A rudder load test method and device based on magnetic force spring

Abstract

A method and apparatus for testing servo motor load based on magnetic springs is disclosed. The apparatus includes a servo motor mounting base (1), a servo motor support (2), and a servo motor (3); a magnetic spring unit, a force sensor (5), a lead screw (10), a magnetic spring stator fixing support (12), and a slider (13); a base plate (14); a slide rail (15), a displacement measurement unit, and a data acquisition and control unit. The magnetic spring unit includes a magnetic spring mover (7) and a magnetic spring stator (8). The method includes establishing a force-displacement characteristic model of the magnetic spring, setting a preload force, driving the servo motor to move, acquiring data in real time, and generating a load curve. This invention uses non-contact magnetic force to test the servo motor load, which is suitable for high-speed dynamic load testing of servo motors and truly reflects the transient performance of the servo motor. This invention can flexibly simulate load curves of different shapes to meet various servo motor testing needs.

Description

Technical Field

[0001] This invention relates to a method and apparatus for testing the load of a servo motor based on a magnetic spring, belonging to the field of servo motor performance testing technology. Background Technology

[0002] As a key actuator in a servo control system, the load capacity of the servo motor directly determines the system's performance. During the research and development and production of servo motors, it is necessary to accurately test their output force at maximum stroke to verify design specifications and ensure reliability.

[0003] Traditional servo load testing often uses mechanical springs as load simulation elements, generating reaction force through spring compression or tension, and measuring the servo output force using a force sensor. However, mechanical springs have the following inherent defects under high-speed, high-frequency reciprocating motion: (1) Fatigue wear: Spring materials are prone to fatigue cracks under cyclic stress, leading to stiffness decay and load curve drift; (2) Plastic deformation: Springs may undergo permanent deformation after long-term use, affecting test repeatability; (3) Loosening problem: High-speed motion causes the spring end fixing structure to loosen, interfering with test accuracy; (4) Vibration interference: When the spring's natural frequency is coupled with the servo's operating frequency, it may introduce additional oscillations, causing test data distortion; (5) High maintenance cost: Springs are consumable parts and need to be replaced regularly, increasing the maintenance workload of the test system.

[0004] To address the aforementioned issues, some testing devices have attempted to employ hydraulic or pneumatic loading methods, but these methods suffer from limitations such as slow response speed, complex control, and high energy consumption.

[0005] Therefore, developing a wear-free, high-precision, and fast-response servo load simulation method has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to address the problems of high wear, short lifespan, and limited testing accuracy of mechanical springs in existing servo motor testing, and to disclose a servo motor load testing method and apparatus based on magnetic springs.

[0007] The technical solution implemented by the present invention is as follows: a servo motor load testing device based on a magnetic spring, comprising a servo motor mounting base, a magnetic spring unit, a force sensor, a displacement measurement unit, a data acquisition and control unit, an air gap adjustment mechanism, and a temperature compensation unit.

[0008] The servo mounting base includes a servo mounting base for the servo under test and a servo bracket for the servo under test, both of which are rectangular plate structures. The servo bracket for the servo under test is vertically mounted on the servo mounting base for the servo under test and is reinforced and fixed by two triangular reinforcing ribs.

[0009] The magnetic spring unit includes a magnetic spring mover and a magnetic spring stator. The magnetic spring mover is composed of two parallelogram-shaped assembled magnets forming an arrow-shaped moving magnet. The magnetic spring stator is composed of two parallelogram-shaped assembled magnets respectively embedded on two parallel rectangular magnetic yokes forming a stationary magnet. The width between the two parallel rectangular magnetic yokes is 5mm wider than the width of the arrow-shaped moving magnet. The four corners of the stationary magnet are fixed to four sliders, which move along a guide rail. The output shaft of the servo motor under test is connected to a force sensor via a first force sensor mounting rod, and the other end of the force sensor is connected to the arrow-shaped moving magnet via a second force sensor mounting rod. When the arrow-shaped moving magnet enters the central cavity of the stationary magnet axially (in the direction of movement of the sliders on the guide rail), the radial gap between the two sides of the arrow-shaped moving magnet and the two middle sides of the stationary magnet remains at 2.5mm.

