A double-motor slewing system of excavator and control method

Abstract

This invention discloses a dual-motor slewing system and control method for excavators. The invention controls two slewing motor assemblies based on the opening of the speed handle, the actual load in the bucket, the actual slewing speed, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder. By adopting a dual-motor slewing configuration, the invention achieves electric slewing of large-tonnage excavators.

Description

Technical Field

[0001] This invention relates to a dual-motor slewing system and control method for an excavator, belonging to the field of new energy construction machinery. Background Technology

[0002] The electrification of excavators has driven the application of electric slewing technology. Compared to traditional hydraulic motor-driven slewing systems, electric slewing offers higher transmission efficiency and enables regenerative braking, further improving the operational efficiency of excavators. While existing technologies have enabled the application of single-motor slewing configurations and control methods for excavator slewing systems, they have not addressed dual-motor slewing for large-tonnage excavators. Summary of the Invention

[0003] This invention provides a dual-motor slewing system and control method for excavators, which solves the problems disclosed in the background art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A dual-motor slewing system for an excavator includes a slewing controller, a first slewing motor assembly, and a second slewing motor assembly. Both the first and second slewing motor assemblies mesh with the excavator's slewing gear. The slewing controller sends control commands to the first and second slewing motor assemblies based on received data such as the speed handle opening, the actual load in the bucket, the slewing speed of the turntable, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder.

[0006] The actual load inside the bucket is collected by a weighing sensor connected to the slewing controller, and the displacement of the hydraulic cylinders of each actuating mechanism is collected by a displacement sensor connected to the slewing controller.

[0007] A control method for a dual-motor slewing system of an excavator, comprising:

[0008] Determine the rotation mode based on the opening of the speed handle and the actual rotation speed;

[0009] Calculate the required torque under the swing mode based on the swing mode, speed handle opening, actual load in the bucket, actual swing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement.

[0010] The required torque is allocated with the goal of maximizing the overall efficiency of the first rotary motor assembly and the second rotary motor assembly.

[0011] Based on the rotation mode and allocation results, control commands are sent to the first rotary motor assembly and the second rotary motor assembly.

[0012] The slewing modes include slewing drive mode, slewing coasting mode, slewing braking mode, slewing lock mode, and slewing reversing mode.

[0013] The rotation mode is determined based on the speed handle opening and the actual rotation speed, including:

[0014] If the speed handle opening is 0 and the actual rotation speed is greater than the rotation motor braking speed threshold, then the rotation mode is the rotation braking mode.

[0015] If the speed handle opening is 0 and the actual rotation speed is not greater than the braking speed threshold of the rotation motor, then the rotation mode is the rotation lock-up mode.

[0016] If the speed handle opening is non-zero and the direction corresponding to the actual rotation speed is opposite to the target rotation direction, then the rotation mode is the rotation reversal mode; where the target rotation speed and direction are determined according to the speed handle opening.

[0017] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening increases, and the actual rotation speed is greater than the target rotation speed, the rotation mode is rotation gliding mode.

[0018] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening increases, and the actual rotation speed is zero or the actual rotation speed is not greater than the target rotation speed, the rotation mode is rotation drive mode.

[0019] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening decreases, and the actual rotation speed is not greater than the target rotation speed or the actual rotation speed is not greater than the rotation motor braking speed threshold, the rotation mode is rotation coasting mode.

[0020] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening decreases, and the actual rotation speed is greater than the target rotation speed or the actual rotation speed is greater than the rotation motor braking speed threshold, the rotation mode is rotation braking mode.

[0021] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was rotation drive mode / rotation coasting mode / rotation braking mode, and the actual rotation speed is not greater than the target rotation speed, the rotation mode is rotation drive mode.

[0022] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was rotation drive mode / rotation coasting mode / rotation braking mode, and the actual rotation speed is greater than the target rotation speed, the rotation mode is rotation braking mode.

