Charging system for legged mobile robot

A charging system for a legged mobile robot that facilitates positioning of a robot to be charged and does not put a load on the robot is provided. The charging system includes a battery 2, a power receiving connector 4 and a movable shutter member 5 capable of being opened and closed on a rear cover 3, which are provided on a robot 1, and a holder 21, a power supplying connector 22, a slide mechanism 23, a base plate 25, a charging power supply 26 and the like, which are provided on a charging station 20. The robot 1 performs a predetermined positioning on the base plate 25 and then moves the center of gravity rearward to connect the power receiving connector 4 to the power supplying connector 22. In this step, when the rear cover 3 of the robot 1 is guided by a first guide section 21a of the holder 21, the slide mechanism 23 allows the holder 21 to move horizontally. Thus, even if the robot 1 and the charging station 20 are slightly misaligned with each other, the robot 1 can be easily positioned correctly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for charging a battery of a legged mobile robot.

2. Description of the Related Art

For example, Japanese Patent Laid-Open No. 2001-179663 discloses a system for charging a battery of a legged mobile robot configured as described below. A power receiving connector used for charging an internal battery is provided near the hip part of the robot, and a power receiving terminal is exposed on the surface of the power receiving connector. On the other hand, a charging station for charging the robot has a power supplying connector, and a power supplying terminals is exposed on the surface of the power supplying connector. The robot moves closer to the charging station and connects the power receiving connector to the power supplying connector. As a result, the power receiving terminal and the power supplying terminal are connected to each other, and the robot is charged.

In the system disclosed in Japanese Patent Laid-Open No. 2001-179663, in order to facilitate alignment between the robot and the charging station, the power receiving connector has a trapezoidal profile narrower at the end close to the power supplying connector, and the power supplying connector has a recess shaped to confirm to the profile of the power receiving connector. Therefore, even if the robot to be charged is slightly misaligned, the trapezoidal power receiving connector is guided by the recess in the power supplying connector and connected to the power supplying connector, and thus, the positioning of the robot to be charged is facilitated (see the paragraphs 0139 and 0145 and FIGS. 7 to 9).

When alignment of the system configured as described above is performed, since the charging station is fixed to the floor or the like, the connector on the robot has to be moved to achieve alignment between the connectors. In the case of the legged mobile robot disclosed in Japanese Patent Laid-Open No. 2001-179663, since the power receiving connector is attached to the hip part, the joints of knees, ankles or the like have to be moved, or the legs have to be displaced, in order to move the power receiving connector.

However, in the case of the legged mobile robot, if the hip part is moved horizontally by moving the joints of knees, ankles or the like without displacing the legs, the center of gravity of the robot is displaced, and therefore, the robot has to be charged with the joints being subjected to a moment. If the robot is charged with the joints being subjected to a moment as described above, additional power is required to maintain the posture of the robot, and there is a possibility that the power consumption during charging increases. If the power receiving connector is displaced by displacing the legs, the legs of the robot are displaced with the power receiving connector and the power supplying connector being partially in contact with each other, so that the connectors are overloaded, and the connectors can be damaged.

Furthermore, the power receiving terminal disclosed in Japanese Patent Laid-Open No. 2001-179663 is always exposed to the outside, and therefore, if the surface of the terminal is soiled with something, the electrical contact between the power receiving terminal and the power supplying terminal can be poor. Furthermore, in the case of the arrangement disclosed in Japanese Patent Laid-Open No. 2001-179663, if spark discharge (ark discharge) occurs when the power receiving terminal and the power supplying terminal are connected to each other for charging of the robot or disconnected from each other after charging of the robot, the spark discharge can cause deterioration of the terminals, the deterioration of the terminals can cause an increase of the resistance between the terminals, and the increase of the resistance can cause heat generation.

SUMMARY OF THE INVENTION

An object of the present invention is to improve a charging system for a legged mobile robot. More specifically, in order to eliminate the disadvantages described above, an object of the present invention is to provide a charging system that facilitates positioning of a robot to be charged and does not put a load on the robot. Another object of the present invention is to provide a charging system that prevents a power receiving terminal from being soiled or deteriorated and does not make any nearby person from feeling uncomfortable.

