KR101851276B1 - The Torque Parameter Estimation Apparatus and Method of BLDC Motor for Torque Calibration of The Dental Implant-Motor - Google Patents

Abstract

A BLDC motor for torque correction of a dental implant motor capable of performing torque correction of a dental implant motor through torque parameter estimation of an electric motor without using a fixed part for performing torque correction of a motorized implant treatment device The present invention relates to an apparatus and method for estimating a torque parameter, comprising: (a) driving a three-phase Y-wire BLDC motor at a maximum; (b) measuring the rotational speed and current of the BLDC motor; (c) estimating a counter electromotive force constant based on the measured rotation speed and current; And (d) estimating a torque constant for torque correction of the implant motor using the estimated back electromotive force constant. The torque parameter estimation method of the BLDC motor for torque correction of the dental implant motor is implemented.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a torque parameter estimating apparatus and method for BLDC motor for torque correction of a dental implant motor,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to torque parameter estimation of a BLDC motor for torque correction of a dental implant motor, and more particularly, To an apparatus and method for estimating torque parameters of a BLDC motor for torque correction of a dental implant motor capable of performing torque correction of an implant motor.

Implant treatment is a treatment method for performing restoration of the function of the teeth. At present, it is a treatment method that satisfies aesthetic elements in addition to functional elements (refer to Non-Patent Documents 1 to 4).

In the initial stage of the implant procedure, all the procedures were performed manually and the procedure time was prolonged. As a result, it was difficult to perform successful procedures such as not maintaining sufficient jaw fixation force when inserting a fixture.

According to the preceding research examples and the clinical guideline of the implant procedure, it is very important to maintain a constant precision torque of 20 Ncm or more (Non-Patent Documents 5 to 7) in insertion of an implant fixture by a surgical instrument. Considering these factors, an implant treatment device has been developed for the accuracy and promptness of the procedure so that successful procedures can be performed.

However, currently commercially available implant treatment devices have a poor torque maintenance accuracy in implant treatment. This is because torque estimation is inaccurate due to the use of pneumatic actuators. Therefore, recent implant treatment devices have been developed and marketed as electric type with easy torque estimation.

Currently available motorized implant treatment devices support torque threshold setting and display of torque information, which improves torque accuracy compared to past pneumatic surgical instruments.

However, the control related constant value changes in the motor due to the change of the mechanical-electrical characteristics due to the heat generation of the motor and other factors during the long-time use of the electric implant treatment device. Therefore, since the accuracy of the torque control is reduced as the electric motor based implants are repeatedly used, torque correction must be performed before the procedure.

Currently, commercially available surgical instruments perform torque correction by estimating the mechanical constant value of the electric motor through a fixed load to solve this problem.

Adell R, Lekholm U, Rockler B, Branemark PI, Osseointegration and its experimental background, The Journal of Prosthetic Dentistry, vol. 50, pp. 399.410, 1983 Branemark PI, George Albert, Albrektsson, Tomas "Tissue-integrated prostheses: Osseointegration in clinical dentistry", Chicago: Quintessence Publishing, pp. 1-35, 1985 Korean Society of Dental Hygienists, Korean Oral and Maxillofacial Implant Society, "Dental Implantology", Seoul, Korea Park, Jin-Ho "Changes in quality of life and treatment satisfaction of oral health before and after implantation of artificial teeth", Graduate School of Kyungpook National University, Doctoral dissertation, 2008 Korean Society of Dentistry, "Clinical Implant Clinical Guidelines" Seoul, Gunja Publishing, 2010 Kim, Min Ho, et al., "A study on the thermal changes of the bone on the implant torque of different types of implants", Journal of Korean Academy of Prosthodontics, Vol. 49, No. 2, pp.168-176, 2011 Kim SH, Kim SJ, Lee KW, Han DH. "The effects of local factors on dental implants: A 19-year retrospective study." J Korean Acad Prosthodont, vol.48, pp.28-40, 2010

However, in the current commercialized instrument, the torque correction is performed by estimating the mechanical constant value of the electric motor through the fixed load. However, since the characteristic of the load is not permanent, the accuracy is guaranteed as the use period becomes longer There is a drawback that can not be.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an implantable dental implant device, An object of the present invention is to provide an apparatus and method for estimating a torque parameter of a BLDC motor for torque correction of a dental implant motor capable of performing torque correction of an implant motor.

