Electrically driven excavator and automatic skirting operation method

Abstract

The present application relates to the technical field of excavators, and particularly relates to an electrically-driven excavator and an automatic edge-approaching operation method. The excavator comprises: a walking system comprising a walking chassis; a rotating mechanism comprising a rotating platform installed on the walking chassis, and a deflector body arranged on the rotating platform; an arm frame, a bottom end of which is installed on the deflector body, and a bucket arranged at a tail end of the arm frame; when the rotating platform and the deflector body rotate in opposite directions, an offset is formed between the arm frame and a longitudinal center plane; a sensing system is used to obtain a lateral distance between the longitudinal center plane of the excavator and a target object; when the bucket needs to perform edge-approaching operation along the target object, an offset distance required by the arm frame is determined according to the lateral distance and a width of the bucket; and according to a distance between the deflector body and a rotating center of the rotating platform and the offset distance, a rotating angle required by the rotating platform and the deflector body is determined to realize the edge-approaching operation.

Description

Technical Field

[0001] This invention relates to the field of excavator technology, specifically to an electrically driven excavator and an automatic edge-trimming operation method. Background Technology

[0002] With the acceleration of urbanization and the increase in urban renewal projects, excavators, especially wheeled excavators, are being used more and more extensively in urban operations. The requirements for excavators in terms of greenness, low noise, and operational flexibility are becoming increasingly stringent. Currently, most existing excavator booms consist of a boom and stick, with some featuring boom sway functionality. New energy excavators are mostly converted from hydraulic systems, still using hydraulic systems, resulting in low operating efficiency. Furthermore, operation is primarily based on single-action lever control, requiring operators to continuously operate the levers for various tasks. This leads to a heavy workload, especially in scenarios requiring operation close to walls or edges. In addition to operating the boom, stick, and slewing for digging, frequent adjustments to the boom sway position are needed to achieve straight-line operation close to walls. Moreover, the construction quality relies entirely on the operator's experience, making quality control difficult. Summary of the Invention

[0003] The purpose of this invention is to provide an electric-driven excavator and an automatic edge-fitting operation method. When the bucket needs to fit along the edge of a target object, the required offset distance of the boom is determined based on the lateral distance and the width of the bucket. The required rotation angle of the turntable and the deflector is determined based on the distance between the deflector and the rotation center of the turntable and the offset distance. This realizes the automated edge-fitting operation of the excavator and improves the operation efficiency.

[0004] In a first aspect, the present invention provides an electrically driven excavator, comprising: The walking system includes the walking chassis; The slewing mechanism includes a turntable mounted on the traveling chassis, and a deflector is provided on the turntable; The boom is mounted on the deflector at its bottom end and has a bucket at its end. In the initial state, the boom is parallel to the longitudinal center plane. When the turntable and the deflector rotate in opposite directions, an offset is formed between the boom and the longitudinal center plane. A sensing system is used to obtain the lateral distance between the longitudinal center plane of the excavator and the target object; When the bucket needs to perform edge-to-edge operation along the target object, the required offset distance of the boom is determined based on the lateral distance and the width of the bucket; the required rotation angle of the turntable and the deflector is determined based on the distance between the rotation center of the deflector and the turntable and the offset distance.

[0005] Optionally, the walking system further includes: The travel drive motor is used to drive the excavator to travel.

[0006] Optionally, the rotary mechanism further includes: A slewing bearing is provided, and the turntable is mounted on the traveling chassis via the slewing bearing. A rotary motor and a reducer, wherein the rotary motor can drive the rotary bearing through the reducer to drive the turntable to rotate relative to the traveling chassis; An encoder, mounted on the turntable, is used to detect the rotation angle of the turntable.