[0023] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was the rotation reversal mode, and the actual rotation speed is not greater than the target rotation speed, the rotation mode is the rotation reversal mode.

[0024] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was the rotation reversal mode, and the actual rotation speed is greater than the target rotation speed, the rotation mode is the rotation braking mode.

[0025] If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, and the rotation mode at the previous moment was the rotation lock mode, then the rotation mode is the rotation lock mode.

[0026] Based on the swing mode, speed handle opening, actual load in the bucket, actual swing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement, calculate the required torque in the swing mode, including:

[0027] If the slewing mode is slewing coasting mode or slewing lock mode, the required torque is 0;

[0028] If the slewing mode is slewing drive mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is the same as the direction of the target slewing speed. The PID algorithm parameters are determined based on the actual load in the bucket, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder.

[0029] If the slewing mode is slewing braking mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is opposite to the direction of the target slewing speed.

[0030] If the slewing mode is the slewing reversal mode and the direction corresponding to the actual slewing speed is opposite to the target slewing direction, 0 is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset braking torque coefficient, the final required torque is calculated.

[0031] If the slewing mode is the slewing reversal mode, and the actual slewing speed is 0 or the direction corresponding to the actual slewing speed is the same as the target slewing direction, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset drive torque coefficient, the final required torque is calculated.

[0032] The PID algorithm parameters are determined based on the actual load inside the bucket, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder, including:

[0033] Calculate the percentage of the cylinder displacement relative to the total cylinder stroke for each actuating mechanism; the actuating mechanism includes the boom, stick, and bucket.

[0034] Based on the stroke percentage of each actuator cylinder, the stroke coefficient of each actuator cylinder is obtained from a preset stroke coefficient table; the stroke coefficient table stores the mapped stroke percentage and stroke coefficient.

[0035] Calculate the rotational resistance torque contribution coefficient of each actuating mechanism based on the stroke coefficient of each actuating mechanism's cylinder.

[0036] Calculate the total rotational resistance torque contribution coefficient based on the rotational resistance torque contribution coefficient of each actuating mechanism.

[0037] Based on the total slewing resistance torque contribution coefficient and the actual load in the bucket, the PID algorithm parameters are obtained from a preset parameter table; the parameter table stores the mapped PID algorithm parameters, the total slewing resistance torque contribution coefficient, and the actual load in the bucket.

[0038] The formula for calculating torque using the piecewise PID algorithm is:

[0039]

[0040] In the formula, T(k) is the torque calculated by the piecewise PID algorithm in the k-th control cycle, P1, l1, and D1 are the PID algorithm parameters, Δv(k) is the difference between the target rotation speed and the actual rotation speed in the k-th control cycle, Δv(k-1) is the difference between the target rotation speed and the actual rotation speed in the (k-1)-th control cycle, and Δv(i) is the difference between the target rotation speed and the actual rotation speed in the i-th control cycle.

[0041] The required torque is allocated with the goal of maximizing the overall efficiency of the first and second rotary motor assemblies, using the following formula:

[0042] If the required torque is greater than the sum of the maximum torque output by the first rotary motor assembly and the second rotary motor assembly at the current rotary speed of the turntable, both the first rotary motor assembly and the second rotary motor assembly will output according to the maximum torque.

[0043] If the required torque is not greater than the sum of the maximum output torques of the first and second rotary motor assemblies at the current turntable rotation speed, the formula for allocating the required torque is:

[0044] Optimize the objective function, max{x*Eff1+y*Eff2}

[0045]

[0046] In the formula, x and y are the torque percentages of the first rotary motor assembly and the second rotary motor assembly, respectively; Eff1 is the efficiency value when the torque percentage allocated to the first rotary motor assembly is x; Eff2 is the efficiency value when the torque percentage allocated to the second rotary motor assembly is y; Treq is the required torque; and Tmax is the maximum allowable output torque of the rotary motor assembly at the current rotary speed of the turntable.

