Patent Description:
Known cleaning systems for aircraft include a cleaning system disclosed in patent document <CIT>. The cleaning system for an engine mounted to a blade of an aircraft, which is disclosed in document <CIT>, is configured to guide cleaning fluid to the engine while the engine is controlled to rotate at a predetermined rotational speed. The rotational speed of the engine is controlled to be substantially <NUM> percent of a predetermined reference rotational speed used during flight of the aircraft.

Document <CIT> discloses a control apparatus according to the preamble of claim <NUM>, and describes in particular a system for washing a gas turbine engine. The system comprises a spray device including at least one nozzles adapted to inject liquid into an inlet of said engine during a washing operation; a wash unit adapted to distribute said liquid to said spray device; and a positioning device adapted to move said spray device in three dimensions, thereby enabling a positioning of said spray device in a washing operation position in said three dimensions relative said engine inlet without any contact between the spray device and the engine. The invention further relates to a vehicle for making the inventive system mobile and to a mobile system for serving a gas turbine engine comprising a mobile vehicle carrying the washing system and a liquid collecting unit comprising a collecting device adapted to collect waste wash liquid emanating from the engine during a washing operation of the engine.

Document <CIT> discloses a system for on-wing engine washing and water reclamation is provided. The system has at least one spray device for introducing a cleaning liquid containing at least water into the engine while the engine is being operated, and an effluent trough for collecting the cleaning liquid from an exit end or underneath side of the engine. In an example, a source of the cleaning liquid and the effluent trough are located on a mobile unit. Further, a treatment system for treating the collected cleaning liquid is also located on a mobile unit.

Document <CIT> discloses a device for a motor vehicle for holding an unmanned aerial vehicle in an inactive state of the unmanned aerial vehicle on the motor vehicle, the aerial vehicle being movable independently of the motor vehicle in an active state. The device has a housing device with a housing cover, wherein an interior space of the housing device forms an aircraft storage space for the unmanned aircraft which is delimited from an ambient region of the motor vehicle. The interior space has a predetermined landing area for the unmanned aircraft to land independently.

The cleaning system disclosed in document <CIT>, which operates with the lower rotational speed of the engine, may not address noise due to the rotation of the engine.

Let us assume that the cleaning system disclosed in the document <CIT> is used to clean a rotor of an electric aircraft; the rotor is rotated by a motor of the electric aircraft. In this assumption, noise due to rotation of the motor may become a major issue. This may be because it is assumed that a place where such an electric aircraft is stored is located near houses and/or commercial facilities.

From this viewpoint, users desire a technology that can clean a rotor of an electric aircraft while preventing an excessive increase in noise.

This is achieved by a control apparatus according to claim <NUM>. Advantageous further developments are as set forth in the dependent claims.

According to the present invention, a control apparatus controls, in the cleaning motor-control mode, the drive motor such that the rotational frequency of the drive motor is lower than the predetermined human-audible frequency range, making it possible to clean the rotor of the electrical aircraft while preventing an excessive increase in noise due to rotation of the drive motor.

The above object, other objects, characteristics, and advantageous benefits of the present disclosure will become apparent from the following description with reference to the accompanying drawings in which:.

Electric drive systems (EDS) <NUM>, to each of which a control apparatus <NUM> according to an exemplary embodiment of the present invention has been applied, are installed in an electric vertical take-off and landing aircraft (eVTOL) <NUM> illustrated in <FIG> and <FIG>. The eVTOL <NUM> includes a plurality of rotors, i.e., rotor fans, <NUM>, and each EDS <NUM> is provided for the corresponding rotor <NUM>, and is configured to control the corresponding rotor <NUM>.

The eVTOL <NUM> is configured as an electrically-driven uncrewed aircraft that can land and take off vertically. The eVTOL <NUM> includes, in addition to the EDSs <NUM>, an airframe <NUM>, a battery <NUM>, a converter <NUM>, a distributor <NUM>, an aircraft control apparatus <NUM>, an aircraft communication unit <NUM>, and an informing unit <NUM>; these components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are illustrated in <FIG>.

The aircraft control apparatus <NUM> is configured as a computer including an unillustrated central processing unit (CPU) and an aircraft storage <NUM>. The aircraft storage <NUM>, which includes a read only memory (ROM) and a random-access memory (RAM), stores one or more control programs. The CPU is configured to run the one or more control programs stored in the aircraft storage <NUM> to accordingly serve as an aircraft controller <NUM> that controls overall operations of the eVTOL <NUM>.

The eVTOL <NUM> includes, as its overall operations, vertical landing and taking-off operations and a flying operation. The eVTOL <NUM> can be configured to perform the vertical landing and taking-off operations and flying operation in accordance with information indicative of a previously scheduled air-route or instructions sent from an external controller <NUM> included in an external apparatus <NUM> described later.

The aircraft controller <NUM> is configured to individually control a rotational angle of each rotor <NUM>.

Additionally, the aircraft controller <NUM> is configured to instruct the control apparatus <NUM> to operate in a selected one of flying motor-control mode, a cleaning motor-control mode and a stop mode for controlling a drive motor <NUM> of a selected EDS <NUM>.

The flying mode represents a mode of controlling each drive motor <NUM> to thereby cause the eVTOL <NUM> to take a flight set forth above.

