] A steering wheel calibration method for a steering drive axle chassis four-wheel steering AGV, comprising the following steps:

[0007] Step 1: Adjust the steering mechanism to return to the middle point position;

[0008] Step 2: Position the tire direction parallel to the frame direction;

[0009] Step 3: Position the left and right tires parallel to each other;

[0010] Step 4: Position the front and rear tires on the same side parallel to each other;

[0011] Step 5: Reset the encoder zero point;

[0012] Step 6: Test the fine adjustment encoder connecting rod;

[0013] Step 7: Adjust the limit.

[0014] Preferably, the operation mode and measurement method of step one are as follows: measuring the right-side oil cylinder steering arm length a and the left-side oil cylinder steering arm length b, and directly inputting an analog signal to the hydraulic proportional valve to adjust the steering, so that a = b, and the steering arm is kept in the middle position.

[0015] Preferably, the operation mode and measurement method of step two are as follows: measuring the distance c from the front edge of the tire A on one side to the main beam and the distance d from the rear edge of the tire A to the main beam, and adjusting the first transverse link adjusting nut so that c = d, to ensure that the tire A on one side is parallel to the vehicle body; measuring the distance e from the front edge of the tire B on the other side to the main beam and the distance f from the rear edge of the tire B to the main beam, and adjusting the second transverse link adjusting nut so that e = f, to ensure that the tire B on the other side is parallel to the vehicle body.

[0016] Preferably, the operation mode and measurement method of step three are as follows: measuring the front edge distance g and the rear edge distance h between the tire A and the tire B, and adjusting the second transverse link adjusting nut so that g = h, to ensure that the coaxial tire A and tire B are parallel.

[0017] Preferably, the operation mode and measurement method of step four are as follows: using a laser level to draw a line on the bottom color mark line j or color mark line k of the front and rear tires on the same side, or on the groove m, adjusting the position of the laser level so that the laser line is parallel to the front wheel color mark line j, color mark line k or groove m, and adjusting the steering transverse link on the rear axle based on the tire A and tire B of the front axle so that the color mark line or groove of the front and rear tires on the same side is parallel to the laser line, to ensure that the front and rear tires on the same side are parallel.

[0018] Preferably, the operation mode and measurement method of step five are as follows: resetting the zero point of the encoder to the current position.

[0019] Preferably, the operation mode and measurement method of step six are as follows: taking the left wheel encoder data as the zero point sampling data for the front axle, and taking the right wheel encoder as the zero point sampling data for the rear axle, and taking the inner wheel encoder data as the sampling data during steering, to complete the wheel angle control of hydraulic steering.

[0020] Preferably, the operation mode and measurement method of step seven are as follows: controlling the hydraulic signal input, and hitting the tires of the front axle and the rear axle to the bottom in the left and right directions respectively, recording the left and right steering angle limits of the four wheels, setting the mechanical limit angle based on the maximum mechanical angle of the front axle and the rear axle, adjusting the first rear limit bolt, the second rear limit bolt, the third rear limit bolt and the fourth rear limit bolt of the front and rear limit of the left and right steering of the front axle or the rear axle, so that the left and right steering limit angles of the four tires are the same, and the maximum control angle set value automatically set by the system should be less than the mechanical limit angle.

[0021] Preferably, the landing test is also included, and the operation mode and measurement method of the landing test are as follows: according to the front and rear wheel lateral offset fine adjustment of the front and rear wheel angle, under the condition that the steering mechanism is in the middle, the left encoder of the front axle is connected with the second adjusting nut on the double-headed bolt on the steering follower rod in a screwed manner, and the right encoder of the rear axle is connected with the first adjusting nut on the double-headed bolt on the steering follower rod in a screwed manner, at this time, the first adjusting nut or the second adjusting nut will make the tire follow due to the self-return of the steering control tire to the encoder zero point, and multiple tests are performed until the standard straight line 15m front and rear wheel lateral offset is less than 5cm.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. The present application solves the demand for wheel initial angle calibration of a multi-axle steering chassis AGV, and the hydraulic steering control can be realized by directly outputting a proportional valve analog quantity or directly giving a target steering angle, so that the demand tool is less, implementation is timely, maintenance is convenient, and re-calibration can be performed according to local conditions during on-site maintenance of the customer, without shipping other equipment;

