BRAKE CONTROL DEVICE AND BRAKE SYSTEM

Abstract

An object of the present invention is to provide a brake control device and a brake system capable of braking with a shortened braking response when switching from non-braking to braking. A brake control device 10 includes a command value calculation unit 4, which calculates an operating command value required to achieve a target thrust value by applying a contact force with which a brake pad 11a is pressed against a brake disc 11b. The command value calculation unit 4 comprises: a distance command calculation unit 43, which calculates a command value required for contact between the brake pad 11a and the brake disc 11b; and a thrust command calculation unit 40, which calculates a command value required to achieve the target thrust from a state in which the brake pad 11a and the brake disc 11b are in contact with each other.If the operating command value is calculated from a state in which the brake pad 11a and the brake disc 11b are separated, the command value calculation unit 4 calculates the operating command value by integrating the command value calculated by the distance command calculation unit 43 and the command value calculated by the thrust command calculation unit 40.

Description

Technical area

[0001] The present invention relates to a brake control device and a brake system that are attached to a vehicle, such as an automobile, and that brake the rotation of wheels. State of the art

[0002] Vehicles such as automobiles are equipped with a braking system that applies braking force to the wheels, depending on how hard the driver presses the brake pedal. Conventionally, many of these braking systems are hydraulic, but recently electric systems have become increasingly common.

[0003] An electric braking system can retract a brake piston, which is difficult with a hydraulic system. This allows for distance control, which maintains a desired gap between the brake pad and the brake disc, thus improving fuel efficiency by reducing brake pad drag. Furthermore, when the pedal is pressed, the braking force is regulated by the distance control system after contact with the brake pad, using a deformation sensor or similar device. For these brake control systems, improving safety and / or brake feel requires techniques to enhance brake response and accuracy. In this context, the techniques described in PTLs 1 to 3, related to distance control and subsequent brake force regulation, are relevant.

[0004] PTL 1 describes an electric braking device comprising: a brake rotor; a brake pad; an electric motor; a linear motion mechanism that converts the rotary motion of the electric motor into a linear motion and transmits the linear motion to the brake pad; and a controller that controls the electric motor. In the described configuration, the controller includes: a motor angular velocity control section that controls an angular velocity of the electric motor and a motor angular velocity limiting section that limits an angular velocity of the electric motor such that an angular velocity ωb of the electric motor in an idle state, controlled by the motor angular velocity control section, is limited when transitioning from a non-braking state, in which a gap is formed between the brake pad and the brake rotor, to a braking state.in which the distance is zero, and an angular velocity ωr of the electric motor in an idle state, which is controlled by the motor angular velocity control section when the state changes from the braking state to the non-braking state, |ωb| > |ωr|, so that it is possible to suppress the generation of operating noise and prevent a response delay of the brake.

[0005] Furthermore, PTL 2 discloses a configuration in which a control means for controlling an electric motor to cause a piston to generate a target thrust, by means of a thrust control based on the piston thrust detected by a thrust sensing means and a position control based on a motor rotational position detected by a position sensing means, changes a distribution of the control amounts of the thrust control and the position control according to the piston thrust detected by the thrust sensing means.

[0006] Furthermore, PTL 3 discloses a configuration in which a block position control unit, which moves a position of a brake block into a position in contact with a brake rotor, and a brake force control unit, which controls a force of pressing the brake block, are provided, and the brake block is first brought into contact with the brake rotor by a block gap in response to a command from the block position control unit, and then a pressing force of the brake block is controlled according to a brake force request command value by switching to a command from the brake force control unit during a braking operation. List of printed materials and patent literature PTL 1: JP 2015-48036 A PTL 2: JP 2003-202042 A PTL 3: JP 2001-239929 A Summary of the invention: Technical problem

[0007] In PTL 1, a lower motor speed is set when switching from braking to non-braking than when switching from non-braking to braking, thus reducing operating noise and minimizing driver inconvenience. Additionally, the movement time to a retracted position increases when the motor speed limit is set low, enabling a high-response braking action upon the next sudden pedal input. However, this does not improve control accuracy or responsiveness when transitioning from a state where the piston is held in the retracted position to the moment of braking.