Another object of the present invention is to provide a motor control apparatus and a motor control method capable of correcting torque of a dental implant motor by calculating control parameters required for torque control based on a BLDC motor having excellent mechanical characteristics and efficiency through a maximum consumed current for a maximum rotation speed of an electric motor And to provide an apparatus and method for estimating a torque parameter of a BLDC motor for correcting a dental implant motor.

In order to accomplish the above object, an apparatus for estimating torque parameters of a BLDC motor for correcting a dental implant motor according to the present invention comprises: a motor control unit for controlling motor driving; A motor driver for driving the three-phase Y-wire BLDC motor to a maximum level under the control of the motor controller; A rotation speed / current measuring unit for measuring a rotation speed and a current when the BLDC motor is driven; A counter electromotive force constant estimating unit for estimating a counter electromotive force constant based on the rotation speed and current amount of the BLDC motor measured by the rotation speed / current measuring unit; And a torque constant estimating unit for estimating a torque constant for torque correction of the implant motor based on the counter electromotive force constant estimated by the counter electromotive force constant estimating unit.

The back electromotive force constant estimating unit estimates the back electromotive force constant by substituting the measured rotational speed (?) And the amount of current (i) into the following equation for calculating the back electromotive force constant.

Where i _max is the no-load maximum consumption current, ω _max R is the motor winding resistance, ω is the rotational speed (RPM), and K _bemf is the motor back-EMF constant.

Wherein the torque constant estimating unit estimates a torque constant by substituting the calculated back electromotive force constant into a relational expression for calculating the following torque constant.

Where T is the motor-applied torque, K _t is the motor torque constant, and K _{RPM / torque} is the RPM-toeque slope constant.

According to another aspect of the present invention, there is provided a method of estimating torque parameters of a BLDC motor for torque correction of a dental implant motor, comprising the steps of: (a) driving a three-phase Y-wire BLDC motor at a maximum; (b) measuring the rotational speed and current of the BLDC motor; (c) estimating a counter electromotive force constant based on the measured rotation speed and current; (d) estimating a torque constant for torque correction of the implant motor using the estimated back electromotive force constant.

According to the present invention, it is possible to accurately estimate a torque parameter capable of performing torque correction of a dental implant motor through torque parameter estimation of an electric motor without using a fixed part, in order to perform torque correction of a motor- There are advantages.

1 is a block diagram of an apparatus for estimating a torque parameter of a BLDC motor for torque correction of a dental implant motor according to the present invention;
FIG. 2 is an equivalent circuit of a three-phase Y-connection BLDC motor and a six-step six-step control diagram applied to the present invention,
FIG. 3 is a flowchart illustrating a torque parameter estimation method of a BLDC motor for torque correction of a dental implant motor according to the present invention.
FIG. 4 is a block diagram showing the hardware components of the torque parameter estimating device used for experiments in the present invention,
5 is a diagram illustrating an experimental environment for torque measurement in the present invention,
6A and 6B are graphs of torque data and current data obtained as experimental results in the present invention,
7 is a graph showing a static torque experiment.

Hereinafter, an apparatus and method for estimating torque parameters of a BLDC motor for torque correction of a dental implant motor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an apparatus for estimating torque parameters of a BLDC motor for correcting a dental implant motor according to a preferred embodiment of the present invention.

