Joint control system based on field weakening control

Abstract

This invention relates to the field of joint control technology, proposing a joint control system based on field weakening control, including a displacement measurement module, a rotation module, a power output module, a control module, and a telescopic arm. The telescopic arm includes several joints and arm segments, with the joints driving the arm segments to extend and retract the telescopic arm. The rotation module changes the orientation of the telescopic arm through rotation. The power output module includes a motor, a field weakening control submodule, and a signal conversion submodule. The field weakening control submodule determines whether to perform field weakening control on the motor's output current based on the motor's rotational speed. The control module generates motor control commands and sends generator control commands to the power output module, causing the end of the telescopic arm to reach the target endpoint. By employing a field weakening control strategy, efficient operation and precise control of the motor are achieved, thereby improving the positioning accuracy and response speed of the telescopic arm.

Description

Technical Field

[0001] This invention relates to the field of joint control technology, and in particular to a joint control system based on weak magnetic control. Background Technology

[0002] With the rapid development of industrial automation and robotics, higher precision and efficiency requirements have been placed on telescopic boom and joint control systems. Traditional joint control systems typically employ direct drive or simple PID control methods, which often fail to achieve ideal control results in complex working environments and under varying load conditions. Therefore, researching and developing a new, efficient joint control system has become an urgent need. In telescopic boom design, the boom, as a common structural form, offers advantages such as simple structure and high flexibility. However, the control of telescopic booms often faces challenges in terms of precision and stability. Especially in applications requiring high-precision positioning and rapid response, achieving precise control of the telescopic boom becomes a critical issue.

[0003] Therefore, to address the above problems, this paper proposes a joint control system based on field weakening control. The aim is to achieve efficient operation and precise control of the motor by adopting a field weakening control strategy, thereby improving the positioning accuracy and response speed of the telescopic boom. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to propose a joint control system based on field weakening control. By employing a field weakening control strategy, the system achieves efficient operation and precise control of the motor, thereby improving the positioning accuracy and response speed of the telescopic boom.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A joint control system based on weak magnetic field control includes: a displacement measurement module, a rotation module, a power output module, a control module, and a telescopic arm;

[0007] The telescopic arm includes several joints and arm segments, with each joint corresponding to one of the arm segments. The joints are used to drive the arm segments to extend and retract the telescopic arm.

[0008] The displacement measurement module is used to measure the displacement vector from the telescopic arm's extension start point to the target end point;

[0009] The rotating module is fixedly connected to one end of the telescopic arm, and the rotating module is used to change the orientation of the telescopic arm by rotating.

[0010] The power output module includes a motor, a field weakening control submodule, and a signal conversion submodule. The field weakening control submodule is used to determine whether to perform field weakening control on the output current of the motor according to the speed of the motor. The signal conversion submodule is used to convert the output current into a drive signal to drive the motor.

[0011] The control module is used to acquire the displacement vector, control the rotation module to rotate, and generate motor control commands based on the displacement vector and the angle between the arm segment and the horizontal plane. It also sends generator control commands to the power output module so that the motor drives several of the joints, causing the end of the telescopic arm to reach the target endpoint.

[0012] Preferably, changing the orientation of the telescopic arm by rotation specifically means rotating the telescopic arm so that it is in the same vertical plane as the target endpoint.

[0013] Preferably, an angle sensor is provided on the arm segment;

[0014] The motor drives several of the joints to bring the end of the telescopic arm to the target endpoint, including:

[0015] The angle sensor is used to measure the angle between the arm segment and the horizontal plane, and the sub-horizontal component and sub-vertical component of each arm segment are calculated based on the angle.

[0016] Calculate the horizontal and vertical components of the displacement vector based on the displacement vector;

[0017] According to the motor control command, the included angle is cyclically adjusted, and the sub-horizontal components of each arm segment are accumulated to obtain the total horizontal component of all arm segments. The sub-vertical components of each arm segment are accumulated to obtain the total vertical component of all arm segments, until the total horizontal component is equal to the horizontal component corresponding to the displacement vector and the total vertical component is equal to the vertical component corresponding to the displacement vector.