[0047] Control commands include:

[0048] When the required torque is not zero, the torque command allocated to each of the first rotary motor assembly and the second rotary motor assembly is sent.

[0049] When the required torque is 0 and the rotation mode is rotation lock-up mode, an electromagnetic braking command is sent to the first rotation motor assembly and the second rotation motor assembly.

[0050] The beneficial effects achieved by this invention are as follows: 1. This invention controls two slewing motor assemblies based on the speed handle opening, actual load in the bucket, actual slewing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement, adopting a dual-motor slewing configuration to achieve electric slewing of large-tonnage excavators; 2. This invention controls according to the slewing mode and, combined with the influence of load and changes in boom, stick, and bucket posture on the excavator's slewing resistance torque, calculates the required torque, improving the control accuracy of drive torque and braking torque, and solving the problem of large slewing impact or slow action response caused by a single torque calculation method; 3. This invention dynamically allocates the torque of the two slewing motor assemblies according to the efficiency characteristics of the slewing motor assemblies, maximizing the overall efficiency of the two slewing motor assemblies while ensuring slewing power and braking performance. Attached Figure Description

[0051] Figure 1 This is a structural block diagram of the dual-motor slewing system of an excavator;

[0052] Figure 2 A flowchart of the control method for a dual-motor slewing system of an excavator;

[0053] Figure 3 Flowchart defined for the slewing mode;

[0054] Figure 4 A flowchart for obtaining PID algorithm parameters;

[0055] Figure 5 This is a curve showing the relationship between the boom travel percentage and the travel coefficient.

[0056] Figure 6 This is a curve showing the relationship between the percentage of stick travel and the travel coefficient.

[0057] Figure 7 The curve showing the relationship between the percentage of bucket travel and the travel coefficient;

[0058] Figure 8 This is a flowchart for calculating the required torque in the slewing reversing mode. Detailed Implementation

[0059] 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.

[0060] like Figure 1 As shown, a dual-motor slewing system for an excavator includes a slewing controller, a first slewing motor assembly, a second slewing motor assembly, a battery, a weighing sensor, and displacement sensors for each actuating mechanism.

[0061] The battery serves as the power source, providing power to the first rotary motor assembly and the second rotary motor assembly.

[0062] The rotary motor assembly is an existing structure, specifically an assembly of components integrating a motor, a motor controller, a reducer, and an electromagnetic brake. Both the first rotary motor assembly and the second rotary motor assembly mesh with the excavator's rotary gear disc to drive the excavator's turntable to rotate.

[0063] The slewing controller is the control component of the entire system. It can directly adopt the existing controller in the excavator. Based on the received speed handle opening, actual load in the bucket, slewing speed of the turntable (calculated from the feedback motor speed of the slewing motor assembly), boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement, it sends control commands to the first and second slewing motor assemblies. Specifically, these commands include torque commands and electromagnetic braking commands.

[0064] The speed handle is the existing handle of the excavator. The speed handle is divided into three opening ranges: center, left swing, and right swing. The opening of the handle corresponds to the target swing speed. When the handle is in the center position, the target swing speed is 0. The larger the opening in the left swing or right swing range, the greater the target swing speed.

[0065] The load cell is connected to the slewing controller to collect the actual load inside the bucket.

[0066] The main actuators include the boom, stick, and bucket. Therefore, the displacement sensors include boom cylinder displacement sensors, stick cylinder displacement sensors, and bucket cylinder displacement sensors, which collect the displacements of the boom cylinder, stick cylinder, and bucket cylinder, respectively. These displacements serve as the basis for the attitude analysis of the excavator's operating device.

[0067] The slewing controller of the above system controls two slewing motor assemblies based on the opening of the speed handle, the actual load in the bucket, the actual slewing speed, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder. It adopts a dual-motor slewing configuration, realizing electric slewing of large-tonnage excavators. Compared with traditional hydraulic slewing, it improves transmission efficiency and realizes slewing braking energy recovery.