[0008] Furthermore, in PTL 2, the distribution of thrust control and position control is modified according to a thrust sensor value and a thrust command value, allowing position control to compensate for insufficient thrust sensor resolution and enabling high-precision control, particularly in low thrust ranges. This improves control accuracy during braking, a problem in PTL 1. However, improved responsiveness is only expected once the brake pad and disc make contact from their initial position and generate the desired thrust.

[0009] On the other hand, in PTL 3, position control is performed from the distance position to the contact position between the block and the disk, and then the system switches to thrust control. This makes it possible to improve the response to the contact position between the block and the disk, thus avoiding the problem of PTL 2. However, in PTL 3, position control is completed immediately before the contact position between the block and the disk at the point of switching between position control and thrust control. Therefore, it is likely that the response will deteriorate due to the converging movement of the piston position.

[0010] Therefore, the present invention provides a brake control device and a brake system that are capable of braking with a shortened brake response when switching from non-braking to braking. Solution to the problem

[0011] To solve the above problems, a brake control device according to the present invention is a brake control device attached to a brake system comprising at least one piston which moves in a linear direction of motion by the rotation of an electric motor, a brake pad which is pressed against a brake disc by the movement of the piston, and a position sensing unit which detects a position of the piston and controls a movement of the piston, and which includes a command calculation unit which calculates an operating command value to bring a pressing force with which the brake pad is pressed against the brake disc to a target thrust value.The command calculation unit contains: a distance command calculation unit, which calculates a command value required for contact between the brake pad and the brake disc; and a thrust command calculation unit, which calculates a command value required to achieve a target thrust from a state in which the brake pad and brake disc are in contact. The command calculation unit calculates the operating command value by integrating the command value calculated by the distance command calculation unit and the command value calculated by the thrust command calculation unit, starting from a state in which the brake pad and brake disc are separated.

[0012] Furthermore, a braking system according to the present invention is a braking system comprising: a piston that moves in a linear direction of motion through the rotation of an electric motor; a brake pad that is pressed against a brake disc by the movement of the piston; a position sensing unit that detects the position of the piston; and a brake control device that controls the movement of the piston. The brake control device includes a command calculation unit that calculates an operating command value to cause the pressing force with which the brake pad is pressed against the brake disc to reach a target thrust value.The command calculation unit contains: a distance command calculation unit, which calculates a command value required for contact between the brake pad and the brake disc; and a thrust command calculation unit, which calculates a command value required to achieve a target thrust from a state in which the brake pad and brake disc are in contact. The command calculation unit calculates the operating command value by integrating the command value calculated by the distance command calculation unit and the command value calculated by the thrust command calculation unit, starting from a state in which the brake pad and brake disc are separated. Advantageous effects of the invention

[0013] According to the present invention, it is possible to provide the brake control device and the brake system with the shortened braking behavior when switching from non-braking to braking.

[0014] Other objects, configurations and effects not described above will emerge from the embodiments described below. Brief description of the drawings Fig. 1] Fig. Figure 1 is a schematic diagram of a braking system according to a first embodiment of the present invention. Fig. 2] Fig. 2 is a functional block diagram of an instruction value calculation unit, which is in Fig. 1 forms the brake control device shown. Fig. 3] Fig. Figure 3 is a flowchart illustrating a procedure for calculating command values. Fig. 4] Fig. Figure 4 is a conceptual diagram that illustrates a calculation method for a [missing information]. Fig. The thrust command calculation unit shown in section 2 is illustrated. Fig. 5] Fig. Figure 5 is a diagram illustrating a change over time of a piston velocity, a change over time of a piston position and a change over time of a block thrust in the braking system according to the first embodiment and a comparative example. Fig. 6] Fig. Figure 6 is a diagram illustrating a change in piston velocity over time in the braking system and a thrust feedback control method according to the first embodiment. Fig. 7] Fig. Figure 7 is a functional block diagram of an instruction value calculation unit of a second embodiment according to a further embodiment of the present invention. Fig. 8] Fig. Figure 8 is a functional block diagram of an instruction value calculation unit of a third embodiment according to a further embodiment of the present invention. Description of the embodiments

[0015] In the following, embodiments of the present invention are described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments, and various modifications and applications that fall within the technological concept of the present invention are also included in the scope of the present invention. [First embodiment]

[0016] Fig. Figure 1 is a schematic diagram of a braking system of a first embodiment according to an embodiment of the present invention and shows a configuration corresponding to an electric brake for one wheel of a plurality of wheels provided in a vehicle.

