Battery charging system

Abstract

This battery charging system (A1) comprises a robot (B1) that travels autonomously and a charger (C1). The robot (B1) has a battery part (1B) for allowing the robot (B1) to operate, a robot control part (2B) that controls the robot (B1), a first PLC communication part (4B) that carries out PLC communication, and a first connector (5B) that connects to the charger (C1). The charger (C1) has a charging control part (1C) that supplies power for charging the battery part (1B), a charger control part (2C) that carries out control of the charger (C1), a second PLC communication part (4C) that carries out PLC communication, and a second connector (5C) that connects to the robot (B1). The first PLC communication part (4B) and the second PLC communication part (4C) transmit and receive, via power lines (9B, 9C) that connect the battery part (1B) and the charging control part (1C), control information for charging. With such a configuration, it is possible to reduce the number of connection terminals in the connectors, and to more easily connect the connectors.

Description

Battery Charging System

[0001] The present invention relates to a battery charging system.

[0002] Various battery charging systems have been proposed, which include a traveling device incorporating an electric motor such as a motor and a battery, and a charger for charging the traveling device. Patent Document 1 discloses an example of a conventional battery charging system. In the battery charging system disclosed in this document, a configuration is adopted in which an automobile, which is an example of a traveling device, and a charger are connected via an adapter. The adapter is used for power supply from the charger to the automobile and for transmission and reception of various signals for control and the like.

[0003] International Publication No. 2018 / 220831

[0004] In the battery charging system, signal transmission and reception are performed by a signal cable separate from the power supply cable for power supply. For this reason, the connectors provided in each of the automobile and the charger need to have connection terminals for power supply and for signals as connection terminals.

[0005] The present invention has been conceived under the above circumstances, and an object thereof is to provide a battery charging system capable of reducing the number of connection terminals of a connector and making connector connection easier.

[0006] The battery charging system provided by the present invention is a battery charging system including an autonomous robot and a charger. The robot includes a battery unit for operating the robot, a robot control unit for controlling the robot, a first PLC communication unit for performing PLC communication, and a first connector for connecting to the charger. The charger includes a charging control unit for supplying power for charging the battery unit, a charger control unit for controlling the charger, a second PLC communication unit for performing PLC communication, and a second connector for connecting to the robot. The first PLC communication unit and the second PLC communication unit transmit and receive control information for charging via a power line connecting the battery unit and the charging control unit.

[0007] In a preferred embodiment of the present invention, the charging control unit transmits authentication data via the second PLC communication unit, and when the robot control unit receives the authentication data, it transmits a charging start instruction via the first PLC communication unit.

[0008] In a preferred embodiment of the present invention, the charger has a charger load switch that turns on or off the electrical connection between the charge control unit and the second connector, and the charge control unit turns on the charger load switch after receiving the charging start instruction from the robot.

[0009] In a preferred embodiment of the present invention, the robot has a robot load switch that turns the electrical connection between the battery unit and the first connector on or off, and the robot control unit turns on the robot load switch after transmitting the charging start instruction.

[0010] In a preferred embodiment of the present invention, the authentication data includes compatibility information between the robot and the charger.

[0011] In a preferred embodiment of the present invention, the charger is equipped with a coupling sensor that detects a proximity state in which the robot and the charger are in close proximity to each other at a predetermined distance or less, and the charger transmits the authentication data when the coupling sensor detects the proximity state.

[0012] In a preferred embodiment of the present invention, the charging control unit has a current / voltage detection unit that detects the current or voltage of the power line, and the current / voltage detection unit detects the current or voltage during periods when PLC communication is not being performed by the first PLC communication unit and the second PLC communication unit, and the charging control unit controls the power to be charged according to the value detected by the current / voltage detection unit.

[0013] According to the present invention, the number of connection terminals of a connector can be reduced, making connector connection easier.

[0014] Other features and advantages of the present invention will become more apparent from the detailed description below with reference to the accompanying drawings.

