CN117784831A - Kinematic control method and system for articulated forklift - Google Patents
Kinematic control method and system for articulated forklift Download PDFInfo
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- CN117784831A CN117784831A CN202311693959.3A CN202311693959A CN117784831A CN 117784831 A CN117784831 A CN 117784831A CN 202311693959 A CN202311693959 A CN 202311693959A CN 117784831 A CN117784831 A CN 117784831A
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Abstract
The invention discloses a kinematic control method of an articulated forklift, which comprises the following steps: (1) Smoothing the received angular velocity and linear velocity at the next moment; (2) Detecting whether the included angle between the front wheel and the rear wheel at the current moment is larger than the maximum included angle, if not, executing the step (3), otherwise, executing the step (4); (3) Adjusting the smoothed angular velocity so that the turning radius is greater than the minimum vehicle body radius; (4) The smoothed angular speed is regulated so as to enable the included angle between the front wheel and the rear wheel at the current moment to be reduced to the set maximum included angle; (5) And distributing the adjusted angular speed and the smoothed linear speed to the speeds of four wheels. After the articulated vehicle body structure is modeled, the steering and speed control of the articulated vehicle are realized through the speed difference of four wheels of the vehicle body, the method can ensure that the vehicle body runs stably, and the diagonal speed is subjected to secondary adjustment, so that the risk of damaging the vehicle body due to overlarge vehicle body corner caused by improper control is prevented.
Description
Technical Field
The invention belongs to the technical field of forklift control, and particularly relates to a kinematic control method and a kinematic control system for an articulated forklift.
Background
The articulated vehicle refers to a wheeled vehicle and a crawler vehicle which are formed by two or more vehicle bodies connected together by a hinging device, and the vehicle bodies can relatively move on a horizontal plane or a vertical longitudinal (or transverse) plane by using a special hydraulic mechanism. It changes the advancing direction by the mutual rotation of the connecting rings between the car bodies. The system has the advantages of larger bearing capacity, high maneuvering performance, stronger cross-country capability and the like, and is widely applied to various engineering fields such as strategic material transportation, agriculture/forestry transportation, rescue and relief work, forest fire control and the like.
The articulated forklift is a four-wheel independent driving wheel forklift, each wheel is driven by an independent motor, has obvious advantages in the aspects of energy optimization management, whole vehicle dynamics control and the like, and mainly comprises a front forklift body and a rear forklift body, wherein the front forklift body and the rear forklift body are connected through a steering pin shaft. The steering mode of the four-wheel articulated forklift is hydraulic power steering, and when steering, the hydraulic power steering system controls the steering hydraulic cylinder to stretch and retract according to a steering command, and drives the front forklift body and the rear forklift body to deflect relatively around the steering pin shaft so as to finish steering.
The vehicle body kinematic model determines the load capacity of the vehicle body during running, the running smoothness of the vehicle body and the like, if the articulated forklift is controlled only based on the differential speed of the front wheels, the rear wheels are used for following control, only the front wheels provide power for driving, the rated load capacity of the vehicle body is reduced, the included angle between the front wheels and the rear wheels cannot be kept fixed, the front wheels and the rear wheels are kept in a straightened state, the turning radius of the vehicle body is increased, and the vehicle body is not flexible to run.
Disclosure of Invention
The invention provides a kinematic control method of an articulated forklift, and aims to improve the problems.
The invention is realized in such a way that a kinematic control method of an articulated forklift truck comprises the following steps:
(1) Smoothing the received angular velocity and linear velocity at the next moment;
(2) Detecting an included angle between a front wheel and a rear wheel at the current momentWhether or not it is greater than the maximum angle phi max If the detection result is negative, executing the step (3), and if the detection result is positive, executing the step (4);
(3) Adjusting the smoothed angular velocity so that the turning radius is greater than the minimum vehicle body radius;
(4) The smoothed angular velocity is regulated to reduce the included angle phi between the front wheel and the rear wheel at the current moment to the set maximum included angle phi max ；
(5) And distributing the adjusted angular speed and the smoothed linear speed to the speeds of four wheels.
Further, if the turning radius of the current articulated forklift is smaller than the minimum body radius L min Then the angular velocity at the next moment is reduced, and the reduced angular velocity is used as w 2 Indicating the angular velocity w 2 Satisfy the following requirements
Wherein w is 1 、v 1 Respectively represent the smoothed angular velocity and linear velocity of the articulated forklift, lmin=min { L } 3 ,L 4 }，L 3 Is the distance between the center of the front axle and the hinge point, L 4 Is the distance between the center of the rear axle and the hinge point.
