Miniature stepping motor rotation torque measuring device and measuring method

Abstract

The invention aims to provide the device and the method for measuring the rotating torque of the micro stepping motor, which are simple in structure, high in test precision and applicable to various micro motor products and different test environment conditions. The device comprises a bottom plate, a power module and a clamp module, the power module comprises a sliding platform, a first pull rope frame and a second pull rope frame, and a fixed end force measurement sensor and a movable end force measurement sensor are arranged at the equal-height positions of the corresponding sides of the first pull rope frame and the second pull rope frame correspondingly; the fixed end force cell sensor and the movable end force cell sensor are matched with the rotating end of a micro stepping motor on the clamp module through a pull rope and a pulley; the measurement method comprises the following steps: step A, carrying out sensor calibration on the fixed end force cell sensor and the mobile end force cell sensor; b, a micro stepping motor and a power module are in butt joint and run to obtain sensor tension data; and step C, calculating the rotating torque. The method is applied to the technical field of rotation torque measurement.

Description

Technical Field

[0001] The present invention is applied to the technical field of rotational torque measurement, and particularly relates to a rotational torque measurement device and method for a micro stepping motor. Background Art

[0002] Micro stepping motors are mainly used in various intelligent wearable devices, such as VR head-mounted intelligent equipment, which is mainly used as a driving execution unit for simulating scenarios. Such micro motors have the characteristics of small size, small torque, and light weight. However, during the assembly process of such micro stepping motors, it is necessary to measure the rotational torque of the motor. Approximate measurement methods include using a torque meter to measure torque, a motor comprehensive tester to measure torque, etc. There are even methods similar to the present invention, but they are rarely used to achieve precise measurement on micro motors. Among them, there is a method of using a motor comprehensive tester to measure torque. The servo motor (or stepping motor) system inside the comprehensive tester drives the DUT to rotate together, and the rotational speeds of the two form a certain rotational speed difference. The measurement of the pull-in torque and pull-out torque of the motor is achieved through parameters such as torque sensors and force converted by the current loop. Since the torques caused by their own moments of inertia in the above methods are much greater than the torque of the DUT, they cannot meet the measurement of micro motors (pull-out torque parameter of 1.4 - 1.65 mNm). Or use a motor comprehensive tester to measure torque. The servo motor (or stepping motor) system inside the comprehensive tester drives the DUT to rotate together, and the rotational speeds of the two form a certain rotational speed difference. The measurement of the pull-in torque and pull-out torque of the motor is achieved through parameters such as torque sensors and force converted by the current loop. Since the torques caused by their own moments of inertia in the above methods are much greater than the torque of the DUT, they cannot meet the measurement of micro motors (pull-out torque parameter of 1.4 - 1.65 mNm). If a rotational torque measurement device and method for a micro stepping motor with a simple structure, high test accuracy, and applicable to various micro motor products and different test environmental conditions can be designed, the above problems can be solved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a rotational torque measurement device and method for a micro stepping motor with a simple structure, high test accuracy, and applicable to various micro motor products and different test environmental conditions.

[0004] The technical solution adopted by the present invention is as follows: The present invention includes a bottom plate, a power module, and a fixture module. The power module includes a sliding platform, a first cable pulling frame, and a second cable pulling frame. The sliding platform and the first cable pulling frame are respectively arranged at both ends of the upper end surface of the bottom plate. The second cable pulling frame is connected to the movable end of the sliding platform. At the same height positions on the corresponding sides of the first cable pulling frame and the second cable pulling frame, a fixed-end force sensor and a movable-end force sensor are respectively arranged. The fixed-end force sensor and the movable-end force sensor are matched with the rotating end of a micro stepping motor on the fixture module through a pulling cable and a pulley.

[0005] Further, the fixture module includes an X-axis linear module, a Y-axis linear module, a Z-axis linear module, and a product fixture. The Y-axis linear module is connected to the movable end of the X-axis linear module. The Z-axis linear module is connected to the movable end of the Y-axis linear module. The product fixture is connected to the movable end of the Z-axis linear module. The second cable pulling frame drives the pulling cable to be matched with the rotating end of the micro stepping motor on the product fixture.