The cleaning motor-control mode represents a mode of causing the drive motor <NUM> of the selected EDS <NUM> to clean the rotor <NUM> of the selected EDS <NUM>.

The stop mode represents a mode of stopping the drive motor <NUM> of the selected EDS <NUM>.

The eVTOL <NUM> of the exemplary embodiment includes, as illustrated in <FIG>, four rotors <NUM> and corresponding four EDSs <NUM>. For the sake of simply illustration, <FIG> illustrates typical two of the four rotors <NUM> and corresponding typical two of the four EDSs <NUM>, and <FIG> illustrates a typical one of the four rotors <NUM> and a corresponding typical one of the four EDSs <NUM>.

The airframe <NUM> constitutes the remaining portion of the eVTOL <NUM> from which the four rotors <NUM> and the four EDSs <NUM> have been removed. The airframe <NUM> is comprised of an airframe body <NUM>, a support strut <NUM>, four first support members <NUM>, and four second support members <NUM>.

The airframe body <NUM> constitutes the fuselage of the eVTOL <NUM>. The eVTOL <NUM> has a center of gravity CM and a body axis AX, and the airframe body <NUM> has a bilaterally symmetrical structure with respect to the body axis AX. The body axis AX of the eVTOL <NUM> according to the exemplary embodiment is defined as an axis that passes through the center of gravity CM and extends along a predetermined front-back direction of the eVTOL <NUM>. The center of gravity CM of the eVTOL <NUM> is defined as the center of gravity of the eVTOL <NUM> with empty weight, such as no cargo.

The eVTOL <NUM> includes an acceleration sensor <NUM> mounted to the airframe <NUM>. The acceleration sensor <NUM> is configured as a three-axis acceleration sensor, and measures a degree of tilt of the eVTOL <NUM> with respect to each axis and/or vibrations related to the eVTOL <NUM>. The measurement results by the acceleration sensor <NUM> are outputted therefrom to the aircraft control apparatus <NUM>.

The support strut <NUM> has a substantially pole-shaped outline, and is secured to the top of the airframe body <NUM>. The support strut <NUM> extends vertically with the eVTOL <NUM> being stopped on the ground. The support strut <NUM> according to the exemplary embodiment is arranged to overlap the center of gravity CM of the eVTOL <NUM> when viewed in the vertical direction. The support strut <NUM> has an upper end, and each of the four first support members <NUM> has opposing first and second ends. The first end of each first support member <NUM> is individually secured to the upper end of the support strut <NUM>.

Each of the four first support members <NUM> has a substantially rodlike outline. The first support members <NUM> are arranged circumferentially at regular intervals while respectively extending radially along a vertical plane perpendicular to the vertical direction. To the second end of each first support member <NUM>, which is located farther from the support strut <NUM> than the first end is, the corresponding rotor <NUM> and the corresponding EDS <NUM> are mounted.

Each of the four second support members <NUM> has a substantially rodlike outline, and joins the respective second ends of a corresponding pair of adjacent first support members <NUM>. For the sake of simplifying illustration, <FIG> illustrates each second support member <NUM> as a straight line.

Each of the four rotors <NUM> is, as illustrated in <FIG>, is mounted to the first end of the corresponding first support member <NUM>, and is also mounted to ends of corresponding adjacent second support members <NUM>; the ends of the corresponding adjacent second support members <NUM> are joined to the first end of the corresponding first support member <NUM>.

The four rotor <NUM> include two front rotors 30a and two rear rotors 30b. The front rotors 30a are located forward of the center of gravity CM of the eVTOL <NUM>, and the rear rotors 30b are located to the rear of the center of gravity CM of the eVTOL <NUM>.

The four rotors <NUM> serve as both lifting rotors for lifting the airframe <NUM>, and cruising rotors for causing the airframe <NUM> to cruise. Specifically, controlling all the four rotors <NUM> to have a predetermined rotational speed enables the four rotors <NUM> to serve as lifting rotors. Controlling the rotational speed of the front rotors 30a and that of the rear rotors 30b to be different from each other enables the four rotors <NUM> to serve as cruising rotors.

Each rotor <NUM> has a rotatory shaft, and is individually controlled to rotate together with the corresponding rotary shaft.

The eVTOL <NUM> includes a rotational speed sensor <NUM> and a torque sensor <NUM> provided for each rotor <NUM>. The rotational speed sensor <NUM> provided for each rotor <NUM> is configured to measure the rotational speed of the corresponding rotor <NUM>. The torque sensor <NUM> provided for each rotor <NUM> is configured to measure rotating torque of the corresponding rotor <NUM>. The measurement results by each rotational speed sensor <NUM> are outputted therefrom to the aircraft control apparatus <NUM>, and the measurement results by each torque sensor <NUM> are outputted therefrom to the aircraft control apparatus <NUM>. Each rotor <NUM> is connected to the corresponding EDS <NUM>.

Each EDS <NUM> connected to the corresponding rotor <NUM> is configured as an electrical drive system for rotatably driving the corresponding rotor <NUM>. That is, each EDS <NUM> is configured to rotatably drive the corresponding rotor <NUM>.

