Method for detecting resistance in stepper motor systems

Abstract

The present invention discloses a method for detecting the resistance of a stepper motor system. The method comprises the following steps: 1. connecting the motor drive line of a detected module composed of a stepper motor to a programmable stepper motor driver; 2. a host computer issues a test command, and the programmable stepper motor driver drives the stepper motor with the rated current I of the stepper motor in the detected motion module; 3. if the load in the detected motion module does not operate, the assembly quality of the detected motion module is judged to be unqualified; if the load operates, the drive current value is gradually reduced until the load in the detected motion module stops operating, and the drive current value at the last level when the load in the detected motion module stops operating is recorded as the minimum drive current value; and then judging whether the assembly quality is qualified. The present invention eliminates the drawbacks of existing manual testing by testers, such as low detection efficiency and unquantifiable detection results, and greatly improves the assembly quality consistency of motion modules of medical devices.

Description

Technical Field

[0001] The present invention relates to a stepper motor system, and in particular to a method for detecting resistance of a stepper motor system. Background Art

[0002] Stepper motors are widely used in medical devices, driving gears, pulleys, and other transmission components to drive loads for precise control. Currently, during the assembly process of medical devices, a motion module consisting of a stepper motor as the power source, transmission components, a driven component (load), and a frame is called a stepper motor system.

[0003] In the mass assembly of stepper motor systems, how can we measure assembly consistency, especially the resistance of the stepper motor system? For example, whether the load (follower) driven by the stepper motor moves smoothly along the linear or curved slideway (track), whether it will get stuck or jammed, and whether it will reduce the service life. The reasons for the resistance of the stepper motor system are: 1. Differences in the materials used, such as uneven surface of the guide rail assembly, that is, processing differences; 2. Differences in the amount of grease; 3. Differences in the skills or experience of the assembly personnel;

[0004] 4. Various factors such as people, machines, materials, and methods.

[0005] Currently, testing the resistance of stepper motor systems typically involves having testers manually slide or rotate the relevant load (component) or listen for unusual sounds or vibrations after power is applied. Because everyone's hand feel varies, and the point where a person touches the load cannot simulate actual force—for example, in a gear or belt drive, the force applied to the load differs from that applied by hand. Consequently, testing the resistance of stepper motor systems is subject to subjectivity, low efficiency, and unquantifiable results.

[0006] Attempts have been made to detect the resistance of a stepper motor system by measuring its current or voltage. However, hybrid stepper motors use a constant current drive, meaning the current is constant. Therefore, resistance detection cannot be achieved by sampling current changes. If resistance is detected by sampling voltage changes, due to the principle of energy conservation, the electrical power input to the stepper motor is converted into both kinetic energy and heat energy. The total power also varies depending on the load, making resistance detection impossible. Summary of the Invention

[0007] The present invention aims to provide a method for detecting the resistance of a stepper motor system, so as to improve working efficiency and detection accuracy.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The method for detecting the resistance of a stepper motor system according to the present invention adopts a step-down current driving strategy, namely:

[0010] Step 1: Connecting the motor drive line of the detected module composed of a stepper motor to the drive port of a programmable stepper motor driver, wherein the programmable stepper motor driver is connected to the host computer via a communication line;

[0011] Step 2: The host computer sends a test instruction to the programmable stepper motor driver, and the programmable stepper motor driver drives the stepper motor with the rated current I of the stepper motor in the detected motion module;

[0012] Step 3: Observe whether the load in the detected motion module is running;

[0013] Step 3.1: If the load is not running, it is determined that the assembly quality of the detected motion module is unqualified;

[0014] Step 3.2: If the load is running, the programmable stepper motor driver drives the stepper motor by gradually reducing the driving current value according to the embedded preset program until the load in the detected motion module stops running; the host computer records the driving current of the programmable stepper motor driver in real time, and records the driving current value of the last step when the load in the detected motion module stops running as the minimum driving current value;

[0015] Step 4: Replace the next detected module of the same type and batch, and repeat steps 2 to 3 until the detection of all detected modules of the same type and batch is completed; the minimum driving current values of the same type and batch are counted, and the average value thereof is used as the standard minimum current value X. The rated current I and the standard minimum current value X are used to drive the detected module, and whether the assembly quality of the detected module is qualified is determined. That is, if the minimum driving current value of the stepper motor of the detected module is greater than the standard minimum current value X, the assembly quality of the detected module is unqualified.

[0016] Optionally, the gradient value of the stepwise reduction of the output current value is 0.1A.