[0010] The force sensor is positioned between the servo motor output shaft and the magnetic spring mover to collect the servo motor output force in real time.

[0011] The displacement measuring unit is installed on the axial extension line of the moving magnet assembly, or set to the side of the moving magnet's trajectory (perpendicular to the direction of movement), and is used to measure the linear displacement of the moving magnet along the axial direction (i.e., the direction of the servo motor output shaft) in real time; the displacement measuring unit measures the servo motor output displacement using an encoder, grating ruler, or laser displacement sensor.

[0012] The data acquisition and control unit includes a storage unit and a display unit, used to save test data and display force-displacement curves in real time; the data acquisition and control unit is connected to the force sensor, displacement sensor and servo motor driver to realize synchronous data acquisition and motion control; it synchronously records the servo motor output force and displacement data, generates a load curve, and controls the servo motor movement in a closed loop according to test requirements; The air gap adjustment mechanism includes a guide rail and a slider. A magnetic spring stator is fixed on the slider. The slider is moved along the guide rail by manual or electric drive to realize the air gap adjustment and the connection with the magnetic spring mover, which is used to adjust the initial air gap between the magnetic spring stator and the magnetic spring mover.

[0013] The temperature compensation unit includes a temperature sensor and a compensation algorithm to eliminate the influence of magnet temperature drift on the test results; the temperature sensor is located near the magnetic spring unit to monitor the magnet temperature in real time, and the compensation algorithm corrects the force measurement value according to the temperature change.

[0014] The servo motor mounting base and the magnetic spring stator fixing support are bolted to both sides of the rectangular base plate along its length. The servo motor under test is mounted on the bracket of the servo motor mounting base. The output shaft of the servo motor under test is mounted on the first force sensor mounting rod via a force sensor mounting rod mounting bolt. The first force sensor mounting rod is mounted on the force sensor via a second force sensor mounting bolt. One end of the second force sensor mounting rod is connected to the other end of the force sensor via the first force sensor mounting bolt, and the other end of the second force sensor mounting rod is connected to the end of the magnetic spring mover with bolt holes via a magnetic spring mover connecting bolt. Long screws are horizontally parallel and symmetrically distributed on both sides of the tail of the magnetic spring stator. The other ends of the two long screws are mounted on the magnetic spring stator fixing support. The position of the magnetic spring stator is changed by adjusting the long screws.

[0015] The magnetic spring unit is composed of permanent magnets, electromagnets, or a combination thereof. By adjusting the shape, size, material type, magnetization direction, array method, or combination of the magnets, precise control of the load curve can be achieved.

[0016] When the magnetic spring unit uses permanent magnets, the magnetic spring stator of the magnetic spring is composed of several identical parallelogram-shaped permanent magnets stacked together to form two corresponding feather-shaped permanent magnets; the magnetic spring mover of the magnetic spring unit is composed of several identical parallelogram-shaped permanent magnets stacked together.

[0017] A servo motor load testing method based on a magnetic spring-driven servo motor load testing device comprises the following steps: (1) Establish the force-displacement characteristic model of the magnetic spring, and perform parametric modeling and simulation analysis of the magnetic spring unit through electromagnetic field simulation software to obtain the characteristic curve of magnetic force changing with displacement.

[0018] (2) Set the initial working point of the magnetic spring. According to the test requirements of the servo motor under test, adjust the initial axial air gap of the magnetic spring unit and set the preload force.

[0019] (3) Drive the servo motor to move, start the servo motor, and make its output shaft drive the magnetic spring mover to move towards the magnetic spring stator.

[0020] (4) Real-time data acquisition: the force sensor acquires the servo motor output force signal, and the displacement sensor acquires the moving magnet displacement signal.