[0007] Optionally, the boom includes: The rear boom and the rear boom electric cylinder, wherein the bottom end of the rear boom is mounted on the deflector; The deflector can be driven by a deflection electric cylinder to rotate the entire boom; the movement stroke of the deflection electric cylinder can be obtained by the sensor built into the deflection electric cylinder to determine the deflection angle of the deflector. A front boom and a front boom electric cylinder, wherein the rear end of the front boom is hinged to the front end of the rear boom; The stick and the stick electric cylinder, wherein the rear end of the stick is hinged to the front end of the front boom; A bucket and a bucket electric cylinder, wherein the bucket is mounted on the front end of the stick.

[0008] Optionally, it also includes: The power system, including the power battery and high and low voltage power distribution system, is used to power the walking system, slewing mechanism, boom and sensing system.

[0009] Optionally, the target object includes a wall or a straight line drawn along the ground.

[0010] Secondly, the present invention provides an automatic edge-trimming operation method for an electric-driven excavator, which is based on the electric-driven excavator and includes the following operation method: The excavator is positioned in its initial state, with the boom parallel to the longitudinal center plane. The greater of the front turning radius of the excavator and half the width of the excavator is determined as the safe parking distance. The excavator is parked against the wall with the standard that the lateral distance between the longitudinal center plane of the excavator and the target is greater than the safe parking distance. The lateral distance between the longitudinal center plane of the excavator and the target object is obtained using the sensing system. The required offset distance of the boom is determined based on the lateral distance and the width of the bucket. The sum of the offset distance and half the width of the bucket needs to reach the lateral distance. The required offset distance of the boom is used to determine the required rotation angle of the turntable and the deflector. The turntable and the deflector are then controlled to rotate by the required angle in the direction closer to the target and away from the target, respectively. At this time, the boom remains parallel to the longitudinal center plane of the excavator and the bucket can perform edge-to-edge operation along the edge of the target.

[0011] Optionally, the formula for calculating the offset distance is: L2 = L1 × sinα Where L2 represents the offset distance between the boom and the longitudinal center plane, L1 represents the distance between the deflector and the rotation center of the turntable, and α represents the angle of rotation of the turntable and the deflector.

[0012] Optionally, the selection criteria for the bucket are: The sum of the bucket width and the maximum offset distance of the boom must be greater than the lateral distance between the longitudinal center plane and the target.

[0013] Optionally, when rotary unloading is required after excavation, the unloading methods include: Detect the unloading position; If the rear turning radius of the excavator is less than the lateral distance between the longitudinal center plane of the excavator and the target object, the turntable is controlled to rotate away from the target object so that the bucket is aligned with the unloading position and the unloading operation is completed. If the rear turning radius of the excavator is greater than or equal to the lateral distance between the longitudinal center plane of the excavator and the target object, control the turntable to rotate away from the target object to the limit position to ensure that the rear of the excavator does not interfere with the target object, and then control the deflector to rotate away from the target object so that the bucket is aligned with the unloading position and the unloading operation is completed.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. When performing edge-hugging operations (particularly suitable for narrow spaces or scenarios requiring precise straight-line operations against a wall), this invention first positions the excavator in its initial state, with the boom parallel to the longitudinal center plane. Then, the greater of the excavator's front turning radius and half the excavator's width is determined as the safe stopping distance. The excavator is then parked against the wall with the lateral distance between the excavator's longitudinal center plane and the target object greater than this safe stopping distance as the standard. A sensing system is then used to obtain the lateral distance between the excavator's longitudinal center plane and the target object at this time. Based on this lateral distance and the bucket width, the required offset distance of the boom can be determined. The sum obtained by adding half the width of the bucket needs to reach the lateral distance; the required rotation angle of the turntable and deflector body is determined according to the required offset distance of the boom, and the turntable and deflector body are controlled to rotate by the required angle in the direction closer to the target and away from the target, respectively. At this time, the boom is kept parallel to the longitudinal center plane of the excavator and the bucket can perform edge-to-edge operation along the edge of the target. The present invention can realize complex digging actions and precise position control through the above method, improve the operation efficiency and the degree of automation. Through the combination of the sensing system and the control system, the automated operation of the excavator is realized, the operation efficiency is improved, and the manual operation is reduced.