[0015] This is a system configuration diagram showing a battery charging system according to the first embodiment of the present invention. This is a system configuration diagram showing the first PLC communication unit of the battery charging system according to the first embodiment of the present invention. This is a schematic configuration diagram showing a battery charging system according to the first embodiment of the present invention. In the battery charging system according to the first embodiment of the present invention, (a) is a plan view showing the second connector, (b) is a front view showing the first connector and the second connector, and (c) is a cross-sectional view along the IVb-IVb line and IVc-IVc line in (b). This is a sequence diagram showing an example of the operation of the battery charging system according to the first embodiment of the present invention. This is a timing chart showing an example of the operation of the battery charging system according to the first embodiment of the present invention. This is a system configuration diagram showing the charger of the battery charging system according to the second embodiment of the present invention. This is a system configuration diagram showing the robot of the battery charging system according to the second embodiment of the present invention. This is a system configuration diagram showing the signal processing unit of the robot according to the second embodiment of the present invention. This is a sequence diagram showing an example of the operation of the battery charging system according to the third embodiment of the present invention.

[0016] Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0017] The terms "first," "second," "third," etc., used in this disclosure are for identification purposes only and are not intended to assign any order to the objects.

[0018] Figures 1 to 5 show a battery charging system according to the first embodiment of the present invention. The battery charging system A1 of this embodiment comprises a robot B1 and a charger C1. The battery charging system A1 is a system that charges the battery unit 1B of the robot B1 using the charger C1.

[0019] Robot B1 is an autonomous robot. The specific applications and configurations of Robot B1 are not limited in any way. Examples of Robot B1 include a cleaning robot that performs cleaning tasks in facilities such as offices, commercial buildings, and factories, and a transport robot that transports goods, food, etc. Robot B1 is appropriately equipped with wheels, motors, and various sensors for autonomous movement. As shown in Figure 1, Robot B1 includes a battery unit 1B, a robot control unit 2B, a power supply unit 3B, a first PLC communication unit 4B, a first connector 5B, a robot load switch 6B, and a power line 9B.

[0020] The battery unit 1B is for supplying power necessary for the operation of robot B1 to various parts of robot B1. The specific configuration of the battery unit 1B is not limited in any way, and in the illustrated example, it has a battery unit 11B and a communication control unit 12B. The battery unit 11B includes a secondary battery such as a lithium-ion battery. The communication control unit 12B includes sensors that detect the voltage and temperature of the battery unit 11B.

[0021] The communication control unit 12B determines abnormal conditions such as overcharging, over-discharging, and high temperature based on the sensor's detection value. When the communication control unit 12B determines that the battery unit 11B is in an abnormal state, it takes appropriate measures such as cutting off power input and output to the battery unit 11B. The communication control unit 12B also transmits information regarding the status of the battery unit 11B, such as the remaining charge and any abnormal conditions, via the first PLC communication unit 4B. This information regarding the status of the battery unit 11B is used as control information for charging control.

[0022] The robot control unit 2B receives information from the charger C1 via the first PLC communication unit 4B, or receives information about the status of the battery unit 11B from the communication control unit 12B of the battery unit 1B. Based on this information, the robot control unit 2B performs on / off control of the robot load switch 6B and data communication to the first PLC communication unit 4B. The robot control unit 2B is composed of, for example, a CPU, memory, and software.

[0023] The power supply unit 3B generates power of the necessary voltage for each part of the robot B1 using power supplied from the battery unit 11B built into the battery unit 1B, or from the charger C1 via the robot load switch 6B.

[0024] The first PLC communication unit 4B uses a PLC (Power Line Communication) to input and output signals to the communication control unit 12B and robot control unit 2B of the battery unit 1B, and to the charger C1. The carrier frequency used by the PLC in the first PLC communication unit 4B is selected depending on the required bit rate, for example, to be low speed (10k to 500kHz) or high speed (2M to 100MHz).

[0025] Figure 2 shows an example of the specific configuration of the first PLC communication unit 4B. The first PLC communication unit 4B in the illustrated example includes a PLC modem 41B and two capacitors 42B. The two capacitors 42B are individually connected to two power lines 9B. The PLC modem 41B transmits and receives signals in a data format that conforms to the standard. The PLC modem 41B has a built-in filter that extracts the carrier wave superimposed on the power line 9B. To improve noise immunity, differential signals are transmitted and received using two lines (Rx / Tx) connected to the PLC modem 41B.

[0026] The first connector 5B is connected to the second connector 5C of the charger C1 (described later) to charge the battery unit 1B of the robot B1 from the charger C1, and to transmit and receive signals such as control information between the robot B1 and the charger C1. The specific configuration of the first connector 5B will be described later.

[0027] The power line 9B connects the first connector 5B and the battery unit 11B of the battery section 1B. The number of power lines 9B is not limited in any way; in the illustrated example, there are two power lines 9B.

