Torque sensor-based motor torque control method

Abstract

The application discloses a motor torque control method based on a torque sensor, and is characterized in that the method comprises the following steps: coupling and connecting a motor with an external torque sensor, acquiring a first torque value Tin based on the torque sensor in the motor, and acquiring a second torque value Tout based on the external torque sensor; configuring a controller, which is used for acquiring a target torque value Te according to a torque constant k of the motor and a set output current value Iq, and determining a transmission efficiency η based on the second torque value Tout and the target torque value Te; configuring a torque model for the controller to acquire a deviation value e between the first torque value Tin and the second torque value Tout; repeating the above steps to acquire a plurality of deviation values e in different temperature intervals; and configuring a torque model matched with a temperature interval for the controller based on an external control signal and an external temperature signal to acquire a control current iq. After the torque control mathematical model is constructed, the torque control is more accurate.

Description

Technical Field

[0001] This invention relates to the field of torque control technology, and in particular to a motor torque control method based on a torque sensor. Background Technology

[0002] Currently, with the increasing number of humanoid robot manufacturers and products, the demand for servo joint modules is growing daily. Existing motors have the following problems: 1. Due to significant interference signals in the current value during motor rotation, the torque value obtained based on current detection is inaccurate; 2. Some manufacturers choose to install an integrated torque sensor at the end of the flange, with the data receiving end located in the servo driver at the front of the servo joint module. This solution is prone to cable breakage; 3. Some manufacturers choose to install a conventional torque sensor at the end of the flange, with the data receiving end located in the servo driver outside the transmission unit. This solution is not conducive to controlling the product's size and weight, resulting in relative redundancy and a larger size and weight.

[0003] To improve torque detection accuracy, this application uses a cup-shaped reducer and adds a torque sensor between the reducer's flexible wheel and the motor. By detecting the metal deformation of the torque sensor, the actual torque value is detected, and the output torque value is derived based on the reduction ratio. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a motor torque control method based on a torque sensor.

[0005] The objective of this invention is achieved through the following technical solution: a motor torque control method based on a torque sensor, characterized by comprising the following steps: coupling the motor to an external torque sensor; obtaining a first torque value Tin based on the torque sensor inside the motor, and obtaining a second torque value Tout based on the external torque sensor; configuring a controller to obtain a target torque value Te based on the motor's torque constant k and a set output current value Iq, and determining the transmission efficiency η based on the second torque value Tout and the target torque value Te; configuring a torque model for the controller to obtain a deviation value e between the first torque value Tin and the second torque value Tout; repeating the above steps to obtain several deviation values ​​e under different temperature ranges; configuring a temperature range-matched torque model for the controller based on an external control signal and an external temperature signal to obtain a control current iq.

[0006] Preferably, the target torque value is obtained by formula It is determined that the transmission efficiency is determined by the formula η=Tout / Te / c, where K t (N·m / A_rms) is the ratio constant between the effective value of the motor line current and the output torque, and c is the reduction ratio of the reducer inside the motor.

[0007] Preferably, the control current is obtained by the formula iq=((Tout / η / c)-e) / k t Sure.

[0008] The present invention has the following advantages: (1) The mechanical deformation torque sensor is used, and the output torque detection is more accurate than the current detection scheme.

[0009] (2) After constructing the torque control mathematical model, the torque control is more accurate.

[0010] (3) It can maintain good and accurate torque control under different temperature environments. Attached Figure Description

[0011] Figure 1 This is a schematic flowchart of the motor torque control method of the present invention; Figure 2 This is a schematic diagram showing the modular connection method of each electronic module; In the diagram, 1-motor, 2-external torque sensor, 3-controller. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the following description: like Figure 1 and Figure 2 As shown, this application provides a motor torque control method based on a torque sensor, comprising the following steps: S1, the motor 1 is coupled to the external torque sensor 2, the first torque value Tin is obtained based on the torque sensor inside the motor, and the second torque value Tout is obtained based on the external torque sensor 2.