[0017] As in Fig. As shown in Figure 1, a braking system 1 mainly comprises a drive mechanism 2, a brake control device 10, a braking mechanism 11, and a mechanism for converting rotation into linear motion 12. The drive mechanism 2 comprises an electric motor 2a and a speed reducer 2b, and the brake control device 10 comprises a motor control unit 3 and a command value calculation unit 4. The braking mechanism 11 has a brake pad 11a and a brake disc 11b arranged so that they come into contact with each other and are separated from each other, and the mechanism for converting rotation / linear motion 12 is a rod-shaped element containing a piston 12a and a feed screw 12b.It should be noted that the motor control unit 3 and the instruction value calculation unit 4 are implemented, for example, by a processor such as a central processing unit (CPU) (not shown), a ROM that stores various programs, a RAM that temporarily stores data during a calculation process, and a storage device such as an external storage device. The processor, e.g., the CPU, reads and executes the various programs stored in the ROM and stores a calculation result, which is an execution result, in the RAM or in the external storage device.

[0018] In the Fig. In the brake system 1 shown in Figure 1, a rotating drive force generated by the electric motor 2a is decelerated by the speed reducer 2b. The decelerated rotating drive force is converted into a linear drive force via the feed screw 12b, and the brake pad 11a is pressed against the brake disc 11b by linearly driving the piston 12a, thereby exerting a braking force on the rotating brake disc 11b. The direction in which the piston 12a approaches the brake disc 11b and the opposite direction are defined as the positive direction and the negative direction, respectively.

[0019] During the braking process described above, the motor control unit 3, which forms the brake control device 10, controls the rotational speed and position of the electric motor 2a and sets the pressing force of the brake pad 11a. Furthermore, the brake control device 10 estimates the braking force of the brake pad 11a based on a thrust detected by a thrust sensor 31 installed in the rotational / linear motion conversion mechanism 12. Additionally, the brake control device 10 estimates the position of the brake pad 11a based on a rotational position detected by a position sensor 32 installed in the electric motor 2a. Note that the position sensor 32 can be attached to the piston 12a to directly detect the position of the piston 12a.

[0020] Here, a control signal line 21, a communication line 22, a communication line 23, and a main power line 26 are connected to the brake control device 10. Additionally, the internal engine control unit 3 and the command value calculation unit 4 are connected to each other via a communication line 24 and a communication line 25. A control command from a host control unit, such as a vehicle control ECU (not shown), is input to the brake control device 10 via the control signal line 21. Communication lines 22 and 23 communicate information other than the control command to the host control unit. Note that the host control unit and the brake control device 10 are separate devices here, but both can be configured as an integrated control unit.

[0021] Details of the command value calculation unit 4 are given below with reference to Fig. 2 described. Fig. 2 is a function block diagram of the command value calculation unit 4, which is in Fig. The brake control device 10 shown in Figure 1 forms the brake control device. As in Fig. As shown in Figure 2, the command value calculation unit 4 comprises a thrust command calculation unit 40, a distance command calculation unit 43, and an operating command calculation unit 44. Furthermore, the thrust command calculation unit 40 includes a thrust deviation calculation unit 41 and a position deviation calculation unit 42.

