JP2007241604A - Command pattern generation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for generating a command pattern that minimizes the temperature rise of a drive motor when a moving amount and a cycle are specified. <P>SOLUTION: Two parameters including at least a speed maximum value ωmax or an acceleration maximum value αmax out of four parameters of the moving amount θmax, the cycle tact, the speed maximum value ωmax and the acceleration maximum value αmax are determined to generate the command pattern with the speed of parabolic shape wherein the moving amount θmax and the cycle tact are specified, the speed is zero at the time 0 and time tact, and an area is the moving amount θmax. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a command pattern generation method for minimizing an effective acceleration value when a motor is driven under a certain condition.

  The temperature rise of the motor when the motor is driven is roughly proportional to the square of the drive current. This is because the copper loss component obtained by multiplying the resistance of the motor by the square of the current occupies a large part due to the temperature rise of the motor. Therefore, reducing the drive current effective value leads to lowering the temperature rise of the motor.

  Since the motor drive current is controlled to have a proportional relationship with the normal torque, it is proportional to the motor acceleration. Accordingly, if a command pattern that minimizes the effective value of acceleration is generated when performing position control, the effective value of drive current can be minimized, and the temperature rise of the motor can also be minimized.

As a conventional method of designating such an acceleration effective value, Patent Document 1 can be cited. In this method, a command pattern represented by a normalization function is deformed by performing a scaling operation or a time-axis expansion / contraction operation, and a specified acceleration effective value is obtained under the limit performance limit.
JP-A-9-128031

  However, although the effective acceleration value can be specified by the above method, a pattern in which this is the minimum cannot be shown. Further, the normalization function itself is also a user's design matter, and it does not indicate what normalization function minimizes the effective acceleration value for a certain movement amount and tact.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method for generating a command pattern that minimizes a temperature increase of a drive motor when a movement amount and a tact are designated.

  In order to solve the above problems, the present invention provides a command pattern having a parabolic shape with a velocity of 0 at time 0 and a time tact and an area of the displacement θmax when a movement amount θmax and a tact tact are specified. Generate.

  According to the command pattern generation method of the present invention, since the effective acceleration value can be minimized under the restrictions of the movement amount and the tact time, the temperature increase of the drive motor can be controlled to the minimum.

  Further, since the movement amount θmax and the tact tact are specified from two parameters including at least the maximum speed value ωmax or the maximum acceleration value αmax among the four parameters, it is easy to generate a command pattern in consideration of the maximum speed and maximum torque of the motor. it can.

  Furthermore, by specifying the acceleration effective value αrms and specifying the acceleration maximum value αmax and determining one of the remaining three parameters, the acceleration effective value itself can be set as the target value, and the temperature rise of the motor can be increased. Can be controlled.

  By determining at least two parameters including the maximum velocity value ωmax or the maximum acceleration value αmax among the four parameters of the movement amount θmax, the tact tact, the maximum velocity value ωmax, and the maximum acceleration value αmax, the movement amount θmax and the tact tact can be determined. Specifically, a command pattern having a parabolic shape with a speed of 0 at a time 0 and a time tact and an area of a movement amount θmax is generated.

  When the movement amount θmax and the tact tact are specified, a command pattern in which the acceleration α (t) at the time t is expressed by Equation 1 can be generated, and the command pattern having a parabolic shape can be generated. This is illustrated in FIG.

  As a result, the effective acceleration value can be minimized under the constraints of the movement amount and the tact. As a reference, the ratio of effective acceleration value αrms, maximum acceleration value αmax, maximum speed value ωmax with a fixed amount of movement θmax and tact tact between a general speed triangular wave pattern and a speed trapezoid pattern as command patterns is shown in FIG. Show.

  According to the command pattern generation method of the present invention, it can be seen that the effective acceleration value is improved by 13% compared to the triangular wave and 5% compared with the trapezoidal wave.

  By integrating the equation 1 from time 0 to time t, the speed ω (t) shown in the equation 2 is derived.

  The maximum acceleration value αmax is obtained by substituting time t = 0 or time tact into Equation 1, and the maximum velocity value ωmax is obtained by substituting time t = tact / 2 into Equation 2. When the obtained two expressions are arranged, Expression 3 and Expression 4 are obtained.

  Expressions 3 and 4 are composed of three parameters among the four parameters of the movement amount θmax, the tact tact, the maximum speed value ωmax, and the maximum acceleration value αmax, and include two parameters including at least the maximum speed value ωmax or the maximum acceleration value αmax. If the parameters are determined, the movement amount θmax and the tact tact can be specified, the speed becomes zero at time 0 and time tact, and the command pattern having a parabolic shape with the area being the movement amount θmax is uniquely defined. Can do.

  The effective acceleration value αrms is obtained from the acceleration α (t) in Equation 1 as shown in Equation 5.

  Therefore, the relationship between the maximum acceleration value αmax obtained by substituting t = 0 into Equation 1 and the effective acceleration value αrms is Equation 6.

  Thus, since the acceleration maximum value αmax is determined from the acceleration effective value αrms, the movement amount θmax and the tact tact are specified by determining one parameter among the remaining three parameters of the movement amount θmax, the tact tact, and the maximum speed value ωmax. It is possible to uniquely define a command pattern having a parabolic shape with a speed of 0 at time 0 and a time tact and an area of the moving amount θmax.

  The above-described embodiment is not limited to a rotary motor, and can be applied to a linear system such as a linear motor. In addition, when applied to an application in which the same moving distance is reciprocated, the acceleration command can be continuously performed and vibration is hardly excited, which is very suitable.

  Since the command pattern generation method of the present invention can minimize the effective acceleration value of the motor and minimize the temperature rise of the motor, it is useful for miniaturization and energy saving of the motor.

Explanatory drawing of the command pattern of the speed parabola shape in the present invention Comparison diagram of the present invention with speed triangle wave and speed trapezoid command pattern

Claims (3)

A command pattern generation method having a parabolic shape with a speed of 0 at time 0 and time tact and an area of movement θmax when a movement amount θmax and a tact tact are designated. By determining at least two of the four parameters of the movement amount θmax, the tact tact, the speed maximum value ωmax, and the acceleration maximum value αmax, including the speed maximum value ωmax or the acceleration maximum value αmax, the movement amount θmax 2. The command pattern generation method according to claim 1, wherein tact tact is specified. 3. The movement amount θmax and the tact tact are specified by specifying the acceleration effective value αrms, specifying the acceleration maximum value αmax, and determining one of the remaining three parameters. Command pattern generation method.