[0028] The robot load switch 6B is located on the power line 9B. The ON / OFF state of the robot load switch 6B allows selection between a conductive state and a disconnected state of the power line 9B. The robot load switch 6B is controlled ON / OFF by the robot control unit 2B.

[0029] Charger C1 is a device for charging the battery unit 1B of robot B1. The specific configuration of charger C1 is not limited in any way. Charger C1 can be installed, for example, in facilities such as offices, commercial facilities, and factories. As shown in Figure 1, charger C1 has a charging control unit 1C, a charger control unit 2C, a power supply unit 3C, a second PLC communication unit 4C, a second connector 5C, a charger load switch 6C, a coupling sensor 8C, and a power line 9C.

[0030] The power supply unit 3C generates power of the voltage required for each part of the charger C1 from the commercial power supply to which the charger C1 is connected. The power supply unit 3C also supplies power to the charging control unit 1C to supply power to the battery unit 1B of the robot B1.

[0031] The charging control unit 1C receives power from the power supply unit 3C and uses it to supply power to the battery unit 1B in the robot B1. The charging control unit 1C controls the current and voltage of the power supplied to the battery unit 1B according to the battery status, such as the remaining charge of the battery unit 11B in the battery unit 1B. When the battery unit 11B is a lithium-ion battery, CCCV (Constant Current, Constant Voltage) is generally adopted as the charging profile. In CCCV, power is first supplied at a constant current (CC) to prevent overcurrent charging, and then at a constant voltage (CV) to prevent overvoltage charging. The charging control unit 1C has a current / voltage detection unit 11C. The current / voltage detection unit 11C is used for these current and voltage controls.

[0032] The charger control unit 2C, via the second PLC communication unit 4C, receives information from the robot B1 or the detection results from the coupling sensor 8C, and performs on / off control of the charger load switch 6C, data communication to the second PLC communication unit 4C, and instructions to the charger control unit 1C. The charger control unit 2C consists of a CPU, memory, software, etc.

[0033] The second PLC communication unit 4C uses a PLC to input and output signals to and from the robot B1 connected to the second connector 5C. The carrier frequency used by the PLC in the second PLC communication unit 4C is selected from low speed (10k to 500kHz) and high speed (2M to 100MHz) depending on the required bit rate. The specific configuration of the second PLC communication unit 4C may be the same as the specific configuration of the first PLC communication unit 4B shown in Figure 2, for example.

[0034] The second connector 5C is connected to the first connector 5B of the robot B1 to charge the battery unit 1B of the robot B1 from the charger C1, and to transmit and receive signals such as control information between the charger C1 and the robot B1. The specific configuration of the second connector 5C will be described later.

[0035] The power line 9C connects to the second connector 5C and the charging control unit 1C. The number of power lines 9C is not limited; in the illustrated example, there are two power lines 9C.

[0036] The charger load switch 6C is located on the power line 9C. The ON / OFF state of the charger load switch 6C allows selection between a conductive state and a disconnected state of the power line 9C. The charger load switch 6C is controlled ON / OFF by the charger control unit 2C.

[0037] The coupling sensor 8C detects when the robot B1 and the charger C1 are in close proximity, such as when the first connector 5B and the second connector 5C are connected. The coupling sensor 8C may be mechanically detected by pressing a switch or the like, or it may be optically detected.

[0038] As shown in Figure 3, the first connector 5B of robot B1 and the second connector 5C of charger C1 are set to be at the same height from the mounting surface, for example. That is, the first connector 5B and the second connector 5C are located in corresponding positions to each other. The coupling sensor 8C acts as a trigger for starting charging, and is configured to detect even if the charger C1 and robot B1 are slightly misaligned vertically or horizontally.

[0039] Figures 4(a) to 4(c) show specific configuration examples of the first connector 5B and the second connector 5C. In the illustrated examples, the first connector 5B has a case 51B and two electrode plates 52B. The second connector 5C has a case 51C and two contacts 52C.

[0040] Case 51B supports two electrode plates 52B. Case 51B has a recess 511B. The recess 511B opens horizontally and accommodates at least a portion of each of the two electrode plates 52B. When the first connector 5B and the second connector 5C are connected, the opening of the recess 511B faces the second connector 5C.

[0041] The two electrode plates 52B are made of a metal such as copper, and in the illustrated example, they are roughly aligned horizontally and separated vertically. Power lines 9B are connected to each electrode plate 52B.