In order to attain the objects described above, a charging system for a legged mobile robot according to the present invention is a charging system that charges a battery of a legged mobile robot, comprising: a charging station on which the robot is charged, in which the robot includes a power receiving connector having a power receiving terminal, and the charging station includes a charging power supply that outputs a charging current to the battery, a power supplying connector designed to be connected to the power receiving connector, a power supplying terminal provided on the power supplying connector and designed to come into contact with the power receiving terminal, guide means that guides the robot to reduce the misalignment between the power receiving connector and the power supplying connector in a predetermined direction when the robot comes close to the charging station for charging, and moving means for moving the guide means in the predetermined direction by the force exerted on the guide means as the robot comes close to the charging station.

In the charging system according to the present invention, if the robot comes close to the charging station to be charged on the charging station, the guide means guides the robot to reduce the misalignment between the power receiving connector and the power supplying connector in the predetermined direction. When the robot is guided by the guide means, a force that moves the robot and the guide means relative to each other in the predetermined direction occurs between the robot and the guide means. When such a force occurs between the two, the moving means moves the guide means in the predetermined direction. Accordingly, there is no need to adjust the joints of knees, ankles or the like to compensate for the misalignment on the part of the robot, so that the robot can be charged in a natural, reasonable posture, and therefore, the robot can be easily controlled. As a result, unlike conventional systems, no power is consumed for maintaining the unreasonable posture of the robot, and thus, the robot can be quickly charged.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the predetermined direction is a horizontal direction which is perpendicular to the direction in which the robot comes close to the charging station for charging. As for the vertical alignment, if the height of the power supplying connector on the charging station is not changed, the robot itself can adjust the height of the power receiving connector. Misalignment of the robot moving to the predetermined position on the charging station is likely to occur in the horizontal direction perpendicular to the direction in which the robot comes close to the charging station for charging. Therefore, by setting the direction of guiding by the guide means and the direction of movement by the moving means to be horizontal and perpendicular to the direction in which the robot comes close to the charging station for charging, the positioning of the robot in the direction in which misalignment is likely to occur is facilitated.

Furthermore, the moving means may have a slide rail that is provided on the charging station and extend horizontally and a slide block capable of horizontally moving along the slide rail, and the power supplying connector may be fixed to the slide block.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the power supplying connector is fixed to the slide block via a rubber bush. With such a configuration, the power supplying connector can move not only horizontally but also vertically to some extent. Therefore, even if the power supplying connector and the power receiving connector are slightly vertically misaligned with each other when the robot is charged on the charging station, the rubber bush can accommodate the misalignment.

Furthermore, it is preferred that the charging system for a legged mobile robot according to the present invention further comprises a locking mechanism that locks the robot and the charging station to maintain the connection between the power receiving terminal and the power supplying terminal when the power receiving terminal and the power supplying terminal are connected to each other. With such a configuration, the locking mechanism maintains the connection between the power receiving terminal and the power supplying terminal even if an external force is exerted on the robot during charging for some reason, so that disconnection between the connectors during charging is prevented.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the guide means includes a guide pin having a tapered tip and provided on one of the robot and the charging station and a guide sleeve having a widened opening and provided on the other of the robot and the charging station to which the guide pin is to be inserted, and the moving means is a floating member having resiliency that enables the guide pin or the guide sleeve to move in the predetermined direction.

With such a configruatin, even if the power supplying connector and the power receiving connector are slightly misaligned with each other, the tapered tip of the guide pin abuts against the inner surface of the widened opening of the guide sleeve, and the guide pin is inserted into the guide sleeve. In addition, since the moving means can move the guide pin or the guide sleeve in the predetermined direction, the power supplying connector can be guided by the guide means to a position where the power supplying connector can be connected to the power receiving connector.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the guide means has a locking mechanism that prevents the guide pin from dropping from the guide sleeve when the guide pin is inserted into the guide sleeve, and the power receiving connector and the power supplying connector are connected to each other. In the case where the locking mechanism is provided for the guide pin and the guide sleeve in this way, the guide means and the locking mechanism may be integrated. Thus, the arrangement of the guide means and the locking mechanism can be downsized.