[0018] Preferably, each of the arm segments is of equal length;

[0019] The cyclic adjustment of the included angle includes: if the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is greater than twice the length of the arm segment, then the joint closest to the rotating module is adjusted first.

[0020] If the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is less than twice the length of the arm segment but greater than the length of the arm segment, then the joint in the middle of the telescopic arm should be adjusted first.

[0021] If the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is less than the arm segment length, then the joint at the end furthest from the rotating module should be adjusted first.

[0022] Preferably, determining whether to perform field weakening control on the motor's output current based on the motor's rotational speed includes:

[0023] Step S1: Determine the target speed of the motor according to the motor control command;

[0024] Obtain the current speed of the motor, and determine whether the speed needs to be increased based on the target speed and the current speed. If the motor needs to be increased, proceed to step S2.

[0025] Step S2: Determine whether the current speed of the motor is lower than the turning speed; if it is lower, proceed to step S3; if it is not lower, proceed to step S4.

[0026] Step S3: Generate the corresponding d-axis and q-axis currents using the MTPA current control method, and then proceed to step S5;

[0027] Step S4: Obtain the d-axis current based on the motor's operating parameters, design parameters, and target speed; obtain the q-axis current limit value based on the maximum current and the d-axis current; and then proceed to step S5.

[0028] Step S5: Input the d-axis current and q-axis current into the controller to obtain the voltages of the d-axis and q-axis, and drive the motor to run according to the voltages of the d-axis and q-axis;

[0029] Step S6: Repeat steps S2-S5 until the current speed reaches the target speed.

[0030] Preferably, the operating parameters in step S4 include: the given current of the q-axis and the feedback current of the q-axis;

[0031] The design parameters include: the rated current of the motor and the rated speed of the motor.

[0032] Preferably, the step of obtaining the d-axis current in step S4 is as follows:

[0033] Real-time acquisition of the given current I along the q-axis qRef Given current I qRef The input is fed into a low-pass filter to obtain the first parameter I′. qRef ;

[0034] Real-time acquisition of q-axis feedback current I q Given current I q The input is fed into a low-pass filter to obtain the second parameter I′. q ;

[0035] Get the first parameter I′ qRef With the second parameter I′ q The difference E is used as the input of the PI controller to obtain the current feedback setpoint D1;

[0036] According to the rated current I n and rated speed ω n Calculate the amplification factor Kc of the feedforward term of the field weakening current;

[0037] Obtain the current rotational speed increment of the field weakening, and adjust the rotational speed increment through the amplification factor Kc to obtain the current feedback setpoint D2;

[0038] The d-axis current I is obtained by adding the feedback reference D1 and the feedforward reference D2. d .

[0039] Preferably, the formula for obtaining the current feedback given term D1 is as follows:

[0040] D1(t)=K p E(t)+K i ∫E(t)dt

[0041] Where t is time, K q With K i These are the proportional gain coefficient and integral gain coefficient in the PI controller, respectively.

[0042] The specific formula for obtaining the magnification factor Kc is as follows:

[0043]

[0044] Where I n Rated current, ω n Rated speed;

[0045] The specific formula for obtaining the feedforward given term D2 is as follows:

[0046] D2=-|(S t -S z )×K c |

[0047] Where S t For the target rotational speed, S z The turning speed is the rotational speed.

[0048] Preferably, the formula for obtaining the limiting value of the q-axis current is as follows:

[0049]

[0050] Where I max For maximum output current, I dThe current is along the d-axis.

[0051] One of the above technical solutions has the following advantages or beneficial effects:

[0052] Through the displacement measurement and control modules, the system can accurately measure the displacement vector of the telescopic boom and adjust the joints to ensure that the other end of the boom reaches the target endpoint. This precise control facilitates the execution of various complex tasks. By weakening the motor's magnetic field through the field weakening control submodule, the back EMF is reduced under limited power input voltage, improving motor efficiency and reducing energy loss. By adjusting the magnetic field strength, the system can respond more quickly to changes in rotational speed, improving the joint's response speed and stability. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the joint control system provided in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the telescopic arm of the joint control system provided in an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of the displacement of the end of the telescopic arm of the joint control system provided in an embodiment of the present invention;

[0056] Figure 4 This is a control flowchart of the telescopic arm of the joint control system provided in an embodiment of the present invention. Detailed Implementation

[0057] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0058] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" 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.