[0015] 2. Compared with the prior art, the present invention improves the control precision by using an electric cylinder to drive the boom, thereby achieving high-precision position and attitude control of the excavator boom; it also improves the degrees of freedom of the excavator by using a multi-degree-of-freedom robotic arm design to achieve multi-degree-of-freedom movement of the excavator boom, thereby improving the excavator's working capacity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an electrically driven excavator. Figure 2 This is a schematic diagram of the control system of an electric drive excavator. Figure 3 This is a schematic diagram of the edge-following operation control of an electric-driven excavator.

[0017] The following are the labeling elements in the diagram: 1. Boom; 2. Slewing mechanism; 3. Power system; 4. Sensing system; 5. Control system; 6. Traveling system; 11. Rear boom; 101. Rear boom electric cylinder; 12. Front boom; 102. Front boom electric cylinder; 13. Stick; 103. Stick electric cylinder; 14. Bucket; 104. Bucket electric cylinder; 15. Oscillating body; 105. Oscillating electric cylinder; 21. Turntable; 22. Slewing bearing; 23. Slewing motor and reducer; 61. Wheeled chassis; 62. Travel drive motor. Detailed Implementation

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0020] The excavator provided by the present invention includes a multi-degree-of-freedom electrically driven boom 1, a slewing mechanism 2, a power system 3, a sensing system 4, a control system 5, and a walking system 6.

[0021] The multi-degree-of-freedom electrically driven excavator boom 1 specifically includes a rear boom 11 and a rear boom electric cylinder 101 that drives its movement, a front boom 12 and a front boom electric cylinder 102 that drives its movement, a stick 13 and a stick electric cylinder 103 that drives its movement, a bucket 14 and a bucket electric cylinder 104 that drives its movement, a deflector 15 that connects the rear boom to the turntable, and a deflector electric cylinder 105 that connects the turntable and the deflector and drives the entire boom to swing left and right. Each electric cylinder is driven by a motor through a reducer to drive a lead screw to achieve the extension and retraction action.

[0022] A resolver position sensor is installed at the tail of the motor of each electric cylinder, which can detect the absolute angular position and rotational speed of the motor in real time. By accumulating the rotational angle, the movement length of the lead screw (electric cylinder) can be accurately calculated. By using the movement lengths of the electric cylinders of the front boom, rear boom, stick, and bucket, as well as the structural dimensions and connection relationships of each part of the boom, the movement angle of each boom section can be calculated. The movement length of the deflection electric cylinder can be obtained by the sensor built into the deflection electric cylinder to calculate the deflection angle of the boom. The advantages of using an electrically driven excavator boom are, firstly, that it eliminates the need to install tilt sensors on each boom section, saving on sensor costs and the complexity of wiring layout; secondly, the motor can achieve precise control of the movement length of the electric cylinder, greatly improving the control accuracy of the boom movement. The excavator uses a multi-degree-of-freedom electrically driven excavator boom with electric cylinders, including the rear boom 11, front boom 12, stick 13, bucket 14, and deflector 15, which improves the excavator's operating freedom and control accuracy, and achieves precise position and attitude control.

[0023] The slewing mechanism 2 includes a turntable 21, a slewing bearing 22, a slewing motor, and a reducer 23. The turntable 21 is mounted on the walking system 6 via the slewing bearing 22. The slewing motor and reducer 23 drive the slewing bearing 22 to drive the turntable 21 to achieve slewing motion. An encoder is installed on the turntable to detect the slewing angle of the turntable.

[0024] The power system 3 mainly includes a power battery and a high and low voltage power distribution system, which provides power to various working components.

[0025] The perception system 4 includes multi-directional cameras, lidar, millimeter-wave radar, RTK navigation system and perception domain controller, which enables the excavator to locate itself and identify targets or obstacles such as walls in the working environment.