[0042] Case 51C supports two contacts 52C. Case 51C has a plurality of support parts 511C. The plurality of support parts 511C support each contact 52C from above and below.

[0043] The two contacts 52C are made of a conductive elastic material containing a metal such as copper. In the illustrated example, each contact 52C includes two parts separated vertically. Each part has, for example, a curved portion that protrudes toward the opposite side in the vertical direction. A gap exists between the two parts into which the electrode plate 52B can enter.

[0044] In the illustrated example, as shown in FIG. 4(c), the plurality of support portions 511C and the two contacts 52C protrude forward in the horizontal direction. When the first connector 5B and the second connector 5C are connected as the robot B1 and the charger C1 approach, the plurality of support portions 511C and the two contacts 52C are accommodated in the recess 511B of the first connector 5B. Further, each electrode plate 52B enters the gap between the contacts 52C, and each electrode plate 52B is sandwiched between the contacts 52C. At this time, since the contact 52C is made of an elastic material, the curved portion of the contact 52C can be pushed by the electrode plate 52B and bent in the vertical direction. Thereby, while widening the gap between the contacts 52C in the vertical direction, it is possible to more reliably sandwich the electrode plate 52B with the contacts 52C, and it is possible to reduce connection failures due to vertical displacement between the first connector 5B and the second connector 5C. Even if some vibration is applied to the first connector 5B or the second connector 5C, in order for the contact 52C and the electrode plate 52B to maintain the contact state, a force for sandwiching the electrode plate 52B by the contact 52C with an elastic force needs to be a certain level or more. In particular, when performing rapid charging, a current of about 50 A may flow through the power line 9B and the power line 9C, and it is important to maintain the contact state in order not to generate a spark or the like. When the electrode plate 52B enters the gap between the contacts 52C due to the force of the contact 52C sandwiching the electrode plate 52B, a frictional force is generated. That is, in order to connect the first connector 5B and the second connector 5C, it is necessary to insert and remove with a force greater than this frictional force. The insertion and removal force, which is the force required for insertion and removal, varies depending on the structure of the connector. For example, it is about 6 N per connection terminal. The insertion and removal force of the entire connector is the value obtained by multiplying this by the number of connection terminals, so it is possible to insert and remove with a smaller force when the number of connection terminals is smaller. Further, if the cross-sectional shape of the end portion of the electrode plate 52B is made into a shape such as a tapered shape where the thickness becomes thinner toward the tip of the end portion, the insertion and removal force can be reduced.

[0045] Also, in the illustrated example, as shown in FIG. 4(b), the horizontal width of the concave portion 511B and the two electrode plates 52B is larger than the horizontal width of the plurality of support portions 511C and the two contacts 52C. Thereby, even if the second connector 5C is displaced from the first connector 5B in the horizontal direction and in a direction orthogonal to the direction in which the first connector 5B and the second connector 5C approach each other, the first connector 5B and the second connector 5C can be properly connected.

[0046] Further, since the PLC communication signal is superimposed on the power lines 9B and 9C for supplying the power for charging the battery unit 1B, the number of connection terminals can be two, and as a result, the force required for attaching and detaching the first connector 5B and the second connector 5C can be suppressed. The attachment and detachment of the first connector 5B and the second connector 5C are performed by the moving propulsion force of the robot B1, but the moving propulsion force has an upper limit value determined by the maximum torque generated by the motor for movement, the maximum current that can be supplied to the motor, etc., so it is preferable that the force for attachment and detachment is reduced.

[0047] Next, charging in the battery charging system A1 will be described below while referring to FIG. 5.

[0048] First, the robot B1 recognizes the position of the charger C1 on the map constructed based on the information such as the indoor shape of the facility to be used and the installed objects, and approaches the charger C1 by autonomous driving. For the position recognition of the robot B1 on the map, a known method is used. For example, a camera image can be used. Also, at this time, a label such as a two-dimensional code may be attached to the charger C1 to perform the recognition of the charger C1 and the alignment of the robot B1 with respect to the charger C1.

[0049] Step S1: Next, the robot B1 approaches the charger C1 to a predetermined position and attempts to connect the first connector 5B and the second connector 5C. In the present embodiment, since the second connector 5C of the charger C1 has a structure that is inserted into the first connector 5B of the robot B1, the robot B1 moves so as to execute this.