[0022] The instruction value processing unit 4 receives a signal from the motor control unit 3 via communication line 24 and outputs a signal to the motor control unit 3 via communication line 25. Note that the actual instruction value processing unit 4 comprises a CPU, a computing device such as a microcomputer, a main memory device such as semiconductor memory, an auxiliary memory device such as a hard disk, and hardware such as a communication device, and each in Fig. The function shown in Figure 2 is realized because the computing device executes a program stored in the memory device while referencing a database or similar recorded in the auxiliary memory device. A description follows, conveniently omitting such a known operation. <Schubbefehlsberechnungseinheit 40>

[0023] The thrust command calculation unit 40 calculates a piston position feed amount required to generate a thrust command value, based on a difference between a thrust command value transmitted by the host vehicle control ECU (not shown) and a thrust signal from the thrust sensor 31, and outputs a thrust command calculation value X1 to the operating command calculation unit 44. [Shear force deviation calculation unit 41]

[0024] The thrust deviation calculation unit 41 calculates a difference between a thrust signal from the thrust sensor 31, which is generated after the piston 12a is moved towards the brake disc 11b and the brake pads 11a and the brake disc 11b come into contact with each other, and the thrust command value transmitted by the host vehicle control ECU (not shown) and outputs a thrust deviation ΔF, which is the calculation result, to the position deviation calculation unit 42. [Position deviation calculation unit 42]

[0025] The position deviation calculation unit 42 converts the thrust deviation ΔF input by the shear deviation calculation unit 41 into a piston position deviation. An example of a procedure for converting the shear deviation ΔF into the piston position deviation is described here. Fig. Figure 4 is a conceptual diagram that illustrates a calculation method of the in Fig. The thrust command calculation unit 40 is illustrated in section 2. Fig. Figure 4 illustrates a stiffness characteristic of a brake caliper. The position deviation calculation unit 42 uses this stiffness characteristic of the brake caliper to perform a conversion into a piston position deviation X1, which corresponds to the thrust deviation ΔF (difference between a thrust command value Fcom and a thrust signal F from the thrust sensor 31) input by the thrust deviation calculation unit 41. Alternatively, the thrust deviation ΔF can be multiplied by a constant value as a fixed gain for the conversion, or a conversion to a rotary position of the electric motor 2a can be performed instead of the piston position. The point is that the piston 12a must be moved to a position in which a desired thrust is generated, making it possible to adjust the piston position until the thrust approaches a desired value. <Abstandsbefehlsberechnungseinheit 43>

[0026] The distance command calculation unit 43 calculates the distance information between the brake pad 11a and the brake disc 11b. For example, a position at which the brake pad 11a and the brake disc 11b come into contact and the thrust force begins to increase when the piston 12a is advanced in the positive direction is stored as the pad contact position. A distance position is defined as a position at which the brake pad 11a is moved in the negative direction by a predetermined amount, which is necessary to prevent slippage from the pad contact position. Any difference between the pad contact position and the distance position at this time is output to the operating command calculation unit 44 as the distance command calculation value X2. Meanwhile, the pad contact position can be a learned contact position as described above or a predefined contact position.The point is that the distance between the spacer position and the block contact position must be provided for accordingly. < Operating command calculation unit 44>

[0027] The operating command calculation unit 44 adds the thrust command calculation value X1 output by the thrust command calculation unit 40 and the distance command calculation value X2 output by the distance command calculation unit 43 to calculate an operating command calculation value X3. In other words, the operating command calculation unit 44 calculates the operating command value by integrating the command value calculated by the thrust command calculation unit 40 and the command value calculated by the distance command calculation unit 43. As a result, when the braking operation is performed from a non-braking state, the command value X3 is generated, taking into account the position information X2 (calculated value of the distance command) until the brake pad 11a comes into contact with the brake disc 11b, and the piston travel amount X1 (thrust command calculation value) required for excitation from the pad contact position.When operating with the command value X3 generated here, a desired thrust with a high response time can be achieved without any piston delay near the block contact position, which is a problem with PTL 3. Generally, the piston speed decreases when the thrust command is small, resulting in poor response to the block contact position in a brake control system that only includes thrust feedback. However, according to the present embodiment, the distance command calculation value X2 and the thrust command calculation value X1 are calculated separately, thus determining a piston speed to the block contact position or a response time independent of the magnitude of the thrust command.