[0068] Based on the above system, this invention also discloses a control method for the above system, such as... Figure 2 As shown, it includes the following steps:

[0069] Step 1: Determine the rotation mode based on the opening of the speed handle and the actual rotation speed.

[0070] Step 2: Calculate the required torque under the swing mode based on the swing mode, speed handle opening, actual load in the bucket, actual swing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement.

[0071] Step 3: Distribute the required torque with the goal of maximizing the overall efficiency of the first rotary motor assembly and the second rotary motor assembly.

[0072] Step 4: Based on the rotation mode and allocation results, send control commands to the first rotary motor assembly and the second rotary motor assembly.

[0073] The above method controls the slewing mode, taking into account the speed handle opening, actual load in the bucket, actual slewing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement in different modes, and calculates the required torque. Thus, with the goal of maximizing the overall efficiency of the two slewing motor assemblies, the required torque is distributed to achieve control of the slewing motor assembly in different modes.

[0074] In this field, slewing modes are categorized into slewing drive mode, slewing coasting mode, slewing braking mode, slewing locking mode, and slewing reversing mode. The determination of the mode requires consideration of the speed handle opening and the actual slewing speed; the specific process can be found in [link to relevant documentation]. Figure 3 :

[0075] 1) Determine if the speed handle opening is 0. If yes, proceed to 2); otherwise, proceed to 3).

[0076] 2) Determine whether the actual rotation speed is greater than the braking speed threshold of the rotary motor. If so, determine that the rotation mode is the rotary braking mode; otherwise, determine that the rotation mode is the rotary lock-up mode.

[0077] 3) Determine whether the direction corresponding to the actual rotation speed (i.e., the actual rotation direction) is opposite to the target rotation direction. If so, determine that the rotation mode is the rotation reversal mode; otherwise, proceed to 4). The target rotation speed and direction are determined according to the opening of the speed handle.

[0078] 4) Determine if the speed handle opening has increased (i.e., continuously increased over several program cycles). If yes, proceed to 5); otherwise, proceed to 7).

[0079] 5) Determine if the actual turning speed is greater than the target turning speed. If so, determine the turning mode as turning and gliding mode; otherwise, proceed to step 6).

[0080] 6) Determine whether the actual rotation speed is 0 or whether the actual rotation speed is not greater than the target rotation speed. If so, determine that the rotation mode is the rotation drive mode.

[0081] 7) Determine if the speed handle opening has decreased. If so, proceed to step 8); otherwise, proceed to step 9.

[0082] 8) Determine whether the actual slewing speed is not greater than the target slewing speed or whether the actual slewing speed is not greater than the slewing motor braking speed threshold. If so, determine that the slewing mode is slewing coasting mode; otherwise, determine that the slewing mode is slewing braking mode.

[0083] 9) Determine whether the previous turning mode was turning drive mode, turning coasting mode, or turning braking mode. If yes, proceed to 10); otherwise, proceed to 11).

[0084] 10) Determine whether the actual slewing speed is not greater than the target slewing speed. If so, determine that the slewing mode is the slewing drive mode; otherwise, determine that the slewing mode is the slewing brake mode.

[0085] 11) Determine whether the previous turning mode was a turning reversal mode. If yes, proceed to 12). If not, that is, the previous turning mode was a turning lock mode, then determine that the turning mode is a turning lock mode.

[0086] 12) Determine whether the actual turning speed is not greater than the target turning speed. If so, determine that the turning mode is the turning reversal mode; otherwise, determine that the turning mode is the turning braking mode.

[0087] In step 2, different torque calculations and measurements are performed under different rotation modes to obtain the required torque for the next moment, as follows:

[0088] If the slewing mode is slewing drive mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is the same as the direction of the target slewing speed.