[0050] Step S2: When robot B1 connects the first connector 5B and the second connector 5C, the coupling sensor 8C of charger C1 detects that robot B1 is in close proximity to charger C1.

[0051] Step S3: Triggered by the detection result of the coupling sensor 8C, the charger control unit 2C of the charger C1 instructs the second PLC communication unit 4C to transmit predetermined authentication data Sg1 to the robot B1. Since the authentication data Sg1 is used for the robot B1 to recognize whether the charger C1 is compatible with the target robot B1, it is desirable that the data be encrypted.

[0052] Step S4: The first PLC communication unit 4B of robot B1 receives the transmitted authentication data Sg1. The robot control unit 2B of robot B1 analyzes the authentication data Sg1 and verifies whether it was transmitted from a charger C1 compatible with it. If it is a compatible charger C1, robot B1 confirms the connection with charger C1. If the data is from an incompatible charger C1, it notifies the robot B1 of the abnormality, such as by sending an alert to the robot B1's administrator.

[0053] Step S5: When the robot control unit 2B of robot B1 recognizes that the authentication data Sg1 is compatible with it, it instructs the first PLC communication unit 4B to issue a charging start command to the charger C1. At the same time, it turns on the robot load switch 6B so that the power supplied from the charger C1 is transmitted to the battery unit 1B.

[0054] Step S6: The charger control unit 2C of charger C1 turns on the charger load switch 6C and instructs the charge control unit 1C to start charging. During charging, the charger control unit 2C obtains information such as the remaining capacity of the battery unit 1B via the second PLC communication unit 4C and transfers it to the charge control unit 1C. The charge control unit 1C controls the voltage and current supplied to the battery unit 1B according to the information of the battery unit 1B. The charge control unit 1C detects that the power line 9C has the appropriate voltage and current using the current / voltage detection unit 11C.

[0055] Step S7: If authentication data Sg1 could not be received in step S4, the robot control unit 2B determines that the connector connection failed and retryes from the alignment in step S1. More specifically, the robot control unit 2B determines that it has failed if authentication data Sg1 cannot be received within a predetermined time from step S1.

[0056] Step S8: When the battery unit 1B reaches a predetermined remaining capacity as a result of charging, the charger control unit 2C of the charger C1 instructs the charger control unit 1C to stop charging.

[0057] Step S9: The charger control unit 2C of charger C1 notifies robot B1 via the second PLC communication unit 4C that charging is complete. At the same time, the charger load switch 6C is turned off.

[0058] Step S10: The robot control unit 2B of robot B1 receives a completion notification Sg3 via the first PLC communication unit 4B. The robot control unit 2B performs termination processing, such as turning off the robot load switch 6B.

[0059] The coupling sensor 8C detects when the robot B1 and the charger C1 are in close proximity, but it cannot detect whether the first connector 5B and the second connector 5C are connected. If the charger C1 starts supplying power while the first connector 5B and the second connector 5C are not connected, there is a risk of electric shock if a user touches the contact 52C of the second connector 5C. In this embodiment, in step S4, the authentication data Sg1 transmitted from the charger C1 is analyzed, and only if the data is appropriate, in step S5, the robot control unit 2B turns on the robot load switch 6B. In this way, power is supplied to the second connector 5C of the charger C1 only when data is received, that is, only when the first connector 5B and the second connector 5C are connected, so there is no risk of electric shock. Similarly, the robot load switch 6B of the robot B1 is turned on only when the first connector 5B and the second connector 5C are connected. Therefore, when the electrode plate 52B of the first connector 5B is exposed, the voltage from the battery unit 1B will not be output to the first connector 5B. Thus, accidents that accidentally short-circuit the two electrode plates 52B can be prevented. The certification data Sg1 contains compatibility information between the charger C1 and the robot B1, so the robot will not be charged by an inappropriate charger by mistake.

[0060] Figure 6 is a timing chart showing an example of the operation of the battery charging system A1. When PLC communication is performed via power line 9C, the voltage level of the signal superimposed on power line 9C is only a few volts. However, when measuring the charging voltage by the current / voltage detection unit 11C while PLC communication is in progress, measurement errors due to the PLC signal occur. For example, in the charging of lithium-ion batteries, even a voltage overhang of 0.1V poses a fire risk, and voltage monitoring in units of 10mV is required. Therefore, to eliminate the influence of the PLC signal used for PLC communication and enable more precise charging voltage measurement, the time for PLC communication and the time for detecting the charging voltage and current are temporally separated, as shown in Figure 6.