[0060] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0061] like Figure 1 As shown, a preferred embodiment of this application includes: a displacement measurement module 1, a rotation module 2, a power output module 3, a control module 4, and a telescopic arm 5;

[0062] The telescopic arm 5 includes a plurality of joints 51 and arm segments 52, wherein each joint 51 corresponds to one arm segment 52, and the joint 51 is used to drive the arm segment 52 to extend or retract the telescopic arm 5.

[0063] The displacement measurement module 1 is used to measure the displacement vector from the extension start point to the target end point of the telescopic arm 5;

[0064] The rotating module 2 is fixedly connected to one end of the telescopic arm 5, and the rotating module 2 is used to change the orientation of the telescopic arm 5 by rotating.

[0065] The power output module 3 includes a motor, a field weakening control submodule, and a signal conversion submodule. The field weakening control submodule is used to determine whether to perform field weakening control on the output current of the motor according to the speed of the motor. The signal conversion submodule is used to convert the output current into a drive signal to drive the motor.

[0066] The control module 4 is used to acquire the displacement vector, control the rotation module 2 to rotate, and generate motor control commands based on the displacement vector and the angle between the arm segment 52 and the horizontal plane. It then sends generator control commands to the power output module 3 so that the motor drives several of the joints 51, causing the end of the telescopic arm 5 to reach the target endpoint.

[0067] Specifically, such as Figure 2As shown, the telescopic arm 5 includes one or more joints 51, each joint 51 corresponding to an arm segment 52. The joints 51 can rotate to drive the arm segment 52 to move. Through the coordination of multiple joints 51, the telescopic function is realized.

[0068] The telescopic boom 5 has a wide range of applications. For example, in the medical field, it is used for surgical assistance, patient positioning, and operation of medical equipment in operating rooms. In the construction and engineering field, it can be used for high-altitude operations, building structure installation, and maintenance. Therefore, this embodiment also includes a displacement measurement module 1. When using the telescopic boom 5, it is necessary to first determine the position where the boom 5 functions. The displacement measurement module 1 is used to measure the displacement vector from the starting point of the telescopic boom 5 to the target endpoint. In this embodiment, the starting point is the position of the first joint 51. The displacement vector can be measured by installing an encoder, laser rangefinder, or optical measurement system on the telescopic boom 5, which will not be elaborated here. It is worth noting that various different devices or tools can be installed at the position away from the starting point, i.e., the end 53 of the telescopic boom, depending on the design purpose and application scenario of the telescopic boom.

[0069] The rotating module 2 is connected to one end of the telescopic arm 5, which enables precise control of the telescopic arm's orientation, allowing it to be accurately positioned and aligned with the target location. The orientation of the telescopic arm 5 can be coarsely adjusted, and then finely adjusted through the joint 51, making the orientation adjustment more precise. This design can adapt to various working scenarios and environmental conditions, improving the applicability and flexibility of the telescopic arm in different applications.

[0070] The motor is the power source for the telescopic boom 5. Depending on the required direction and speed of movement, the motor generates corresponding rotational force and torque to propel the telescopic boom 5 in its telescopic motion. Field weakening control is a motor control technology. The field weakening control submodule is responsible for monitoring the motor's speed. When the motor is running at low speed, it still needs a stable speed and output power. When the motor is running at high speed, the magnetic field of the motor will increase. Given a limited power input voltage, it is necessary to reduce the back EMF to increase the speed. Therefore, field weakening control allows the motor to respond more flexibly to control signals, quickly adjusting its speed and output power, thus improving the system's response speed and control performance. After field weakening control by the submodule, the output current of the submodule is converted into a drive signal. Upon receiving the drive signal, the motor can provide a more stable output, thereby achieving precise control and movement.