[0089] The selection of PID algorithm parameters depends on the actual load inside the bucket and the posture of the working device, namely the actual load inside the bucket, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder. The influence of the working device posture on the PID parameters is reflected by the contribution coefficient of the total slewing resistance torque. The specific calculation process is as follows: Figure 4 As shown:

[0090] S1) Calculate the percentage of the cylinder displacement of each actuating mechanism relative to the total stroke of the cylinder (the difference between the length of the cylinder in the fully retracted state and the length in the fully extended state is the total stroke of the cylinder).

[0091] S2) Based on the stroke percentage of each actuator cylinder, obtain the stroke coefficient of each actuator cylinder from the preset stroke coefficient table; wherein, the stroke coefficient table stores the mapped stroke percentage and stroke coefficient.

[0092] The relationship between the percentage of cylinder stroke and the stroke coefficient usually needs to be determined based on the actual vehicle structural parameters. The data relationship in the stroke coefficient table can be seen from this table. Figure 5 , Figure 6 , Figure 7 As shown in the figure, the stroke coefficient of each actuator is set according to the influence of its cylinder stroke on its moment of inertia relative to the slewing center. When the percentage of boom cylinder stroke increases, the stroke coefficient first increases and then decreases; the stroke coefficients of the stick and bucket both decrease as the percentage of cylinder stroke increases. When the stroke coefficients of the boom, stick, and bucket are all 1, it corresponds to the excavator's maximum digging radius posture, and the moment of inertia of the working device relative to the slewing center is the largest; when the boom, stick, and bucket cylinders are fully extended and the stroke coefficients are all 0, the moment of inertia of the working device relative to the slewing center is the smallest.

[0093] S3) Calculate the rotational resistance torque contribution coefficient of each actuating mechanism based on the cylinder stroke coefficient of each actuating mechanism; specifically, it is the product of the cylinder stroke coefficient and the weighting coefficient. Here, the weighting coefficient k... arm k rod k bucket The parameters are set based on the magnitude of the influence of boom, stick, and bucket attitude changes on the swing resistance torque. These parameters typically need to be determined in conjunction with the actual vehicle's structural parameters. Below is a set of reference values ​​for implementation, k. arm k rod k bucket The values ​​are 0.6, 0.3, and 0.1, respectively.

[0094] S4) Calculate the total resistance torque contribution coefficient based on the rotational resistance torque contribution coefficient of each motion mechanism; specifically, it is the sum of the rotational resistance torque contribution coefficients of all motion mechanisms.

[0095] S5) Based on the total resistance torque contribution coefficient and the actual load in the bucket, obtain the PID algorithm parameters from the preset parameter table; wherein, the parameter table stores the mapped PID algorithm parameters, the total resistance torque contribution coefficient, and the actual load in the bucket.

[0096] After the total resistance torque contribution coefficient is calculated, the PID parameters can be divided into multiple intervals, such as 20 intervals, based on the actual load inside the bucket. Each interval corresponds to a set of proportional parameters P1, integral parameters I1, and derivative parameters D1, which are the PID algorithm parameters. The parameter table for selecting parameters is shown in Table 1.

[0097] Table 1 Parameter Table

[0098]

[0099]

[0100] A piecewise PID algorithm is employed to calculate the required torque. This ensures that the required slewing drive torque increases with heavier loads or greater moment of inertia corresponding to the working device's posture, and decreases with lighter loads or smaller moment of inertia, thereby improving the control accuracy of the slewing drive torque. The specific calculation formula is as follows:

[0101]

[0102] In the formula, T(k) is the torque calculated by the piecewise PID algorithm in the k-th control cycle, Δv(k) is the difference between the target rotation speed and the actual rotation speed in the k-th control cycle, Δv(k-1) is the difference between the target rotation speed and the actual rotation speed in the (k-1)-th control cycle, and Δv(i) is the difference between the target rotation speed and the actual rotation speed in the i-th control cycle.

[0103] If the slewing mode is slewing coasting mode or slewing lock mode, the required torque is 0. However, in slewing lock mode, electromagnetic braking needs to be activated to lock the slewing mechanism, that is, an electromagnetic braking command is sent to the first slewing motor assembly and the second slewing motor assembly.