[0028] The in Fig. The functional block of instruction value calculation unit 4 shown in section 2 is actually executed by software stored in the memory of a microcomputer. This calculation process is described below with reference to... Fig. 3 described. Fig. Figure 3 is a flowchart illustrating a command value calculation procedure. <<Schritt S10> >

[0029] In step S10, a host control unit, such as an ECU (not shown), determines whether a vehicle is currently in a braking state. This determination can be based on whether a driver depresses the brake pedal by a predetermined amount or more and whether a deceleration command value is zero or greater. If the vehicle is not in a braking state, the processing continues to its conclusion and waits for the next start time. Conversely, if the vehicle is in a braking state, the processing proceeds to the next step, S11. <<Schritt S11> >

[0030] In step S11, a thrust of the brake block 11a is detected by an output of the thrust sensor 31 installed in the rotation / linear motion conversion mechanism 12 via the communication line 24, and a rotational position of the electric motor 2a is detected by an output of the position sensor 32 installed in the electric motor 2a.<Schritt S12> >

[0031] In step S12, a piston position calculation unit (not shown) converts the rotational position of the electric motor 2a obtained in step S11 into a linear direction of motion according to a ratio between rotation and linear motion as in the following formula (1). Xp=θ×(L / ε)[mm]

[0032] Note that Xp is a piston position [mm], θ is a motor rotation position [rpm], L is a pitch [mm / revolution] of the feed spindle 12b and ε is a speed reduction ratio of the speed reducer 2b.

[0033] This information is stored in a temporary memory area of ​​RAM provided in a microcomputer and used for calculations performed in the subsequent control steps. Note that it is also possible to acquire information other than this, according to brake system 1. <<Schritt S13> >

[0034] In step S13, the thrust command calculation unit 40 calculates the thrust deviation ΔF between the thrust command value Fcom received from the control signal line 21 via the communication line 24 and the thrust signal F determined by the thrust sensor 31 in step S11 using the following formula (2). ΔF=Fcom−F[N]

[0035] Additionally, the stiffness characteristic of the brake caliper shown in Figure 4 is used here as described above to convert the ΔF obtained by formula (2) into a positional deviation. Now ΔF is in Fig. 4 is calculated by formula (2), and the piston feed amount required to generate the desired thrust Fcom at this time is X1 (thrust command calculation value) shown on the horizontal axis. <<Schritt S14> >

[0036] In step S14, the distance command calculation unit 43 calculates the difference X2 (distance command calculation value) between the detected or estimated block contact position Xp and a piston position Xc that maintains a distance in the non-braking state, using the following formula (3). X2=Xp−Xc[m] <<Schritt S15> >

[0037] In step S15, the operating command calculation unit 44 adds X1 (thrust command calculation value) and X2 (distance command calculation value) calculated in steps S13 and S14 to calculate the operating command value of the piston position using the following formula (4). X3=X1+X2[m] <<Schritt S16> >

[0038] In step S16, after piston 12a has operated for one control cycle with the operating command value X3 calculated in step S15, the thrust command calculation unit 40 determines whether the braking force has reached the thrust command value Fcom. If reaching and convergence are detected, piston 12a stops operating and moves to the end of its cycle. However, if the driver changes the amount of brake pedal actuation during braking, the loop from step S11 to step S16 is executed accordingly at any given time, and a piston position operates to fulfill the desired thrust.

[0039] The effect of the present invention is in Fig. 5 shown. Fig. Figure 5 is a diagram illustrating the temporal changes of piston velocity, piston position, and block thrust in brake system 1 according to the present embodiment and a comparative example. The comparative example presented here is a case using the technique described in PTL 3. In the present embodiment, the position command X2 (calculated value of the distance command) from the distance position to the block contact position and the piston position thrust amount X1 (thrust command calculation value) that satisfies the thrust command value are added to obtain the control command X3 (operating command calculation value) through the above calculation. Therefore, it is not necessary to switch the control, and the piston velocity does not decrease near the pad contact position, as shown in the upper part of Figure 5. Fig. The temporal change in piston speed shown in Figure 5 illustrates this. Furthermore, the electric motor 2a is gently moved into a position where a desired thrust is generated, as can be seen from the temporal change in the piston position in the middle part of Figure 5. Fig. 5 is evident. Furthermore, the responsiveness can be improved, as shown in the lower part of Fig. Figure 5 shows the temporal change in the pillow thrust.