[0061] To prevent overcharging of the battery unit 1B, the robot control unit 2B requests the communication control unit 12B to transmit the battery status of the battery unit 1B (step S1), and the communication control unit 12B transmits the battery status of the battery unit 1B via the first PLC communication unit 4B (step S2). For example, the communication control unit 12B transmits the battery status every 10 ms (period T = 10 ms). The charger control unit 2C of the charger C1 transfers the received information regarding the battery status to the charge control unit 1C. The charge control unit 1C controls the supplied voltage and current according to the battery status. The charger control unit 2C receives the information regarding the battery status and, after a certain period of time has elapsed, instructs the charge control unit 1C to detect the supplied voltage and current values ​​(step S3). The charge control unit 1C measures the voltage and current values ​​using the current / voltage detection unit 11C. Thereafter, the same procedure is repeated every period T.

[0062] With this type of control, the time spent on PLC communication and the time spent measuring the voltage and current of the power line 9C are separated. Therefore, when measurements are being taken, the PLC communication signals are not superimposed, enabling more accurate measurements. In this embodiment, the communication control unit 12B of the battery unit 1B has the function of periodically transmitting information about the battery state. However, the charger control unit 2C of the charge control unit 1C may periodically request the transmission of the battery state, and the communication control unit 12B of the battery unit 1B may respond to this request.

[0063] Next, we will explain the operation of the battery charging system A1.

[0064] According to this embodiment, signals are transmitted and received between the first connector 5B and the second connector 5C using PLC communication via power lines 9B and 9C, rather than using dedicated signal lines. This reduces the number of connection terminals for the first connector 5B and the second connector 5C, and the insertion / removal force required for connection is reduced, making it easier to connect the first connector 5B and the second connector 5C.

[0065] When the coupling sensor 8C detects that the robot B1 and the charger C1 are within a predetermined distance of each other, the charger control unit 2C transmits authentication data Sg1. This allows the authentication data Sg1 to be transmitted at a time when there is a high probability that the first connector 5B and the second connector 5C are connected.

[0066] Figures 7 to 10 show other embodiments of the present invention. In these figures, elements that are the same as or similar to those in the above embodiments are denoted by the same reference numerals. Furthermore, the configurations of each part in each modification and each embodiment can be appropriately combined with each other to the extent that no technical inconsistencies arise.

[0067] Figure 7 shows a second embodiment of the charger. In this embodiment, the charger C2 has a charge control unit 1C which includes a filter 12C. The filter 12C is located between the current / voltage detection unit 11C and the charger load switch 6C. The filter 12C is, for example, a low-pass filter. Since the power for charging is DC, the PLC signal can be removed by providing the filter 12C.

[0068] The superimposed frequencies used in PLC communication are 10 kHz to 500 kHz or 2 MHz to 100 MHz, but filter 12C functions more effectively in the higher frequency range of 2 MHz to 100 MHz. Furthermore, if the superimposed frequencies used in PLC communication are limited to a specific frequency band, a notch filter may be used as filter 12C, and only that specific frequency band may be removed by filter 12C. This suppresses the influence of the PLC signal, allowing for more accurate measurement of the voltage on the power line 9C.

[0069] Figure 8 shows a second embodiment of the robot. In this embodiment, robot B2 is configured to be able to start from shutdown mode. When robot B2 is powered off, such as when not in use, it enters shutdown mode to reduce power consumption of the battery unit 1B. In shutdown mode, only some functions of the robot control unit 2B are operating, and most functions necessary for the movement of robot B2, such as the first PLC communication unit 4B, are stopped from operating by methods such as not supplying power. Similarly, if the remaining charge of the battery unit 11B falls below a predetermined value, robot B2 also enters shutdown mode. If a lithium-ion battery is used in the battery unit 11B, over-discharge can lead to degradation and make it impossible to recharge. Therefore, to prevent over-discharge, robot B2 switches to a shutdown mode with low power consumption.

[0070] When robot B2 is in shutdown mode, even if the user manually connects it to charger C1 or charger C2, charging will not occur because the functions necessary for charging control in the robot control unit 2B are stopped. In particular, if the robot is in shutdown mode because the battery unit 11B has a low charge level, robot B2 cannot operate until the battery unit 11B is charged. Therefore, a mechanism is needed that will start charging even when connected to charger C1 or charger C2 while in shutdown mode.