Each EDS <NUM> includes, as illustrated in <FIG>, a driver <NUM>, a drive motor <NUM>, a gearbox <NUM>, a rotational speed sensor <NUM>, a current sensor <NUM>, a voltage sensor <NUM>, a torque sensor <NUM>, and the control apparatus <NUM> described above.

The driver <NUM> is configured as an electronic device comprised of an unillustrated inverter and a controller for controlling the inverter. The inverter is comprised of power switching devices, such as insulated gate bipolar transistors (IGBTs) and/or metal-oxide-semiconductor field-effect transistors (MOSFETs). The inverter is configured to supply, to the drive motor <NUM>, a drive voltage that is determined based on a duty factor; the duty factor is specified by a control signal supplied from the controller. The controller of the driver <NUM> is electrically connected to the control apparatus <NUM>, and is configured to supply the control signal to the inverter based on an instruction supplied from the control apparatus <NUM>.

The drive motor <NUM> is comprised of, for example, a brushless motor according to the exemplary embodiment. The drive motor <NUM> is configured to output, to the gearbox <NUM>, rotating motion in accordance with the drive voltage and a drive current supplied from the inverter of the driver <NUM>. The drive motor <NUM> can be comprised of any motor, such as an induction motor or a reluctance motor in place of the brushless motor.

The gearbox <NUM> physically joins the drive motor <NUM> and the rotor <NUM> to each other. Specifically, the gearbox <NUM>, which is comprised of a plurality of gears, is configured to reduce the rotating motion supplied from the drive motor <NUM> to accordingly transfer the reduced rotating motion to the rotor <NUM>. The gearbox <NUM> can be omitted, so that the rotary shaft of the rotor <NUM> can be directly coupled to the drive motor <NUM>.

The rotational speed sensor <NUM> and the torque sensor <NUM> are provided for the drive motor <NUM>. The rotational speed sensor <NUM> is configured to measure the rotational speed of the drive motor <NUM>. The torque sensor <NUM> is configured to measure rotating torque generated by the drive motor <NUM>.

The current sensor <NUM> and the voltage sensor <NUM> are arranged between the driver <NUM> and the drive motor <NUM>. The current sensor <NUM> is configured to measure the drive current supplied from the driver <NUM> to the drive motor <NUM>, and the voltage sensor <NUM> is configured to measure the drive voltage supplied from the driver <NUM> to the drive motor <NUM>.

The measurement results by each of the sensors <NUM> to <NUM> are outputted therefrom to the control apparatus <NUM> through the driver <NUM>.

The control apparatus <NUM> provided for each EDS <NUM> is configured as a computer comprised of a CPU 19a, a storage 19b, an input/output (I/O) interface 19c.

The storage 19b stores one or more control programs. The CPU 19a is configured to run the one or more control programs stored in the storage 19b to function as a drive controller <NUM>, a measurement-result retrieving unit <NUM>, a normality determiner <NUM>, and a cleaning instructor <NUM>.

The drive controller <NUM> is configured to send, to the driver <NUM>, control instructions based on commanded values sent from the aircraft control apparatus <NUM> to accordingly rotatably drive the corresponding rotor <NUM>. The commanded values include, for example, a commanded rotational speed for the drive motor <NUM> in each of motor-control modes; the motor-control modes include a flying motor-control mode and a cleaning motor-control mode.

Specifically, the drive controller <NUM> instructs, based on the commanded rotational speed for the drive motor <NUM> in the cleaning motor-control mode, the driver <NUM> to rotate the drive motor <NUM> at a controlled rotational speed whose equivalent rotational frequency that is lower than a predetermined human-audible frequency range. For example, the drive controller <NUM> instructs the driver <NUM> to rotate the drive motor <NUM> at a controlled rotational speed whose equivalent rotational frequency is lower than a predetermined human-audible frequency range. According to the invention, the drive controller <NUM> controls, through the driver <NUM>, the drive motor <NUM> such that the frequency of rotation of the drive motor <NUM> is lower than <NUM>/A Hz where A represents a positive integer indicative of the number of blades of the rotor <NUM>.

The measurement-result retrieving unit <NUM> is configured to retrieve the measurement results including.

The normality determiner <NUM> is configured to determine, based on the measurement results retrieved by the measurement-result retrieving unit <NUM>, whether there is an abnormal situation in the eVTOL <NUM>. How the normality determiner <NUM> determines whether there is an abnormal situation in the eVTOL <NUM> will be described later.

The cleaning instructor <NUM> is configured to instruct cleaning equipment <NUM> illustrated in <FIG> and <FIG> to perform a cleaning task for cleaning the rotors <NUM> in the cleaning motor-control mode.

The cleaning instructor <NUM> is additionally configured to instruct the cleaning equipment <NUM> to stop the cleaning routine when it is determined that there is an abnormal situation in the eVTOL <NUM> during controlling of the drive motor <NUM> in the cleaning motor-control mode.

The cleaning equipment <NUM> of the exemplary embodiment is comprised of, as illustrated in <FIG>, a first pole member 200a and a second pole member 200b. The first pole member 200a is located on the ground to extend in perpendicular to the ground. The second pole member 200b extends horizontally from the extending end of the first pole member 200a. Specifically, the first and second pole members 200a and 200b are integrated with each other to have a substantially L shape. The first pole member 200a is configured such that its height relative to the ground is adjustable.