[0024] 2. Strong flexibility, not limited by the size of the vehicle body, suitable for various size heavy-load AGVs, and can be operated for various wheel track and wheelbase vehicle models, if 3D four-wheel positioning is used, it will be limited by the size, and the length of the heavy-load AGV is usually between 5m and 20m, and the self-weight is between 3 tons and 20 tons, for these special vehicles, special size 3D four-wheel positioning equipment needs to be specially customized, the customization delivery cycle is long and the cost is high, which will delay the project progress, and the present application is not limited by the size of the vehicle body except the lifting capacity of the gantry vehicle, and has the ability of rapid deployment and implementation;

[0025] 3. No special space is occupied, the tool used by the present application is simple, no field wiring, no large equipment, and no need to reserve a maintenance position. DETAILED DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of the chassis in the present application;

[0027] Figure 2 is a structural schematic diagram of the front axle in the present application Figure 1 ;

[0028] Figure 3 is a structural schematic diagram of the front axle in the present application Figure 2 ;

[0029] Figure 4 is a position diagram of the left encoder in the present application;

[0030] Figure 5 is a position diagram of the right encoder in the present application;

[0031] Figure 6 The structure diagram of the color code line in the present application.

[0032] In the figure: 1, steering arm; 2, tire A; 3, main beam; 4, first transverse link adjusting nut; 5, second transverse link adjusting nut; 6, tire B; 7, front axle; 8, rear axle; 9, encoder; 10, steering follow-up rod; 11, first adjusting nut; 12, second adjusting nut; 13, double-headed bolt; 14, first rear limiting bolt; 15, second rear limiting bolt; 16, third rear limiting bolt; 17, fourth rear limiting bolt; 18, steering transverse link. DETAILED DESCRIPTION

[0033] The present application will be further described below by specific embodiments and in conjunction with the drawings.

[0034] Example 1

[0035] A steering wheel calibration method of a steering drive axle chassis four-wheel steering AGV, comprising the following steps:

[0036] Step one: adjust the steering mechanism to the middle point position;

[0037] Step two: position the tire direction parallel to the frame direction;

[0038] Step three: position the left and right tires parallel;

[0039] Step four: position the front and rear tires on the same side parallel;

[0040] Step five: reset the zero point of the encoder 9;

[0041] Step six: test the fine-tuning encoder 9 connecting rod;

[0042] Step seven: adjust the limit.

[0043] Example 2

[0044] As shown in Figure 2 A steering wheel calibration method of a steering drive axle chassis four-wheel steering AGV, the operation mode and measurement method of step one are as follows: measure the right side cylinder steering arm length a and the left side cylinder steering arm length b, directly input analog signal to the hydraulic proportional valve to adjust the steering, so that a = b, and ensure that the steering arm 1 is in the middle position.

[0045] As shown in Figure 1As shown, the operation mode and measurement method of step two are as follows: measure the distance c from the front edge of tire A2 on one side to the main beam 3 and the distance d from the rear edge of tire A2 to the main beam 3, and adjust the first transverse link adjusting nut 4 so that c = d, ensuring that tire A2 on one side is parallel to the vehicle body; measure the distance e from the front edge of tire B6 on the other side to the main beam 3 and the distance f from the rear edge of tire B6 to the main beam 3, and adjust the second transverse link adjusting nut 5 so that e = f, ensuring that tire B6 on the other side is parallel to the vehicle body.

[0046] The operation mode and measurement method of step three are as follows: measure the front edge distance g and the rear edge distance h between tire A2 and tire B6, and adjust the second transverse link adjusting nut 5 so that g = h, ensuring that the coaxial tire A2 and tire B6 are parallel.

[0047] The adjustment mode of step one, step two and step three is the adjustment mode of front axle 7, and the adjustment mode of the two tires on rear axle 8 is the same as that of tire A2 and tire B6 on front axle 7.

