CN113152549B - Control method of wheel-leg combined type excavator autonomous displacement control system - Google Patents

Abstract

The invention discloses a control method of an autonomous displacement control system of a wheel-leg combined excavator, which comprises the following steps: controlling a support oil cylinder, determining the moving distance L of the excavator, controlling 4 oil cylinders including a movable arm, an arm, a bucket and a telescopic arm of a 4-degree-of-freedom working device, compounding vertical linear motion, supporting a vehicle body, calculating the displacement of the oil cylinder of the working device in each control beat, calculating the rotation angle of a walking motor in each control beat, controlling the compound motion of the arm and the telescopic arm oil cylinder of the working device, adjusting the transverse and longitudinal postures, eliminating transverse and longitudinal errors, and controlling the conversion from the walking state to the working state; the control method realizes the complete machine displacement of the wheel-leg combined excavator and the posture adjustment after the displacement in a combined control mode of the excavating device and the chassis mechanism of the wheel-leg combined excavator under the condition of no manual intervention.

Description

Control method of wheel-leg combined type excavator autonomous displacement control system

Technical Field

The invention belongs to the technical field of excavator control, and particularly relates to a posture adjustment control method of an autonomous displacement control system in a continuous displacement excavation operation process of a wheel-leg combined excavator.

Background

With the rapid development of artificial intelligence technology, unmanned equipment has gradually moved from laboratories to battlefields, and unmanned engineering machinery has become an important direction for engineering machinery development. The excavator is a typical engineering machine with a complex structure and mechanism, and the unmanned technology of the excavator has certain representativeness, model and portability. The wheel-leg combined excavator is widely applied due to the strong obstacle crossing capability and the capability of operating on a large slope, and is mainly used for occasions such as construction of work, road rush repair and the like. The longitudinal distance of the working surface of the excavation task is longer and far beyond the working range of the excavator, after the excavation operation of one station is finished, the excavator needs to move to the next station to continue excavation, after the position is moved, the connection and the direction consistency of the working surface of the subsequent operation and the preorder working surface need to be ensured, and meanwhile, the posture of the excavator needs to meet the requirements of operation stability and safety, so the whole vehicle displacement control is a key link for the automatic control of the continuous excavation operation of the excavator. The invention is applied to a wheel-leg combined excavator, and the excavating device of the wheel-leg combined excavator is structurally shown in figure 1 and comprises a movable arm, an arm, a telescopic arm, a bucket and a hydraulic system. The wheel-leg combined chassis of the excavator is a flexible chassis, and comprises a front claw, a front arm joint, a front wheel, a front leg shutdown device, a front hinge joint, a base, a rear hinge joint, a rear leg joint, a rear wheel hub and a rear wheel, as shown in figure 2. Compared with a rigid chassis of a common excavator, the wheel-leg combined chassis comprises 12 degrees of freedom, the difficulty of displacement control of the whole excavator is increased, an autonomous displacement control system and a control method are urgently needed, autonomous displacement control of the excavator is realized, and a foundation is laid for autonomous control of long-working-face displacement and continuous excavation operation.

At present, a wheel-leg combined excavator is taken as a control object, and the independent displacement control of the excavator is realized in a combined control mode of an excavating device and a chassis mechanism, so that the control method is still blank in China. In the aspect of control objects, the control objects of the current domestic excavator autonomous displacement control system are mainly two types of excavators: wheel chassis excavators and crawler chassis excavators, basically rigid chassis; in the aspect of an autonomous displacement control mode, the existing control method mainly realizes the displacement of the excavator by controlling the forward or backward movement of a chassis walking mechanism, and the autonomous displacement control is realized by the cooperation of a working device and the chassis.

Disclosure of Invention

The invention aims to provide a control method of an autonomous displacement control system of a wheel-leg combined excavator, which realizes complete machine displacement of the wheel-leg combined excavator and posture adjustment after the displacement without manual intervention.

