阅读说明：本技术 无线通信装置和无线通信方法 (Wireless communication apparatus and wireless communication method ) 是由 伊藤尚祐 于 2019-04-23 设计创作，主要内容包括：无线通信装置具有：发送部(140),其设置于旋转装置的旋转部(110),发送无线信号；接收部(150),其设置于旋转装置的固定部(120),接收无线信号并基于无线信号来计算通信品质水平；通信周期决定部(160),其基于通信品质水平(Q)来决定通信周期(Tc),使得通信周期(Tc)与旋转部(110)的旋转周期(Tr)的1以上的整数倍的周期(Trn)同步；以及同步调整部(170),其使通信周期(Tc)增加或减少使得通信品质水平(Q)上升,使发送部(140)与接收部之间的通信定时追随于旋转周期(Tr)。(A wireless communication device is provided with: a transmission unit (140) that is provided to the rotating unit (110) of the rotating device and that transmits a wireless signal; a receiving unit (150) that is provided in a fixed unit (120) of the rotating device, receives the wireless signal, and calculates a communication quality level based on the wireless signal; a communication cycle determination unit (160) that determines a communication cycle (Tc) on the basis of the communication quality level (Q), such that the communication cycle (Tc) is synchronized with a cycle (Trn) that is an integer multiple of 1 or more of the rotation cycle (Tr) of the rotating unit (110); and a synchronization adjustment unit (170) that increases or decreases the communication period (Tc) to increase the communication quality level (Q) and causes the communication timing between the transmission unit (140) and the reception unit to follow the rotation period (Tr).)

1. A wireless communication apparatus, characterized in that,

the wireless communication device has:

a transmission unit that is provided in a rotating unit of the rotating device and transmits a wireless signal;

a receiving unit that is provided in a fixed part of the rotating device, receives the wireless signal, and calculates a communication quality level based on the wireless signal;

a communication cycle determination unit that determines a communication cycle based on the communication quality level such that the communication cycle is synchronized with a cycle that is an integral multiple of 1 or more of a rotation cycle of the rotating unit; and

and a synchronization adjustment unit that increases or decreases the communication cycle to increase the communication quality level and causes the communication timing between the transmission unit and the reception unit to follow the rotation cycle.

2. The wireless communication apparatus of claim 1,

the wireless communication device further has a sensing part which is provided to the rotation part and detects physical information,

the transmission unit transmits the wireless signal indicating the physical information.

3. The wireless communication device according to claim 1 or 2,

the synchronization adjusting unit increases or decreases the communication cycle based on a result of calculating an influence of the increase or decrease of the communication cycle on the communication quality level so as to increase the communication quality level.

4. The wireless communication apparatus according to any one of claims 1 to 3,

the communication cycle determination unit synchronizes the communication cycle with a cycle that is an integral multiple of 1 or more of the rotation cycle based on an aliasing signal that appears according to a sampling theorem when the communication cycle is greater than the rotation cycle.

5. The wireless communication apparatus according to any one of claims 1 to 4,

the synchronization adjustment unit switches the communication cycle to a cycle that is an integral multiple of 1 or more of the rotation cycle and is different from the value set by the communication cycle determination unit so that the communication cycle approaches the communication cycle command value when the communication cycle differs from the predetermined communication cycle command value by a predetermined threshold value or more.

6. The wireless communication apparatus according to any one of claims 1 to 5,

the communication cycle determination unit calculates a relationship between the communication cycle and the rotation cycle by performing autocorrelation processing on the communication quality level acquired with the fixed communication cycle for a predetermined period, and synchronizes the communication cycle with a cycle that is an integral multiple of 1 or more of the rotation cycle.

7. The wireless communication apparatus according to any one of claims 1 to 5,

the communication cycle determination unit calculates a relationship between the communication cycle and the rotation cycle by performing fourier analysis on the communication quality level acquired with the fixed communication cycle for a predetermined period, and synchronizes the communication cycle with a cycle that is an integral multiple of 1 or more of the rotation cycle.