[0026] The control system 5 mainly includes an upper-mounted operation controller, controllers for each electric cylinder, a slewing motor controller, and a travel controller. The upper-mounted controller receives status information from each electric cylinder and, combined with information provided by the sensing system, sends commands to the electric cylinder controllers and slewing motor controllers according to a trajectory planning algorithm to control the boom and slewing movements. The excavator detects itself and its surrounding environment through the sensing system 4, and, in conjunction with the upper-mounted control system and the travel control system, performs machine positioning and precise digging. Through automated edge-following control logic, it achieves edge-following straight-line digging and unloading operations.

[0027] The walking system 6 includes a wheeled walking chassis 61 and a walking drive motor 62 to enable the excavator to walk, and also includes sensors to detect the walking posture.

[0028] The distance from the deflection center of the deflector 15 at the bottom of the boom 1 to the rotation center of the turntable 21 is L1. The rotation angle α of the deflector 15 (which is essentially the deflection angle between the boom 1 and the longitudinal center plane of the excavator) and the rotation angle of the turntable 21 are θ. When the boom deflection angle α and the turntable rotation angle θ are the same and opposite in direction, it ensures that the boom 1 operates along the machine body direction (the longitudinal center plane of the excavator), that is, the bucket 14 operates close to the wall. At this time, the offset distance from the center of the boom 1 (the deflection center of the deflector 15) to the longitudinal center plane of the vehicle is L2 = L1 × sinα. The bucket width is W. The larger the boom deflection angle α, the larger the offset distance L2, and the larger the range of lateral movement that the boom 1 can perform relative to the longitudinal center plane of the vehicle. The range of lateral movement is L2 + W / 2 (offset distance + bucket width / 2).

[0029] When the excavator is rotating, the turntable 21 rotates around the rotation center. The front rotation radius is R1 (the distance from the farthest point of the front of the excavator to the rotation center), the rear rotation radius is R2 (the distance from the farthest point of the front of the excavator to the rotation center), and the overall width of the excavator is D.

[0030] The following is how the excavator can automatically perform straight-line excavation (or excavate along a pre-drawn straight line or other designated target on the ground) when working close to a wall: 1) Detect that the boom 1 is in the initial driving position (in the initial state, the rotation center of the turntable 21 is located on the longitudinal center plane of the excavator, and the rotation center of the deflector 15 can be located on the longitudinal center plane of the excavator or deviate from the longitudinal center plane), and the boom 1 is parallel to the machine body direction (the longitudinal center plane of the excavator). If not, adjust the posture of the boom 1 so that the boom 1 is parallel to the machine body direction, so that the deflection angle α of the deflector 15 is 0 and the rotation angle θ of the turntable 21 is 0. 2) Determine the safe parking position of the excavator against the wall based on the vehicle width D and the front turning radius R1 (determine the greater of the excavator's front turning radius R1 and half the excavator width D / 2 as the safe parking distance). If R1≤D / 2, the excavator can be parked along the wall (the lateral distance between the excavator's longitudinal center plane and the wall is greater than D / 2); if R1>D / 2, the distance between the excavator and the wall when parking must be greater than R1-D / 2 (the lateral distance between the excavator's longitudinal center plane and the wall is greater than R1).

[0031] 3) Perform fuselage positioning. The perception system 4 uses the RTK navigation system to locate the vehicle body information and uses the camera and LiDAR to locate the wall and surrounding environment information. The perception domain controller combines the vehicle body and environmental information to perform path planning and sends it to the walking controller for fuselage positioning. 4) Calculate the lateral distance L between the longitudinal center plane of the excavator and the wall based on the machine's positioning coordinates and the wall's position coordinates; 5) Select a bucket 14 of appropriate size for digging operations. The sum of the offset distance and half the width of the bucket 14 must reach the lateral distance. To ensure wall-hugging operation, if R1≤D / 2, L2+W / 2>D / 2 must be satisfied; if R1>D / 2, L2+W / 2>R1 must be satisfied. Thus, a bucket of appropriate width must be selected, meaning L2+W / 2 must be greater than the safe stopping distance (the larger of the front turning radius R1 and half the width of the excavator D / 2) for the bucket to achieve wall-hugging operation.