[0021] (5) Generate a load curve, record the collected output force and displacement data synchronously, plot the actual output force-displacement curve of the servo motor, and compare it with the preset magnetic spring characteristic curve to evaluate the performance of the servo motor.

[0022] The initial axial air gap adjustment is achieved manually or automatically, with an axial air gap adjustment range of 0-50mm and a corresponding preload adjustment range of 0-1200N.

[0023] The electromagnetic field simulation includes two-dimensional or three-dimensional static magnetic field simulation. The simulation parameters include magnet material, geometric dimensions, magnetization direction and relative position. The magnetic force value under different displacements is obtained through parametric scanning.

[0024] The magnetic spring unit can also be designed as a multi-level coaxial arrangement of magnetic rings or a magnet array structure to extend the force range or adjust the stiffness curve.

[0025] The working principle of this invention is as follows: Utilizing the non-contact magnetic coupling characteristics of a magnetic spring, the continuously changing load force experienced by a servo motor during operation is simulated by observing the variation of the repulsive or attractive force between magnets with relative displacement. The magnetic spring is essentially a non-contact, controllable stiffness element; when the servo motor pushes the moving magnet, it needs to overcome the magnetic force to do work, and this magnetic force is the "load" felt by the servo motor. By pre-designing the shape, size, material, and arrangement of the magnets through simulation, specific force-displacement curves (linear, increasing, decreasing, etc.) can be obtained, thereby simulating different load conditions.

[0026] The advantages of this invention are as follows: It employs non-contact magnetic force to test servo motor loads, completely avoiding mechanical contact and frictional wear. This makes it suitable for high-frequency reciprocating tests, with a service life far exceeding that of mechanical springs. The magnetic force characteristics are stable, with no hysteresis or frictional noise, and the test repeatability error is less than ±0.5%. The magnetic response time is in the microsecond range, making it suitable for high-speed dynamic load testing of servos and accurately reflecting their transient performance. This invention utilizes pre-optimized design through electromagnetic field simulation, allowing for real-time adjustment of the axial air gap or replacement of the magnet module to flexibly simulate load curves of different shapes, meeting various servo motor testing needs. This invention integrates a data acquisition and control system, enabling automation of the testing process and digital management of test results. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the servo motor load testing device based on a magnetic spring according to the present invention; Figure 2 This is an external view of the servo motor load testing device based on a magnetic spring according to the present invention; Figure 3 This is a flowchart of the steps of the servo motor load testing method based on magnetic springs of the present invention; Figure 4 shows the magnetic field distribution of the magnetic spring; Figure 4(a) shows the direction and density distribution of the magnetic flux lines when the stroke of the magnetic spring mover is 60 mm; Figure 4(b) shows the direction and density distribution of the magnetic flux lines when the stroke of the magnetic spring mover is 120 mm; Figure 4(c) shows the magnetic induction intensity distribution cloud map of the magnetic spring unit; Figure 4(d) shows the magnetic induction intensity distribution cloud map of another section of the magnetic spring unit. Figure 5 The force-displacement characteristic curve of the magnetic spring unit; In the diagram, 1 is the mounting base for the servo motor under test; 2 is the support for the servo motor under test; 3 is the servo motor under test; 4 is the first mounting rod of the force sensor; 5 is the force sensor; 6 is the second mounting rod of the force sensor; 7 is the magnetic spring mover; 8 is the magnetic spring stator; 9 is the stator locking nut; 10 is the lead screw; 11 is the lead screw fixing nut; 12 is the magnetic spring stator fixing support; 13 is the slider; 14 is the base plate; 15 is the slide rail; 16 is the magnetic spring mover connecting bolt; 17 is the first mounting bolt of the force sensor; 18 is the second mounting bolt of the force sensor; and 19 is the mounting bolt of the first mounting rod of the force sensor. Detailed Implementation

[0028] The specific embodiments of the present invention are shown in the accompanying drawings.

[0029] The structure of the servo load testing device based on the magnetic spring in this embodiment is as follows: Figure 1 and Figure 2 As shown.