[0104] If the slewing mode is slewing braking mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed (slewing braking has two cases: when the handle returns to the center position, the target speed is 0; when the handle opening decreases relative to the previous time but does not return to the center position, the corresponding target speed decreases but is not 0). Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is opposite to the direction of the target slewing speed. The selection of PID parameters is the same as in the slewing drive mode, so that the calculated output braking torque demand is greater when the load is greater or the rotational inertia corresponding to the working device posture is greater, and the calculated output braking torque demand is smaller when the load is smaller or the rotational inertia corresponding to the working device posture is smaller, thereby improving the slewing braking torque control accuracy. The specific calculation method is the same as the slewing drive torque calculation.

[0105] See Figure 8 If the slewing mode is a slewing reversal mode and the direction corresponding to the actual slewing speed is opposite to the target slewing direction, 0 is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset braking torque coefficient, the final required torque is calculated. If the slewing mode is a slewing reversal mode and the actual slewing speed is 0 or the direction corresponding to the actual slewing speed is the same as the target slewing direction, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset drive torque coefficient, the final required torque is calculated. In order to improve the torque response speed in the slewing reversal mode and ensure the smoothness during low-speed slewing braking and high-speed slewing drive, the higher the slewing speed, the larger the braking torque coefficient and the smaller the drive torque coefficient, but all torque coefficients are greater than 1. The drive torque coefficient and braking torque coefficient can be obtained from the torque coefficient table, see Table 2 for details.

[0106] Table 2 Torque Coefficient Table

[0107]

[0108]

[0109] After calculating the required torque, the required torque is allocated with the goal of maximizing the overall efficiency of the first and second rotary motor assemblies. Specifically, the execution torque of the two rotary motor assemblies can be allocated based on the current turntable rotation speed and the efficiency diagram of the rotary motor assembly. This maximizes the overall efficiency of the two rotary motor assemblies during rotary drive and rotary braking, achieving the goal of low drive energy consumption and high braking energy recovery. Under this strategy, if the working efficiency of using a single rotary motor assembly is higher, there may be a situation where only one rotary motor assembly outputs torque, while the other rotary motor assembly does not output torque.

[0110] The specific implementation method is as follows:

[0111] A1) If the required torque is greater than the sum of the maximum torque output by the first rotary motor assembly and the second rotary motor assembly at the current rotary speed of the turntable, both the first rotary motor assembly and the second rotary motor assembly will output according to the maximum torque.

[0112] A2) If the required torque is not greater than the sum of the maximum output torques of the first and second rotary motor assemblies at the current turntable rotation speed, the formula for allocating the required torque is:

[0113] Optimize the objective function, max{x*Eff1+y*Eff2}

[0114]

[0115] In the formula, x and y are the torque percentages of the first rotary motor assembly and the second rotary motor assembly, respectively; Eff1 is the efficiency value obtained by looking up the motor efficiency chart when the torque percentage allocated to the first rotary motor assembly is x; Eff2 is the efficiency value obtained by looking up the motor efficiency chart when the torque percentage allocated to the second rotary motor assembly is y; Treq is the required torque; and Tmax is the maximum allowable output torque of the rotary motor assembly at the current rotary speed of the turntable.

[0116] Specifically, the required torque is divided into 100 equal parts. The efficiency of the rotary motor assembly under each allocation ratio is calculated by traversal method. The torque allocation ratio with the highest comprehensive efficiency is then used to allocate the torque of the two rotary motor assemblies.

[0117] When the required torque is not zero, the torque command allocated to each of the first and second rotary motor assemblies is sent; when the required torque is zero and the rotary mode is the rotary lock-up mode, the electromagnetic brake start command is sent to the first and second rotary motor assemblies.