In the case where the locking mechanism is provided for the guide pin and the guide sleeve in this way, the guide means may have rotating means capable of rotating the guide pin, the guide sleeve may have a guide slit composed of a longitudinal slit extending in the axial direction toward the opening of the guide sleeve and an engaging slit extending in the circumferential direction of the guide sleeve from the root of the longitudinal slit, the guide pin may have an engaging protrusion that protrudes from the periphery thereof and is capable of being inserted into the guide slit, and when the power receiving connector and the power supplying connector are connected to each other, the engaging protrusion may be inserted into the longitudinal slit of the guide slit, and then inserted into the engaging slit of the guide slit by the action of the rotating means, and then held in that state.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the power receiving connector is provided inside the robot and covered with a lid capable or being opened and closed, and the lid is closed when the power receiving connector and the power supplying connector are not connected to each other and opened when the power supplying connector comes close to the power receiving connector. With such a configuration, when the power receiving connector and the power supplying connector are not connected to each other, the power receiving connector is housed in the robot, covered with the lid and therefore shielded from the outside, so that there is no possibility that the power receiving terminal comes into contact with an outside obstacle or the like during movement of the robot. In addition, since the power receiving connector and the power receiving connector are housed in the robot except during charging, the power receiving terminal and the power receiving connector are not affected by the outside environment of the robot and are prevented from being soiled.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that the charging station includes connection detection means for detecting whether the power receiving terminal and the power supplying terminal are connected to each other, and charging control means for making the charging power supply supply a charging current to the battery to charge the battery via the power supplying terminal and the power receiving terminal when the connection detection means detects that the power receiving terminal and the power supplying terminal are connected to each other. With such a configuration, the charging current is supplied only after the power receiving terminal and the power supplying terminal are connected to each other, and therefore, there is no possibility that a spark discharge occurs between the power receiving terminal and the power supplying terminal when the connectors are connected to each other.

Furthermore, in the charging system for a legged mobile robot according to the present invention, it is preferred that, when stopping charging of the battery, the charging control means stops the supply of the charging current from the charging power supply to the battery before disconnecting the power receiving terminal and the power supplying terminal. With such a configuration, since the supply of the charging current is stopped before the connectors are disconnected, there is no possibility that a spark discharge occurs between the power receiving terminal and the power supplying terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, a charging system according to an embodiment of the present invention will be described with reference toFIGS. 1 to 9.FIG. 1is a diagram showing a robot that is being charged on a charging station of the charging system according to this embodiment.FIG. 2is a plan view of the robot shown inFIG. 1and some components arranged in the rear cover of the robot.FIG. 3(a) is a cross-sectional view of a power supplying connector and a power receiving connector, andFIG. 3(b) is a cross-sectional view taken along the line b-b inFIG. 3(a).FIG. 4is a circuit diagram of the charging system according to this embodiment.FIG. 5is a flowchart illustrating a charging operation of the robot.FIGS. 6(a) to6(d) are diagrams for illustrating the charging operation of the robot.FIGS. 7(a) and7(b) are diagrams for illustrating a connecting operation in the case where the robot and the charging station are misaligned with each other.FIGS. 8(a) to8(d) are diagrams for illustrating connection between the power receiving connector and the power supplying connector.FIG. 9is a flowchart illustrating an operation of disconnecting the power receiving connector and the power supplying connector from each other.

As shown inFIG. 1, the charging system for a legged mobile robot has a charging station20that charges a battery2of a legged mobile robot1. The charging station20comprises a holder (guide means)21that holds a rear cover3provided on the back of the robot1, a power supplying connector22provided on the holder21, a slide mechanism (moving means)23that holds the holder21and the power supplying connector22in a horizontally movable manner, a support strut24that supports the slide mechanism23, a base plate25that supports the support strut24in an upright position, and a charging power supply26that charges the battery2of the robot1. In addition, on the surface of the base plate25, there is provided a reference position mark27for the robot1to recognize the stopping position using a visual sensor (not shown) provided in the head of the robot1.

As shown inFIG. 2, the holder21has first guide sections21athat horizontally radially extend toward the robot1and a second guide section21bthat is substantially U-shaped when observed from a top view to conform to the contour of the rear cover3of the robot1. According to this embodiment, the first guide sections21aand the second guide section21bconstitute the guide means. The slide mechanism23has a slide rail23athat extends horizontally and is fixed to the support strut24and a slide block23bthat can move horizontally along the slide rail23a. The holder21is fixed to the slide block23bvia a rubber bush23c. This allows the holder21to move vertically and horizontally relative to the slide block23bto some extent.

Furthermore, as shown inFIG. 2, the power supplying connector22extends forward (rightward in the drawing) from the center of the holder21. As shown inFIGS. 3(a) and3(b), the power supplying connector22has a block-shaped power supplying connector housing28and a power supplying terminal29in the power supplying connector housing28. As shown inFIGS. 3(a) and3(b), the power supplying connector housing28has protrusion members28athat protrude toward the power receiving connector4. In addition, the power supplying connector housing28has latch fixing holes28b, into which a fitting latch8described later is inserted, formed in both lateral side surfaces thereof. The power supplying terminal29is composed of a pair of charging terminals29aand29jand eight signal terminals29bto29ifor signal transmission. The charging terminals29aand29jare disposed on both lateral sides of the signal terminals29bto29i. Furthermore, as shown inFIG. 3(a), the charging terminals29aand29jof the power supplying terminal29are flat terminals having recesses29a′ and29j′ in the contact surface, respectively, and the signal terminals29bto29iare flat terminals that have a flat contact surface.