The cleaning equipment <NUM> includes, as illustrated in <FIG>, a equipment controller <NUM> and an equipment communication unit <NUM>. The equipment controller <NUM> is configured to perform control of the cleaning equipment <NUM>. Specifically, the equipment controller <NUM> performs control of at least the cleaning equipment <NUM> for spraying cleaning fluid, performing cleaning of any object using one or more brushes, and/or drying the cleaned object. <FIG> for example illustrates that the cleaning equipment <NUM> is spraying cleaning fluid to the eVTOL <NUM>.

The equipment communication unit <NUM> has a function of performing wireless communications with any device. For example, the equipment communication unit <NUM> can communicate with the aircraft communication unit <NUM>. As the wireless communications, the equipment communication unit <NUM> can use (i) commercial very high frequency (VHF) telecommunications, (ii) telecommunications, such as fourth-generation technology standard telecommunications (<NUM>) or fifth-generation technology standard telecommunications (<NUM>), provided by telecommunication cooperations, and/or (iii) wireless LAN communications in accordance with, for example, the IEEE <NUM>,<NUM> communications standard. The equipment communication unit <NUM> can use wired communications in accordance with the universal serial bus (USB) standard or the IEEE <NUM> communications standard.

The cleaning equipment <NUM> is configured to execute cleaning of at least one of the rotors <NUM> in accordance with a cleaning program previously stored in the storage 19b. The cleaning program includes, for example, (i) a cleaning-fluid spraying phase, (ii) a brushing phase, and (iii) a drying phase. For example, execution time setting for each of the cleaning-fluid spraying phase, brushing phase, and drying phase can be inputted from the external apparatus <NUM>.

As the external apparatus <NUM>, can be used a management/control computer for determining the execution time setting for each of the cleaning-fluid spraying phase, brushing phase, and drying phase. As such a management/control computer, can be used a server arranged in, for example, an air-traffic control room or a personal computer brought into any place in the eVTOL <NUM> by a maintenance worker who performs maintenance, checking, and cleaning of the eVTOL <NUM>.

In accordance with the cleaning-fluid spraying phase of the cleaning program, the cleaning equipment <NUM> sprays cleaning fluid from a predetermined portion of the existing end of the second pole member 200b to a selected rotor <NUM>. Because the height of the first pole member 200a of the cleaning equipment <NUM> is adjustable, the height of the predetermined portion of the second pole member 200b can be adjusted to tailor the height of the selected rotor <NUM> located on the ground. The cleaning equipment <NUM> of the exemplary embodiment uses water as the cleaning fluid, but can use any type of cleaning chemicals in place of water.

In accordance with the brushing phase of the cleaning program, the height of the second pole member 200b of the cleaning equipment <NUM> is controlled so that one or more unillustrated brushes mounted to a surface of the existing end of the second pole member 200b, which faces the selected rotor <NUM>, move. Thie results in the one or more brushes are fixedly positioned to abut onto the selected rotor <NUM>. While the one or more brushes abut onto the selected rotor <NUM>, the selected rotor <NUM> is controlled to rotate, so that the one or more brushes clean the selected rotor <NUM>.

In accordance with the drying phase of the cleaning program, the selected rotor <NUM> is controlled to rotate at a predetermined rotational speed that is higher than that used in the brushing phase or the cleaning-fluid spraying phase. This rotation of the selected rotor <NUM> removes droplets of water and dirt attached to the selected rotor <NUM> from the selected rotor <NUM>.

The storage 19b, which includes a ROM and a RAM, stores one or more control programs and the cleaning program. The storage 19b is additionally configured to store the measurement results sent from the sensors set forth above.

The I/O interface 19c is configured to enable the control apparatus <NUM> to communicate with external devices to thereby input and/or output various settings and/or values. The I/O interface 19c is configured to output instructions sent from instructions sent from the cleaning instructor <NUM> using wire communications or wireless communications to the cleaning equipment <NUM> through the aircraft communication unit <NUM>.

The battery <NUM> is comprised of a lithium-ion battery, and serves as one power supply source in the eVTOL <NUM>. The battery <NUM> is configured to mainly supply electrical power to the driver <NUM> included in each EDS <NUM> to accordingly drive, through the driver <NUM>, the drive motor <NUM> of each EDS <NUM>. The battery <NUM> can be comprised of any secondary battery, such as a nickel-metal-hydride battery in place of the lithium-ion battery. The eVTOL <NUM> can include, in addition to or in place of the battery <NUM>, any power supply source, such as a fuel battery and/or a power generator.

The converter <NUM>, which is connected to the battery <NUM>, is configured to step down a voltage across the battery <NUM> to accordingly supply the stepped-down voltage to unillustrated auxiliary devices and the aircraft control apparatus <NUM>.

The distributor <NUM> is configured to distribute the voltage across the battery <NUM> to the driver <NUM> of each EDS <NUM>.

The external apparatus <NUM> includes the external controller <NUM> set forth above and an external communication unit <NUM>.

