BACKGROUND

Technical Field

The present invention relates to a communication apparatus.

Description of the Related Art

Robot apparatuses equipped with an articulated robot arm have been used as production apparatuses in production lines for manufacturing products. A robot arm of this type operates a workpiece using an end effector attached to a distal end of the robot arm and manufactures articles, such as industrial products and parts. Examples of an end effector include a robot hand as a gripping apparatus and other tools such as an instrument.

A robot hand that functions as an end effector is provided with a finger portion configured to grip a workpiece. The rotation force of a built-in motor of the robot hand is converted to a linear operation by a gear, and the linear operation is transmitted to the finger portion so that the finger portion grips a workpiece.

For example, an alternating-current (AC) servo motor, a stepping motor, or a direct-current (DC) motor is used as a built-in motor of an end effector. Conventional techniques generally use a communication cable extended in a robot arm to transmit a control signal for controlling a built-in motor of an end effector to the motor via the communication cable.

Since a robot arm is being constantly moved, a bending-resistant communication cable is used in a robot arm. Further, since various signals corresponding to the number of finger portions and the number of mounted sensors are transmitted during control of a robot hand, the number of communication cables increases. This raises issues about decrease in bending-resistance of communication cables and increase in thickness of robot arms for enough space for the communication cables. Not only the robot apparatuses but also various production apparatuses have the issues relating to wiring.

In response to the above-described issues, various wireless communication methods in production apparatuses have been discussed for a wireless environment in production apparatuses.

For example, methods that use a protocol that enables high-speed communication, such as Ethernet for Control Automation Technology (EtherCAT), CC-Link Industrial Ethernet (CC-LinkIE), PROFIBUS Decentralized Peripherals (PROFIBUS-DP), or Mechatrolink-III, in addition to conventional Control Area Network (CAN) and Recommended standard (RS)-485 are discussed.

Further, Japanese Patent Application Laid-Open No. 2005-217799 discusses a method in which data that is difficult to transmit by wire, such as high-speed data and data that needs to be multiplexed to be transmitted via a bus line, is wirelessly transmitted whereas data that does not require high-speed, high-volume data transfer is transmitted by wire in order to reduce communication cables in various electronic apparatuses. With the method, the communication cables for transmitting data that needs to be multiplexed can be reduced.

A robot arm can be oriented in various orientations depending on an operation to be executed. Thus, there is a possibility that a blocking object comes between a control apparatus and an end effector and reflects radio waves or the end effector is brought outside a communicable region and the wireless communication is consequently disconnected, which can cause an erroneous operation or loss of real-time properties, depending on the orientation of the robot arm. Disconnection of wireless communication described above can also occur in a production apparatuses that include a movement mechanism configured to move a communication target.

The method discussed in Japanese Patent Application Laid-Open No. 2005-217799 is intended for electronic apparatuses, such as a laptop personal computer (PC), in a situation where wireless communication is stable because a blocking object is not likely to come between a transmission target and a reception target and the transmission target and the reception target are not likely to be brought outside the communicable region. Thus, the method is not applicable for a case where wireless communication may be disconnected when a communication target moves.

SUMMARY

In response to the above-described issues, the present invention is directed to a communication apparatus with which occurrences of an erroneous operation and loss of real-time properties are reduced even in a case where wireless communication is disconnected.

According to an aspect of the present disclosure, a communication apparatus includes a transmission apparatus configured to transmit operation data for an apparatus, a reception apparatus configured to receive the operation data, a wireless communication unit via which the transmission apparatus and the reception apparatus wirelessly communicate with each other, and a cable configured to connect the transmission apparatus and the reception apparatus, wherein the transmission apparatus transmits a synchronization signal to the reception apparatus via the cable, the synchronization signal indicating a timing to execute the operation data, and wherein the transmission apparatus transmits the operation data corresponding to an operation of the apparatus in a predetermined period to the reception apparatus using the wireless communication unit.

Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