Now, referring toFIGS. 2,3(a) and3(b), an arrangement of the power receiving connector4provided on the robot1will be described. The power receiving connector4is provided in the rear cover3of the robot1along with the battery2and is shielded from the outside of the rear cover3by a movable shutter member (lid member)5except during charging as shown inFIGS. 3(a) and3(b). The movable shutter member5is composed of a shutter5athat covers the surface of the power receiving connector4, a shutter case5bthat holds one edge of the shutter5aso that the shutter5acan pivot about the edge, and a shutter spring5cthat biases the shutter case5btoward the surface of the rear cover3.

As shown inFIGS. 3(a) and3(b), the power receiving connector4has a power receiving connector housing6and a power receiving terminal7capable of moving back and forth provided in the power receiving connector housing6. In addition, on both lateral sides of the power receiving connector housing6, the power receiving connector4has a pair of fitting latches8capable of moving back and forth in a direction perpendicular to the direction of attachment and detachment of the power supplying connector22. The power receiving terminal7is composed of charging terminals7aand7jto which a charging current is supplied and eight signal terminals7bto7ifor signal transmission. The charging terminals7aand7jare disposed on both lateral sides of the signal terminals7bto7i. The charging terminals7aand7jand the signal terminals7bto7ihave a semispherical tip and are spring-pin-type terminals that are biased toward the power supplying terminal29by a spring9. The charging terminals7aand7jextend toward the power supplying connector22beyond the tips of the signal terminals7bto7i.

As shown inFIG. 3(a), the fitting latch8has a claw member8athat can move back and forth and has a chamfered, arc-shaped edge at one side at which the claw member8acomes into contact with the power supplying connector22, a spring8bfor biasing the claw member8ain a direction that the claw member8aprotrudes, a solenoid8cfor pulling the claw-member8ain a direction that the claw member8ais retracted, and an unlatching detection switch8dthat detects unlatching when the claw member8ais kept in the retracted position. According to this embodiment, the fitting latches8and the latch fixing holes28bformed in the power supplying connector22constitute a locking mechanism.

Now, referring toFIG. 4, a circuit diagram of the charging system will be described. The robot1has a controller30that controls the operations of the arms, the legs and the like of the robot1and serves as charge control means during charging, and an unlatching switch31that performs unlatching using the solenoid8cof the fitting latch8. In addition, the robot1has a pair of charging lines32aand32jconnected to the charging terminals7aand7j, a power supply output OFF line33connected to the signal terminal7bfor transmitting a power supply output OFF signal, and an unlatching command line34that connects the unlatching switch31and the controller30to each other. The controller30and the signal terminal7dof the power-receiving connector4are connected to each other via a connection detection line35.

When the power receiving connector4is connected to the power supplying connector22, the connection detection line35is connected to the signal terminal7eof the power receiving connector4via a line36described later and grounded via a line37. Furthermore, the connection detection line35is connected to a power supply Vcc via a resistor38a. The unlatching switch31is intended to interrupt electric power supply from the power supply Vcc to the solenoid8c, the line to the power supply Vcc is connected to an unlatching command line39via a resistor38b, and the unlatching command line39is connected to the unlatching detection switch8d.

The charging station20has a pair of charging lines40aand40jextending from the charging power supply26and connected to the charging terminals29aand29j, a power supply output OFF line41connected to the signal terminal29bfor receiving the power supply output OFF signal, and a line36that connects the signal terminals29dand29eto each other. According to this embodiment, the controller30, the connection detection line35, the line36and the line37constitute connection detecting means.

Now, referring toFIGS. 5 and 6, a charging operation of the robot1will be described. First, when the controller30determines that the battery2has to be charged because the remaining capacity of the battery2becomes lower than a predetermined level, for example, the robot1searches for and locates the charging station20with the visual sensor (not shown). Once the visual sensor locates the charging station20, the controller30makes the robot1move to a predetermined position near the charging station20(step S1). Then, the robot1performs a first positioning to a predetermined position on the base plate25of the charging station20(step S2). Then, the robot1makes a 180-degree turn to aim the rear cover3at the holder21(step S3). Then, the robot1determines the position at which the robot1should rest with reference to the reference position mark27on the surface of the base plate25of the charging station20and performs a second positioning (step S4). Then, the robot1shifts the center of gravity rearward to displace the waist rearward, thereby bringing the rear cover3close to the holder21(step S5).