The aircraft communication unit <NUM> has a function of performing wireless communications with any device. For example, the aircraft communication unit <NUM> enables each EDS <NUM> and the external communication unit <NUM> of the external apparatus <NUM> to communicate various information with each other, and enables each EDS <NUM> and the cleaning equipment <NUM> to communicate various information with each other. The aircraft communication unit <NUM> can communicate with the aircraft communication unit <NUM>. As the wireless communications, the aircraft communication unit <NUM> can use (i) commercial very high frequency (VHF) telecommunications, (ii) telecommunications, such as fourth-generation technology standard telecommunications (<NUM>) or fifth-generation technology standard telecommunications (<NUM>), provided by telecommunication cooperations, and/or (iii) wireless LAN communications in accordance with, for example, the IEEE <NUM>,<NUM> communications standard. The equipment communication unit <NUM> can use wired communications in accordance with the universal serial bus (USB) standard or the IEEE <NUM> communications standard.

The cleaning program according to the exemplary embodiment can serve as a motor-control program for cleaning recited in claims described later.

The CPU 19a serves as the cleaning instructor <NUM> to instruct the cleaning equipment <NUM> to perform cleaning in accordance with the cleaning program previously stored in the storage 19b, so that the CPU 19a and/or the cleaning equipment <NUM> start execution of a rotor cleaning routine, which is illustrated in <FIG>, that cleans a selected rotor <NUM> of the eVTOL <NUM>. Specifically, the CPU 19a and/or the cleaning equipment <NUM> execute, as the rotor cleaning routine, the cleaning-fluid spraying phase, the brushing phase, and the drying phase while the eVTOL <NUM> is stopped on the ground.

In step S10 of the rotor cleaning routine, the CPU 19a receives the execution time setting for the cleaning-fluid spraying phase determined and sent from the external apparatus <NUM>. Next, the CPU 19a serves as the drive controller <NUM> to instruct the driver <NUM> to rotate the selected rotor <NUM> and accelerate the rotational speed of the selected rotor <NUM> in step S12. After the operation in step S12, the cleaning equipment <NUM> is controlled to spray water as an example of cleaning fluid to the rotating rotor <NUM>. While the rotational speed of the selected rotor <NUM> is accelerating, centrifugal force induced by the rotating selected rotor <NUM> enables the sprayed water to reach every part of the selected rotor <NUM> up to the outer periphery thereof.

Next, the CPU 19a serves as the measurement-result retrieving unit <NUM> to retrieve, from the rotational speed sensor <NUM>, the rotational speed of the drive motor <NUM> as a measurement result by the rotational speed sensor <NUM> in step S14. Then, in step S14, the CPU 19a serves as the drive controller <NUM> to determine whether the rotational speed of the drive motor <NUM> measured by the rotational speed sensor <NUM> has reached a predetermined target rotational speed used for cleaning-fluid spraying.

In response to determination that the rotational speed of the drive motor <NUM> has not reached the predetermined target rotational speed (NO in step S14), the rotor cleaning routine returns to the operation in step S12.

Otherwise, in response to determination that the rotational speed of the drive motor <NUM> has reached the predetermined target rotational speed (YES in step S14), the CPU 19a serves as the drive controller <NUM> to instruct the driver <NUM> to perform a normal rotating operation that rotates the drive motor <NUM> while maintaining the rotational speed of the drive motor <NUM> substantially at the target rotational speed in step S16.

Next, the CPU 19a serves as the drive controller <NUM> to determine whether a counted execution time of the cleaning-fluid spraying phase has reached the execution time setting for the cleaning-fluid spraying phase in step S18. In response to determination that the counted execution time of the cleaning-fluid spraying phase has not reached the execution time setting for the cleaning-fluid spraying phase (NO in step S18), the rotor cleaning routine returns to the operation in step S16. Otherwise, in response to determination that the counted execution time of the cleaning-fluid spraying phase has reached the execution time setting for the cleaning-fluid spraying phase (YES in step S18), the CPU 19a serves as the drive controller <NUM> to instruct the driver <NUM> to reduce the rotational speed of the drive motor <NUM> in step S20.

Next, the CPU 19a serves as the drive controller <NUM> to determine whether the rotational speed of the drive motor <NUM> has reached zero in step S22. In response to determination that the rotational speed of the drive motor <NUM> has not reached zero (NO in step S22), the rotor cleaning routine returns to the operation in step S20.

Otherwise, in response to determination that the rotational speed of the drive motor <NUM> has reached zero (YES in step S22), the CPU 19a serves as the drive controller <NUM> to determine whether all the cleaning-fluid spraying phase, brushing phase, and drying phase have been completely executed in step S24. At that time, because the brushing phase and the drying phase have not been executed yet (NO in step S24), the rotor cleaning routine returns to the operation in step S10.

In step S10, the CPU 19a receives the execution time setting for the brushing phase determined and sent from the external apparatus <NUM>. After the operation in step S10, the cleaning equipment <NUM> is controlled so that the one or more brushes of the cleaning equipment <NUM> move, and thereafter are fixedly positioned to abut onto the selected rotor <NUM>.

Next, the CPU 19a serves as the drive controller <NUM> to instruct the driver <NUM> to rotate the selected rotor <NUM> and accelerate the rotational speed of the selected rotor <NUM> in step S12. While the rotational speed of the selected rotor <NUM> is accelerating, the rotating selected rotor <NUM> with water drops is cleaned by the one or more brushes.