[0030] This embodiment of the servo load testing device based on magnetic spring includes a servo testing mechanism mounting base, a magnetic spring unit, a force sensor 5, a displacement measurement unit, a data acquisition and control unit, an air gap adjustment mechanism, and a temperature compensation unit.

[0031] The servo motor testing mechanism mounting base of this embodiment includes a servo motor mounting base, a magnetic spring stator fixing support 12, a base plate 14, and slide rails 15. The servo motor mounting base and the magnetic spring stator fixing support 12 are respectively installed and fixed to the rectangular base plate 14 along its length by bolts; two slide rails 15 are installed parallel to each other along the length of the base plate between the servo motor mounting base and the magnetic spring stator fixing support. The servo motor mounting base includes a servo motor mounting base 1 under test, a servo motor support 2 under test, and triangular reinforcing ribs. The servo motor support 2 under test is vertically installed on the servo motor mounting base 1 under test and is reinforced and fixed by two triangular reinforcing ribs to form the servo motor mounting base.

[0032] The magnetic spring unit of the device in this embodiment uses a permanent magnet; the permanent magnet magnetic spring unit includes a magnetic spring mover (moving magnet) 7 and a magnetic spring stator (stationary magnet) 8; the four corners of the magnetic spring stator 8 are fixed on four sliders respectively, and the four sliders are placed on the guide rail and can move linearly along the guide rail; the output shaft of the servo motor under test is connected to the force sensor 5 through the first force sensor mounting rod 4, and the other end of the force sensor 5 is connected to the magnetic spring mover 7 through the second force sensor mounting rod 6.

[0033] The stationary magnet is a large magnet composed of 20 small parallelogram magnets of 60×40×5. There are two large magnets in total, which are embedded in two parallel rectangular magnetic yokes. The stationary magnets are distributed on the left and right sides of the mover. The moving magnet is a large magnet composed of 20 small parallelogram magnets of 60×40×5. There are two large magnets in total, which together form an arrow-shaped magnet structure. The radial gap between the moving magnet and the stationary magnet is 2.5mm.

[0034] Each parallelogram (non-rectangular) small magnet has a side length of 60mm and 40mm, and the interior angle θ of the parallelogram is 75° or 105°. Multiple such parallelogram magnets can be spliced ​​together to form a ring or arc array. This arrangement, which is not at a 90° angle, can achieve magnetic field focusing, causing the magnetic field lines to concentrate in a specific direction, and the radial forces to cancel each other out. Through symmetrical arrangement, the radial magnetic pull forces cancel each other out, retaining only the axial force. This results in high space utilization, allowing more magnets to be arranged in a limited space.

[0035] The N pole of the moving magnet is located on the right end face of the moving magnet (closer to the stationary magnet). In a typical arrangement of a magnetic spring, the opposing surfaces of the moving and stationary magnets are usually filled with opposite polarities (e.g., the moving magnet is the N pole and the stationary magnet is the S pole) to generate an attractive force as a load.

[0036] The S pole of the stationary magnet is located on the left end face of the stationary magnet (closer to the moving magnet), opposite to the N pole of the moving magnet. This N-S relative arrangement generates an attractive force, meaning the force that the moving magnet needs to overcome when moving towards the stationary magnet is the load force of the servo motor.

[0037] In this embodiment, the force sensor 5 is positioned between the servo motor output shaft and the magnetic spring mover to collect the servo motor output force in real time. The displacement measurement unit is mounted on the axial extension line of the moving magnet assembly, or positioned to the side of the moving magnet's trajectory (perpendicular to the direction of motion), to measure the linear displacement of the moving magnet along the axial direction (i.e., the servo motor output shaft direction) in real time. The data acquisition and control unit includes a storage unit and a display unit to save test data and display the force-displacement curve in real time.