[0071] As an example of such a mechanism, robot B2 further has a signal processing unit 7B. The signal processing unit 7B is connected to the power line 9B and the robot control unit 2B, and when the robot B2 is powered off (when the robot control unit 2B is in shutdown mode), if charger C1 or charger C2 is connected, it activates the robot control unit 2B via a PLC signal.

[0072] Figure 9 shows a specific example of the configuration of the signal processing unit 7B. The signal processing unit 7B in the illustrated example includes a differential amplifier 71B, a filter 72B, a comparator 73B, and two capacitors 74B. The two capacitors 74B are individually connected to the two power lines 9B. The differential amplifier 71B differentially amplifies the PLC signals superimposed on the two power lines 9B. The filter 72B extracts the carrier waves superimposed on the two power lines 9B. The comparator 73B binarizes the PLC signals that have passed through the filter 72B.

[0073] The differential amplifier 71B removes common-mode noise mixed in the two power lines 9B by differential amplification of the two power lines 9B, and also amplifies the PLC signal to a predetermined signal level. The filter 72B extracts only the signal bandwidth of the PLC signal from the output of the differential amplifier 71B. As needed, an LPF (low-pass filter) or BPF (band-pass filter) is used as the filter 72B. The comparator 73B converts the output of the filter 72B into a binarized signal of the signal level used by the robot control unit 2B. The comparator 73B outputs a high level when the input signal is above a predetermined value, and a low level when it is below a predetermined value.

[0074] Figure 10 shows the charging control in a battery charging system equipped with robot B2.

[0075] Step S1: The user moves robot B2 by pushing it or the like, and connects the first connector 5B and the second connector 5C.

[0076] Step S2: Once the first connector 5B and the second connector 5C are connected, the coupling sensor 8C detects that the robot B2 is in close proximity to the chargers C1 and C2.

[0077] Step S3: Triggered by the detection result of the coupling sensor 8C, the charger control unit 2C instructs the second PLC communication unit 4C to transmit predetermined authentication data Sg1 to the robot B2.

[0078] Step S4: The first PLC communication unit 4B of robot B2 is not operating in shutdown mode and therefore cannot receive data. Instead, the signal processing unit 7B processes the PLC signal and sends the binarized signal to the robot control unit 2B. This binarized signal is connected to the CPU startup terminal included in the robot control unit 2B. The startup terminal is configured to detect the rising and falling edges of the input signal and perform the CPU startup process. Therefore, the CPU can start the startup process without decoding the PLC signal, and the CPU performs the startup process. The startup process includes supplying power to the first PLC communication unit 4B and initial settings. In addition, it enables the operation of functions necessary for charging robot B2. Power may also be supplied to indicators and display circuits that show that charging is in progress. Once the startup process is complete, the startup terminal is disabled so that the startup process is not performed again by PLC communication during charging.

[0079] Step S5: The charger control unit 2C is configured to resend authentication data Sg1 at predetermined time intervals if it does not receive a charging start instruction Sg2 from robot B2 within a predetermined time. Since the charger control unit 2C has not received a charging start instruction Sg2 from robot B2, it resends authentication data Sg1 at predetermined time intervals. In some cases, the charging start instruction Sg2 may not be received because the first connector 5B and the second connector 5C are not properly connected, so the resending of authentication data Sg1 is performed only for a certain period of time. If the charging indicator does not light up after a certain period of time has elapsed, the user can recognize that the connection is not correct. In this case, the user manually moves robot B2 to reconnect the first connector 5B and the second connector 5C.

[0080] Step S6: The first PLC communication unit 4B of robot B2 receives the transmitted authentication data Sg1. The robot control unit 2B analyzes the authentication data Sg1 and verifies whether it was transmitted from chargers C1 and C2 that are compatible with it. If the data is from an incompatible charger, it notifies the robot B2's administrator of the abnormality, such as by sending an alert.

[0081] Step S7: When the robot control unit 2B of robot B2 recognizes that the authentication data Sg1 is compatible with it, it instructs the first PLC communication unit 4B to issue a charging start command Sg2 to chargers C1 and C2. At the same time, it turns on the robot load switch 6B so that the power supplied from chargers C1 and C2 is transmitted to the battery unit 1B.