[0032] 6) Calculate the value of L2 based on the bucket width W and the lateral distance L. The calculation formula is L=L2+W / 2.

[0033] 7) Calculate the boom deflection angle α1 based on L2=L1×sinα; 8) Calculate the stroke of the deflection electric cylinder 105 of boom 1 based on the boom deflection angle α1 and structural dimension information; 9) The work controller sends a control signal to the rotary motor controller to drive the turntable to rotate towards the wall by an angle θ1=α1, and sends a control signal to the controller of the deflection electric cylinder 105 of the boom 1 to deflect the boom 1 away from the wall by an angle α1. After the above operation, the excavator's bucket 14 can perform edge-to-edge operation along the wall edge; 10) The perception domain controller plans the boom trajectory based on the input information such as the specific location and depth of the excavation using a trajectory planning algorithm, and sends the instructions to the upper work controller. The work controller then sends motion instructions to the electric cylinder controllers of the boom to perform the excavation operation.

[0034] When unloading material by rotating the excavator, care must be taken to ensure that the tail section does not collide with the wall during rotation to guarantee construction safety.

[0035] The action logic during unloading is as follows: 1) Detect the unloading position and calculate the horizontal position (perpendicular to the vehicle body direction) of the unloading point center relative to the excavator center. 2) If the rear turning radius of the excavator is less than the lateral distance between the longitudinal center plane of the excavator and the wall, R2 < D / 2, or D / 2 < R2 < L, then the turntable 21 driven by the rotary motor will move the boom 1 away from the wall. The camera and laser radar will be used to locate the unloading point. The operation controller will issue motion commands according to the boom trajectory planning algorithm to carry out the unloading operation. The deflection cylinder does not need to move.

[0036] 3) If the rear turning radius of the excavator is greater than or equal to the lateral distance between the longitudinal center plane of the excavator and the wall, and if R2 > L, then when turning to unload, the angle θ2 ≤ θ1 of the motor-driven turntable turning away from the wall must be limited. The turntable is controlled to rotate away from the wall to the limit position to ensure that the rear of the excavator does not interfere with the wall. If the unloading position cannot be reached, the operation controller sends a control signal to make the boom deflector move, so that the boom continues to deflect away from the wall to the angle α2 or the maximum deflection angle to achieve the purpose of unloading.

[0037] In summary, this embodiment improves control precision compared to existing technologies by employing an electric cylinder to drive the boom, achieving high-precision position and attitude control of the excavator arm. It also increases the excavator's degrees of freedom through a multi-degree-of-freedom robotic arm design, enabling multi-degree-of-freedom movement of the excavator arm and enhancing its operational capabilities. Furthermore, this embodiment improves operational efficiency and automation by combining a sensing system and a control system, achieving automated operation, increasing efficiency, and reducing manual intervention.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electrically driven excavator, characterized in that, include: The walking system includes the walking chassis; The slewing mechanism includes a turntable mounted on the chassis, and a deflector body is provided on the turntable. The deflector body can be driven by a deflector electric cylinder to rotate the entire boom. The movement stroke of the deflector electric cylinder can be obtained by a sensor built into the deflector electric cylinder to determine the deflection angle of the deflector body. The boom is mounted on the deflector at its bottom end and has a bucket at its end. In the initial state, the boom is parallel to the longitudinal center plane. When the turntable and the deflector rotate in opposite directions, an offset is formed between the boom and the longitudinal center plane. The sensing system is used to obtain the lateral distance between the longitudinal center plane of the excavator and the target object; when the bucket needs to perform edge operation along the target object, the required offset distance of the boom is determined based on the lateral distance and the width of the bucket; the required rotation angle of the turntable and the deflector is determined based on the distance between the deflector and the rotation center of the turntable and the offset distance. The control system includes an overhead crane operation controller, controllers for each electric cylinder, and a slewing motor controller. The overhead crane operation controller receives the status information of each electric cylinder and, in conjunction with the information provided by the sensing system, sends commands to the electric cylinder controllers and the slewing motor controller according to the trajectory planning algorithm to control the boom and slewing motion. The rotary mechanism also includes: A slewing bearing is provided, and the turntable is mounted on the traveling chassis via the slewing bearing. A rotary motor and a reducer, wherein the rotary motor can drive the rotary bearing through the reducer to drive the turntable to rotate relative to the traveling chassis; An encoder, mounted on the turntable, is used to detect the rotation angle of the turntable; The boom includes: The rear boom and the rear boom electric cylinder, wherein the bottom end of the rear boom is mounted on the deflector; A front boom and a front boom electric cylinder, wherein the rear end of the front boom is hinged to the front end of the rear boom; The stick and the stick electric cylinder, wherein the rear end of the stick is hinged to the front end of the front boom; A bucket and a bucket electric cylinder, wherein the bucket is mounted on the front end of the stick.