[0038] The data acquisition and control unit of the device in this embodiment is connected to the force sensor, displacement sensor and servo motor driver to realize synchronous data acquisition and motion control; it synchronously records the servo motor output force and displacement data, generates a load curve, and controls the servo motor motion in a closed loop according to the test requirements.

[0039] In this embodiment, the displacement sensor is a Panasonic HG-C1400-P laser displacement sensor, used to acquire the travel distance of the servo motor under test; measurement range: 400±200mm; output signal: 0~5V; repeatability: 300μm. The force sensor is an SBT710-200KG tension / compression sensor, used to acquire the load of the magnetic spring; measurement range: 0~1960N; overall error: ≤0.05%; transmitter: SBT912 dual-channel analog output, output range: -10V~10V.

[0040] like Figure 1 As shown, the servo motor under test 3 is fixed to the servo motor mounting base 1 via the servo motor support 2. The servo motor output shaft is connected to the force sensor 5, and the rear end of the force sensor 5 is connected to the magnetic spring mover 7. The magnetic spring stator 8 is fixed on the adjustable slider 13, and the slider 13 moves along the guide rail 15 to adjust the initial axial air gap. The displacement sensor is installed on the side of the moving magnet to monitor its displacement in real time. The data acquisition and control system is connected to the force sensor, displacement sensor, and servo motor driver to realize synchronous data acquisition and motion control.

[0041] Figure 4 shows the magnetic field distribution of the magnetic spring in this embodiment.

[0042] Figure 4(a) shows the magnetic circuit when the distance between the moving magnet and the stationary magnet is large (large air gap). As can be seen from the figure, the magnetic flux lines originate from the N pole of the moving magnet, pass through the air gap, and enter the S pole of the stationary magnet, forming a complete closed magnetic circuit. At this time, due to the large air gap, the magnetic flux lines diverge slightly in the air gap region, but the overall direction is regular, with no obvious magnetic leakage. The magnetic flux density is moderate, indicating that the magnetic field strength is relatively weak at this time, corresponding to a small magnetic force (approximately 0 N) near a displacement of 60 mm in the figure. This state corresponds to the initial position of the servo motor test (initial axial air gap is largest, load is smallest).

[0043] Figure 4(b) shows the magnetic circuit state when the distance between the moving magnet and the stationary magnet is minimal (the air gap is minimal). Compared to Figure 4, the moving magnet has moved to its extreme position close to the stationary magnet, and the air gap is significantly reduced. It can be observed that the magnetic flux lines are highly concentrated in the air gap region, and the magnetic field density is significantly increased, indicating that the magnetic field strength has reached its maximum value. The magnetic field lines pass through the air gap almost perpendicularly, with short and regular paths, resulting in the highest magnetic circuit efficiency. This state corresponds to the maximum magnetic force (approximately 1209.9 N) at a displacement of 120 mm in the figure, which is the maximum load position when the servo motor has its maximum stroke. The concentrated distribution of magnetic field lines verifies the physical mechanism that the magnetic force increases as the displacement decreases.

[0044] Figure 4(c) shows the magnetic flux density distribution cloud map of the magnetic spring unit. The figure uses a color gradient to represent the magnitude of the magnetic flux density: the red / warm area represents the high-intensity region, with a maximum value of 2561.476 mT (approximately 2.56 T), appearing on the surface of the permanent magnet; the blue / cool area represents the low-intensity region, with a minimum value of 3.347 mT, appearing in areas far from the magnet or at the edge of the air gap. As can be seen from the figure, the magnetic field is mainly concentrated in the air gap region between the magnets, forming an effective magnetic coupling path and providing the necessary conditions for generating axial magnetic force. The simulation results verify the rationality of the magnetic circuit design; the magnetic field distribution is uniform, with no obvious magnetic leakage or distortion.