[0006] The described method for measuring the rotational torque includes the following steps Step A: Calibrate the fixed-end force sensor and the movable-end force sensor. Step B: Connect the micro stepping motor to the power module and run it to obtain sensor pulling force data. Step C: Calculate the rotational torque. Among them, step B can be further divided into the following sub-steps: Step B: Connect the two ends of the pulling cable to the fixed-end force sensor and the movable-end force sensor respectively. The connection direction of the pulling cable to the fixed-end force sensor is D, and the connection direction of the pulling cable to the movable-end force sensor is D. Step B: Adjust the connection line between the micro stepping motor and the fixed-end force sensor and the movable-end force sensor to be parallel through the X-axis linear module, the Y-axis linear module, and the Z-axis linear module. Connect the rotating end of the micro stepping motor to the pulley, and the middle part of the pulling cable winds around the outer edge of the pulley once. Step B: The sliding platform drives the movable-end force sensor to pre-tighten the pulling cable to the initial tension, so that the rotating end of the micro stepping motor is in a friction balance state. Step B: The upper computer sends an instruction to control the micro stepping motor to rotate synchronously at a rated speed with a certain configuration. At the same time, an instruction is sent to the sliding platform, and the sliding platform moves in the direction of D, so that the friction force between the pulling cable and the pulley gradually increases. Step B: The host computer synchronously reads the data of the two groups of the fixed-end force sensor and the mobile-end force sensor. When the sliding platform of the D force moves the pulling force to a certain force point position, the micro stepping motor stops rotating and is marked as the Pull-out point; Step B: After the micro stepping motor remains stable at the Pull-out point, the sliding platform moves in the D direction. When the micro stepping motor resumes rotation, it is marked as the Pull-in point, and the data of the two groups of the fixed-end force sensor and the mobile-end force sensor are recorded.

[0007] Further, the sensor calibration in Step A can be divided into the following sub-steps: Step A: Connect the fixed-end force sensor and the mobile-end force sensor to the test tooling respectively; Step A: Perform hanging measurements with multiple groups of standard weights, read the measured values, and then compare them with the weight values of the standard weights; Step A: Use the calibration software to calibrate the standard values of the force sensors according to the comparison results of the weight values, and write the calibrated KB coefficients into the controllers of the fixed-end force sensor and the mobile-end force sensor; Step A: Install the calibrated fixed-end force sensor and mobile-end force sensor on the first rope pulling frame and the second rope pulling frame respectively.

[0008] Further, in Step C, the data of the two states obtained through Step B and Step B are calculated by the formula respectively to calculate the torque data of the micro stepping motor at the Pull-out point and the Pull-in point, and obtain the pull-out torque and the pull-in torque, where F is the static reaction force sensed by the fixed-end force sensor, F is the moving force sensed by the mobile-end force sensor, D is the diameter of the pulley, and D is the diameter of the pulling rope.

[0009] Further, after the measurement is completed, a torque curve graph is drawn based on the pull-out torque, the pull-in torque and the real-time data obtained through Step C, and the positions of the Pull-out point and the Pull-in point are marked.

[0010] The beneficial effects of the present invention are as follows: The miniature stepping motor is equipped with a small pulley, and the torque is amplified through the radius of the pulley. The rotation torque of the miniature motor is measured by winding the pulling rope around the pulley and cooperating with a precision force measuring sensor. This method can incorporate the advantages of other existing measurement methods on the market and is very suitable for large-scale mass production of the rotation torque detection of miniature motors. At the same time, the movement of the pulling rope is controlled by the sliding platform to drive the rotation of the miniature stepping motor, and then the rotation torque of the miniature stepping motor is measured in the form of pulling force by using a high-precision force measuring (tensile and compressive force sensor). While ensuring high precision, it can not only measure the rotation torque of the miniature motor, but also adapt to any product with a motor and different test environmental conditions, comprehensively covering different test requirements. The structure is simple, the operation is convenient, and the measured data is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a perspective view of the present invention; Figure 2 is a perspective view of the power module; Figure 3 is a perspective view of the fixture module; Figure 4 is a schematic flow chart of the measurement method; Figure 5 is a schematic structural diagram of the pulling force measurement of the pulling rope; Figure 6 is a curve diagram of the pull-in torque and the pull-out torque. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] Such as Figures 1 to 6As shown in the figure, in this embodiment, the present invention includes a bottom plate 1, a power module 2 and a fixture module 3. The power module 2 includes a sliding platform 21, a first cable rack 22 and a second cable rack 23. The sliding platform 21 and the first cable rack 22 are respectively arranged at both ends of the upper end surface of the bottom plate 1. The second cable rack 23 is connected to the movable end of the sliding platform 21. At the same height on the corresponding sides of the first cable rack 22 and the second cable rack 23, a fixed-end force sensor 4 and a mobile-end force sensor 5 are respectively arranged. The fixed-end force sensor 4 and the mobile-end force sensor 5 are matched with the rotating end of a micro stepping motor 8 on the fixture module 3 through a tension cable 6 and a pulley 7. Thus, it can be seen that a small pulley 7 is sleeved on the rotating end of the micro stepping motor 8, and the torque is amplified through the radius of the pulley 7. The rotation torque of the micro motor is measured by the way of winding the tension cable 6 around the pulley 7 and cooperating with a precision force sensor. The movement of the tension cable 6 is controlled by the sliding platform 21 to drive the rotation of the movable end of the micro stepping motor 8, and then the rotation torque of the micro stepping motor 8 is measured in the form of tension by using a high-precision force measurement (tensile and compressive force sensor). While ensuring high precision, it can not only test the rotation torque of the micro motor 8, but also adapt to any product with a motor and different test environmental conditions, comprehensively covering different test requirements. The structure is simple, the operation is convenient, and the measured data is more stable.