[0082] Step S8: The charger control unit 2C turns on the charger load switch 6C and instructs the charge control unit 1C to start charging. During charging, the charger control unit 2C obtains information such as the remaining capacity of the battery unit 1B via the second PLC communication unit 4C and transfers it to the charge control unit 1C. The charge control unit 1C controls the voltage and current supplied to the battery unit 1B according to the information from the battery unit 1B. The charge control unit 1C detects that the power line 9C has the appropriate voltage and current using the current / voltage detection unit 11C.

[0083] Step S9: When the battery unit 1B reaches a predetermined remaining capacity as a result of charging, the charger control unit 2C instructs the charger control unit 1C to stop charging.

[0084] Step S10: The charger control unit 2C notifies the robot B2 via the first PLC communication unit 4B that charging is complete. At the same time, the charger control unit 2C turns off the charger load switch 6C.

[0085] Step S11: The robot control unit 2B receives a completion notification Sg3 via the first PLC communication unit 4B. The robot control unit 2B performs termination processing, such as turning off the robot load switch 6B.

[0086] Even when robot B2 is in shutdown mode, the user can activate robot control unit 2B and start the functions necessary for charging simply by connecting it to chargers C1 and C2. This is highly convenient as the user does not need to operate any switches or input screens to activate the robot. Furthermore, since the first PLC communication unit 4B does not need to be kept running to receive PLC data for activating robot control unit 2B in shutdown mode, power consumption can be reduced.

[0087] The battery charging system according to the present invention is not limited to the embodiments described above. The specific configuration of each part of the battery charging system according to the present invention can be modified in various ways.

[0088] A1: Battery charging system, B1, B2: Robot, C1, C2: Charger, 1B: Battery unit, 1C: Charging control unit, 2B: Robot control unit, 2C: Charger control unit, 3B, 3C: Power supply unit, 4B: First PLC communication unit, 4C: Second PLC communication unit, 5B: First connector, 5C: Second connector, 6B: Robot load switch, 6C: Charger load switch, 7B: Signal processing unit, 8C: Coupling sensor, 9B, 9C: Power line, 11B: Battery unit, 11C: Voltage detection unit, 12B: Communication control unit, 12C: Filter, 41B: PLC modem, 42B: Capacitor, 51B, 51C: Case, 52B: Electrode plate, 52C: Contact, 71B: Differential amplifier, 72B: Filter, 73B: Comparator, 74B: Capacitor, 511B: Recess, 511C: Support part, Sg1: Authentication data, Sg2: Charging start instruction, Sg3: Completion notification, T: Period

Claims

1. A battery charging system comprising an autonomous robot and a charger, wherein the robot includes a battery unit for operating the robot, a robot control unit for controlling the robot, a first PLC communication unit for performing PLC communication, and a first connector for connecting to the charger, and the charger includes a charging control unit for supplying power to charge the battery unit, a charger control unit for controlling the charger, a second PLC communication unit for performing PLC communication, and a second connector for connecting to the robot, and the first PLC communication unit and the second PLC communication unit transmit and receive control information for charging via a power line connecting the battery unit and the charging control unit.

2. The battery charging system according to claim 1, wherein the charging control unit transmits authentication data via the second PLC communication unit, and when the robot control unit receives the authentication data, it transmits a charging start instruction via the first PLC communication unit.

3. The battery charging system according to claim 2, wherein the charger has a charger load switch for turning on or off the electrical connection between the charge control unit and the second connector, and the charge control unit turns on the charger load switch after receiving the charging start instruction from the robot.

4. The battery charging system according to claim 2, wherein the robot has a robot load switch for turning on or off the electrical connection between the battery unit and the first connector, and the robot control unit turns on the robot load switch after transmitting the charging start instruction.

5. The battery charging system according to claim 2, wherein the authentication data includes compatibility information between the robot and the charger.

6. The battery charging system according to claim 2, wherein the charger is equipped with a coupling sensor that detects a proximity state in which the robot and the charger are in close proximity to each other at a predetermined distance or less, and the charger transmits the authentication data when the coupling sensor detects the proximity state.

7. The battery charging system according to claim 2, wherein the charging control unit has a current / voltage detection unit that detects the current or voltage of the power line, the current / voltage detection unit detects the current or voltage during periods when PLC communication is not being performed by the first PLC communication unit and the second PLC communication unit, and the charging control unit controls the power to be charged according to the value detected by the current / voltage detection unit.

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