At this time, if the holder21and the rear cover3are slightly horizontally misaligned with each other as shown inFIG. 7(a), the holder21is aligned to the rear cover3as described below. First, the rear cover3abuts against the first guide section21aof the holder21. If the rear cover3further moves toward the holder21from this state, the rear cover3pushes the holder21leftward inFIG. 7(a). Since the slide mechanism23enables the holder21to move horizontally, when the rear cover3pushes the first guide section21aof the holder21, the holder21slides upward inFIG. 7(b). And the rear cover3is guided by the first guide section21aof the holder21and housed in the second guide section21b. In this way, the power receiving connector4and the power supplying connector22are horizontally aligned with each other.

As for vertical alignment between the power receiving connector4and the power supplying connector22, since the robot1is charged on the base plate25of the charging station20, and the height of the power receiving connector4of the robot1can be readily controlled, vertical misalignment between the connectors is unlikely to occur. Therefore, according to this embodiment, the holder21does not have a vertical alignment mechanism like the horizontal slide mechanism but has a simple mechanism, such as the rubber bush23c.

Now, referring toFIG. 8, an operation of connecting the power receiving connector4to the power supplying connector22will be described. As the rear cover3of the robot1is guided by the second guide section21bof the holder21, the state shown inFIG. 8(a) changes to the state shown inFIG. 8(b). Specifically, the protrusion members28aof the power supplying connector housing28comes into contact with the shutter case5bof the movable shutter member5. The protrusion members28aof the power supplying connector housing28are formed to abut against the shutter case5bat both lateral sides of the shutter5ain the side view. Therefore, if the power supplying connector housing28is pushed rightward inFIG. 8(b), the shutter case5bmoves rightward while pushing the shutter spring5c. Thus, as shown inFIG. 8(c), the shutter5ais pushed by the power receiving connector housing6and opened. Then, if the power supplying connector housing28is further pushed rightward from the state shown inFIG. 8(c), the power supplying terminal29and the power receiving terminal7come into contact with each other and are connected to each other as shown inFIG. 8(d).

Since the charging terminals7aand7jof the power receiving terminal7protrude toward the power supplying connector22beyond the tips of the signal terminals7bto7ias shown inFIG. 3(a), when the power receiving connector4and the power supplying connector22are connected to each other, the charging terminals7aand7jfirst come into contact with the charging terminals29aand29j. Then, when the power receiving connector4and the power supplying connector22move closer to each other, the springs9of the charging terminals7aand7jare pressed, and the signal terminals7bto7icome into contact with the signal terminals29bto29i.

Once the signal terminal7dand the signal terminal29dcome into contact with each other, as shown in the circuit diagram ofFIG. 4, the connection detection line35is grounded via the line36on the power supplying connector22, the signal terminal7eand the line37, and thus, connection between the power receiving terminal7and the power supplying terminal29is detected (Yes in step S6). If the unlatching detection switch8dis not opened in this state, the controller30determines that the fitting latches8are normally fitted into the latch fixing holes28b(Yes in step S7). When the controller30confirms that the power supplying connector22and the power receiving connector4are connected to each other through the process described above, the controller30permits the charging operation (step S8), allowing the charging power supply26to supply a charging current to the battery2via the charging terminals29aand29jand the charging terminals7aand7j, thereby charging the battery2(step S9).

Then, except the case where a work request is externally received (No in step S10), charging of the battery continues until the controller30confirms that the battery2is completely charged (Yes in step S11). If a work request is externally received (if Yes in step S10), the controller30extracts a work model, which is the same as or similar to the requested work, from a plurality of work models stored in a storage device (not shown) of the controller30and calculates the workload (step S14). Then, based on the calculated workload, the controller30determines whether the current remaining capacity of the battery2suffices for the work (step S15) and, if the current remaining capacity suffices for the work, terminates the charging operation and carries out the requested work. If the current remaining capacity of the battery does not suffice for the requested work, the controller30informs the person who has requested the work that the work cannot be carried out (step S16) and continues the charging operation (No in step S11).