[0013] As Figure 3 shown, in this embodiment, the fixture module 3 includes an X-axis linear module 31, a Y-axis linear module 32, a Z-axis linear module 33 and a product fixture 34. The Y-axis linear module 32 is connected to the movable end of the X-axis linear module 31. The Z-axis linear module 33 is connected to the movable end of the Y-axis linear module 32. The product fixture 34 is connected to the movable end of the Z-axis linear module 33. The second cable rack 23 drives the tension cable 6 to cooperate with the rotating end of the micro stepping motor 8 on the product fixture 34. Thus, it can be seen that different motors have different sizes, and the heights and plane positions during testing are also different. The relative positions of the micro stepping motor 8 and the tension cable 6 can be adjusted through the X-axis linear module 31, the Y-axis linear module 32 and the Z-axis linear module 33, so that the force on the micro stepping motor 8 is more uniform and the measured data is more stable.

[0014] As Figure 4 shown, the rotation torque measurement method includes the following steps: Step A: Calibrate the fixed-end force sensor 4 and the mobile-end force sensor 5. Step B: Docking the micro stepping motor 8 with the power module 2 and running to obtain sensor tension data. Step C: Calculate the rotation torque. Among them, step B can be further divided into the following sub-steps: Step B1: Connect both ends of the tension rope 6 to the fixed-end force sensor 4 and the mobile-end force sensor 5 respectively. The connection direction of the tension rope 6 to the fixed-end force sensor 4 is E1, and the connection direction of the tension rope 6 to the mobile-end force sensor 5 is E2; Step B2: Adjust the connection line between the micro stepping motor 8 and the fixed-end force sensor 4 and the mobile-end force sensor 5 to be parallel through the X-axis linear module 31, the Y-axis linear module 32 and the Z-axis linear module 33. Connect the rotating end of the micro stepping motor 8 to the pulley 7, and the middle part of the tension rope 6 winds around the outer edge of the pulley 7 once; Step B3: The sliding platform 21 drives the mobile-end force sensor 5 to pre-tighten the tension rope 6 to the initial tension, so that the rotating end of the micro stepping motor 8 is in a friction balance state; Step B3: The host computer sends an instruction to control the micro stepping motor 8 to rotate synchronously at a rated speed with a certain configuration, and at the same time sends an instruction to the sliding platform 21. The sliding platform 21 moves in the direction of E2, so that the friction force between the tension rope 6 and the pulley 7 gradually increases; Step B4: The host computer synchronously reads the data of the two groups of the fixed-end force sensor 4 and the mobile-end force sensor 5. When the sliding platform 21 that applies the force in the direction of E2 moves the tension to a certain force point position, the micro stepping motor 8 stops rotating and is marked as the Pull-out point; Step B5: After the micro stepping motor 8 stabilizes at the Pull - out point, the sliding platform 21 moves in the E1 direction. When the micro stepping motor 8 resumes rotation, it is marked as the Pull - in point, and two groups of data from the fixed - end force sensor 4 and the mobile - end force sensor 5 are recorded. It can be seen that the host computer sends instructions to control the micro stepping motor 8 to drive the pulley 7 to rotate synchronously at a rated speed (8V, 0.51A, 900PPS) with a certain configuration. At the same time, instructions are sent to the sliding platform 21 to gradually pull the tension rope 6 in the direction of E2 using the sliding platform, so that the friction between the tension rope 6 and the pulley 7 gradually increases. The host computer will synchronously use the photoelectric sensor to detect the rotation speed of the micro stepping motor 8 and synchronously read the data of the force sensors in the two force directions of E1 and E2. When the sliding platform 21 in the direction of the E2 - direction force moves to a certain force point position, the host computer will detect through the photoelectric sensor that the micro stepping motor 8 stops rotating. The force at this position where the micro stepping motor 8 stops rotating is marked as the Pull - out point. After maintaining for a period of time at the Pull - out point, the sliding platform 21 gradually moves step - by - step in the E1 direction. At this time, the friction between the tension rope 6 and the pulley 7 gradually decreases. When the friction overcomes the assistance and decreases to a certain extent, the micro stepping motor 8 resumes normal rotation (8V, 0.51A, 900PPS) from the stationary state. We mark this point position as the Pull - in point, and calculate the data of the Pull - out point and the Pull - in point to obtain the rotational torque.