[0071] In this embodiment, the rotation of the rotation module 2 and the movement of the telescopic arm 5 are both controlled by the control module 4. First, the displacement vector from the starting point to the target endpoint is obtained, and a motor control command is sent to the motor to make the motor control the rotation module 2 to rotate. Then, the telescopic arm 5 is controlled to extend and retract. Finally, the end 53 of the telescopic arm acts on the target endpoint, thereby achieving precise control and movement of the telescopic arm 5.

[0072] Preferably, in another embodiment, changing the orientation of the telescopic arm 5 by rotation specifically means rotating the telescopic arm 5 so that it is in the same vertical plane as the target endpoint.

[0073] Specifically, when the telescopic arm 5 and the target endpoint are on the same vertical plane, unnecessary lateral movement can be reduced, increasing the stability of the telescopic arm 5. Placing the telescopic arm 5 and the target endpoint on the same vertical plane can help avoid collisions or interference between the telescopic arm 5 and surrounding objects. This is especially important when operating in confined spaces or complex environments. It can simplify motion planning and control, make it easier to determine the path and distance that the telescopic arm 5 needs to move, reduce the control complexity of the control module 4, and improve efficiency.

[0074] Furthermore, an angle sensor is provided on the arm segment 52;

[0075] The steps of driving several of the joints 51 with a motor to bring the end of the telescopic arm 52 to the target endpoint include:

[0076] S401: Use the angle sensor to measure the angle between the arm segment 52 and the horizontal plane, and calculate the sub-horizontal component and sub-vertical component of each arm segment based on the angle;

[0077] Angle sensors include tools that can measure angles, such as gyroscopes, tilt sensors, or rotary encoders. Figure 4 As shown, when the control module 4 controls the telescopic boom 5, the angle sensor installed on each boom segment 52 measures the angle θ between each boom segment 52 and the horizontal plane, as follows: Figure 3 As shown, the angle between the first arm segment and the horizontal plane is θ1, and so on. The angle between the second arm segment and the horizontal plane is θ2, the angle between the third arm segment and the horizontal plane is 0°, and the angle between the fourth arm segment and the horizontal plane is θ4. For example, the length of the first arm segment 52 is d1, and the sub-horizontal component of the first arm segment 52 is d. x1 =d1cosθ1, the sub-vertical component is d y1 =d1sinθ1, and so on, to calculate the sub-horizontal and sub-vertical components corresponding to all arm segments 52.

[0078] S402: Calculate the horizontal and vertical components corresponding to the displacement vector based on the displacement vector;

[0079] Specifically, assuming the displacement vector is D, the horizontal component D can be calculated similarly based on the angle between the displacement vector and the horizontal plane. x And the vertical component, here let the vertical component be D. y .

[0080] S403: According to the motor control command, the included angle is cyclically adjusted, and the sub-horizontal components of each arm segment are accumulated to obtain the total horizontal component of all arm segments. The sub-vertical components of each arm segment are accumulated to obtain the total vertical component of all arm segments, until the total horizontal component matches the horizontal component D corresponding to the displacement vector. x The equal and total vertical components are equal to the vertical components corresponding to the displacement vector.