According to this embodiment, the slide mechanism23enables wide horizontal movement of the holder21. In addition, the power receiving terminal7is a spring-pin-type terminal, the power supplying terminal29is a flat terminal, and such characteristics of the terminals can also help to accommodate misalignment between the terminals to some extent. Therefore, in most cases, charging of the robot1can be accomplished by the process described above. However, in the case where connection between the power receiving terminal7and the power supplying terminal29is not detected in step (S6) described above within a predetermined time from the time when the rear cover3is brought close to the holder21in step (S5) described above for some reason, or in the case where fitting of the fitting latches8into the latch fixing holes28bis not confirmed in step (S7) described above, an error process is carried out as described below.

First, the robot1detects the deviation of the standing position thereof from the lateral center position of the charging station20by means of the visual sensor (not shown) that detects the reference position mark27on the base plate25. If the deviation falls within a limit value and can be compensated for only by moving the waist, without moving the legs (Yes in step S12), the robot1moves the waist to adjust the position of the power receiving connector4(step S5). On the other hand, if the deviation exceeds the limit value and cannot be compensated for without the leg movement (No in step S12), the position of the waist is restored to the position before connection (step S13), and the second positioning is carried out again (step S4).

Now, referring toFIGS. 5,4and9, an operation of separating the robot1being charged from the charging station20will be described. First, referring toFIG. 5, when the charging is completed (Yes in step S11), or when a work is externally requested, and the work can be carried out (Yes in step S15), a separation operation described below is started. First, referring toFIG. 4, the controller30transmits the power supply-output OFF signal to the charging station20via the power supply output OFF lines33and41. As a result, the charging current supplied from the charging power supply26to the battery2is interrupted (step S21).

Then, when the voltage between the paired charging terminals7aand7jbecomes lower than a predetermined threshold (Yes in step S22), the controller30performs the unlatching process of the fitting latches8(step S23). The unlatching process of the fitting latches8is performed with the unlatching switch31closed by the controller30and the solenoid8cenergized by the power supply Vcc. As a result of the unlatching process, the claw members8aare drawn toward the respective solenoids8cand disengaged from the latch fixing holes28bin the power supplying connector housing28of the power supplying connector22, so that the power receiving connector4and the power supplying connector22can be disconnected from each other. At the same time, the unlatching detection switch8dis turned on, and the controller30is informed of the unlatching of the fitting latches8(Yes in step S24).

When the controller30confirms the unlatching of the fitting latches, the controller30controls the robot1to move the waist of the robot1back to the position before charging (step S25). When the power receiving connector4and the power supplying connector22are disconnected from each other by this operation, the signal terminals7bto7iand the signal terminals29bto29iare also disconnected from each other, so that the connection detection line35is opened. Thus, the controller30confirms that the power receiving connector4and the power supplying connector22are normally disconnected from each other (Yes in step S26). In this way, separation of the robot1from the charging station20is completed. At this time, the shutter spring5cpushes the shutter case5b, so that the state shown inFIG. 8(d) changes back to the state shown inFIG. 8(a), and the front of the power receiving connector4is closed by the shutter5a.

If the voltage between the paired charging terminals7aand7jdoes not become lower than the predetermined threshold in step (S22) described above, if the unlatching of the fitting latches8is not detected in step (S24) described above, or if it is determined that the waist of the robot1has to be moved beyond a limit value in step (S27), an error process is carried out by informing the abnormality by an alarm or the like provided in the robot1, for example (step S28).

The charging system according to this embodiment can charge the robot1without laterally moving the center of gravity of the robot1, so that the robot1can be easily controlled during charging. In addition, since the center of gravity of the robot1does not laterally move, and the robot1can lean against the charging station20during charging, the power required to maintain the posture of the robot1during charging can be reduced. In addition, since the power receiving terminal7is housed in the rear cover3of the robot1except during charging, there is no possibility that the power receiving terminal7comes into contact with an outside obstacle and is damaged thereby when the robot1moves.

In addition, since the charging terminals7aand7jof the power receiving terminal7protrude toward the power supplying connector22beyond the tips of the signal terminals7bto7i, spark discharge can be prevented from occurring on the signal terminals7bto7i, so that deterioration of the terminals due to the spark discharge can be prevented. The charging terminals29aand29jof the power supplying connector22have the recesses29a′ and29j′, respectively, formed in the contact surface, and the charging terminals7aand7jof the power receiving connector4have the semispherical tip. Therefore, the charging connectors29aand29jand the charging connectors7aand7jare in surface contact with each other over a wide contact area. As a result, the resistance between the terminals is reduced.