A torque parameter estimating apparatus for a BLDC motor for correcting a dental implant motor according to the present invention includes a motor control unit 10, a motor driving unit 20, a BLDC motor 30, a rotational speed / current measuring unit 40, And a torque constant estimating unit 60. The torque estimating unit 60 includes a torque estimating unit 60,

The motor control unit 10 controls the motor driving and the motor driving unit 20 drives the three-phase Y-connecting BLDC motor 30 to the maximum speed under the control of the motor control unit 10. [

The rotation speed / current measuring unit 40 measures the rotation speed RPM and the current i during driving of the BLDC motor 30. The counter electromotive force constant estimating unit 50 calculates the rotation speed / And serves to estimate a counter electromotive force constant based on the rotation speed and the current amount of the BLDC motor measured by the controller 40.

In addition, the torque constant estimating unit 60 estimates a torque constant for torque correction of the implant motor based on the counter electromotive force constant estimated by the counter electromotive force constant estimating unit 60.

FIG. 3 is a flowchart illustrating a method of estimating torque parameters of a BLDC motor for torque correction of a dental implant motor according to the present invention. FIG. 3 (a) illustrates a step (S10) of driving a three-phase Y-wire BLDC motor at maximum; (b) measuring the rotational speed and current of the BLDC motor (S20); (c) estimating a counter electromotive force constant based on the measured rotational speed and current (S30); (d) estimating a torque constant for torque correction of the implant motor using the estimated back electromotive force constant (S40).

An apparatus and method for estimating a torque parameter of a BLDC motor for torque correction of a dental implant motor having the above-described structure will now be described in detail.

A typical BLDC motor has a stator made of a permanent magnet and a stator made of a coil. Unlike a DC motor in which a voltage is supplied through a brush, phase control is performed through switching by phase conversion. Also, it has a three-phase structure so that accurate rotation direction control can be performed during switching. This three-phase control requires six-step six-step control based on the back electromotive force waveform. Also, the torque and the rotation characteristics of the motor of the BLDC motor are changed according to the connection type of the stator.

In order to control the BLDC motor, the motor control unit 10 generates a motor control signal using the Six-Step control step shown in FIG.

In response to this motor control signal, the motor driving unit 20 drives the three-phase Y-connection BLDC motor 30 to the maximum.

When the BLDC motor 30 is driven, the rotational speed / current measuring unit 40 measures the rotational speed and the amount of current. Here, the rotational speed can be measured using a hall sensor, and a current sensor can be used as the current amount.

Then, the counter electromotive force constant estimating unit 50 estimates a counter electromotive force constant based on the measured rotation speed and the amount of current.

The three-phase Y-connection is connected in series with two resistors (R) and inductance (L) components per step. Therefore, the relationship between the current i and the rotational speed? Is summarized as shown in Equation 1 below.

Where i _max is maximum no-load current, _max is no-load maximum rotational speed, i is motor current, V is motor-applied voltage, R is motor winding resistance, L is motor winding inductance, V _bemf is the counter-electromotive force of the motor, and K _bemf is the counter-electromotive force constant of the motor.

At this time, the magnitude of the counter electromotive force is proportional to the rotation speed and acts in the opposite direction to the applied voltage. The inertia of the rotor when the motor is driven does not have a significant effect on the control at constant speed rotation. In addition, since the inductance value is very small, the inductance component is ignored, assuming that there is no abrupt current change affecting the control. The torque of the motor in consideration of this is expressed by the following equation (2).

Where T is the motor-applied torque, and K _t is the motor torque constant.

Next, the maximum driving current for the maximum rotation speed is calculated, and the back electromotive force constant is calculated using the following equation (3).

Where i _max is the no-load maximum consumption current, ω _max R is the motor winding resistance, ω is the rotational speed (RPM), and K _bemf is the motor back-EMF constant.

Next, the torque constant estimating unit 60 calculates a torque constant through the following equation (4) using the RPM-torque slope constant and the back electromotive force constant defined by Equation (3).

Where T is the motor-applied torque, K _t is the motor torque constant, and K _{RPM / torque} is the RPM-toeque slope constant.

And estimates the torque parameters necessary for torque correction through torque feedback by current feedback and rotational speed feedback through the computed Equation (4).

The present inventors have verified the accuracy and reliability of the torque control through the test torque measurement by experiment and verification of the proposed torque parameter estimation technique.