Thereafter, the operations in steps S14 to S22 for the brushing phase are carried out in the same manner as those for the cleaning-fluid spraying phase.

In response to determination that the rotational speed of the drive motor <NUM> has reached zero (YES in step S22), the CPU 19a serves as the drive controller <NUM> to determine whether all the cleaning-fluid spraying phase, brushing phase, and drying phase have been completely executed in step S24. At that time, because the drying phase has not been executed yet (NO in step S24), the rotor cleaning routine returns to the operation in step S10.

In step S10, the CPU 19a receives the execution time setting for the drying phase determined and sent from the external apparatus <NUM>.

Next, the CPU 19a serves as the drive controller <NUM> to instruct the driver <NUM> to rotate the selected rotor <NUM> and accelerate the rotational speed of the selected rotor <NUM> in step S12.

While the rotational speed of the selected rotor <NUM> is accelerating, centrifugal force induced by the rotating selected rotor <NUM> blows away dirty and/or water drops attached to the selected rotor <NUM>, thus drying the selected rotor <NUM>.

Thereafter, the operations in steps S14 to S22 for the drying phase are carried out in the same manner as those for the cleaning-fluid spraying phase.

In response to determination that the rotational speed of the drive motor <NUM> has reached zero (YES in step S22), the CPU 19a serves as the drive controller <NUM> to determine whether all the cleaning-fluid spraying phase, brushing phase, and drying phase have been completely executed in step S24. At that time, because all the cleaning-fluid spraying phase, brushing phase, and drying phase have been completely executed (YES in step S24), the CPU 19a terminates the rotor cleaning routine.

The drive controller <NUM> is, as described above, configured to control, through the driver <NUM>, the rotational speed of the drive motor <NUM> in the cleaning motor-control mode to a target rotational speed whose equivalent rotational frequency is lower than the predetermined human-audible frequency range, that is, lower than <NUM>/A Hz where A represents the positive integer indicative of the number of blades of the rotor <NUM>. In particular, the drive controller <NUM> is configured to determine the target rotational speeds in the respective cleaning-fluid spraying, brushing, and drying phases to be different from one another. Optimum values used for the respective target rotational speeds depend on, for example, the radius of the rotor (fan) <NUM>. For example, the value of the target rotational speed used in the drying phase is higher than any other values of the target rotational speeds in the respective cleaning-fluid spraying phase and brushing phase, and the value of the target rotational speed used in the cleaning-fluid spraying phase is lower than any other values of the target rotational speeds in the respective brushing phase and dying phase. The value of the target rotational speed in the brushing phase is determined between the value of the target rotational speed used in the drying phase and the value of the target rotational speed in the cleaning-fluid spraying phase.

The CPU 19a is programmed to execute, in step with start the rotor cleaning routine, an abnormal situation determination routine illustrated in <FIG>. The abnormal situation determination routine represents a routine of determining whether there is an abnormal situation in the eVTOL <NUM> during execution of the rotor cleaning routine. The abnormal situation determination routine aims to forestall the occurrence of an abnormal situation, for example, an abnormal cleaning situation of the rotor <NUM> by the cleaning equipment <NUM>. For example, the occurrence of an abnormal situation in the eVTOL <NUM> during execution of the rotor cleaning routine would result in, such as an abnormal cleaning situation of the rotor <NUM>, uncontrollable movement of the rotor <NUM>, which causes (i) the one or more brushes fixedly positioned in contact with the rotor <NUM> to fly or (ii) the eVTOL <NUM> to be out of balance.

In step S100 of the abnormal situation determination routine, the CPU 19a serves as the normality determiner <NUM> to determine, based on each measurement result of the rotational speed of the drive motor <NUM>, whether an abnormal rotational speed is detected. For example, the CPU 19a serves as the normality determiner <NUM> to determine whether each measurement result of the rotational speed of the drive motor <NUM> is within the predetermined allowable rotational-speed range to accordingly determine whether an abnormal rotational speed, which lies outside the predetermined allowable rotational-speed range, is detected.

In response to determination that an abnormal rotational speed is detected (YES in step S100), the CPU 19a stops the rotor cleaning routine illustrated in <FIG> in step S110, and thereafter terminates the abnormal situation determination routine.

For example, in response to determination that an abnormal rotational speed is detected (YES in step S100), the CPU 19a serves as.

In step S110, the CPU 19a changes the motor control mode from the cleaning motor-control mode to the stop mode.

Otherwise, in response to determination that the rotational speed of the drive motor <NUM> is within the allowable rotational-speed range, i.e., no abnormal rotational speed is detected (NO in step S100), the CPU 19a continues the cleaning motor-control mode in step S102. Additionally, in step S102, the CPU 19a serves as the normality determiner <NUM> to determine whether abnormal resistance is detected.

Specifically, during execution of the cleaning task, force acts on the rotor (fan) <NUM> from the one or more brushes abutting onto the rotor <NUM> in the direction of stopping rotation of the rotor <NUM>. This may result in a deviation between (i) a value of the target rotational speed to be controlled by the drive controller <NUM> through the driver <NUM> and (ii) a measured value of the rotational speed by the rotational speed sensor <NUM>. The level of the deviation means resistance to rotation of the rotor <NUM>. Additionally, the abnormal resistance means the level of the deviation is outside a predetermined allowable resistance-level range.