[0081] Specifically, the control module 4 continuously generates motor control commands based on the current angle between each arm segment 52 and the horizontal plane, driving the motor to produce drive current. The signal conversion submodule converts the motor's output current into drive signals to drive the telescopic arm 5, continuously adjusting the angle between each arm segment 52 and the horizontal plane, and calculating the total horizontal and vertical components of all arm segments 52, for example, as... Figure 3 As shown, the sub-horizontal components of the first to fourth arm segments are d x1 d x2 d x3 and d x4 By adjusting the angle between each of the arm segments 52 and the horizontal plane, d x1 +d x2 +d x3 +d x4 =D x That is, the sum of all sub-level components equals the total level component. Similarly, make d y1 +d y2 +d y3 +d y4 =Dy means that the sum of all sub-vertical components equals the total vertical component, the sum of all sub-horizontal components equals the total horizontal component, and the sum of all sub-vertical components equals the total vertical component. This indicates that the end of the telescopic arm 5 has reached the target position in space, thus completing the control of the telescopic arm 5. By decomposing the motion of the telescopic arm into horizontal and vertical components, the calculation and control process can be greatly simplified, positioning accuracy can be improved, and path planning can be optimized. The control module 4 can dynamically adjust the included angle of each arm segment 52 according to the direction and magnitude of the target displacement vector, thereby adapting to different working scenarios and task requirements. Through the automated adjustment process, the operating efficiency can be improved and the need for manual intervention can be reduced, especially in applications that require frequent attitude adjustments.

[0082] In another embodiment, each of the arm segments 52 is of equal length;

[0083] The cyclic adjustment of the included angle includes: if the distance from the end of the telescopic arm 5 furthest from the rotating module 2 to the target endpoint is greater than twice the length of the arm segment 52, then the joint 51 closest to the rotating module 2 is adjusted first.

[0084] If the distance from the end of the telescopic arm 5 furthest from the rotating module 2 to the target endpoint is less than twice the length of the arm segment 52 but greater than the length of the arm segment, then the joint 51 in the middle of the telescopic arm should be adjusted first.

[0085] If the distance from the end of the telescopic arm 5 furthest from the rotating module 2 to the target endpoint is less than the length of the arm segment 52, then the joint 51 furthest from the rotating module 2 is adjusted first.

[0086] Specifically, when the length of each arm segment 52 is equal, and the telescopic arm 5 is relatively long, adjusting the angle of which arm segment 52 will produce different effects. When the distance from the end of the telescopic arm 5 furthest from the rotating module 2 (i.e., the end 53 of the telescopic arm) to the target endpoint is greater than twice the length of the arm segment 52, prioritizing the adjustment of the joint 51 closest to the rotating module 2 (i.e., the first joint 51) ensures that the telescopic arm 5 moves faster as a whole when it is far from the target. If the distance is still greater than twice the length of the arm segment 52 after adjusting the first joint 51, then the second joint 51 is adjusted. When the distance from the end of the telescopic arm 5 furthest from the rotating module 2 (i.e., the end 53 of the telescopic arm) to the target endpoint is less than twice the length of the arm segment 52 but greater than the length of the arm segment 52, priority is given to adjusting the joint 51 in the middle of the telescopic arm 5. For example, if the telescopic arm 5 has 5 joints 51, then the third joint 51 is adjusted first. This avoids excessive posture adjustments, as the adjustment of the middle arm segment 52 can affect the posture of the entire system, making it easier for the system to reach the desired target position.

[0087] When the distance from the end of the telescopic arm 5 furthest from the rotating module 2, i.e. the end 53 of the telescopic arm, to the target endpoint is less than the length of the arm segment 52, then the joint 51 of the end 53 of the telescopic arm is adjusted first. By adjusting the joint 51 of the end 53 of the telescopic arm, since actuators with different functions can be installed at the end 53 of the telescopic arm, the position of the actuator will be more directly affected. This is suitable for situations where more precise control of the actuator position is required, such as situations where accurate positioning or precise operation of the target is required.

[0088] Furthermore, the step of determining whether to perform field weakening control on the output current of the motor based on the motor speed includes: step S1: determining the target speed of the motor according to the motor control command;

[0089] Obtain the current speed of the motor, and determine whether the speed needs to be increased based on the target speed and the current speed. If the motor needs to be increased, proceed to step S2.

[0090] Specifically, when controlling the telescopic boom 5, after the motor receives the motor control command, the motor control command will be input into the encoder. The encoder determines the target speed of the motor, that is, the motor speed required to reach the command. When the current speed of the motor is lower than the target speed, the motor speed will be increased. At this time, the current output will be increased to achieve the purpose of increasing the speed.