2. The electrically driven excavator according to claim 1, characterized in that, The walking system also includes: The travel drive motor is used to drive the excavator to travel.

3. The electrically driven excavator according to claim 1, characterized in that, Also includes: The power system, including the power battery and high and low voltage power distribution system, is used to power the walking system, slewing mechanism, boom and sensing system.

4. The electrically driven excavator according to claim 1, characterized in that, The subject matter includes walls or straight lines drawn along the ground.

5. An automatic edge-trimming operation method for an electrically driven excavator, characterized in that, The operation is carried out using an electrically driven excavator according to any one of claims 1-4, and the method of operation includes: The excavator is positioned in its initial state, with the boom parallel to the longitudinal center plane. The greater of the front turning radius of the excavator and half the width of the excavator is determined as the safe parking distance. The excavator is parked against the wall with the standard that the lateral distance between the longitudinal center plane of the excavator and the target is greater than the safe parking distance. The lateral distance between the longitudinal center plane of the excavator and the target object is obtained using the sensing system. The required offset distance of the boom is determined based on the lateral distance and the width of the bucket. The sum of the offset distance and half the width of the bucket needs to reach the lateral distance. The required offset distance of the boom is used to determine the required rotation angle of the turntable and the deflector. The turntable and the deflector are then controlled to rotate by the required angle in the direction closer to the target and away from the target, respectively. At this time, the boom remains parallel to the longitudinal center plane of the excavator and the bucket can perform edge-to-edge operation along the edge of the target.

6. The automatic edge-following operation method for an electrically driven excavator according to claim 5, characterized in that, The formula for calculating the offset distance is: L2 = L1 × sinα Where L2 represents the offset distance between the boom and the longitudinal center plane, L1 represents the distance between the deflector and the rotation center of the turntable, and α represents the angle of rotation of the turntable and the deflector.

7. The automatic edge-following operation method for an electrically driven excavator according to claim 5, characterized in that, The selection criteria for the bucket are as follows: The sum of the bucket width and the maximum offset distance of the boom must be greater than the lateral distance between the longitudinal center plane and the target.

8. The automatic edge-following operation method for an electrically driven excavator according to claim 5, characterized in that, When unloading is required after excavation, the unloading methods include: Detect the unloading position; If the rear turning radius of the excavator is less than the lateral distance between the longitudinal center plane of the excavator and the target object, the turntable is controlled to rotate away from the target object so that the bucket is aligned with the unloading position and the unloading operation is completed. If the rear turning radius of the excavator is greater than or equal to the lateral distance between the longitudinal center plane of the excavator and the target object, control the turntable to rotate away from the target object to the limit position to ensure that the rear of the excavator does not interfere with the target object, and then control the deflector to rotate away from the target object so that the bucket is aligned with the unloading position and the unloading operation is completed.

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