[0048] As shown in Figure 6 The operation mode and measurement method of step four are as follows: use a laser level to draw a line on the bottom of the front and rear tires on the same side (it must be the bottom, otherwise it cannot be ensured that the laser level and the tire direction are on the same straight line) color mark line j or color mark line k, or on the groove m, adjust the position of the laser level so that the laser line is parallel to the front wheel color mark line j, color mark line k or groove m, and adjust the steering tie rod 18 on the rear axle 8 based on the tire A2 and tire B6 on the front axle 7 so that the color mark line or groove of the front and rear tires on the same side is parallel to the laser line, ensuring that the front and rear tires on the same side are parallel. (The heavy load AGV is usually used in port and factory, which can be easily lifted on a horizontal fixed support platform by a gantry crane).

[0049] As shown in Figures 3-5 The operation mode and measurement method of step five are as follows: reset the zero points of the four encoders 9 to the current positions.

[0050] The operation mode and measurement method of step six are as follows: the front axle 7 takes the left wheel encoder data as zero point sampling data, the rear axle 8 takes the right wheel encoder as zero point sampling data, and the inner wheel encoder data is taken as sampling data when steering, completing the wheel angle control of hydraulic steering.

[0051] The operation mode and measurement method of step seven are: control the hydraulic signal input, hit the tires of the front axle 7 and the rear axle 8 to the left and right directions respectively to the bottom, record the left and right turning angle limits of the four wheels, set the mechanical limit angle according to the maximum mechanical angle of the front axle 7 and the rear axle 8, adjust the first rear limiting bolt 14, the second rear limiting bolt 15, the third rear limiting bolt 16 and the fourth rear limiting bolt 17 of the front and rear limiting of the left and right turning of the front axle 7 or the rear axle 8, so that the left and right turning limiting angles of the four tires are the same, and the maximum control angle set value set by the system should be less than the mechanical limiting angle to avoid mechanical structure impact (for example, the maximum mechanical turning angle of the axle itself is 40°, the mechanical limiting angle is set to 38°, and the maximum control turning angle is set to 36°).

[0052] That is, after hitting the front and rear wheels to the left and right maximum angles respectively by the hydraulic signal, the values of the encoder 9 are read, the first rear limiting bolt 14, the second rear limiting bolt 15, the third rear limiting bolt 16 and the fourth rear limiting bolt 17 of the front and rear limiting of the left and right turning of the front axle 7 or the rear axle 8 are adjusted, so that the left and right maximum turning angles of the front axle 7 and the rear axle 8 are the same.

[0053] It also includes a landing test, and the operation mode and measurement method of the landing test are: according to the front and rear wheel transverse offset fine adjustment of the front and rear wheel angle, under the condition of the steering mechanism returning to the center, the left encoder of the front axle 7 is connected tightly with the second adjusting nut 12 on the double-headed bolt 13 on the steering follower rod 10, and the right encoder of the rear axle 8 is connected tightly with the first adjusting nut 11 on the double-headed bolt 13 on the steering follower rod 10, at this time, because the steering control tire self-returns to the encoder zero point, the first adjusting nut 11 or the second adjusting nut 12 will make the tire follow, and multiple tests are performed until the standard straight line 15m front and rear wheel transverse offset <5cm is met. The other parts are the same as example 1.

[0054] The inner wheel encoder angle is used as the control program reference value when steering, and the left wheel encoder angle of the front axle 7 and the right wheel encoder angle of the rear axle 8 are used as the reference values when returning to the center, under the action of the control program, the first adjusting nut 11 and the second adjusting nut 12 of the double-headed bolt 13 of the left front wheel and the right rear wheel encoder connecting rod can be adjusted to realize the fine adjustment of the wheel angle.