[0091] If speed increase is not required, since the target speed is lower than the current speed, it is only necessary to reduce the current output. In this case, field weakening control is not involved, so it is only necessary to use the controller to control the motor speed.

[0092] Step S2: Determine whether the current speed of the motor is lower than the turning speed; if it is lower, proceed to step S3; if it is not lower, proceed to step S4.

[0093] Step S3: Generate the corresponding d-axis and q-axis currents using the MTPA current control method, and then proceed to step S5;

[0094] Specifically, the output current I is divided into the current I output along the d-axis. d And the current I output to the q-axis q , where current I q The main control is applied to the current in the direction of torque, where the current I... d The main control is of the current in the direction of the magnetic field; field weakening control is a method of controlling the current I. q and current I d The control method aims to weaken the motor's magnetic field, reduce back electromotive force (EMF) under limited power input voltage, and thus increase motor speed. Therefore, this invention first determines whether the current speed is below the turning point. When the current speed is below the turning point, it means the motor is still operating in the constant torque region, and there is no need to use field weakening control to reduce the motor's back EMF or increase speed. In this case, the MTPA method is used to control the current I... d Set it to 0, then calculate the minimum current I used. q To generate as much torque as possible, enabling the motor to quickly increase its speed and rapidly approach the target speed, due to I d In the 0=0 control mode, the motor's d-axis current is always zero, reducing electromagnetic interference and vibration caused by changes in the d-axis current, which helps maintain the stable operation of the motor.

[0095] Step S4: Obtain the d-axis current based on the motor's operating parameters, design parameters, and target speed; obtain the q-axis current limit value based on the maximum current and the d-axis current; and then proceed to step S5.

[0096] Specifically, when the motor's current speed exceeds the turning speed, the motor control enters the field weakening control stage. Based on operating parameters and design parameters, the d-axis current is controlled and the q-axis current is limited. This allows the motor to quickly reach the target speed while simultaneously limiting the q-axis current. If the q-axis current I... d Excessive current can cause significant torque fluctuations in the motor's dynamic response, affecting its stable operation. Limiting the q-axis current command can reduce torque fluctuations and enhance motor stability.

[0097] Step S5: Input the d-axis current and q-axis current into the controller to obtain the voltages of the d-axis and q-axis, and drive the motor to run according to the voltages of the d-axis and q-axis;

[0098] Finally, I can be... q I d The inverse PARK transformation generates Ua and Ub control signals, which are then sent to the SVPWM module to generate drive signals to control the motor.

[0099] Step S6: Repeat steps S2-S5 until the current speed reaches the target speed.

[0100] In this embodiment, when operating the telescopic boom 5, the current speed of the motor is detected in real time, and different processing methods are selected according to different current speeds, so that the motor can run smoothly when the speed is increased. Moreover, the adjustment does not need to rely on complex magnetic control algorithms, which improves the stability of the weak magnetic speed and the anti-interference ability, and also makes the motor speed adjustment easy to implement in engineering.

[0101] Furthermore, the operating parameters in step S4 include: the given current of the q-axis and the feedback current of the q-axis;

[0102] The design parameters include: the rated current of the motor and the rated speed of the motor.

[0103] Specifically, the real-time acquisition of the q-axis given current and feedback current allows the control system to accurately determine the motor's current operating state, thereby enabling more precise current distribution and voltage output. The motor's rated current and rated speed are parameters determined during the design phase to ensure the motor's safety and stability under standard operating conditions. Considering these parameters in field weakening control prevents damage to the motor from exceeding its design limits. Based on the motor's design parameters, the field weakening control strategy can be optimized to ensure the motor maintains high efficiency and power output even at high speeds.

[0104] Furthermore, the steps for obtaining the d-axis current in step S4 are as follows:

[0105] Real-time acquisition of the given current I along the q-axis qRef Given current I qRef The input is fed into a low-pass filter to obtain the first parameter I′. qRef ;

[0106] Real-time acquisition of q-axis feedback current I q Given current I q The input is fed into a low-pass filter to obtain the second parameter I′. q ;

[0107] By acquiring the given and feedback currents of the q-axis in real time and processing them using a low-pass filter, more stable and accurate current parameters can be obtained. This method helps to precisely control the motor's operation, improving stability and reliability.