[0040] Here, a proportional-integral control (PI control) by feedback of a thrust sensor value or similar is conceivable as a method for smooth driving without switching the control as in the present invention. Fig. Figure 6 illustrates a change in piston velocity over time in the braking system and a method for thrust force control according to the present embodiment. The upper diagram of Fig. Figure 6 illustrates the change in piston speed over time in the brake system 1 of the present embodiment, and the lower diagram of Fig. Figure 6 illustrates the change in piston speed over time in the thrust feedback control method. As shown in the diagram above. Fig. As shown in Figure 6, the piston speed at the block contact position or reaction time is determined independently of the magnitude of the thrust command (at the time of a high thrust command and at the time of a low thrust command) according to the braking system 1 of the present embodiment. On the other hand, as shown in the lower diagram of Fig. Figure 6 shows the piston velocity as a function of the command size in the PI control of the thrust feedback control procedure. Therefore, the piston velocity decreases, and the response becomes poor at low thrust commands. Increasing the gain in the PI control of the thrust feedback control can prevent the velocity decrease, but this results in overshoot.

[0041] As described above, it is possible to provide the brake control device and the brake-capable braking system with the shortened braking behavior when switching from non-braking to braking according to the present embodiment.

[0042] Furthermore, the safety and feel of the brake can be improved according to the present embodiment. [Second embodiment]

[0043] Fig. Figure 7 is a functional block diagram of an instruction value calculation unit of a second embodiment according to a further embodiment of the present invention. The present embodiment differs from the first embodiment in that an instruction value calculation unit 4a further includes a velocity instruction calculation unit 45. Other configurations are the same as in the first embodiment, the same components as in the first embodiment are identified by the same reference numerals, and the description that overlaps with the first embodiment is omitted below.

[0044] As in Fig. As shown in Figure 7, the command value calculation unit 4a according to the present embodiment includes, in addition to the thrust command calculation unit 40 with the thrust deviation calculation unit 41 and the position deviation calculation unit 42, the distance command calculation unit 43 and the operating command calculation unit 44, the velocity command calculation unit 45.

[0045] The speed command calculation unit 45 generates a speed command to follow a position command value received from the operating command calculation unit 44. In practice, it is conceivable to take the difference between the position command value and the current piston position and multiply the difference by a gain to obtain the speed command. Alternatively, the speed command can also be calculated from an equation of motion, taking into account the inertia of a push button. In the present embodiment, the operating command calculation value X3 is output as the speed command to the motor control unit 3 using the above calculation.

[0046] The same effect as in the first embodiment described above can also be achieved in the present embodiment. [Third embodiment]

[0047] Fig. Figure 8 is a functional block diagram of an instruction value calculation unit of a third embodiment according to a further embodiment of the present invention. The present embodiment differs from the first embodiment in that an instruction value calculation unit 4b further comprises the velocity instruction calculation unit 45 and a torque instruction calculation unit 46. Other configurations are the same as in the first embodiment, the same components as in the first embodiment are designated by the same reference numerals, and the description that overlaps with the first embodiment is omitted below.

[0048] As in Fig.As shown in Figure 8, the command value calculation unit 4b according to the present embodiment includes, in addition to the thrust command calculation unit 40 with the thrust deviation calculation unit 41 and the position deviation calculation unit 42, the distance command calculation unit 43 and the operating command calculation unit 44, the velocity command calculation unit 45 and the torque command calculation unit 46.