According to the embodiment described above, the holder21has the first guide sections21aand the second guide section21b. However, the present invention is not limited thereto, and the holder21may have only a component like the first guide sections21a, which extend horizontally radially toward the robot1. Furthermore, according to this embodiment, the holder21and the slide block23bare coupled with each other by the rubber bush23c. However, the present invention is not limited thereto, and a slide mechanism capable of moving vertically and horizontally may be provided to enable the slide block23bto slide not only horizontally but also vertically.

Now, a charging system for a legged mobile robot according to a second embodiment of the present invention will be described with reference toFIGS. 10 to 12.FIG. 10is a diagram illustrating an arrangement of a power receiving connector and the like in the rear cover of a robot according to the second embodiment.FIG. 11is a diagram illustrating an arrangement of essential internal components of a charging station according to the second embodiment.FIG. 12is a diagram showing connection between a power receiving connector and a power supplying connector according to the second embodiment. In the following description of the second embodiment, the same components as in the embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted. Furthermore, inFIG. 10, illustration of the shutter member of a rear cover3of a robot1′ is omitted.

The charging system according to the second embodiment has a charging station20′ that charges a battery2(seeFIG. 1) of a legged mobile robot1′. The charging system has a power receiving connector4shown inFIG. 10and a power supplying connector22shown inFIG. 11that are the same as those in the embodiment described above and a circuit arrangement that is the same as that shown inFIG. 4except for the part involved with the fitting latch8. On the other hand, generally, the charging system according to the second embodiment has guide means, a locking mechanism and moving means that are different from those according to the embodiment described above.

According to the second embodiment, the guide means is composed of a pair of guide sleeves50provided on the robot1′ and a pair of guide pins60(60a,60b) provided on the charging station20′. As shown inFIG. 10, the guide sleeves50are metal cylinders having a widened open end. The guide sleeves50are disposed on the left and right sides of the power receiving connector4on the robot1′. As shown inFIG. 11, the guide pins60aand60bare circular columns made of metal having a conical tip. The guide pins60aand60bare disposed on the left and right sides of the power supplying connector22on the charging station20′.

According to the second embodiment, the locking mechanism is composed of guide slits51formed in the guide sleeves50, engaging pins (engaging protrusions)61formed on the periphery of the guide pins60and capable of moving in the guide slits51, a guide pin motor62(rotating means) for rotating the guide pin60aof the pair of guide pins60aand60b, and a linkage mechanism63coupled to the guide pin motor62to rotate the other guide pin60b. The guide slit51is composed of a longitudinal slit51aextending in the axial direction of the guide sleeve50toward the open end thereof and an engaging slit51bextending in the circumferential direction of the guide sleeve50from the inner end of the longitudinal slit51a. A pair of such guide slits51are formed in the left and right walls of the guide sleeve50. Furthermore, The engaging slits51bof the paired guide slits51extend in the same direction (clockwise in the second embodiment) when seen from the side of the open end of the guide sleeve50. The engaging pins61are circular columns made of metal, which penetrate through the respective guide pins60and are fixed thereto.

The guide pin motor62is disposed at the bottom of the guide pin60aand fixed to a connector holder64that holds the power supplying connector22and the guide pins60aand60b. The linkage mechanism63is a member that couples the rotary part of the guide pin motor62to the other guide pin60b, thereby rotating the other guide pin60bin addition to the guide pin60a. Furthermore, the connector holder64has a position sensor65for detecting the position of the robot1′ on the surface facing the robot1′. The position sensor65detects that the guide pins60are inserted into the respective guide sleeves50, and the engaging pins61reach the inner ends of the longitudinal slits51aof the guide slits51based on the distance between the rear cover3′ of the robot1′ and the position sensor65.

In addition, according to the second embodiment, the moving means is composed of a first rubber floating66and a second rubber floating67(floating part) shown inFIG. 11. The first rubber floating66has a cylindrical shape and has a coil spring66aintegrally formed therein. With such a configuration, the axial length of the first rubber floating66can be expanded or shrunk by a predetermined length (about 25 mm in the second embodiment). In addition, as shown inFIG. 11, the first rubber floating66couples a supporting rod68described later and the rear part of the connector holder64to each other.

As shown inFIG. 11, the supporting rob68is a cylindrical rod member and is held in the charging station20′ by a fulcrum holder69, the second rubber floating67and a floating holder70. In addition, the supporting rod68has a double-pipe configuration between the connector holder64and the fulcrum holder69, and the distance between the connector holder64and the fulcrum holder69can be changed. Since the connector holder64and the supporting rod68are coupled to each other by the first rubber floating66, the distance between the connector holder64and the fulcrum holder69can be changed by about 25 mm.