Further, if the turning radius of the current articulated forklift is greater than or equal to the minimum body radius L min Then there is no need for the angular velocity w at the next time 1 Adjusting, i.e. the adjusted angular velocity w 2 ＝w 1 。
Further, if the linear velocity at the next time is zero, the angular velocity w at the next time is given 1 And controlling the hinged forklift to stop rotating when the direction of the hinged forklift is consistent with the direction of the rotating angle.
Further, the angular velocity w at the next time is given 1 Opposite to the rotation angle, the angular velocity w is not required 1 Correction, i.e. the adjusted angular velocity w 2 ＝w 1 。
Further, at the next moment of the articulated fork truckCalculating the included angle phi between the front wheel and the rear wheel at the current moment and the maximum included angle phi when the linear speed is not zero max Deviation between ΔΦ=Φ - Φ max The angular velocity w at the next moment is adjusted based on the following model 2 ：
w 2 ＝k 1 *w 1 +k 2 *Δφ。
Further, the direction of the articulated forklift is divided into forward, backward and in-situ rotation; when the linear speed is 0 or more, the front wheel is used as a main driving wheel, the rear wheel is used as an auxiliary driving wheel, and when the linear speed is less than 0, the rear wheel is used as a main driving wheel, and the front wheel is used as an auxiliary driving wheel.
Further, the four-wheel speed distribution method specifically comprises the following steps:
(1) Will adjust the angular velocity w 2 The smoothed following velocity v 1 As a control value of the center of the first axle where the main driving wheel is located, further calculating the speeds of wheels on two sides of the first axle based on a differential wheel model;
(2) Calculating the angular velocity and the linear velocity of the second axle center according to the angular velocity and the linear velocity of the first axle center;
(3) The angular velocity and the linear velocity of the second axle center are calculated based on the differential wheel model.
The invention is realized in that a kinematic control system for an articulated forklift truck, the system comprising:
the receiving unit is used for receiving the angular speed and the linear speed at the next moment, the receiving unit is in communication connection with the processing unit, and the processing unit controls the speed output of the four wheels of the articulated forklift based on the kinematics control method of the articulated forklift.
After the articulated vehicle body structure is modeled, the steering and speed control of the articulated vehicle are realized through the speed difference of four wheels of the vehicle body, the method can ensure that the vehicle body runs stably and smoothly, and the diagonal speed is secondarily adjusted, so that the risk of damaging the vehicle body due to overlarge vehicle body rotation angle caused by improper control is prevented.
Drawings
Fig. 1 is a flow chart of a kinematic control method of an articulated forklift provided by an embodiment of the invention;
fig. 2 is a schematic structural diagram of an articulated forklift model according to an embodiment of the present invention.
Detailed Description
The following detailed description of the embodiments of the invention, given by way of example only, is presented in the accompanying drawings to aid in a more complete, accurate, and thorough understanding of the inventive concepts and aspects of the invention by those skilled in the art.
Fig. 1 is a flow chart of a kinematic control method of an articulated forklift according to an embodiment of the present invention, and is described with reference to an articulated forklift model provided in fig. 2, in which a wheel distance between two front wheels is L 1 The wheel spacing of the two rear wheels is L 2 The distance between the center of the front axle connecting the two front wheels and the hinge point is L 3 The distance between the center of the rear axle connecting the two rear wheels and the hinge point is L 4 ，L 3 、L 4 The two are all the vehicle body radiuses of the articulated forklift, and the included angle between the front wheel and the rear wheel is phi max For a set maximum included angle, the method specifically comprises the following steps:
(1) Smoothing the received angular velocity and linear velocity at the next moment;
the method is characterized in that the phenomenon that the change of angular speed and linear speed at the front moment and the rear moment is too large to cause the shaking of the hinged forklift body is avoided, and the adopted smoothing method is an existing method and is not described in detail;
(2) Detecting an included angle between a front wheel and a rear wheel at the current momentWhether or not it is greater than the maximum angle phi max If the detection result is negative, executing the step (3), and if the detection result is positive, executing the step (4);
(3) Adjusting the smoothed angular velocity so that the turning radius is greater than the minimum vehicle body radius;
the smoothed angular velocity and linear velocity of the articulated forklift are respectively w 1 、v 1 Representing that the articulated forklift needs to meet the requirement that the turning radius is larger than the maximum in the movement processThe radius of the trolley body, i.e. L min ＝min{L 3 ,L 4 If the current turning radius is greater than or equal to the minimum vehicle body radius, the angular velocity w at the next moment is not required 1 Adjusting, i.e. the adjusted angular velocity w 2 ＝w 1 If the current turning radius is smaller than the minimum vehicle body radius, the angular velocity at the next moment is reduced, and the reduced angular velocity is used as w 2 Represented by w 2 Satisfy the following requirements
