JP2013121244A - Apparatus and method for actuator control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve stable thrust control without being affected by a change in an actuator displacement in controlling a hybrid actuator.SOLUTION: In controlling a hybrid actuator, the thrust of the actuator is controlled in a combination of feedback control and feed forward control, and a feedback gain is set based on at least one of the displacement, speed and acceleration of the actuator.

Description

 The present invention relates to an actuator control apparatus and method.

  In recent years, as a next-generation actuator, a hybrid type actuator (hybrid actuator) combining a hydraulic type and an electric type capable of high power control while obtaining a large thrust is drawing attention. For example, Patent Document 1 below discloses a hybrid actuator control method that realizes a quick response without impairing existing advantages such as control stability. Patent Document 2 below discloses a configuration of a hybrid actuator that realizes reduction of inertial resistance, energy saving, and energy regeneration in a high-frequency region.

JP 2001-241381 A JP 2009-255785 A

  When the hybrid actuator is operated in the thrust control state, the actuator displacement is arbitrarily changed according to the generated thrust state depending on the characteristics (elasticity, viscosity, etc.) of the object on which the actuator thrust is to be applied. Conventionally, a method for stably realizing the thrust control in a state in which the actuator displacement changes arbitrarily has not been established.

 The present invention has been made in view of the above-described circumstances, and an object of the present invention is to realize stable thrust control without being affected by changes in actuator displacement when controlling a hybrid actuator.

 In order to achieve the above object, according to the present invention, as a first solving means related to an actuator control apparatus, an actuator control apparatus for controlling a hybrid actuator, wherein the actuator is a combination of feedback control and feedforward control. And a means for setting a feedback gain based on at least one of the displacement, velocity or acceleration of the actuator.

 Further, in the present invention, as a second solving means related to the actuator control device, in the first solving means, when the actuator includes a hydraulic cylinder, a hydraulic pump, and a servo motor, based on a pressure detection result of the hydraulic cylinder. Calculating a thrust generated by the hydraulic cylinder, multiplying a deviation between the thrust generated by the hydraulic cylinder and the thrust command value by the feedback gain to calculate a feedback command value, and feedforward based on the speed of the hydraulic cylinder A command value is calculated, a value obtained by adding the feedback command value and the feedforward command value is calculated as a final request command value, and a motor command signal for causing the hydraulic cylinder to generate the request command value A method of outputting to the servo motor driver is adopted.

 On the other hand, in the present invention, as a first solving means related to the actuator control method, there is an actuator control method for controlling a hybrid actuator, which controls the thrust of the actuator by combining feedback control and feedforward control. The feedback gain is set based on at least one of the displacement, speed or acceleration of the actuator.

 According to the present invention, when controlling a hybrid actuator, stable thrust control can be realized without being affected by changes in actuator displacement.

It is a schematic block diagram of the actuator control system which concerns on this embodiment. 3 is a flowchart showing a thrust control operation of the actuator control device 4. FIG. 6 is a supplementary explanatory diagram regarding thrust control operation of the actuator control device 4.

 FIG. 1 is a schematic configuration diagram of an actuator control system according to the present embodiment. As shown in FIG. 1, an actuator control system according to the present embodiment includes a hybrid actuator (hereinafter referred to as a hybrid actuator) 1 combining a hydraulic type and an electric type, a motor driver 2, and a signal conversion / amplifier. 3 and the actuator control device 4.

 The hybrid actuator 1 includes a hydraulic cylinder 11, a hydraulic pump 12, a servo motor 13, a shuttle valve 14, an oil storage tank 15, a first pressure sensor 16, a second pressure sensor 17, and a linear sensor 18. It is configured. Further, the hydraulic cylinder 11 includes a cylinder 11a, a piston 11b, and a rod 11c.

 The cylinder 11a is a cylindrical part that contains oil inside as a working fluid. The piston 11b is a disk-shaped component that divides the internal space of the cylinder 11a into two chambers (first chamber R1 and second chamber R2) and is reciprocally moved along the inner wall of the cylinder 11a. The rod 11c is a rod-like component having one end fixed to the piston 11b so that its own central axis coincides with the central axis of the piston 11b. The other end of the rod 11c penetrates outward from the first chamber R1 side of the cylinder 11a, and is connected to an object (not shown) to which a thrust generated in the hydraulic cylinder 11 is to be applied.