In order to achieve the purpose of the invention, the technical scheme of the invention is that the method comprises the following steps:

the method comprises the following steps: the support leg oil cylinders are controlled, the support legs are retracted, and the chassis of the excavator is controlled to be parallel to the ground by adjusting the joint oil cylinders of the chassis, so that the stability of the excavator is ensured;

step two: determining the moving distance L of the excavator;

step three: controlling 4 oil cylinders including a movable arm, a bucket rod, a bucket and a telescopic arm of the 4-degree-of-freedom working device, compounding vertical linear motion, supporting a vehicle body, enabling a front wheel to be away from the ground, and enabling the vehicle body to be lifted by a distance D, namely enabling the distance between the center of the front wheel and the ground to be D;

step four: calculating the displacement of a working device oil cylinder in each control beat, after a front wheel is raised, the movement of a vehicle body is mainly matched by the working device oil cylinder and a walking motor to complete the movement control of the excavator, during the concrete implementation, the displacement of the oil cylinder related to each control beat needs to be calculated, the displacement x of the excavator in the next beat is calculated according to the moving speed v and the beat period T, the target displacement Dd and Ds of a bucket rod and a telescopic arm in the next beat are calculated according to a space geometric transformation method, and the displacement in the subsequent beats of the bucket rod and the telescopic arm oil cylinder is obtained in sequence through cyclic calculation until the displacement reaches the target position;

step five: calculating the rotation angle of the walking motor in each control beat, and calculating the rotation angle Rm of each beat of the walking motor according to the displacement x of the excavator until the walking motor reaches a target position;

step six: controlling the bucket rod and the telescopic arm oil cylinder of the working device to perform composite motion by taking a contact point of the bucket and the ground as a fulcrum, wherein the displacement of each control beat bucket rod and the displacement of each telescopic arm are Dd and Ds respectively; simultaneously controlling the rotation angle Rm of the walking motor until the excavator shifts to a target position;

step seven: adjusting the transverse posture, eliminating transverse errors, adopting a method of forward and backward solving a coordinate system by the rotary excavator working device when the transverse deviation DisY is larger than D1 and smaller than D2, realigning the X1 axis of the excavation working surface with the direction of the X axis before shifting, adopting the excavator working device to lift the rear leg, rotate the revolving shaft, lift the front leg again and reversely rotate the revolving shaft when the DisY is larger than D2, and realigning the orientation of the excavator with the orientation before shifting;

step eight: adjusting the longitudinal posture, eliminating transverse and longitudinal errors, wherein the reason for the dislocation of the longitudinal working surface is mainly generated by positioning control precision, substituting the DisX into the trajectory planning during next fixed-point excavation, and correspondingly increasing and decreasing the X coordinate of the designed excavation point in the X-axis direction according to the DisX value;

step nine: and (4) controlling the walking state to be converted into the working state, controlling the supporting legs to be unfolded towards two sides after the excavator is shifted to the target position, then moving downwards to be inserted into the ground, and completing preparation for excavating operation by the excavator.

The invention has the beneficial effects that:

the wheel-leg combined excavator comprises 16 joints, wherein 4 joints of the excavating device and 12 joints of the chassis have strong obstacle-crossing and slope-climbing capabilities and can safely work on a steep slope. The invention solves the difficult problem of composite control of the excavating device and the chassis mechanism of the 16-joint excavator, realizes the autonomous displacement control of the wheel-leg composite excavator without the participation of manpower, ensures that the excavator can autonomously displace to the next station and continuously operate according to the information of an excavating task, the current position of the excavator, the excavating condition of the previous station and the like after finishing the operation at one station, and realizes the autonomous control of the continuous excavating operation of a long operation surface. On the technical level, the excavator is autonomously controlled by fixed-point excavation operation, the continuous excavation operation autonomous control stage is advanced, and the autonomous control capability is basically close to the manual operation level.

Drawings

Fig. 1 is a schematic structural view of a digging device of a wheel-leg combined excavator.

Fig. 2 is a schematic structural view of a wheel-leg composite chassis.