[0015] As Figure 4 shown, in this embodiment, the sensor calibration in step A can be divided into the following sub - steps: Step A1: Connect the fixed - end force sensor 4 and the mobile - end force sensor 5 to the test tooling respectively; Step A2: Perform hanging measurements through multiple groups of standard weights, read the measured values, and then compare them with the weight values of the standard weights; Step A3: Calibrate the standard values of the force sensors using calibration software based on the weight - value comparison results, and write the calibrated KB coefficient into the controllers of the fixed - end force sensor 4 and the mobile - end force sensor 5; Step A4: Install the calibrated fixed-end force sensor 4 and the mobile-end force sensor 5 on the first cable pulley bracket 22 and the second cable pulley bracket 23 respectively. Thus, before measurement, the fixed-end force sensor 4 and the mobile-end force sensor 5 are respectively fixed on the workpieces designed in the early stage. Use ropes to hang standard weights of 50g, 100g, and 200g respectively, read the measured values on the upper computer, and then compare them with the weight values of the standard weights. Use the calibration software to calibrate the standard values of the force sensors, and write the calibrated KB coefficient into the force sensor controller to achieve the calibration of the sensors.

[0016] As Figure 4 and Figure 5 shown, in this embodiment, the data of the two states obtained through step B4 and step B5 in step C are respectively calculated by the formula to obtain the torque data of the micro stepping motor 8 at the Pull-out point and the Pull-in point, and obtain the pull-out torque and the pull-in torque. Among them, F1 is the static reaction force sensed by the fixed-end force sensor 4, F2 is the moving force sensed by the mobile-end force sensor 5, E1 is the diameter of the pulley 7, and E2 is the diameter of the tension rope 6. Thus, it can be seen that the rotational torques at different points can be calculated through the above formula.

[0017] As Figure 6 shown, in this embodiment, after the measurement is completed, the pull-out torque, the pull-in torque, and the real-time data obtained through step C are used to draw a torque curve graph, and the positions of the Pull-out point and the Pull-in point are marked.

[0018] Although the embodiments of the present invention are described with actual solutions, they do not constitute a limitation to the meaning of the present invention. For those skilled in the art, the modifications of its implementation solutions according to this specification and the combinations with other solutions are obvious.

Claims

1. A device for measuring the rotational torque of a micro stepping motor, comprising a base plate (1), a power module (2) and a fixture module (3), characterized in that: The power module (2) includes a sliding platform (21), a first cable pulling frame (22), and a second cable pulling frame (23). The sliding platform (21) and the first cable pulling frame (22) are respectively arranged at both ends of the upper end surface of the bottom plate (1). The second cable pulling frame (23) is connected to the movable end of the sliding platform (21). Fixed-end force sensors (4) and movable-end force sensors (5) are respectively arranged at the same height on the corresponding sides of the first cable pulling frame (22) and the second cable pulling frame (23). The fixed-end force sensor (4) and the movable-end force sensor (5) are matched with the rotating end of a micro stepping motor (8) on the fixture module (3) through a pulling cable (6) and a pulley (7).