 The hydraulic pump 12 is, for example, a two-way discharge type variable displacement pump. The input shaft is connected to the rotation shaft of the servo motor 13 and one discharge port of the hydraulic cylinder 11 is connected via the first flow path L1. The other discharge port is connected to the first chamber R1, and the other discharge port is connected to the second chamber R2 of the hydraulic cylinder 11 via the second flow path L2. In such a two-way discharge type hydraulic pump 12, the oil discharge direction (in other words, from which discharge port oil is discharged) is determined by the rotation direction of the input shaft, and the rotation of the input shaft is determined. The discharge flow rate is determined by the number.

 The servo motor 13 is an AC servo motor, for example, and has a rotating shaft that rotates in accordance with a motor drive signal supplied from the motor driver 2. As described above, since the rotation shaft of the servo motor 13 is connected to the input shaft of the hydraulic pump 12, by controlling the rotation direction and the rotation speed (rotation speed) of the servo motor 13, The discharge direction and the discharge flow rate can be arbitrarily controlled.

 That is, by controlling the rotation direction and the rotation speed of the servo motor 13, an arbitrary pressure difference can be generated between the first chamber R1 and the second chamber R2 of the hydraulic cylinder 11, and as a result, the hydraulic cylinder 11 The thrust of can be controlled arbitrarily. As is well known, an encoder is built in the servo motor 13, and an output pulse signal of the encoder is fed back to the motor driver 2.

 The shuttle valve 14 has two input ports, one connected to the first flow path L1 and the other connected to the second flow path L2, one output port communicating with the oil storage tank 15, and two input ports. The valve body moves between the input ports according to the pressure difference. When the pressure difference between the two input ports exceeds the specified value, the above valve body moves to the low pressure side to The input port on the side communicates with the output port, and the oil introduced into the input port on the high pressure side is discharged from the output port to the oil storage tank 15. The oil storage tank 15 is a container for storing oil discharged from the shuttle valve 14.

 The first pressure sensor 16 detects the internal pressure Pr of the first chamber R1 of the hydraulic cylinder 11, and outputs a signal corresponding to the detection result to the signal conversion / amplifier 3. The second pressure sensor 17 detects the internal pressure Ph in the second chamber R2 of the hydraulic cylinder 11, and outputs a signal corresponding to the detection result to the signal conversion / amplifier 3. The linear sensor 18 detects the displacement x of the piston 11 b of the hydraulic cylinder 11 and outputs a signal corresponding to the detection result to the signal conversion / amplifier 3.

 The motor driver 2 generates a motor driving signal (driving current) for driving the servo motor 13 in accordance with a motor command signal (PWM modulated pulse signal) input from the actuator control device 4 and supplies the servo motor 13 with the motor driving signal. Output. As described above, the encoder output of the servo motor 13 is fed back to the motor driver 2, and feedback control is performed in the motor driver 2 so that the deviation between the motor command signal and the encoder output becomes zero. .

 The signal conversion / amplifier 3 converts and amplifies signals input from the first pressure sensor 16, the second pressure sensor 17, and the linear sensor 18, and then outputs these signals to the actuator control device 4.

 The actuator control device 4 is a microcontroller in which a CPU (Central Processing Unit), a memory, an input / output interface, and the like are integrated, and converts signals from the first pressure sensor 16, the second pressure sensor 17, and the linear sensor 18. Based on a signal input through the amplifier 3, a motor command signal for making the thrust of the hybrid actuator 1 (thrust of the hydraulic cylinder 11) coincide with the thrust command value is generated and output to the motor driver 2.

Next, the operation of the actuator control system configured as described above will be described in detail with reference to FIGS.
The actuator control device 4 performs thrust control of the hybrid actuator 1 according to the main routine shown in FIG. As shown in FIG. 2 (a), the actuator control device 4 first performs the processing of step S1 from the first pressure sensor 16, the second pressure sensor 17, and the linear sensor 18 via the signal conversion / amplifier 3. Based on the input signal, the detected values of the displacement x of the hydraulic cylinder 11 (piston 11b), the internal pressure Pr of the first chamber R1 and the internal pressure Ph of the second chamber R2 of the hydraulic cylinder 11 are acquired.

 And the actuator control apparatus 4 performs in parallel the feedback calculation process which is the process of step S2, and the feedforward calculation process which is the process of step S3. Specifically, the actuator control device 4 performs feedback calculation processing according to the subroutine shown in FIG. 2B, and performs feedforward calculation processing according to the subroutine shown in FIG.

 As shown in FIG. 2B, the actuator control device 4 sets the feedback gain G based on the displacement x of the hydraulic cylinder 11 as the process of step S21 in the feedback calculation process. Here, the feedback gain G may be set to a value proportional to the displacement x of the hydraulic cylinder 11 as shown in FIG.