To this end, a controller for driving a BLDC motor is required, and a BLDC motor controller uses the same components as those shown in FIG.

The measurement range of the static torque measurement was selected from 0 - 20 Ncm, and the measurement method was measured with a torque sensor. The error rate of the mean value was derived from the measured data and the accuracy of the parameter was determined. For the reliability of the experiment, the torque correction through the torque driver was performed and then the experiment was performed. 5 is an illustration of an experimental environment for torque measurement.

From the initial drive, the maximum drive current for the maximum rotational speed was derived and the parameters were estimated. As a result of the experiment, current and torque sensor data as shown in FIGS. 6A and 6B were obtained. In the experimental data, it is judged that the irregular change of the torque is caused by the characteristics of the torque sensor and the coupling for connection of the rotation axis.

Based on the above experiment, the static torque measurement value and the torque calculated by the current are compared as shown in FIG. In the comparative graph of FIG. 7, an error occurs between the measurement torque in the range of 0-120 mNm and the torque calculated through the current value.

The reason for this error is considered to be due to the rotation axis alignment between the torque sensor and the handpiece for the experiment.

Based on the experimental data, it was confirmed that the error rate calculated through the standard deviation was 5.54%.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The present invention is applied to a technique of estimating a torque parameter of a BLDC motor for torque correction of a dental implant motor.

10: Motor control section
20:
30: BLDC motor
40: rotational speed / current measuring unit
50: Back electromotive force constant
60: torque constant estimating unit

Claims (7)

An apparatus for estimating torque parameters of a BLDC motor for correction of a dental implant motor,
A motor control unit for controlling motor driving;
A motor driver for driving the three-phase Y-wire BLDC motor to a maximum level under the control of the motor controller;
A rotation speed / current measuring unit for measuring a rotation speed and a current when the BLDC motor is driven;
A counter electromotive force constant estimating unit for estimating a motor counter electromotive force constant based on the rotation speed and current amount of the BLDC motor measured by the rotation speed / current measuring unit; And
And a torque constant estimator for estimating a torque constant for torque correction of the implant motor based on the counter electromotive force constant estimated by the counter electromotive force constant estimator,
Wherein the torque constant estimator comprises:
Equation

together with,
Estimates a torque constant K _t by using a motor back EMF constant K _bemf , an RPM-torque slope constant (K _{RPM / Torque} ) and a motor winding resistance R estimated by the counter electromotive force constant estimating unit,
Wherein the back electromotive force constant estimating unit estimates the motor back electromotive force constant by substituting the measured rotational speed (?) And the amount of current (i) into the following counter electromotive force constant calculation expression: torque of the BLDC motor for torque correction of the dental implant motor / RTI >

Where _max is the maximum no-load current consumption, _max is the no-load maximum rotational speed, R is the motor winding resistance, ω is the rotational speed (RPM), and K _bemf is the motor back-EMF constant.
delete delete delete A method for estimating a torque parameter of a BLDC motor for torque correction of a dental implant motor,
(a) driving a three-phase Y-wire BLDC motor to a maximum;
(b) measuring the rotational speed and current of the BLDC motor;
(c) estimating a motor back electromotive force constant based on the measured rotational speed and current; And
(d) estimating a torque constant for torque correction of the implantation motor using the estimated motor back EMF constant,
In the step (d), a torque constant is estimated by substituting the estimated motor back EMF constant and the RPM-torque slope constant into a relational expression for calculating the following torque constant,

Where T is the motor-applied torque, K _t is the motor torque constant, K _{RPM / torque} is the RPM-toeque slope constant and R is the motor winding resistance,
The step (c) includes the step of estimating the motor back electromotive force constant by substituting the measured rotational speed (?) And the amount of current (i) into the motor back electromotive force constant calculation expression described below. A method for estimating a torque parameter of a BLDC motor.

Where _max is the maximum no-load current consumption, _max is the no-load maximum rotational speed, R is the motor winding resistance, ω is the rotational speed (RPM), and K _bemf is the motor back-EMF constant. delete delete

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