2. The rotational torque measuring device for a micro stepping motor according to claim 1, characterized in that: The fixture module (3) includes an X-axis linear module (31), a Y-axis linear module (32), a Z-axis linear module (33), and a product fixture (34). The Y-axis linear module (32) is connected to the movable end of the X-axis linear module (31). The Z-axis linear module (33) is connected to the movable end of the Y-axis linear module (32). The product fixture (34) is connected to the movable end of the Z-axis linear module (33). The second cable pulling frame (23) drives the pulling cable (6) to be matched with the rotating end of the micro stepping motor (8) on the product fixture (34).

3. The measuring method of a measuring device for the rotational torque of a micro stepping motor according to claim 2, characterized in that, It includes the following steps: Step A: Calibrate the fixed-end force sensor (4) and the movable-end force sensor (5). Step B: Docking the micro stepping motor (8) with the power module (2) and running to obtain sensor pulling force data. Step C: Calculate the rotational torque. Among them, step B can be further divided into the following sub-steps: Step B1: Connect both ends of the pulling cable (6) to the fixed-end force sensor (4) and the movable-end force sensor (5) respectively. The connection direction of the pulling cable (6) to the fixed-end force sensor (4) is E1, and the connection direction of the pulling cable (6) to the movable-end force sensor (5) is E2. Step B2: Adjust the connection line between the micro stepping motor (8) and the fixed-end force sensor (4) and the movable-end force sensor (5) to be parallel through the X-axis linear module (31), the Y-axis linear module (32), and the Z-axis linear module (33). Connect the rotating end of the micro stepping motor (8) to the pulley (7), and the middle part of the pulling cable (6) winds around the outer edge of the pulley (7). Step B3: The sliding platform (21) drives the movable-end force sensor (5) to pre-tighten the pulling cable (6) to the initial tension, so that the rotating end of the micro stepping motor (8) is in a friction balance state. Step B3: The upper computer sends an instruction to control the micro stepping motor (8) to rotate synchronously at a rated speed with a certain configuration, and at the same time sends an instruction to the sliding platform (21). The sliding platform (21) moves in the direction of E2, so that the friction force between the pulling cable (6) and the pulley (7) gradually increases. Step B4: The host computer synchronously reads the two groups of data of the fixed-end force sensor (4) and the mobile-end force sensor (5). When the sliding platform (21) of the E2 acting force moves the pulling force to a certain force point position, the micro stepping motor (8) stops rotating and is marked as the Pull-out point; Step B5: After the micro stepping motor (8) stabilizes at the Pull-out point, the sliding platform (21) moves in the E1 direction. When the micro stepping motor (8) resumes rotation, it is marked as the Pull-in point, and the two groups of data of the fixed-end force sensor (4) and the mobile-end force sensor (5) are recorded.

4. The measuring method of a measuring device for the rotational torque of a micro stepping motor according to claim 3, characterized in that: Among them, the sensor calibration in Step A can be divided into the following sub-steps: Step A1: Connect the fixed-end force sensor (4) and the mobile-end force sensor (5) to the test tooling respectively; Step A2: Perform hanging measurements with multiple groups of standard weights, read the measured values, and then compare them with the weight values of the standard weights; Step A3: Calibrate the standard values of the force sensors using calibration software based on the weight value comparison results, and write the calibrated KB coefficient into the controllers of the fixed-end force sensor (4) and the mobile-end force sensor (5); Step A4: Install the calibrated fixed-end force sensor (4) and mobile-end force sensor (5) on the first cable pulley bracket (22) and the second cable pulley bracket (23) respectively.

5. The measuring method of a measuring device for the rotational torque of a micro stepping motor according to claim 4, characterized in that: In step C, the data of the two states obtained through step B4 and step B5 are calculated by the formula to calculate the torque data of the micro stepping motor (8) at the Pull-out point and the Pull-in point respectively, and the pull-out torque and the pull-in torque are obtained, where F1 is the static reaction force sensed by the fixed-end force sensor (4), F2 is the moving force sensed by the mobile-end force sensor (5), E1 is the diameter of the pulley (7), and E2 is the diameter of the tension rope (6).

6. The measuring method of a measuring device for the rotational torque of a micro stepping motor according to claim 5, characterized in that: After the measurement is completed, a torque curve graph is drawn based on the pull-out torque, pull-in torque, and real-time data obtained in Step C, and the positions of the Pull-out point and the Pull-in point are marked.

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