In response to determination that the level of the deviation is outside the predetermined allowable resistance-level range so that the abnormal resistance is detected (YES in step S102), the CPU 19a stops the rotor cleaning routine illustrated in <FIG> in step S110, and thereafter terminates the abnormal situation determination routine. The specific operation in step S110 in response to determination that the abnormal resistance is detected is substantially identical to that in response to determination that an abnormal rotational speed is detected, the specific operation in step S110 in response to determination that the abnormal resistance is detected.

Otherwise, in response to determination that the level of the deviation is within the predetermined allowable resistance-level range, i.e., no abnormal resistance is detected (NO in step S102), the CPU 19a continues the cleaning motor-control mode in step S104. Additionally, in step S104, the CPU 19a serves as the normality determiner <NUM> to determine whether abnormal vibrations are detected.

The abnormal vibrations can include vibrations, which are caused by the airframe <NUM> of the eVTOL <NUM> and measured by the acceleration sensor <NUM>, being outside a predetermined allowable vibration range defined during the cleaning task.

The abnormal vibrations can include vibrations, which cause the airframe <NUM> to tilt at angles and are measured by the acceleration sensor <NUM>; the angles of tilt of the airframe <NUM> being outside a predetermined allowable angular range defined during the cleaning task.

In response to determination that abnormal vibrations are detected (YES in step S104), the CPU 19a stops the rotor cleaning routine illustrated in <FIG> in step S110, and thereafter terminates the abnormal situation determination routine. The specific operation in step S110 in response to determination that the abnormal resistance is detected is substantially identical to that in response to determination that an abnormal rotational speed is detected, the specific operation in step S110 in response to determination that the abnormal resistance is detected.

Otherwise, in response to determination that no abnormal vibrations are detected (NO in step S104), the CPU 19a continues the cleaning motor-control mode in step S106. Additionally, in step S106, the CPU 19a serves as the normality determiner <NUM> to determine whether abnormal power is detected.

The abnormal power means a power level calculated based on a measured value of the drive current by the current sensor <NUM> and a measured value of the drive voltage by the voltage sensor <NUM> being outside a predetermined allowable power-level range defined during the cleaning task.

In response to determination that abnormal power is detected (YES in step S106), the CPU 19a stops the rotor cleaning routine illustrated in <FIG> in step S110, and thereafter terminates the abnormal situation determination routine. The specific operation in step S110 in response to determination that the abnormal resistance is detected is substantially identical to that in response to determination that an abnormal rotational speed is detected, the specific operation in step S110 in response to determination that the abnormal resistance is detected.

Otherwise, in response to determination that no abnormal power is detected (NO in step S106), the CPU 19a continues the cleaning motor-control mode in step S108. Additionally, in step S108, the CPU 19a serves as the drive controller <NUM> to determine whether the rotor cleaning routine illustrated in <FIG> has been completed. In response to determination that the rotor cleaning routine illustrated in <FIG> has not been completed yet (NO in step S108), the abnormal situation determination routine returns to step S100. Otherwise, in response to determination that the rotor cleaning routine illustrated in <FIG> has been completed (YES in step S108), the CPU 19a terminates the abnormal situation determination routine.

The operation of changing the motor control mode from the cleaning motor-control mode to the stop mode in step S110 included in the abnormal situation determination routine can correspond to an operation of stopping the drive motor <NUM> in the claims described later.

The control apparatus <NUM> of the exemplary embodiment described above is configured to control, in the cleaning motor-control mode, the rotational speed of the drive motor <NUM> such that the rotational frequency equivalent to the controlled rotational speed is lower than the predetermined human-audible frequency range. This configuration therefore makes it possible to clean the rotor <NUM> of the eVTOL <NUM> while preventing an excessive increase in noise due to rotation of the rotor <NUM>.

Specifically, the control apparatus <NUM> is configured to adjust the rotational frequency of the drive motor <NUM> of the rotor <NUM> to be lower than <NUM>/A Hz where A represents a positive integer indicative of the number of blades of the rotor <NUM>. This configuration therefore efficiently reduces noise whose level is based on the number of blades of the rotor <NUM>.

The control apparatus <NUM> includes the measurement-result retrieving unit <NUM> configured to retrieve, from, for example, each sensor <NUM>, <NUM>, <NUM>, and <NUM>, the corresponding measurement results, and the normality determiner <NUM> configured to determine, based on the retrieved measurement results, whether there is an abnormal situation in the eVTOL <NUM>. The control apparatus <NUM> is configured to stop, in the cleaning motor-control mode, the cleaning task of the rotor <NUM> in response to determination that there is an abnormal situation in the eVTOL <NUM>. This configuration therefore avoids the occurrence of an abnormal situation in the eVTOL <NUM> during cleaning the rotor <NUM>.

The control apparatus <NUM> additionally includes the cleaning instructor <NUM> and the I/O interface 19c. This configuration makes it possible to send an instruction that instructs the cleaning equipment <NUM> to perform the cleaning task for cleaning the rotors <NUM>.