[0118] The above method controls the slewing mode and combines the effects of load and changes in the posture of the boom, stick, and bucket on the excavator's slewing resistance torque to calculate the required torque, improving the control accuracy of drive torque and braking torque, and solving the problem of large slewing impact or slow action response caused by a single torque calculation method. It abandons the above method and dynamically allocates the torque of the two slewing motor assemblies based on their efficiency characteristics. While ensuring slewing power and braking performance, it maximizes the overall efficiency of the two slewing motor assemblies, achieving the goal of low slewing drive energy consumption and high slewing braking energy recovery.

[0119] 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. A control method for a dual-motor slewing system of an excavator, characterized in that, The system includes a slewing controller, a first slewing motor assembly, and a second slewing motor assembly; both the first and second slewing motor assemblies mesh with the excavator's slewing gear; the slewing controller sends control commands to the first and second slewing motor assemblies based on the received speed handle opening, actual load in the bucket, slewing speed of the turntable, displacement of the boom cylinder, displacement of the stick cylinder, and displacement of the bucket cylinder; The method includes: The slewing mode is determined based on the opening of the speed handle and the actual slewing speed; the slewing modes include slewing drive mode, slewing coasting mode, slewing braking mode, slewing lock mode, and slewing reversing mode. Calculate the required torque under the swing mode based on the swing mode, speed handle opening, actual load in the bucket, actual swing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement. The required torque is allocated with the goal of maximizing the overall efficiency of the first rotary motor assembly and the second rotary motor assembly. Based on the rotation mode and allocation results, control commands are sent to the first rotary motor assembly and the second rotary motor assembly; The above calculation of the required torque in swing mode, based on the swing mode, speed handle opening, actual load in the bucket, actual swing speed, boom cylinder displacement, stick cylinder displacement, and bucket cylinder displacement, includes: If the slewing mode is slewing coasting mode or slewing lock mode, the required torque is 0; If the slewing mode is slewing drive mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is the same as the direction of the target slewing speed. The PID algorithm parameters are determined based on the actual load in the bucket, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder. If the slewing mode is slewing braking mode, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the required torque, where the direction of the required torque is opposite to the direction of the target slewing speed. If the slewing mode is the slewing reversal mode and the direction corresponding to the actual slewing speed is opposite to the target slewing direction, 0 is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset braking torque coefficient, the final required torque is calculated. If the slewing mode is the slewing reversal mode, and the actual slewing speed is 0 or the direction corresponding to the actual slewing speed is the same as the target slewing direction, the slewing speed corresponding to the speed handle opening is taken as the target slewing speed. Based on the difference between the target slewing speed and the actual slewing speed, a piecewise PID algorithm is used to calculate the initial required torque. Based on the initial required torque and the preset drive torque coefficient, the final required torque is calculated. The above-mentioned allocation of required torque aims to maximize the overall efficiency of the first rotary motor assembly and the second rotary motor assembly, including: If the required torque is greater than the sum of the maximum torque output by the first rotary motor assembly and the second rotary motor assembly at the current rotary speed of the turntable, both the first rotary motor assembly and the second rotary motor assembly will output according to the maximum torque. If the required torque is not greater than the sum of the maximum output torques of the first and second rotary motor assemblies at the current turntable rotation speed, the formula for allocating the required torque is: Optimize the objective function, max{x*Eff1+y*Eff2} In the formula, x and y are the torque percentages of the first rotary motor assembly and the second rotary motor assembly, respectively; Eff1 is the efficiency value when the torque percentage allocated to the first rotary motor assembly is x; Eff2 is the efficiency value when the torque percentage allocated to the second rotary motor assembly is y; Treq is the required torque; and Tmax is the maximum allowable output torque of the rotary motor assembly at the current rotary speed of the turntable.