[0108] Get the first parameter I′ qRef With the second parameter I′ q The difference E is used as the input of the PI controller to obtain the current feedback setpoint D1;

[0109] By calculating the difference E between the given current and the feedback current and using it as the input to the PI controller, a feedback setpoint D1 for adjusting the current can be obtained. The PI controller can effectively reduce errors and improve the accuracy of current control.

[0110] According to the rated current I n and rated speed ω n Calculate the amplification factor Kc of the feedforward term of the field weakening current;

[0111] The calculated amplification factor Kc is determined based on the motor's rated current and rated speed. By adjusting the speed increment through the amplification factor Kc, the motor can be ensured to operate in a highly efficient and stable state.

[0112] Obtain the current rotational speed increment of the field weakening, and adjust the rotational speed increment through the amplification factor Kc to obtain the current feedback setpoint D2;

[0113] The d-axis current I is obtained by adding the feedback reference D1 and the feedforward reference D2. d .

[0114] Combining feedback control and feedforward control, the d-axis current is obtained through simple addition, without relying on complex algorithms, and the d-axis current can be accurately obtained. The feedforward reference term D1 of the field weakening current can improve the speed response of the motor during rapid speed switching, while the feedback reference term of the field weakening current ensures the speed stability of the motor under heavy load. This field weakening control method has low computational load, simple structure, and high operational stability.

[0115] Furthermore, the formula for obtaining the current feedback given term D1 is as follows:

[0116] D1(t)=K p E(t)+K i ∫E(t)dt

[0117] Where t is time, K q With K i These are the proportional gain coefficient and integral gain coefficient in the PI controller, respectively.

[0118] Where the amplification factor K is obtained c The specific formula for obtaining it is as follows:

[0119]

[0120] Where I n Rated current, ω n Rated speed;

[0121] The specific formula for obtaining the feedforward given term D2 is as follows:

[0122] D2=-|(S t -S z )×K c |

[0123] Where S t For the target rotational speed, S z The turning speed is the rotational speed.

[0124] Furthermore, the formula for obtaining the limit value of the q-axis current is as follows:

[0125]

[0126] Where I max For maximum output current, I d The current is along the d-axis.

[0127] Specifically, since the q-axis current is directly related to the electromagnetic torque, precise control of the q-axis current can ensure the required torque output of the motor. However, excessively high q-axis current may cause the motor to overheat or be damaged. Therefore, by limiting the maximum value of the q-axis current command, the motor can be ensured to operate within a safe range while optimizing torque output. Excessively high q-axis current may cause large torque fluctuations in the motor during dynamic response, affecting the stable operation of the motor. Therefore, in this invention, the q-axis current is limited by the maximum output current and the d-axis current. The purpose is to weaken the motor's magnetic field, reduce the back EMF when the power input voltage is limited, and thus increase the motor speed. Therefore, the decision to perform field weakening control is based on the current speed of the motor, thereby better controlling the telescopic boom 5.