8. The wireless communication apparatus according to any one of claims 1 to 7,

the wireless communication device further has a rotation period sensing part that detects the rotation period of the rotation part,

the communication cycle determining unit synchronizes the communication cycle with a cycle that is an integral multiple of 1 or more of the rotation cycle detected by the rotation cycle sensing unit.

9. The wireless communication apparatus according to any one of claims 1 to 8,

the rotating device is a motor.

10. A radio receiving method for receiving a radio signal transmitted from a transmission unit provided in a rotating unit of a rotating device,

the wireless communication method has the steps of:

calculating a communication quality level based on the wireless signal;

determining a communication period based on the communication quality level such that the communication period is synchronized with a period that is an integral multiple of 1 or more of a rotation period of the rotating portion; and

the communication quality level is increased by increasing or decreasing the communication cycle, and the communication timing with the transmitter unit is made to follow the rotation cycle.

Technical Field

The present invention relates to a wireless communication apparatus and a wireless communication method.

Background

A wireless communication device has been developed which detects physical information such as temperature by a sensor attached to a rotating portion such as a rotor of a motor or a tire of a vehicle, transmits a wireless signal indicating the physical information by a transmitter attached to the rotating portion, and receives the wireless signal by a receiver attached to a fixed portion such as a housing of the motor or a vehicle body. Patent document 1 proposes a wireless communication device that performs wireless communication at a communication timing according to a rotational position of a wheel of a vehicle.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2004-359119 (e.g., paragraph 0030)

Disclosure of Invention

Problems to be solved by the invention

However, in the device of patent document 1, it is necessary to measure in advance the relationship between the rotational position of the wheel and the communication quality (for example, the reception level). Therefore, when the optimum rotational position during communication changes depending on the rotational speed of the wheel, a change in radio wave environment, or the like, it is necessary to measure the relationship between the rotational position of the wheel and the communication quality again.

An object of the present invention is to provide a wireless communication apparatus and a wireless communication method capable of adjusting communication between a rotating portion and a fixed portion to an optimum timing.

Means for solving the problems

A wireless communication apparatus according to an aspect of the present invention includes: a transmission unit that is provided in a rotating unit of the rotating device and transmits a wireless signal; a receiving unit that is provided in a fixed part of the rotating device, receives the wireless signal, and calculates a communication quality level based on the wireless signal; a communication cycle determination unit that determines a communication cycle based on the communication quality level such that the communication cycle is synchronized with a cycle that is an integral multiple of 1 or more of a rotation cycle of the rotating unit; and a synchronization adjustment unit that increases or decreases the communication cycle to increase the communication quality level and causes the communication timing between the transmission unit and the reception unit to follow the rotation cycle.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the communication between the rotating portion and the fixed portion can be adjusted to an optimum timing.

Drawings

Fig. 1 is a block diagram schematically showing the configuration of a wireless communication device according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing an example of the hardware configuration of the wireless communication apparatus according to embodiment 1.

Fig. 3 is a schematic diagram showing a rotating unit and a fixed unit provided with the radio communication device according to embodiment 1.

Fig. 4 is a graph showing a relationship between the rotation angle of the rotating portion and the communication quality level calculated by the receiving portion.

Fig. 5 is a graph showing a relationship between time when the rotating unit rotates and the communication quality level calculated by the receiving unit.

Fig. 6 is a graph showing a relationship between a communication period and a communication quality level.

Fig. 7 is a graph showing a relationship between a communication period and a communication quality level.

Fig. 8 is a graph showing a relationship between an alias signal (alias signal) and each frequency in embodiment 2 of the present invention.

Fig. 9 is a graph showing the relationship between the aliasing signals and the frequencies at the same time in embodiment 2.

Fig. 10 is a schematic diagram showing a rotating unit and a fixed unit of a wireless communication device according to embodiment 4 of the present invention.

Detailed Description

Hereinafter, a radio communication apparatus and a radio communication method according to embodiments of the present invention will be described with reference to the drawings. The following embodiments are merely examples, and various modifications can be made within the scope of the present invention.

EXAMPLE 1 (1).