(4) The smoothed angular velocity is regulated to reduce the included angle phi between the front wheel and the rear wheel at the current moment to the set maximum included angle phi max ；
In the embodiment of the invention, if the linear speed at the next moment is zero, the front wheel center of the articulated forklift rotates in situ, and the included angle between the front wheel and the rear wheel is formedReaching the maximum included angle, if the angular velocity w at the next moment is given 1 And the rotation direction is still consistent with the rotation angle direction, the articulated forklift is controlled to stop rotating, and when the angular speed w of the next moment is given 1 When the direction of the rotation angle is opposite to that of the front wheel, the included angle phi between the front wheel and the rear wheel can be reduced, and the diagonal speed w is not needed 1 Correction, i.e. the adjusted angular velocity w 2 ＝w 1 。
When the linear speed of the next moment of the articulated forklift is not zero, calculating an included angle phi between the front wheel and the rear wheel at the current moment and a maximum included angle phi max Deviation between ΔΦ=Φ - Φ max The angular velocity at the next moment is adjusted based on the following model:
w 2 ＝k 1 *w 1 +k 2 *Δφ
the final purpose of the model is to keep delta phi at 0, i.e. to maintain the angle between the front and rear wheelsMaintaining maximum rotation angle valueφ max Without increasing, it is known from the model that the angular velocity w at the next time 2 Based on the proportionality coefficient k 1 (0＜k 1 < 1) is reduced to zero, at which time Δφ is increased, after which the angular velocity w 2 The reverse increase eventually keeps delta phi at a heave adjustment around zero.
(5) And distributing the adjusted angular speed and the smoothed linear speed to the speeds of four wheels.
In the embodiment of the invention, if the direction of the articulated forklift is divided into forward, backward and in-situ rotation; when the linear speed is greater than or equal to 0, the vehicle body is indicated to walk forwards, the front wheel is used as a main driving wheel at the moment, the rear wheel is used as an auxiliary driving wheel, the in-situ rotating row is used as one of the forward directions of the vehicle body, the linear speed is 0 at the moment, the angular speed is not 0, and when the linear speed is less than 0, the vehicle body is indicated to walk backwards, the rear wheel is used as the main driving wheel at the moment, and the front wheel is used as the auxiliary driving wheel.
(51) When the front wheel is used as a main driving wheel and the rear wheel is used as an auxiliary driving wheel, the adjusted angle w 2 Linear velocity v after smoothing 1 As the angular velocity w and the linear velocity v of the front axle center, the velocity of four wheels is calculated as follows:
(1) The output values of the left side and the right side of the front wheel calculate the speed V of the front wheel on the left side according to a differential wheel model 1 The speed of the right front wheel is V 2 The method comprises the following steps:
(2) According to the angular velocity w of the front axle centre 2 And linear velocity v 1 Calculating the angular velocity w and the linear velocity v' of the rear axle center, i.e
(3) Calculating the speed values of the two rear wheels according to the angular speed w 'and the linear speed V' of the center of the rear axle, wherein the left rear wheel is V 3 The speed of the right rear wheel is V 4 The method comprises the following steps:
the linear velocity output of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel is V 1 、V 2 、V 3 And V 4 。
(52) When the rear wheel is used as a main driving wheel and the front wheel is used as an auxiliary driving wheel, the adjusted angle w 2 Linear velocity v after smoothing 1 As the angular velocity w 'and the linear velocity v' of the rear axle center, the velocity of four wheels is calculated as follows:
(1) The output values of the left side and the right side of the rear wheel calculate the speed V of the left side rear wheel according to a differential wheel model 3 The speed of the right rear wheel is V 4 The method comprises the following steps:
(2) The angular velocity w and the linear velocity v of the center of the front axle are calculated according to the angular velocity w 'and the linear velocity v' of the center of the front axle, namely:
(3) Calculating the speed values of the two front wheels according to the angular speed w and the linear speed V of the axle center of the front axle center, wherein the speed of the left front wheel is V 1 The speed of the right front wheel is V 2 The method comprises the following steps:
the linear velocity output of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel is V 1 、V 2 、V 3 And V 4 。
The invention also provides a kinematic control system of the articulated forklift, which comprises:
the receiving unit is used for receiving the angular speed and the linear speed at the next moment, the receiving unit is in communication connection with the processing unit, and the processing unit controls the speed output of the four wheels of the articulated forklift based on the kinematics control method of the articulated forklift.