[0128] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0129] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A joint control system based on weak magnetic field control, characterized in that, include: Displacement measurement module, rotation module, power output module, control module, and telescopic boom; The telescopic arm includes several joints and arm segments, with each joint corresponding to one of the arm segments. The joints are used to drive the arm segments to extend and retract the telescopic arm. The displacement measurement module is used to measure the displacement vector from the telescopic arm's extension start point to the target end point; The rotating module is fixedly connected to one end of the telescopic arm, and the rotating module is used to change the orientation of the telescopic arm by rotating. The power output module includes a motor, a field weakening control submodule, and a signal conversion submodule. The field weakening control submodule is used to determine whether to perform field weakening control on the output current of the motor according to the speed of the motor. The signal conversion submodule is used to convert the output current into a drive signal to drive the motor. The control module is used to acquire the displacement vector, control the rotation module to rotate, and generate motor control commands based on the displacement vector and the angle between the arm segment and the horizontal plane. It also sends generator control commands to the power output module so that the motor drives several of the joints, causing the end of the telescopic arm to reach the target endpoint. The step of determining whether to perform field weakening control on the output current of the motor based on the motor speed includes: Step S1: Determine the target speed of the motor according to the motor control command; Obtain the current speed of the motor, and determine whether the speed needs to be increased based on the target speed and the current speed. If the motor needs to be increased, proceed to step S2. Step S2: Determine whether the current speed of the motor is lower than the turning speed; if it is lower, proceed to step S3; if it is not lower, proceed to step S4. Step S3: Generate the corresponding d-axis and q-axis currents using the MTPA current control method, and then proceed to step S5; Step S4: Obtain the d-axis current based on the motor's operating parameters, design parameters, and target speed; obtain the q-axis current limit value based on the maximum current and the d-axis current; and then proceed to step S5. Step S5: Input the d-axis current and q-axis current into the controller to obtain the voltages of the d-axis and q-axis, and drive the motor to run according to the voltages of the d-axis and q-axis; Step S6: Repeat steps S2-S5 until the current speed reaches the target speed; The operating parameters in step S4 include: the given current of the q-axis and the feedback current of the q-axis; The design parameters include: the rated current of the motor and the rated speed of the motor; The steps for obtaining the d-axis current in step S4 are as follows: Real-time acquisition of the given current along the q-axis , give current The input is fed into a low-pass filter to obtain the first parameter. ; Real-time acquisition of q-axis feedback current , give current The input is fed into a low-pass filter to obtain the second parameter. ; Get the first parameter With the second parameter The difference E is used as the input of the PI controller to obtain the current feedback setpoint D1; According to the rated current and rated speed Calculate the amplification factor Kc of the feedforward term of the field weakening current; Obtain the current rotational speed increment of the field weakening, and adjust the rotational speed increment through the amplification factor Kc to obtain the current feedforward given term D2; The d-axis current is obtained by adding the current feedback reference D1 and the current feedforward reference D2. ; The formula for obtaining the current feedback reference term D1 is as follows: ； Where t is time, and These are the proportional gain coefficient and integral gain coefficient in the PI controller, respectively. The formula for obtaining the magnification factor Kc is as follows: ； in For rated current, Rated speed; The formula for obtaining the current feedforward reference term D2 is as follows: ； in For the target speed, The turning speed; The formula for obtaining the q-axis current limit value is as follows: ； in For maximum output current, The current is along the d-axis.

2. The joint control system according to claim 1, characterized in that, The method of changing the orientation of the telescopic arm by rotation specifically means rotating the telescopic arm so that it is in the same vertical plane as the target endpoint.

3. The joint control system according to claim 2, characterized in that, An angle sensor is installed on the arm segment; The motor drives several of the joints to bring the end of the telescopic arm to the target endpoint, including: The angle sensor is used to measure the angle between the arm segment and the horizontal plane, and the sub-horizontal component and sub-vertical component of each arm segment are calculated based on the angle. Calculate the horizontal and vertical components of the displacement vector based on the displacement vector; According to the motor control command, the included angle is cyclically adjusted, and the sub-horizontal components of each arm segment are accumulated to obtain the total horizontal component of all arm segments. The sub-vertical components of each arm segment are accumulated to obtain the total vertical component of all arm segments, until the total horizontal component is equal to the horizontal component corresponding to the displacement vector and the total vertical component is equal to the vertical component corresponding to the displacement vector.

4. The joint control system according to claim 3, characterized in that, Each of the arm segments is of equal length; The cyclic adjustment of the included angle includes: if the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is greater than twice the length of the arm segment, then the joint closest to the rotating module is adjusted; If the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is less than twice the arm segment length but greater than the arm segment length, then the joint in the middle of the telescopic arm is adjusted. If the distance from the end of the telescopic arm furthest from the rotating module to the target endpoint is less than the length of the arm segment, then the joint at the end furthest from the rotating module is adjusted.

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