Claims

1. A method for calibrating the steering wheels of a four-wheel steering AGV with a steering drive axle chassis, characterized in that: The steps include: Step 1: Adjust the steering mechanism back to the center position; Step 2: Align the tire direction with the frame direction; Step 3: Position the left and right tires to be parallel; Step 4: Align the front and rear wheels so that the tires on the same side are parallel; Step 5: Reset the zero point of encoder (9); Step 6: Test the fine-tuning encoder (9) connecting rod; Step 7: Adjust the limit switch; The operation and measurement method of step one is as follows: measure the length a of the right oil cylinder steering arm and the length b of the left oil cylinder steering arm, and directly input analog signal to the hydraulic proportional valve to adjust the steering so that a=b, ensuring that the steering arm (1) is in the middle position; The operation and measurement method of step two are as follows: measure the distance c from the front edge of tire A (2) on one side to the main beam (3) and the distance d from the rear edge of tire A (2) to the main beam (3), and adjust the first crossbar adjusting nut (4) so ​​that c=d, ensuring that tire A (2) on one side is parallel to the vehicle body; measure the distance e from the front edge of tire B (6) on the other side to the main beam (3) and the distance f from the rear edge of tire B (6) to the main beam (3), and adjust the second crossbar adjusting nut (5) so that e=f, ​​ensuring that tire B (6) on the other side is parallel to the vehicle body; The operation and measurement method of step three are as follows: measure the front edge distance g and the rear edge distance h between tire A (2) and tire B (6), and adjust the second horizontal tie rod adjusting nut (5) so that g=h, to ensure that the coaxial tire A (2) and tire B (6) are parallel; The operation and measurement method of step four are as follows: use a laser level to mark the line on the bottom color mark line j or color mark line k of the front and rear tires on the same side, or on the groove m. Adjust the position of the laser level so that the laser line is parallel to the front tire color mark line j, color mark line k or groove m. Use the tires A (2) and B (6) of the front axle (7) as the standard to adjust the steering tie rod (18) on the rear axle (8) so that the front and rear tire color mark lines or grooves are parallel to the laser line, ensuring that the front and rear tires on the same side are parallel.

2. The method for calibrating the steering wheels of a four-wheel steering AGV with a steering drive axle chassis according to claim 1, characterized in that: The operation and measurement method of step five is as follows: reset the zero point of the encoder (9) to the current position.

3. The method for calibrating the steering wheels of a four-wheel steering AGV with a steering drive axle chassis according to claim 2, characterized in that: The operation and measurement method of step six are as follows: the front axle (7) uses the left wheel encoder data as the zero point sampling data, the rear axle (8) uses the right wheel encoder as the zero point sampling data, and the inner wheel encoder data is used as the sampling data when steering to complete the wheel angle control of hydraulic steering.

4. The method for calibrating the steering wheels of a four-wheel steering AGV with a steering drive axle chassis according to claim 3, characterized in that: The operation and measurement method of step seven are as follows: control the hydraulic signal input, turn the tires of the front axle (7) and the rear axle (8) to the left and right respectively, record the left and right steering angle limit values ​​of the four wheels, set the mechanical limit angle according to the maximum mechanical angle of the front axle (7) and the rear axle (8), adjust the first rear limit bolt (14), the second rear limit bolt (15), the third rear limit bolt (16) and the fourth rear limit bolt (17) of the left and right steering of the front axle (7) or the rear axle (8) so that the left and right steering limit angles of the four tires are the same, and the maximum control angle setting value automatically set by the system should be less than the mechanical limit angle.

5. The method for calibrating the steering wheels of a four-wheel steering AGV with a steering drive axle chassis according to claim 4, characterized in that: It also includes a landing test. The operation and measurement method of the landing test is as follows: adjust the front and rear wheel angles slightly according to the lateral offset of the front and rear wheels when going straight. Under the condition that the steering mechanism returns to center, tighten the left encoder of the front axle (7) to the second adjusting nut (12) on the double-headed bolt (13) on the steering follower rod (10), and tighten the right encoder of the rear axle (8) to the first adjusting nut (11) on the double-headed bolt (13) on the steering follower rod (10). At this time, because the steering control tire returns to the encoder zero point, the first adjusting nut (11) or the second adjusting nut (12) will make the tire follow. Repeat the test until the standard lateral offset of the front and rear wheels is <5cm when going straight for 15m.

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