The control apparatus <NUM> is configured to control, in the cleaning motor-control mode, the drive motor <NUM> in accordance with the cleaning program previously stored in the storage 19b, making it possible to automatically perform each of the cleaning-fluid spraying phase, brushing phase, and drying phase of the cleaning task.

The rotational frequency of the drive motor <NUM> according to the exemplary embodiment is controlled by the control apparatus <NUM> to be lower than <NUM>/A Hz where A represents a positive integer indicative of the number of blades of the rotor <NUM>, but the present disclosure is not limited thereto. Specifically, the rotational frequency of the drive motor <NUM> according to the exemplary embodiment can be adjusted by the control apparatus <NUM> to a value lower than the predetermined human-audible frequency range.

The measurement-result retrieving unit <NUM> of the control apparatus <NUM> according to the exemplary embodiment is configured to retrieve the measurement results including.

The present disclosure is however not limited to this configuration. Specifically, the measurement-result retrieving unit <NUM> of the control apparatus <NUM> according to the exemplary embodiment can be configured to retrieve a part of the measurement results.

The cleaning instructor <NUM> of the control apparatus <NUM> according to the exemplary embodiment is configured to send, to the cleaning equipment <NUM>, one or more instructions that instruct the cleaning equipment <NUM> to perform (i) a cleaning-fluid spraying task, (ii) a brushing task, and (iii) a drying task. Additionally, the cleaning instructor <NUM> can be configured to send, to the cleaning equipment <NUM>, one or more instructions that instruct the cleaning equipment <NUM> to perform other types of cleaning tasks. For example, the cleaning instructor <NUM> can send, to the cleaning equipment <NUM>, a task of covering each rotor <NUM> with wax coating.

The control apparatus <NUM> is configured to control, in the cleaning motor-control mode, the drive motor <NUM> in accordance with the cleaning program previously stored in the storage 19b, but the present disclosure is not limited thereto. Specifically, the control apparatus <NUM> can be configured to control the drive motor <NUM> in accordance with one or more instructions sent from any external apparatus, such as the external apparatus <NUM>.

The control apparatus <NUM> according to the exemplary embodiment is installed in the eVTOL <NUM>, but can be installed in any other types of electric aircrafts. The eVTOL <NUM> according to the exemplary embodiment, which is configured as an uncrewed aircraft, but can be configured as a crewed aircraft.

The control apparatus <NUM> according to the exemplary embodiment is programmed to execute the abnormal situation determination routine, but can be programmed not to execute the abnormal situation determination routine.

The control apparatus <NUM> according to the exemplary embodiment is configured to control the drive motor <NUM> in one of the motor-control modes including at least three drive-motor control modes, such as the flying motor-control mode, the cleaning motor-control mode, and the stop mode, but can be configured control the drive motor <NUM> in any one of the flying motor-control mode and the cleaning motor-control mode. The control apparatus <NUM> can also be configured to control the drive motor <NUM> in any type control mode in addition to the flying motor-control mode, the cleaning motor-control mode, and the stop mode.

To sum up, it is preferable that the control apparatus <NUM> according to the present disclosure can be configured to selectively control the drive motor <NUM> in at least one of the flying motor-control mode and the cleaning motor-control mode.

The present disclosure is not limited to the above exemplary embodiment and the other embodiments and/or modifications, and can be implemented by various configurations within the scope of the present disclosure. For example, technical features included in the above exemplary embodiment and the other embodiments and/or modifications, which correspond to technical features included in exemplary measures described in the SUMMARY of the present disclosure, can be freely combined with each other or can be freely replaced with another feature in order to solve a part or all of the above issue and/or achieve a part or all of the above advantageous benefits. One or more of the technical features included in the above exemplary embodiment, which are not described as essential elements in the specification, can be deleted as necessity arises.

The control apparatuses and their control methods described in the present disclosure can be implemented by a dedicated computer including a memory and a processor programmed to perform one or more functions embodied by one or more computer programs.

The control apparatuses and their control methods described in the present disclosure can also be implemented by a dedicated computer including a processor comprised of one or more dedicated hardware logic circuits.

The control apparatuses and their control methods described in the present disclosure can further be implemented by a processor system comprised of a memory, a processor programmed to perform one or more functions embodied by one or more computer programs, and one or more hardware logic circuits.

Claim 1:
A control apparatus (<NUM>) for controlling a drive motor (<NUM>) that drives a rotor (<NUM>) installed in an electrical aircraft, the control apparatus being configured to:
instruct the drive motor (<NUM>) to selectively operate in at least two motor-control modes that include:
a flying motor-control mode for causing the electrical aircraft to fly, in which the control apparatus (<NUM>) is configured to control the drive motor (<NUM>) in accordance with a flying instruction sent from an aircraft control apparatus (<NUM>) for controlling how the electrical aircraft flies; and
a cleaning motor-control mode for cleaning the rotor (<NUM>), in which the control apparatus (<NUM>) is configured to control the drive motor in accordance with an externally sent instruction and/or a cleaning-motor control program previously stored in the control apparatus (<NUM>);
characterized in that
the control apparatus (<NUM>) is further configured to control, in the cleaning motor-control mode, the drive motor (<NUM>) to rotate at a predetermined rotational frequency that is lower than <NUM>/A Hz where A represents a positive integer indicative of the number of blades of the rotor (<NUM>).