While the present invention has been described by way of example, it should be apparent that the practice of the invention is not limited by the foregoing, but rather is intended to cover various insubstantial modifications of the method concepts and teachings of the invention, either as applied to other applications without modification, or as applied directly to other applications, without departing from the scope of the invention.
Claims (9)
1. A method for kinematically controlling an articulated forklift, the method comprising the steps of:
(1) Smoothing the received angular velocity and linear velocity at the next moment;
(2) Detecting an included angle between a front wheel and a rear wheel at the current momentWhether or not it is greater than the maximum angle phi max If the detection result is negative, executing the step (3), and if the detection result is positive, executing the step (4);
(3) Adjusting the smoothed angular velocity so that the turning radius is greater than the minimum vehicle body radius;
(4) The smoothed angular velocity is regulated to reduce the included angle phi between the front wheel and the rear wheel at the current moment to the set maximum included angle phi max ；
(5) And distributing the adjusted angular speed and the smoothed linear speed to the speeds of four wheels.
2. The method of kinematic control of an articulated forklift as defined in claim 1, wherein if the turning radius of the current articulated forklift is smaller than the minimum body radius L min Then the angular velocity at the next moment is reduced, and the reduced angular velocity is used as w 2 Indicating the angular velocity w 2 Satisfy the following requirements
Wherein w is 1 、v 1 Respectively represent the smoothed angular velocity and linear velocity of the articulated forklift, lmin=min { L } 3 ,L 4 }，L 3 Is the distance between the center of the front axle and the hinge point, L 4 Is the distance between the center of the rear axle and the hinge point.
3. The method of kinematic control of an articulated forklift as defined in claim 1, wherein if the turning radius of the current articulated forklift is greater than or equal to the minimum body radius L min Then there is no need for the angular velocity w at the next time 1 Adjusting, i.e. the adjusted angular velocity w 2 ＝w 1 。
4. The method for kinematically controlling an articulated forklift according to claim 1, wherein if the linear velocity at the next moment is zero, the angular velocity w at the next moment is given 1 And controlling the hinged forklift to stop rotating when the direction of the hinged forklift is consistent with the direction of the rotating angle.
5. Method for kinematically controlling an articulated fork truck according to claim 1, characterized in that the angular velocity w at the given next moment is 1 Opposite to the rotation angle, the angular velocity w is not required 1 Correction, i.e. the adjusted angular velocity w 2 ＝w 1 。
6. The method for kinematically controlling an articulated fork truck according to claim 1, wherein the angle phi between the front wheel and the rear wheel and the maximum angle phi at the current moment are calculated when the linear velocity of the articulated fork truck at the next moment is not zero max Deviation between ΔΦ=Φ - Φ max The angular velocity w at the next moment is adjusted based on the following model 2 ：
w 2 ＝k 1 *w 1 +k 2 *Δφ。
7. The method of kinematic control of an articulated forklift of claim 1, wherein the direction of the articulated forklift is divided into forward, backward and in-situ rotation; when the linear speed is 0 or more, the front wheel is used as a main driving wheel, the rear wheel is used as an auxiliary driving wheel, and when the linear speed is less than 0, the rear wheel is used as a main driving wheel, and the front wheel is used as an auxiliary driving wheel.
8. The method for kinematically controlling an articulated fork lift truck according to claim 1, wherein the four-wheel speed distribution method comprises the following steps:
(1) Will adjust the angular velocity w 2 The smoothed following velocity v 1 As a control value of the center of the first axle where the main driving wheel is located, further calculating the speeds of wheels on two sides of the first axle based on a differential wheel model;
(2) Calculating the angular velocity and the linear velocity of the second axle center according to the angular velocity and the linear velocity of the first axle center;
(3) The angular velocity and the linear velocity of the second axle center are calculated based on the differential wheel model.
9. A kinematic control system for an articulated forklift, the system comprising:
the receiving unit is used for receiving the angular speed and the linear speed at the next moment, and is in communication connection with the processing unit, and the processing unit is used for controlling the speed output of the four wheels of the articulated forklift based on the kinematics control method of the articulated forklift according to any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311693959.3A CN117784831A (en) | 2023-12-08 | 2023-12-08 | Kinematic control method and system for articulated forklift |
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| CN202311693959.3A CN117784831A (en) | 2023-12-08 | 2023-12-08 | Kinematic control method and system for articulated forklift |
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| CN117784831A true CN117784831A (en) | 2024-03-29 |
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| CN202311693959.3A Pending CN117784831A (en) | 2023-12-08 | 2023-12-08 | Kinematic control method and system for articulated forklift |
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- 2023-12-08 CN CN202311693959.3A patent/CN117784831A/en active Pending
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