[0049] The torque command calculation unit 46 generates a torque command or a current / voltage command to follow a velocity command value received from the velocity command calculation unit 45. In practice, it is conceivable to take the difference between the velocity command value and a current piston velocity and multiply the difference by a gain to obtain the torque command. Alternatively, the velocity command value can also be calculated from an equation of motion, taking into account the inertia of a probe. The above calculation outputs the operating command calculation value X3 as a torque command or current / voltage command to the motor control unit 3 in the present embodiment.

[0050] As described above, it is possible to achieve the same effect as in the first embodiment described above by sending the torque or current / voltage command to the motor control unit in the present embodiment. List of reference numbers 1. Braking system 2 Drive mechanism 2a Electric motor 2b Speed ​​reducer 3 Engine control unit 4, 4a, 4b Command value calculation unit 10 Brake control device 11. Braking mechanism 11a Brake pad 11b Brake disc 12 Rotation / linear motion conversion mechanism 12a Piston 12b Feed spindle 21 Control signal line 22, 23, 24, 25 Communications line 26 Main power line 31 Thrust sensor 32 Position sensor 40 Thrust command calculation unit 41 Unit of calculation for shear deviation 42 Position deviation Calculation unit 43 Distance command calculation unit 44 Operating command calculation unit 45 Speed ​​command calculation unit 46 Torque command calculation unit

Claims

[1] Brake control device attached to a brake system (1) comprising at least one piston (12a) which moves in a linear direction by the rotation of an electric motor (2a), a brake pad (11a) which is pressed against a brake disc (11b) by the movement of the piston (12a), and a position sensing unit (32) which detects a position of the piston (12a) and controls a movement of the piston (12a), with a command calculation unit that calculates an operating command value to bring a pressing force with which the brake pad (11a) is pressed against the brake disc (11b) to a target shear value, where the command calculation unit contains: a distance command calculation unit (43) that calculates a command value required for contact between the brake pad (11a) and the brake disc (11b); and a thrust command calculation unit (40) that calculates a command value required to achieve a target thrust from a state in which the brake pad (11a) and the brake disc (11b) are in contact with each other, and The command calculation unit calculates the operating command value by integrating the command value calculated by the distance command calculation unit (43) and the command value calculated by the thrust command calculation unit (40) when calculating the operating command value from a state in which the brake pad (11a) and the brake disc (11b) are separated from each other. [2] Brake control device according to claim 1, wherein the command calculation unit contains an operating command calculation unit (44), and The operating command calculation unit (44) integrates the command value calculated by the distance command calculation unit (43) and the command value calculated by the thrust command calculation unit (40) and outputs a position command with respect to a feed amount of the piston (12a) or the electric motor (2a) as an operating command value. [3] Brake control device according to claim 2, wherein the command calculation unit also includes a velocity command calculation unit (45), The velocity command calculation unit (45) outputs a velocity command regarding the feed rate of the piston (12a) or the electric motor (2a) as an operating command value based on an output from the operating command calculation unit (44). [4] Brake control device according to claim 3, wherein the command calculation unit also includes a torque command calculation unit (46), The torque command calculation unit (46) outputs a torque command regarding the feed rate of the piston (12a) or the electric motor (2a) as an operating command value based on an output from the velocity command calculation unit (45). [5] Brake control device according to claim 1, wherein the operating command value causes a piston speed to decrease monotonically after contact between the brake pad (11a) and the brake disc (11b), and a piston speed is determined up to a position in which the brake pad (11a) and the brake disc (11b) come into contact with each other, without dependence on a magnitude of the target thrust. [6] Brake control device according to claim 2, wherein the operating command calculation unit (44) receives an operating command value of a piston position by adding the command value calculated by the distance command calculation unit (43) and the command value calculated by the thrust command calculation unit (40), and outputs the resulting operating command value of the piston position as the operating command value. [7] Braking system (1), with: a piston (12a) which moves in a linear direction of motion through the rotation of an electric motor (2a); a brake pad (11a) which is pressed against a brake disc (11b) by the movement of the piston (12a); a position sensing unit (32) that detects the position of the piston (12a); and a brake control device that controls a movement of the piston (12a), wherein the brake control device according to claim 1 is used as the brake control device.

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