[0017] The principle of gradually reducing the output current value is to take into account the impact of lubrication on the test during the movement of the detected motion module. According to the lubrication principle, the friction force of the detected motion module is relatively large in the initial stage of movement, and it enters the equilibrium stage after lubrication. Therefore, the accuracy of the minimum drive current value is greatly improved.

[0018] The advantages of the present invention are embodied in the following aspects:

[0019] 1. By testing the resistance of the stepper motor system, the drawbacks of low testing efficiency and unquantifiable test results caused by the existing testing by manually sliding or rotating the relevant load (component) by the tester are eliminated, thereby greatly improving the assembly quality consistency of the motion module of medical equipment;

[0020] 2. The open-loop control system implements current descending input to measure the minimum drive current, which leaves a margin for the motion module design, helps to improve the service life of the motion module, and verifies whether the rated current of the motion module design is reasonable. It also detects whether there are other conditions such as interference in the motion module. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a detection flow chart of the present invention.

[0022] Figure 2 Schematic diagram of a detection system established according to the method of the present invention. DETAILED DESCRIPTION

[0023] The following describes an embodiment of the present invention in detail with reference to the accompanying drawings. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific working process. However, the protection scope of the present invention is not limited to the following embodiment.

[0024] like Figure 1 、 2 As shown, the method for detecting the resistance of a stepper motor system according to the present invention adopts a step-down current driving strategy, namely:

[0025] Step 1: Connecting the motor drive line of the detected module composed of a stepper motor to the drive port of a programmable stepper motor driver, wherein the programmable stepper motor driver is connected to the host computer via a communication line;

[0026] Step 2: The host computer issues a test command to the programmable stepper motor driver. The programmable stepper motor driver drives the stepper motor at the rated current I of the stepper motor in the detected motion module and sends the output drive current value to the host computer for recording and display. The programmable stepper motor driver selected is the MSST5 / 10-S driver produced by Shanghai Mingzhi Electric Co., Ltd. This driver can change the output current value by modifying parameters through software.

[0027] Step 3: Observe whether the load in the detected motion module is running;

[0028] Step 3.1: If the load is not running, it is determined that the assembly quality of the detected motion module is unqualified;

[0029] In step 3.2, if the load is running, the programmable stepper motor driver drives the stepper motor by gradually reducing the driving current value according to the embedded preset program until the load in the detected motion module stops running. Advantageously or illustratively, the gradient value of the stepwise reduction of the output current value is 0.1A. Of course, other gradient values can also be selected as needed.

[0030] The host computer records the driving current of the programmable stepper motor driver in real time, and records the driving current value of the last stage when the load in the detected motion module stops running as the minimum driving current value;

[0031] Step 4: Replace the next detected module of the same type and batch, and repeat steps 2 to 3 until the detection of all detected modules of the same type and batch is completed; the minimum driving current values of the same type and batch are counted, and the average value thereof is used as the standard minimum current value X. The rated current I and the standard minimum current value X are used to drive the detected module, and whether the assembly quality of the detected module is qualified is determined. That is, if the minimum driving current value of the stepper motor of the detected module is greater than the standard minimum current value X, the assembly quality of the detected module is unqualified.

Claims

1. A method for detecting resistance of a stepper motor system, characterized in that: Adopt a step-down current driving strategy, namely: Step 1: Connecting the motor drive line of the detected module composed of a stepper motor to the drive port of a programmable stepper motor driver, wherein the programmable stepper motor driver is connected to the host computer via a communication line; Step 2: The host computer sends a test instruction to the programmable stepper motor driver, and the programmable stepper motor driver drives the stepper motor with the rated current I of the stepper motor in the detected motion module; Step 3: Observe whether the load in the detected motion module is running; Step 3.1: If the load is not running, it is determined that the assembly quality of the detected motion module is unqualified; Step 3.2: If the load is running, the programmable stepper motor driver drives the stepper motor by gradually reducing the driving current value according to the built-in preset program until the load in the detected motion module stops running. The host computer records the driving current of the programmable stepper motor driver in real time, and records the driving current value of the last step when the load in the detected motion module stops running as the minimum driving current value. Step 4: Replace the next detected module of the same type and batch, and repeat steps 2 to 3 until the detection of all detected modules of the same type and batch is completed; the minimum driving current values of the same type and batch are counted, and the average value thereof is used as the standard minimum current value X. The rated current I and the standard minimum current value X are used to drive the detected module, and whether the assembly quality of the detected module is qualified is determined. That is, if the minimum driving current value of the stepper motor of the detected module is greater than the standard minimum current value X, the assembly quality of the detected module is unqualified.

2. The method for detecting the resistance of a stepper motor system according to claim 1, wherein: The gradient value of the output current value is 0.1A.

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