Structure of (1-1)

Fig. 1 is a block diagram schematically showing the configuration of a wireless communication device according to embodiment 1. The wireless communication apparatus is an apparatus capable of implementing the wireless communication method according to embodiment 1. The wireless communication device according to embodiment 1 is provided in a rotary device 100 having a rotary unit 110 and a stationary unit 120. The rotating device 100 is, for example, a motor. In this case, the rotating portion 110 is a rotor that rotates, and the fixed portion 120 is a housing including a stator.

The wireless communication device according to embodiment 1 includes a sensing unit 130, a transmitting unit 140 as a communication device, a receiving unit 150 as a communication device, a communication cycle determining unit 160, and a synchronization adjusting unit 170. The sensing unit 130 and the transmitting unit 140 are provided in the rotating unit 110. The receiving unit 150, the communication cycle determining unit 160, and the synchronization adjusting unit 170 are provided in the fixed unit 120. However, the communication cycle determining unit 160 and the synchronization adjusting unit 170 are not necessarily provided in the fixed unit 120. The communication cycle determining unit 160 and the synchronization adjusting unit 170 may be provided in a computer connected to the receiving unit 150, a server connected to the receiving unit 150 via a network, or the like so as to be able to communicate with each other.

The sensing part 130 detects physical information. The sensing part 130 is also referred to as a sensor. The transmission unit 140 is, for example, a transmitter that transmits a wireless signal indicating the physical information acquired by the sensing unit 130. When the physical information acquired by the sensing unit 130 is temperature, the sensing unit 130 measures the temperature (for example, the temperature of the rotating shaft) using a temperature sensor such as a thermocouple. The physical information measured by the sensing unit 130 may be a rotation speed, a rotation angular acceleration, a magnetic flux, vibration, and acceleration of the rotating unit 110, a voltage and a current in a wire or a winding provided in the rotating unit 110, or the like.

The rotating device 100 may be a vehicle such as an automobile. In this case, the rotating portion 110 is a wheel (or tire), and the fixed portion 120 is a vehicle body. Further, in the case where the rotary device 100 is a helicopter, the rotary part 110 is a blade (i.e., a rotary blade), and the fixed part 120 is a helicopter main body. In the case where the rotary device 100 is an aircraft, the rotary part 110 is a propeller and the fixed part 120 is an aircraft body. When the rotary device 100 is an air conditioner, the rotary part 110 is a fan, and the fixed part 120 is an air conditioner body. However, the rotating apparatus 100 is not limited thereto.

The receiving unit 150 includes a receiver that receives the wireless signal transmitted from the transmitting unit 140. The receiving unit 150 calculates a communication quality level Q, which is an index indicating communication quality, based on the radio signal. The communication quality level Q calculated by the receiving unit 150 is a value indicating how good the communication quality is. The communication quality level Q is, for example, a reception Strength (RSSI), a reciprocal of an error rate, a Signal to Noise Ratio (SNR), or the like. The higher the communication quality level Q, the better the communication quality. However, the communication quality level Q is not limited thereto.

The communication cycle determination unit 160 determines the communication cycle Tc to be a cycle Trn (N × Tr) seconds that is an integral multiple (that is, N times) of 1 or more of the rotation cycle Tr [ seconds ] of the rotating unit 110, based on the communication quality level Q. That is, the communication cycle determining unit 160 determines the communication cycle Tc to be Tc ═ Trn (N × Tr) based on the communication quality level Q. The rotation period Tr of the rotation part 110 is a time period for which the rotation part 110 rotates 1 turn.

The synchronization adjustment unit 170 increases or decreases the communication cycle Tc to increase the communication quality level Q, and adjusts the communication timing between the transmission unit 140 and the reception unit 150. That is, the synchronization adjustment unit 170 changes (i.e., increases or decreases) the communication period Tc to increase the communication quality level Q, and makes the communication period Ta after the change follow the rotation period Tr. Further, the wireless signal is transmitted from the transmission unit 140 to the reception unit 150 at a certain cycle and for a fixed short period of time.