FIG. 3 is a schematic diagram of a control system according to the present invention.

Fig. 4 is a schematic diagram of the calculation of the moving distance.

Fig. 5 is a schematic diagram of the shift effect.

FIG. 6 is a diagram illustrating a method for motion error cancellation.

In the figure: 1 is a boom, 2 is an arm, 3 is a telescopic arm, 4 is a bucket, h1 is an excavating device hydraulic system, 11 is a front claw, 12 is a front arm joint, 13 is a front wheel, 14 is a front leg joint, 15 is a front hinge joint, 16 is a base, 17 is a rear hinge joint, 18 is a rear leg joint, 19 is a rear wheel hub, 20 is a rear wheel, 101 is a main controller, 102 is a positioning navigation device, 103 is a wheel speed meter, 201 is a lower computer controller, 202 is a hydraulic system, 203 is an actuator, 204 is a sensor system.

Detailed Description

The technical solution in the embodiments of the present invention is clearly and completely described below with reference to the accompanying drawings.

The autonomous displacement control system of the wheel-leg combined excavator, as shown in fig. 3, comprises: the system comprises a main controller 101, a positioning navigation device 102, a wheel speed meter 103, a lower computer controller 201, a hydraulic system 202, an actuator 203 and a sensor system 204. The main controller 101, the positioning navigation device 102, the wheel speed meter 103 and the lower computer controller 201 are connected through a CAN bus; the lower computer controller 201 receives the instruction of the main controller 101 and resolves the instruction into an electric signal, the electric signal is output to a corresponding electromagnetic valve in the hydraulic system 202 to drive a hydraulic oil cylinder, a motor and the like in the execution mechanism 203 to complete related actions, and the sensor system 204 acquires pressure and displacement signals of the execution mechanism 203 and uploads the pressure and displacement signals to the main controller 101 through the lower computer controller 201 to serve as a reference for subsequent logic operation.

Preferably, the main controller 101, the main CPU is the i7-2655UE processor, and the operating system is Windows CE. And the system is responsible for planning and logic control, receives the information of the lower computer and forms a target control quantity.

Preferably, the positioning navigation device 102 is used for selecting a shelf product to realize the detection of the heading, the posture and the position of the excavator.

Preferably, the wheel speed meter 103 is composed of a hall sensor and an induction device, and is located on the hub of the excavator to detect the running speed of the excavator.

Preferably, the lower computer controller 201 is composed of a programmable controller and a conditioning circuit, receives the instruction of the main controller 101, and calculates the instruction into an electric signal to control the opening size of the hydraulic valve.

Preferably, the hydraulic system 202 is composed of a pump, a valve, a motor, a hydraulic cylinder, and the like, and the hydraulic system 202 receives an electric signal from the lower computer controller 201, drives the actuator 203, and drives the excavator to move, and specifically includes: a hydraulic pump, a hydraulic valve, an electromagnetic valve, a hydraulic oil cylinder, a motor, and the like for driving the excavator boom 1, the arm 2, the telescopic arm 3, the bucket 4, the forearm joint 12, the front wheel 13, the front leg joint 14, the rear leg joint 18, and the rear wheel 20 to move.

Preferably, the actuator 203 comprises a 4-degree-of-freedom working device and a chassis mechanism, wherein the 4-degree-of-freedom working device comprises a movable arm 1, an arm 2, a telescopic arm 3 and a bucket 4, and the chassis mechanism comprises a front claw 11, a front arm joint 12, a front wheel 13, a front leg joint 14, a front hinge joint 15, a base 16, a rear hinge joint 17, a rear leg joint 18, a rear hub 19 and a rear wheel 20.

Preferably, the sensor system 204 includes a displacement sensor, a hydraulic system pressure sensor and a data acquisition module, and realizes the acquisition and uploading of the position information of each joint of the actuator 203, and the sensor system 204 acquires the pressure and displacement signals of the actuator 203 and uploads the pressure and displacement signals to the main controller 101 through the lower computer controller 201.