As shown in FIG. 3B, when the displacement x of the hydraulic cylinder 11 changes from x1 to x2, the pressure change amount ΔP in the second chamber R2 of the hydraulic cylinder 11 is expressed by the following equation (1). The
ΔP = K · ΔV / Vp = K · Q / Vp (1)
In the above equation (1), K is the bulk modulus, ΔV is the volume change amount of the second chamber R2, Vp is the displacement volume of the hydraulic pump 12, and Q is the discharge flow rate of the hydraulic pump 12 (Q = Vp · n = ΔV; n is the number of rotations of the servomotor 13). Assuming that the pressure P1 = P2 = constant, when V → Q, P1 = K · Q / Vp, and when 2V → 2Q, P2 = K · 2Q / Vp = 2P1.

 Then, the actuator control device 4 performs the process of step S22 in the feedback calculation process, such as the displacement x of the hydraulic cylinder 11, the internal pressure Pr of the first chamber R1 of the hydraulic cylinder 11, the internal pressure Ph of the second chamber R2, and the piston 11b. Based on the pressure receiving area Ar on the first chamber R1 side and the pressure receiving area Ah on the second chamber R2 side, the thrust (cylinder generated thrust) fa currently generated in the hydraulic cylinder 11 is calculated (see FIG. 3C). ).

Specifically, for example, when the displacement x> 0, the actuator control device 4 includes the pressure receiving area Ar (m ² ) on the first chamber R1 side of the piston 11b and the internal pressure Pr (MPa) of the first chamber R1 below. Based on the equation (2), the cylinder generated thrust fa (kN) is calculated.
^{fa = -Ar · Pr · 10 6} /1000 ··· (2)
For example, when the displacement x <0, the actuator control device 4 includes the pressure receiving area Ah (m ² ) on the second chamber R2 side of the piston 11b and the internal pressure Ph (MPa) of the second chamber R2 (3) Based on the equation, cylinder generated thrust fa (kN) is calculated.
^{fa = Ah · Ph · 10 6} /1000 ··· (3)

 Then, the actuator control device 4 calculates a deviation Δf (= fc−fa) between the thrust command value fc (kN) and the cylinder generated thrust fa calculated in step S22 as the process of step S23 in the feedback calculation process. . The thrust command value fc may be a value set in advance in the actuator control device 4 or may be a value instructed from an external host control device.

 Then, the actuator control device 4 calculates a feedback command value Fb from the feedback gain G set in step S21 and the thrust deviation Δf calculated in step S23 as the process of step S24 in the feedback calculation process. For example, when the feedback gain G set when the displacement x> 0 is G1, Fb = G1 · Δf, and when the feedback gain G set when the displacement x <0 is G2, Fb = G2 · Δf. .

 On the other hand, as shown in FIG. 2 (c), the actuator control device 4 differentiates the displacement x of the hydraulic cylinder 11 as the process of step S31 in the feedforward calculation process, whereby the speed of the hydraulic cylinder 11 (the piston 11b) (Movement speed) is calculated.

 Then, the actuator control device 4 performs the processing in step S32 in the feedforward calculation processing, such as the displacement x of the hydraulic cylinder 11, the cylinder speed (dx / dt) calculated in step S31, and the first chamber R1 side of the piston 11b. Based on the pressure receiving area Ar, the pressure receiving area Ah on the second chamber R2 side, the displacement volume Vp of the hydraulic pump 12, and the maximum rotation speed Nmax of the servo motor 13, a feedforward command value (speed deviation) Ff is calculated (FIG. 3 ( c)).

Specifically, for example, when the displacement x> 0, the actuator control device 4 determines the pressure receiving area Ar (m ² ) of the piston 11b on the first chamber R1 side, the cylinder speed dx / dt, and the displacement volume Vp ( The feedforward command value Ff is calculated based on the following equation (4) including m ³ / rev) and the maximum rotation speed Nmax (rpm) of the servo motor 13.
Ff = Ar · (dx / dt) / Vp · 60 / Nmax (4)
Further, for example, when the displacement x <0, the actuator control device 4 determines the pressure receiving area Ah (m ² ) of the piston 11b on the second chamber R2 side, the cylinder speed dx / dt, and the displacement volume Vp (m ³ / The feedforward command value Ff is calculated based on the following equation (5) including rev) and the maximum rotational speed Nmax (rpm) of the servo motor 13.
Ff = Ah · (dx / dt) / Vp · 60 / Nmax (5)

 When the actuator control device 4 calculates the feedback command value Fb and the feedforward command value Ff by executing the above subroutine, the actuator control device 4 returns to the main routine of FIG. The final request command value F (= Fb + Ff) is calculated by adding the value Fb and the feedforward command value Ff. In order to calculate the request command value F, the feedforward command value Ff is dimensionless, and therefore the feedback command value Fb must also be dimensionless. Since the unit of the thrust deviation Δf of the feedback command value Fb is “kN”, the unit of the feedback gain G may be set so as to make this unit dimensionless.