2. The control method for the dual-motor slewing system of an excavator according to claim 1, characterized in that, The rotation mode is determined based on the speed handle opening and the actual rotation speed, including: If the speed handle opening is 0 and the actual rotation speed is greater than the rotation motor braking speed threshold, then the rotation mode is the rotation braking mode. If the speed handle opening is 0 and the actual rotation speed is not greater than the braking speed threshold of the rotation motor, then the rotation mode is the rotation lock-up mode. If the speed handle opening is non-zero and the direction corresponding to the actual rotation speed is opposite to the target rotation direction, then the rotation mode is the rotation reversal mode; where the target rotation speed and direction are determined according to the speed handle opening. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening increases, and the actual rotation speed is greater than the target rotation speed, the rotation mode is rotation gliding mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening increases, and the actual rotation speed is zero or the actual rotation speed is not greater than the target rotation speed, the rotation mode is rotation drive mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening decreases, and the actual rotation speed is not greater than the target rotation speed or the actual rotation speed is not greater than the rotation motor braking speed threshold, the rotation mode is rotation coasting mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening decreases, and the actual rotation speed is greater than the target rotation speed or the actual rotation speed is greater than the rotation motor braking speed threshold, the rotation mode is rotation braking mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was rotation drive mode / rotation coasting mode / rotation braking mode, and the actual rotation speed is not greater than the target rotation speed, the rotation mode is rotation drive mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was rotation drive mode / rotation coasting mode / rotation braking mode, and the actual rotation speed is greater than the target rotation speed, the rotation mode is rotation braking mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was the rotation reversal mode, and the actual rotation speed is not greater than the target rotation speed, the rotation mode is the rotation reversal mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, the previous rotation mode was the rotation reversal mode, and the actual rotation speed is greater than the target rotation speed, the rotation mode is the rotation braking mode. If the speed handle opening is non-zero, the direction corresponding to the actual rotation speed is the same as the target rotation direction, the speed handle opening remains unchanged, and the rotation mode at the previous moment was the rotation lock mode, then the rotation mode is the rotation lock mode.

3. The control method for the dual-motor slewing system of an excavator according to claim 1, characterized in that, The PID algorithm parameters are determined based on the actual load inside the bucket, the displacement of the boom cylinder, the displacement of the stick cylinder, and the displacement of the bucket cylinder, including: Calculate the percentage of the cylinder displacement relative to the total cylinder stroke for each actuating mechanism; the actuating mechanism includes the boom, stick, and bucket. Based on the stroke percentage of each actuator cylinder, the stroke coefficient of each actuator cylinder is obtained from a preset stroke coefficient table; the stroke coefficient table stores the mapped stroke percentage and stroke coefficient. Calculate the rotational resistance torque contribution coefficient of each actuating mechanism based on the stroke coefficient of each actuating mechanism's cylinder. Calculate the total rotational resistance torque contribution coefficient based on the rotational resistance torque contribution coefficient of each actuating mechanism. Based on the total slewing resistance torque contribution coefficient and the actual load in the bucket, the PID algorithm parameters are obtained from a preset parameter table; the parameter table stores the mapped PID algorithm parameters, the total slewing resistance torque contribution coefficient, and the actual load in the bucket.

4. The control method for the dual-motor slewing system of an excavator according to claim 1, characterized in that, The formula for calculating torque using the piecewise PID algorithm is: In the formula, T(k) is the torque calculated by the piecewise PID algorithm in the k-th control cycle, P1, l1, and D1 are the PID algorithm parameters, Δv(k) is the difference between the target rotation speed and the actual rotation speed in the k-th control cycle, Δv(k-1) is the difference between the target rotation speed and the actual rotation speed in the (k-1)-th control cycle, and Δv(i) is the difference between the target rotation speed and the actual rotation speed in the i-th control cycle.

5. The control method for the dual-motor slewing system of an excavator according to claim 1, characterized in that, Control commands include: When the required torque is not zero, the torque command allocated to each of the first rotary motor assembly and the second rotary motor assembly is sent. When the required torque is 0 and the rotation mode is rotation lock-up mode, an electromagnetic braking command is sent to the first rotation motor assembly and the second rotation motor assembly.

Images