Fig. 2 is a diagram showing an example of the hardware configuration of the wireless communication apparatus according to embodiment 1. Fig. 2 shows a structure provided in the fixing portion 120. As shown in fig. 2, the wireless communication apparatus has a processor 201 as an information processing section and a memory 202 as a storage section for storing information. The processor 201 and the memory 202 execute the operation performed by the communication cycle determination unit 160 and the operation performed by the synchronization adjustment unit 170. The processor 201 and the memory 202 are for example part of a computer. A program is installed in the memory 202. The program is installed, for example, via a network or from a storage medium storing information. The program may include a program for performing a process of determining a communication cycle and a process of adjusting synchronization, which will be described later. The processor 201 executes the processing on the fixed unit 120 side of the wireless communication apparatus by executing the program stored in the memory 202. The whole or a part of the structure of the radio communication apparatus on the fixed unit 120 side may be constituted by a control circuit constituted by a semiconductor integrated circuit. The memory 202 may include various storage devices such as a semiconductor storage device, a hard disk device, and a device for recording information in a removable recording medium.

Next, a relationship between the rotation angle θ of the rotating unit 110 and the communication quality level Q will be described. Fig. 3 is a diagram showing a relationship between the rotating portion 110 and the fixed portion 120 and the rotation angle θ, as viewed in a direction parallel to the rotation axis. As shown in fig. 3, the rotary part 110 rotates about the rotation axis in the rotation direction. The fixed portion 120 is disposed so as to face the rotating portion 110 without contacting the rotating portion 110, for example. The positional relationship between the transmission unit 140 and the reception unit 150 changes according to the rotation angle θ. Therefore, the propagation path of the radio signal changes according to the rotation angle θ, and the communication quality level Q changes according to the change of the propagation path. In particular, when the rotating portion 110 is a rotor of a motor, the rotational speed is higher than when the rotating portion 110 is a tire of a vehicle, and thus the doppler effect is more likely to be affected. In addition, when the rotating portion 110 is a rotor of a motor, the radio wave environment is easily affected by the electromagnetic shielding effect and reflection caused by a metal case of the motor.

Fig. 4 is a graph showing a relationship between the rotation angle θ of the rotating portion 110 and the communication quality level Q calculated by the receiving portion 150. For example, as shown in fig. 4, when the rotation angle θ changes as the rotation portion 110 rotates, the communication quality level Q changes. When the communication quality level Q is the rotation angle θ at which the communication quality level Q is the highest value (that is, the rotation angle θ is θ p), the communication between the transmission unit 140 and the reception unit 150 is performed, thereby improving the stability of the communication.

Fig. 5 is a graph showing a relationship between time when the rotating portion 110 rotates and the communication quality level calculated by the receiving portion 150. As understood from fig. 5, the communication quality level Q repeatedly varies every rotation period Tr. The communication cycle determination unit 160 detects, as a communication timing, a timing corresponding to the rotation angle θ at which the communication quality level Q is high, which appears for each rotation cycle Tr.

As can be seen from fig. 5, the communication cycle determination unit 160 can estimate the rotation cycle Tr based on the variation in the communication quality level Q. For example, the communication cycle determination unit 160 can estimate the rotation cycle Tr by detecting the peak interval of the communication quality level Q. Further, the communication cycle determination unit 160 can estimate the rotation cycle Tr by detecting the repetitive signal using autocorrelation processing. The communication cycle determination unit 160 can estimate the rotation cycle Tr by calculating the frequency characteristic using fourier analysis. If the communication quality level Q is subjected to fourier analysis, the characteristic of the frequency region having a peak within the rotation period Tr is obtained. However, the estimation method of the rotation period Tr is not limited thereto. The communication cycle determination unit 160 can also improve the accuracy by estimating the rotation cycle Tr more frequently than the determination of the communication timing.