 Then, the actuator control device 4 performs a motor command signal (that is, a generated thrust of the hydraulic cylinder 11) for causing the hydraulic cylinder 11 to generate the request command value F calculated in step S4 as the process of step S5 in the main routine. A motor command signal for matching with the thrust command value is generated and output to the motor driver 2. When the actuator control device 4 repeatedly performs the processing of the main routine as described above at a constant period, the thrust generated by the hydraulic cylinder 11 is maintained at the thrust command value.

 The change in thrust (pressure) generated by the hydraulic cylinder 11 is determined from the discharge flow rate (cylinder discharge flow rate) of the hydraulic cylinder 11 corresponding to the operation (speed) of the hydraulic cylinder 11 and the rotation state of the servo motor 13. It is determined by the balance with the discharge flow rate (pump discharge flow rate). That is, when the cylinder discharge flow rate> pump discharge flow rate, the cylinder generated thrust (pressure) increases, and when the cylinder discharge flow rate <pump discharge flow rate, the cylinder generated thrust (pressure) decreases, and the cylinder discharge flow rate = pump discharge In the case of flow rate, the cylinder generated thrust (pressure) is maintained at the current level, so the calculation output of the feedback control of the cylinder generated thrust is the motor rotation speed that generates the pump discharge flow rate equivalent to the cylinder discharge flow rate. It is desirable to use

 Therefore, the motor rotation speed command value that is the control calculation output is the motor rotation speed that estimates the cylinder discharge flow rate from the cylinder speed to the feedback control calculation output based on the cylinder thrust deviation and generates a pump discharge flow rate equivalent to the flow rate. The value is added. Further, since the optimum value of the feedback gain G differs depending on the displacement x of the hydraulic cylinder 11, by providing a function for setting the value according to the displacement x of the hydraulic cylinder 11, it is influenced by changes in the actuator displacement. And stable thrust control can be realized.

Of course, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the hybrid actuator 1 including the hydraulic cylinder 11, the hydraulic pump 12, and the servo motor 13 is illustrated. However, the hydraulic or pneumatic cylinder that operates with the pressure of fluid other than oil as the working fluid and the servo motor 13. It may be a hybrid system. Also, other types of motors may be used instead of the servo motor 13.
In the above-described embodiment, the case where the feedback gain is set based on the displacement of the hydraulic cylinder 11 is exemplified. However, based on the value required for the system, any value of the displacement, speed, or acceleration of the hydraulic cylinder 11 is used. Therefore, it is desirable to set the feedback gain based on at least one of the displacement, speed or acceleration of the hydraulic cylinder 11 according to the performance required for the system.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid actuator, 2 ... Motor driver, 3 ... Signal conversion and amplifier, 4 ... Actuator control apparatus, 11 ... Hydraulic cylinder, 12 ... Hydraulic pump, 13 ... Servo motor, 14 ... Shuttle valve, 15 ... Oil storage tank, 16 ... 1st pressure sensor, 17 ... 2nd pressure sensor, 18 ... Linear sensor, 11a ... Cylinder, 11b ... Piston, 11c ... Rod

Claims (3)

An actuator control device for controlling a hybrid actuator,
An actuator control apparatus characterized by controlling the thrust of the actuator by combining feedback control and feedforward control, and setting a feedback gain based on at least one of displacement, speed or acceleration of the actuator. When the actuator includes a hydraulic cylinder, a hydraulic pump and a servo motor,
Calculate the generated thrust of the hydraulic cylinder based on the pressure detection result of the hydraulic cylinder,
A feedback command value is calculated by multiplying the deviation between the generated thrust of the hydraulic cylinder and the thrust command value by the feedback gain,
Calculate a feedforward command value based on the speed of the hydraulic cylinder,
A value obtained by adding the feedback command value and the feedforward command value is calculated as a final request command value,
Outputting a motor command signal for causing the hydraulic cylinder to generate the required command value to the servo motor driver;
The actuator control apparatus according to claim 1. An actuator control method for controlling a hybrid actuator,
An actuator control method characterized by controlling the thrust of the actuator by combining feedback control and feedforward control, and setting a feedback gain based on at least one of displacement, speed, or acceleration of the actuator.

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