[0013] Specifically, the flange of the servo joint module is connected to an external high-precision torque sensor device to ensure that the external sensor can collect accurate actual data from the flange side.

[0014] S2, Configure controller 3 to obtain the target torque value Te based on the motor's torque constant k and the set output current value Iq, and determine the transmission efficiency η based on the second torque value Tout and the target torque value Te.

[0015] Specifically, most current motor torque control modes are based on output current and the corresponding torque constant to achieve torque output and control. Essentially, this is a closed-loop control based on current output, and cannot achieve closed-loop control based on torque output. The torque sensor in this application is installed at the input end of the harmonic reducer, and its measurement accuracy is slightly lower than that of a sensor mounted on the end flange. Therefore, it is necessary to construct a mathematical model between current, torque constant, motor end torque, and end torque using an external torque sensor. In an ideal permanent magnet synchronous motor without cogging effect and core saturation, the electromagnetic torque equation is T = Where P is the pole pair number, iq,1d are the components of the current vector on the d-axis and q-axis, respectively. For permanent magnet flux linkage. This application adopts the control mode of id=0, and the torque calculation equation can be expressed as: .

[0016] Ideally, as long as the quadrature-axis current iq remains constant, the output torque will be absolutely constant. Therefore, set... , where K t (N·m / A_rms): The proportionality constant between the effective value of the motor line current and the output torque. T cmd The target torque is consistent with Te. q_cmd Similar to iq, it represents current.

[0017] The transmission efficiency is determined by the formula η=Tout / Te / c, where c is the reduction ratio of the reducer inside the motor.

[0018] S3, configure the torque model for controller 3 to obtain the deviation value e between the first torque value Tin and the second torque value Tout.

[0019] Specifically, by repeatedly comparing the values ​​at the torque input and output ends, Tout = (iq) is constructed. k t +e) c The torque model of η is used to obtain the deviation value e.

[0020] S4. Repeat steps S1-S3 to obtain several deviation values ​​e under different temperature ranges.

[0021] Specifically, taking a 25-degree Celsius environment as an example, the motor has 8 pole pairs, and the harmonic reducer is a cup-type harmonic reducer with a reduction ratio of 101 (steel wheel output), specification 20. The transmission efficiency of the harmonic reducer is 69.5%, and the torque constant is 0.112 (Nm / A). According to equipment measurements, multiple sets of end torques were measured within the rated current, and the final calculated transmission efficiency of the motor is 67.3%, with e = -0.06.

[0022] S5, based on external control signals and external temperature signals, configures a torque model for controller 3 that matches the temperature range in order to obtain the control current iq.

[0023] Specifically, the control current can be expressed by the formula iq = ((Tout / η / c) - e) / k t Perform the calculation.

[0024] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A motor torque control method based on a torque sensor, characterized in that, Includes the following steps: The motor (1) is coupled to an external torque sensor (2), and a first torque value Tin is obtained based on the torque sensor inside the motor (1), and a second torque value Tout is obtained based on the external torque sensor (2); Configure the controller (3) to obtain the target torque value Te based on the motor torque constant k and the set output current value Iq, and determine the transmission efficiency η based on the second torque value Tout and the target torque value Te; Configure a torque model for the controller (3) to obtain the deviation value e between the first torque value Tin and the second torque value Tout; Repeat the above steps to obtain several deviation values ​​e under different temperature ranges; Based on the external control signal and the external temperature signal, a torque model matching the temperature range is configured for the controller (3) to obtain the control current iq.

2. The motor torque control method according to claim 1, characterized in that, The target torque value is obtained through the formula It is determined that the transmission efficiency is determined by the formula η=Tout / Te / c, where K t (N·m / A_rms) is the ratio constant between the effective value of the motor line current and the output torque, and c is the reduction ratio of the reducer inside the motor.

3. The motor torque control method according to claim 2, characterized in that, The control current is obtained through the formula iq=((Tout / η / c)-e) / k t Sure.

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