The working principle is as follows: the positioning navigation device 102 is used for obtaining the current position information of the excavator, the main controller 101 generates the control quantity of each working period through planning and logical operation according to the current position information of the excavator and the moving target position information, the control quantity is transmitted to the lower computer controller 201 through the CAN bus, the lower computer controller 201 controls the opening degree of the valve port in the hydraulic system 202 according to the control quantity, further driving the position of the corresponding joint in the actuator 203 to move in one control cycle, realizing backward movement of the excavator in one working cycle in a compound motion mode, calculating the moving distance of the excavator in the current working cycle by using the wheel speed meter 103, acquiring displacement information of the actuator by the sensor system 204, comparing the displacement information with a target control quantity, the control quantity of the next period is obtained through the logic calculation of the main controller 101, and the system enters the autonomous control stage of the next working period. And the rest is repeated until the excavator autonomously moves to the target position.

The wheel-leg combined type excavator autonomous displacement control and posture adjustment control method combines four wheel legs of an excavator walking device and a working device to be regarded as a multi-foot parallel robot, and based on a multi-foot parallel robot motion control technology, complete machine displacement of the excavator and posture adjustment after the position is changed are achieved. All actions are completed by the excavator automatically without manual intervention. The method comprises the following steps:

the method comprises the following steps: the support legs are retracted. The specific implementation mode is as follows: the support leg oil cylinders are controlled, the support legs are retracted, and the chassis of the excavator is controlled to be parallel to the ground by adjusting the joint oil cylinders of the chassis, so that the stability of the excavator is ensured;

step two: the movement distance L is determined. As shown in fig. 4, in order to ensure the continuous and regular excavation working surface of the front station and the rear station, the moving distance L of the excavator is determined by comprehensively considering factors such as the bucket structure, the structure shape of the excavated area, the operation range of the excavator and the like;

step three: the vehicle body is supported. The specific implementation mode is as follows: controlling 4-degree-of-freedom working devices to comprise 4 oil cylinders including a movable arm 1, a bucket rod 2, a telescopic arm 3 and a bucket 4, compounding vertical linear motion, and supporting a vehicle body to enable a front wheel 13 to be away from the ground, wherein the vehicle body lifting distance is D, namely the distance between the center of the front wheel 13 and the ground is D;

step four: and calculating the displacement of the working device oil cylinder in each control beat. After the front wheel 13 is raised, the movement of the vehicle body is mainly matched with a walking motor through a working device oil cylinder, so that the movement control of the excavator is completed, and in the concrete implementation, the displacement of the oil cylinder related to each control beat needs to be calculated. The specific implementation mode is as follows: calculating the displacement x of the excavator with the next beat according to the moving speed v and the beat period T, calculating target displacement Dd and Ds of the boom 2 and the telescopic arm 3 with the next beat according to a space geometric transformation method, and circularly calculating to sequentially obtain the displacement in the subsequent beats of the oil cylinders of the boom 2 and the telescopic arm 3 until the target position is reached;

step five: and calculating the rotation angle of the walking motor in each control beat. Calculating a rotation angle Rm of each beat of a walking motor according to the displacement x of the excavator until a target position is reached;

step six: controlling the vehicle body to move backwards. The specific implementation mode is as follows: as shown in fig. 5, the control device arm 2 and the telescopic arm 3 are controlled to perform oil cylinder compound motion by taking the contact point of the bucket 4 and the ground as a pivot, and the displacement of the arm 2 and the telescopic arm 3 is Dd and Ds respectively during each control cycle; simultaneously controlling the rotation angle Rm of the walking motor until the excavator shifts to a target position;

step seven: and adjusting the transverse posture to eliminate transverse errors. The method for eliminating the transverse error comprises the following steps: when the lateral deviation DisY is larger than D1 and smaller than D2, the X1 axis of the excavation work surface is realigned in the direction of the X axis before shifting by a method of solving the coordinate system in the forward and reverse directions of the rotary excavator work device. When DisY is larger than D2, the excavator working device is used for lifting the rear leg, rotating the rotating shaft, lifting the front leg, reversely rotating the rotating shaft and realigning the orientation of the excavator to the orientation before displacement;