The communication cycle determination unit 160 determines the communication cycle Tc, for example, by setting, as the communication timing, a timing after a cycle Trn (N × Tr) that is an integral multiple (that is, N times) of 1 or more (that is, N times) of the rotation cycle Tr from a timing at which the communication quality is the best within the period of the rotation cycle Tr. That is, the communication cycle determining unit 160 determines the communication cycle Tc to be a cycle Trn that is an integral multiple of 1 or more of the rotation cycle Tr. The communication period Tc is set to be several times the rotation period Tr, that is, it is desirable to set the value of N as large as possible within a range in which the communication quality level Q can be obtained at good timing. This shortens the communication time between the transmission unit 140 and the reception unit 150, and can suppress power consumption in the transmission unit 140. In addition, when the rotating unit 110 is provided with a transmission unit other than the transmission unit 140 (that is, another transmission unit), the value of N is set to a large value, thereby preventing interference between the plurality of transmission units.

The synchronization adjustment unit 170 calculates the influence of the increase or decrease in the communication cycle Tc on the increase or decrease in the communication quality level Q, and increases or decreases the communication cycle Tc so as to increase the communication quality level Q, thereby synchronously tracking the communication timing. Further, the synchronization adjustment unit 170 increases or decreases the communication cycle Tc by Δ Tc so that the communication cycle Tc is finely changed, that is, so that the communication cycle Tc is changed to Tc + Δ Tc or Tc — Δ Tc, instead of increasing or decreasing the communication cycle Tc to the cycle Trn which is an integral multiple of the rotation cycle Tr when the communication timing is synchronously tracked.

Actions of 1-2

Fig. 6 is a graph showing the relationship between the communication cycle and the communication quality level Q in embodiment 1. After the determination processing of the communication cycle Tc by the communication cycle determination unit 160 is completed, when the synchronization adjustment unit 170 performs communication at a certain communication timing a and at a timing earlier than the timing at which the communication quality is expected to be good and obtains the communication quality level Qa, the communication cycle Tc is changed to a longer communication cycle Tc + Δ Tc, that is, the communication cycle Ta after the change, so that the communication quality level Q becomes a higher communication quality level Qb. It is understood that by this operation, the communication quality is improved at the next communication timing B. After the communication quality is improved, the synchronization adjustment unit 170 may return the communication cycle to the communication cycle Tc to adjust the communication timing.

Fig. 7 is a graph showing the relationship between the communication cycle and the communication quality level Q in embodiment 1. After the determination processing of the communication cycle Tc by the communication cycle determination unit 160 is completed, if the synchronization adjustment unit 170 performs communication at a certain communication timing C and at a timing later than the timing at which the communication quality is expected to be good and the communication quality level Qc is obtained, the communication quality level is decreased to Qd at the next communication timing D and the communication quality is deteriorated if the communication cycle Tc is changed to the longer communication cycle Tc + Δ Tc. In this way, when the communication quality deteriorates when the communication cycle Tc is changed, the sign of the amount of change in the communication cycle Tc is changed. That is, when the synchronization adjustment unit 170 performs communication at a certain communication timing C and later than a timing at which good communication quality is expected to be obtained to obtain the communication quality level Qc, if the communication cycle Tc is changed to the shorter communication cycle Tc — Δ Tc, the communication quality level rises to Qe at the next communication timing E, and the communication quality improves. By repeating these operations or by repeating the process by changing the value of Δ Q, the communication cycle determination unit 160 can synchronize the communication cycle with the rotation cycle Tr.

The communication cycle determination unit 160 may constantly perform the operation of determining the communication cycle Tc, and the communication cycle determination unit 160 may perform the operation of determining the communication cycle Tc at predetermined time intervals, so as to reduce the calculation load. For example, when the rotation period Tr of the rotating unit 110 is fixed and does not change, the synchronization adjusting unit 170 may be operated so that the communication timing follows the rotation period Tr without operating the communication period determining unit 160.

When the rotation period Tr of the rotating unit 110 changes, the communication period determining unit 160 performs an operation of determining the communication period Tc each time the rotation period Tr changes, and after the communication period Tc is determined, the synchronization adjusting unit 170 operates so that the communication timing follows the rotation period Tr.

Effect of (1-3)

As described above, in the radio communication apparatus according to embodiment 1, the communication stability can be improved by making the communication timing follow the optimum rotation angle θ.