[0045] Figure 4(d) shows the magnetic flux density distribution cloud map of another cross-section of the magnetic spring unit, illustrating the magnetic field distribution perpendicular to the direction shown in Figure 4(a). The magnetic flux density range is also from 3.347 mT to 2561.476 mT. As can be seen from the figure, the magnetic field is highly concentrated inside the magnet and in the air gap region, and the magnetic field lines are regularly oriented, indicating that the magnetic circuit design has good axisymmetry, which ensures that the radial forces experienced by the moving magnet cancel each other out during axial movement, thereby ensuring smooth motion.

[0046] This embodiment uses Ansys Maxwell software to perform two-dimensional / three-dimensional electromagnetic field simulation on the magnetic spring unit, establishing a magnetic force-displacement relationship model between the moving and stationary magnets. Simulation parameters include: magnet material is neodymium iron boron (N52), magnet dimensions are 102mm diameter × 63mm × 50mm, and initial axial air gap is 5mm. Magnetic force values ​​under different displacements were obtained through parametric scanning, and the results are shown in the table below.

[0047] ; Figure 5 The figure shows the force-displacement characteristic curve of the magnetic spring unit. The horizontal axis represents displacement (in mm), and the vertical axis represents magnetic force (in newtons). The curve illustrates the change in magnetic force as displacement increases. It can be seen from the curve that the magnetic force increases non-linearly as displacement decreases (air gap increases). Within the stroke range of 59 mm to 120 mm, the magnetic force smoothly increases from 0 N to approximately 1210 N without abrupt changes or fluctuations, which meets the incremental load characteristics required for servo motor load testing. This curve serves as a preset characteristic of the magnetic spring and is used for comparison and evaluation with the actual output force of the servo motor.

[0048] The servo motor load test procedure in this embodiment is as follows: (1) Based on the rated load of the servo motor under test, adjust the position of the static magnet through the air gap adjustment mechanism and set the initial axial air gap to 10mm; (2) Start the data acquisition system and set the sampling frequency to 1kHz; (3) Control the servo motor to move at a constant speed from the initial position to the maximum stroke of 120mm, and collect force and displacement data simultaneously; (4) Record the collected tensile and compressive sensor measurement data and laser displacement data synchronously, plot the output force-displacement curve of the tested servo motor, and compare it with the simulation characteristic curve to evaluate the mechanical performance of the magnetic spring; (5) After the test is completed, save the data and generate a test report.

Claims

1. A servo motor load testing device based on a magnetic spring, characterized in that, The device includes a servo motor mounting base, a magnetic spring unit, a force sensor, a displacement measurement unit, a data acquisition and control unit, an air gap adjustment mechanism, and a temperature compensation unit. The servo mounting base includes a base and a bracket, both of which are rectangular plate structures. The bracket is vertically mounted on the base and is reinforced and fixed by two triangular reinforcing ribs. The magnetic spring unit includes a magnetic spring mover and a magnetic spring stator. The magnetic spring mover is composed of two parallelogram-shaped assembled magnets forming an arrow-shaped moving magnet. The magnetic spring stator is composed of two parallelogram-shaped assembled magnets embedded on two parallel rectangular magnetic yokes forming a stationary magnet. The width between the two rectangular magnetic yokes is 5mm wider than the width of the arrow-shaped moving magnet of the stator. The four corners of the stationary magnet are fixed to four sliders, which move along the guide rail. The output shaft of the servo motor under test is connected to a force sensor through a first force sensor mounting rod, and the other end of the force sensor is connected to the arrow-shaped moving magnet through a second force sensor mounting rod. The force sensor is located between the servo motor output shaft and the magnetic spring mover to collect the servo motor output force in real time. The displacement measuring unit is installed on the axial extension line of the moving magnet assembly or set on the side of the moving magnet's motion trajectory. It is used to measure the linear displacement of the moving magnet along the axial direction in real time. The displacement measuring unit measures the displacement output by the servo motor and uses an encoder, grating ruler or laser displacement sensor. The data acquisition and control unit includes a storage unit and a display unit, used to save test data and display force-displacement curves in real time; the data acquisition and control unit is connected to the force sensor, displacement sensor and servo motor driver to realize synchronous data acquisition and motion control; it synchronously records the servo motor output force and displacement data, generates a load curve, and controls the servo motor movement in a closed loop according to test requirements; The air gap adjustment mechanism includes a guide rail and a slider. A static magnet is fixed on the slider. The slider is moved along the guide rail by manual or electric drive to realize air gap adjustment and connection with the magnetic spring mover. It is used to adjust the initial axial air gap between the magnetic spring stator and the magnetic spring mover. The temperature compensation unit includes a temperature sensor and a compensation algorithm module, which are used to eliminate the influence of magnet temperature drift on the test results. The temperature sensor is located near the magnetic spring unit to monitor the magnet temperature in real time, and the compensation algorithm module corrects the force measurement value according to the temperature change.