step eight: and adjusting the longitudinal posture to eliminate transverse and longitudinal errors. As shown in fig. 6, the cause of the vertical working plane misalignment is mainly caused by the positioning control accuracy. The longitudinal shift error DisX is eliminated by the following method: substituting the DisX into the trajectory plan of the next fixed point excavation, and correspondingly increasing and decreasing the X coordinate of the designed excavation point in the X-axis direction according to the DisX value;

step nine: and controlling the walking state to be converted into the working state. After the excavator is shifted to the target position, the control supporting legs are unfolded towards two sides, then the control supporting legs are moved downwards to be inserted into the ground, and the excavator finishes preparation for excavation operation.

The described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

Claims (1)

1. The control method of the autonomous displacement control system of the wheel-leg combined excavator is characterized by comprising the following steps of:

the method comprises the following steps: the support leg oil cylinders are controlled, the support legs are retracted, and the chassis of the excavator is controlled to be parallel to the ground by adjusting the joint oil cylinders of the chassis, so that the stability of the excavator is ensured;

step two: determining the moving distance L of the excavator;

step three: 4 oil cylinders of a movable arm (1), a bucket rod (2), a telescopic arm (3) and a bucket (4) in the 4-degree-of-freedom working device are controlled to perform compound vertical linear motion, a vehicle body is supported, a front wheel (13) is separated from the ground, the vehicle body lifting distance is D, namely the distance between the center of the front wheel (13) and the ground is D;

step four: calculating the displacement of a working device oil cylinder in each control beat, matching the front wheel (13) with a walking motor to finish the movement control of the excavator by the aid of the working device oil cylinder and the walking motor after the front wheel is raised, calculating the displacement of the oil cylinder related to each control beat during concrete implementation, calculating the displacement x of the excavator in the next beat according to the movement speed v and the beat period T, calculating target displacement Dd and Ds of a bucket rod (2) and a telescopic arm (3) in the next beat according to a space geometric transformation method, and circularly calculating the displacement in subsequent beats of the oil cylinders of the bucket rod (2) and the telescopic arm (3) until the displacement reaches a target position;

step five: calculating the rotation angle of the walking motor in each control beat, and calculating the rotation angle Rm of each beat of the walking motor according to the displacement x of the excavator until the walking motor reaches a target position;

step six: controlling the bucket rod (2) and the telescopic arm (3) to perform oil cylinder compound motion by taking a contact point of the bucket (4) and the ground as a fulcrum, wherein the displacement of each control beat bucket rod (2) and the displacement of each telescopic arm (3) are Dd and Ds respectively; simultaneously controlling the rotation angle Rm of the walking motor until the excavator shifts to a target position;

step seven: adjusting the transverse posture, eliminating transverse errors, adopting a method of forward and backward solving a coordinate system by the rotary excavator working device when the transverse deviation DisY is larger than D1 and smaller than D2, realigning the X1 axis of the excavation working surface with the direction of the X axis before shifting, adopting the excavator working device to lift the rear leg, rotate the revolving shaft, lift the front leg again and reversely rotate the revolving shaft when the DisY is larger than D2, and realigning the orientation of the excavator with the orientation before shifting;

step eight: adjusting the longitudinal posture, eliminating transverse and longitudinal errors, wherein the reason for the dislocation of the longitudinal working surface is mainly generated by positioning control precision, substituting the DisX into the trajectory planning during next fixed-point excavation, and correspondingly increasing and decreasing the X coordinate of the designed excavation point in the X-axis direction according to the DisX value;

step nine: and (4) controlling the walking state to be converted into the working state, controlling the supporting legs to be unfolded towards two sides after the excavator is shifted to the target position, then moving downwards to be inserted into the ground, and completing preparation for excavating operation by the excavator.

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