In an environment in which the rotation speed is high and the radio wave environment fluctuates due to reflection of metal, such as a motor, even when the optimum rotational position fluctuates, the communication timing corresponding to the optimum rotational position can be dynamically determined, and the stability of communication can be improved.

In addition, when the communication cycle determination unit 160 performs autocorrelation processing or fourier analysis, even in an environment where the communication quality level Q is likely to vary, the communication timing can be made to follow the rotation cycle Tr of the rotation unit 110, and the stability of communication can be improved.

In addition, in the wireless communication device according to embodiment 1, since a means (for example, a rotation angle sensor or a rotation period sensor) for detecting the rotation angle θ of the rotating unit 110 is not provided, the installation space can be reduced, and the configuration on the side of the fixed unit 120 can be made smaller.

Further, the synchronization adjustment unit 170 determines the direction of increase or decrease of the communication cycle Tc based on the measured change in the communication quality level Q, thereby improving the accuracy of the synchronization tracking.

EXAMPLE 2 (2).

The radio communication apparatus according to embodiment 2 is different from the radio communication apparatus according to embodiment 1 in that, when the communication period Tc is greater than the rotation period Tr, the communication period determination unit 160 synchronizes the communication period with the period Trn that is an integral multiple of 1 or more of the rotation period Tr based on an alias signal that appears according to the sampling theorem. The radio communication apparatus according to embodiment 2 is the same as the radio communication apparatus according to embodiment 1 except for the operation of the communication cycle determination unit 160. Therefore, in the description of embodiment 2, reference is also made to fig. 1 to 3.

Fig. 8 and 9 are diagrams showing examples of frequency characteristics of the communication quality level Q. Fig. 8 and 9 graphically show the relationship between the aliasing signal and each frequency. If the communication quality level Q is subjected to fourier analysis, the characteristic of the frequency region having a peak at the rotation frequency fr is obtained. From fig. 8, the relationship of the communication frequency fc (i.e., the reciprocal of the communication period Tc), the rotation frequency fr (i.e., the reciprocal of the rotation period Tr), and the aliasing signal of the rotation frequency fr in the frequency domain can be known. At this time, when the rotation frequency fr is greater than the communication frequency fc/2, which is the frequency of obtaining the communication quality level Q, as shown in fig. 8, an aliasing signal fa corresponding to the rotation frequency fr appears at fa | fr-Nfc | (N is an integer of fr < fc/2). Therefore, the rotation frequency fr (or the rotation period Tr) cannot be directly calculated from the detected aliasing signal fa, and the synchronization cannot be simply obtained.

Here, in order to synchronize the communication cycle Tc with the cycle Trn that is an integral multiple of 1 or more of the rotation cycle Tr, the communication cycle determining unit 160 may change the communication frequency fc so that fa becomes 0. Fig. 9 shows an example of frequency characteristics of the communication quality level Q when synchronized. That is, the communication cycle determining unit 160 may change the communication frequency fc by Δ fc so that | fr-N (fc + Δ fc) | becomes 0. Here, when N is not known, the communication cycle determination unit 160 may repeatedly change the communication frequency fc and calculate the frequency characteristic to obtain Δ fc where | fr-N (fc + Δ fc) | is 0.

As described above, according to the wireless communication apparatus of embodiment 2, by using the aliasing signal occurring according to the sampling theorem, synchronization can be achieved even if the communication cycle Tc is long, that is, even if the frequency of acquiring the communication quality level Q is low. Thus, the wireless communication device can acquire synchronization even in an environment such as a motor in which the rotation period Tr is short, that is, an environment in which the rotation speed is high. Further, the wireless communication apparatus can acquire synchronization even in an environment where the communication cycle Tc is long, that is, an environment where the communication frequency is low, and power consumption can be suppressed.

EXAMPLE 3 (3).