2. The servo motor load testing device based on a magnetic spring according to claim 1, characterized in that, The servo motor mounting base and the magnetic spring stator fixing support are bolted to both sides of the rectangular base plate along its length. The servo motor under test is mounted on the bracket of the servo motor mounting base. The output shaft of the servo motor under test is mounted on the first mounting rod of the force sensor via a force sensor mounting rod mounting bolt. The first mounting rod of the force sensor is mounted on the force sensor via a second mounting bolt of the force sensor. One end of the second mounting rod of the force sensor is connected to the other end of the force sensor via the first mounting bolt of the force sensor, and the other end of the second mounting rod of the force sensor is connected to the end of the magnetic spring mover with bolt holes via a magnetic spring mover connecting bolt. Long screws are horizontally parallel and symmetrically distributed on both sides of the tail of the magnetic spring stator. The other ends of the two long screws are mounted on the magnetic spring stator fixing support. The position of the magnetic spring stator is changed by adjusting the long screws.

3. The servo motor load testing device based on a magnetic spring according to claim 1, characterized in that, The magnetic spring unit is composed of permanent magnets, electromagnets, or a combination thereof. By adjusting the shape, size, material type, magnetization direction, array method, or combination of the magnets, precise control of the load curve can be achieved.

4. The servo motor load testing device based on a magnetic spring according to claim 3, characterized in that, When the magnetic spring unit uses permanent magnets, the magnetic spring stator of the magnetic spring is composed of several identical parallelogram-shaped permanent magnets stacked together to form two corresponding feather-shaped permanent magnets; the magnetic spring mover of the magnetic spring unit is composed of several identical parallelogram-shaped permanent magnets stacked together.

5. The servo load testing method of the servo load testing device based on a magnetic spring according to any one of claims 1-4, characterized in that, The method steps are as follows: (1) Establish a force-displacement characteristic model of the magnetic spring, and perform parametric modeling and simulation analysis of the magnetic spring unit through electromagnetic field simulation to obtain the characteristic curve of magnetic force changing with displacement; (2) Set the initial working point of the magnetic spring, adjust the initial axial air gap of the magnetic spring unit and set the preload force according to the test requirements of the servo motor under test; (3) Drive the servo motor to move, start the servo motor, and make its output shaft drive the magnetic spring mover to move towards the magnetic spring stator; (4) Real-time data acquisition: force sensor acquires servo motor output force signal, displacement sensor acquires moving magnet displacement signal; (5) Generate a load curve, record the collected output force and displacement data synchronously, plot the actual output force-displacement curve of the servo motor, and compare it with the preset magnetic spring characteristic curve to evaluate the performance of the servo motor.

6. A method for testing the load of a servo motor based on a magnetic spring according to claim 5. Its characteristic is that... The initial axial air gap adjustment is achieved manually or automatically, with an axial air gap adjustment range of 0-50mm and a corresponding preload adjustment range of 0-1200N.

7. A method for testing the load of a servo motor based on a magnetic spring according to claim 5. Its characteristic is that... The electromagnetic field simulation includes two-dimensional or three-dimensional static magnetic field simulation. The simulation parameters include magnet material, geometric dimensions, magnetization direction and relative position. The magnetic force value under different displacements is obtained through parametric scanning.

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