The radio communication apparatus according to embodiment 3 is different from the radio communication apparatus according to embodiment 1 or 2 in that, when the communication cycle Tc differs from the predetermined communication cycle command value T0 by a predetermined threshold value Th or more, the synchronization adjustment unit 170 switches the communication cycle Tc to a cycle Trn that is an integral multiple of 1 or more of the rotation cycle Tr and is different from the value set by the communication cycle determination unit 160, so that the communication cycle Tc approaches the communication cycle command value T0. The wireless communication device according to embodiment 3 is the same as the wireless communication device according to embodiment 1 or 2, except for the operation of the communication cycle determination unit. Therefore, in the description of embodiment 2, reference is also made to fig. 1 to 3.

In order to make the communication cycle Tc follow the rotation cycle Tr, the synchronization adjustment unit 170 changes the communication cycle Tc along with the change of the rotation cycle Tr. At this time, when the rotation period Tr is greatly reduced (that is, the rotation frequency fr is increased), communication is performed at a frequency more than necessary. Further, when the rotation period Tr is greatly increased (that is, the rotation frequency fr is decreased), communication cannot be performed with sufficient frequency.

In order to solve the above problem, in the radio communication apparatus according to embodiment 3, when a difference between the communication cycle Tc and the predetermined communication cycle command value T0 is equal to or greater than the predetermined threshold Th, the synchronization adjustment unit 170 switches the communication cycle Tc to a cycle Trn that is an integral multiple of 1 or greater of the rotation cycle Tr and is different from the value set by the communication cycle determination unit 160, so that the communication cycle Tc approaches the communication cycle command value T0. When the communication cycle Tc is larger than the rotation cycle Tr and N is unknown, the synchronization adjustment unit 170 changes the communication cycle Tc to a cycle Trn which is an integral multiple thereof or to a cycle obtained by dividing the communication cycle Tc by an integer thereof so that the communication cycle Tc approaches the communication cycle command value T0. Here, since the communication cycle Tc may be out of synchronization by changing the communication cycle Tc to a cycle obtained by dividing the communication cycle Tc by an integer, the communication cycle determination unit 160 needs to execute the processing again.

As described above, according to the wireless communication device of embodiment 3, it is possible to perform communication at a cycle close to the target communication cycle command value T0

EXAMPLE 4 (4).

Fig. 10 is a schematic diagram showing a rotating unit 110 and a fixed unit 120 provided with the radio communication device according to embodiment 4. The radio communication apparatus according to embodiment 4 differs from the radio communication apparatuses according to embodiments 1 to 3 in that the communication cycle determining unit 160a includes a rotation cycle sensing unit 161 that senses the rotation cycle Tr of the rotating unit 110, and synchronizes the communication cycle Tc with a cycle Trn that is an integral multiple of 1 or more of the rotation cycle Tr. The radio communication apparatus according to embodiment 4 is the same as the radio communication apparatuses according to embodiments 1 to 3, except for the operation of the communication cycle determination unit 160 a. Therefore, in the description of embodiment 4, reference is also made to fig. 1 to 3.

As shown in fig. 10, in embodiment 4, the rotation period Tr is acquired by using the rotation period sensing unit 161, and the communication period Tc is synchronized with the rotation period Tr. The rotation period sensing unit 161 is, for example, a magnetic rotation speed sensor, an optical rotation speed sensor, or the like. The rotation cycle sensing unit 161 may be provided outside the communication cycle determination unit 160 a.

As described above, according to the radio communication apparatus of embodiment 4, the communication cycle Tc and the rotation cycle Tr can be synchronized with high accuracy by performing the synchronization process using the sensed rotation cycle Tr. Further, even in the case where the rotation period is directly sensed, by adjusting the communication period in accordance with the communication quality level, communication can be performed at an appropriate timing with respect to the rotation angle.

Further, according to the radio communication apparatus of embodiment 4, the process of calculating the rotation period Tr is not necessary as compared with the apparatuses shown in embodiments 1 to 3, and therefore, the processing time can be shortened.

Variation example of "5".

The configurations of the wireless communication apparatuses according to embodiments 1 to 4 can be combined as appropriate.

Description of the reference symbols

100 a rotation device, 110 a rotation part, 120 a fixed part, 130 a sensing part, 140 a transmitting part, 150 a receiving part, 160a communication cycle determining part, 161 a rotation cycle sensing part, 170 a synchronization adjusting part.