The second rubber floating67is a circular column member, through the center of which the supporting rod68penetrates, and is held by the floating holder70at the periphery thereof. Since the supporting rod68is supported by the second rubber, floating67, the supporting rod68can radially move by a predetermined amount (about 4 mm in the second embodiment) due to the resiliency of the second rubber floating67. In addition, a balance weight71is mounted on the supporting rod68at a position behind the second rubber floating67.

Furthermore, as shown inFIG. 11, the fulcrum holder69and the floating holder70are both fixed to a supporting plate72in the charging station20′. The supporting plate72can be moved in the axial direction of the supporting rod68by an axial actuator73.

Now, operations of the guide means, the locking mechanism and the moving means of the charging system according to the second embodiment will be described. For charging the robot1′, the robot1′ is moved to a predetermined position on the charging station20′ through the steps S1to S4shown inFIG. 5. Then, the robot1′ displaces the waist position rearward by displacing the center of gravity as in step S5shown inFIG. 5, thereby bringing the power receiving connector4close to the power supplying connector22.

At this time, even if the power receiving connector4and the power supplying connector22are slightly misaligned with each other as shown inFIG. 12, the guide pins60can be inserted into the depth of the guide sleeves50along the inner surface of the guide sleeves50, because the tips of the guide pins60are conical, and the open ends of the guide sleeves50are widened. At this time, the guide pins60are fixed to the connector holder64, the connector holder64is coupled to the supporting rod68, and the supporting rod68is supported swingably by the charging station20′ via the fulcrum holder69and held by the second rubber floating67in such a manner that the supporting rod68can radially move by a predetermined amount. As a result, the guide pins60can also radially move by the predetermined amount.

In addition, when the robot1′ leans against the charging station20′, the first rubber floating66receives the load of the robot1′ in the direction of movement of the robot1′. Therefore, even if the robot1′ quickly lean against the charging station20′ for some reason, the resiliency of the first rubber floating66softens the impact. Thus, the charging system according to the second embodiment can always smoothly establish the connection between the power supplying connector22and the power receiving connector4.

In addition, when the engaging pins61on the guide pins60are guided by the longitudinal slits51aof the guide slits51in the guide sleeves50and inserted to the inner ends of the longitudinal slits51a, the position sensor65detects that the engaging pins61on the guide pins60reach the inner ends of the longitudinal slits51aand informs a controller30of that. In response to this information, the controller30makes the guide pin motor62rotate the guide pin60aand the linkage mechanism63rotate the other guide pin60b, thereby making the engaging pins61enter the engaging slits51bof the guide slits51. Then, the controller30stops the movement of the guide pins60aand60bin this state.

Through the operation described above, the power receiving connector4and the power supplying connector22are connected to each other with reliability. Then, after it is confirmed that a power receiving terminal7and a power supplying terminal29are connected to each other as in step S6inFIG. 4, the controller30starts charging of the battery2of the robot1′. At this time, even if an external force is exerted on the robot1′ for some reason, the connectors are not disconnected during charging because the guide pins60and the guide sleeves50are engaged with each other by the engaging pins61and the engaging slits51b.

Now, an operation of separating the robot1′ from the charging station20′ of the charging system according to the second embodiment will be described. Also in this second embodiment, before disconnecting the power receiving connector4from the power supplying connector22, the charging current supplied to the battery2from a charging power supply26is stopped (see S21inFIG. 9). Then, the controller30makes the guide pin motor62rotate in the direction opposite to that for connecting the connectors, thereby moving the engaging pins61on the guide pins60from the engaging slits51bto the longitudinal slits51aof the guide slits51formed in the guide sleeves50.

After the guide pins60are rotated and disengaged from the guide sleeves50, the controller30controls the robot1′ to restore the position of the waist of the robot1′ before charging (see S25inFIG. 9). In this step, the power receiving connector4and the power supplying connector22are disconnected from each other. The remaining steps of the control operation are the same as those shown inFIG. 9excluding steps S23and S24.

As described above, according to the second embodiment, the guide pins60and the guide sleeves50constitute the guide means and the locking mechanism, and the first rubber floating66and the second rubber floating67constitute the moving means. As a result, the whole of the charging system can be downsized. Specifically, because the guide pins60extending in the moving direction of the robot1′ are provided in place of the slide mechanism23, the charging station20′ can be made compact in its widthdirection, which leads to improvement in the flexibility of layout in installing the charging station '20.

In addition, according to the second embodiment, the supporting plate72can be moved in the axial direction of the supporting rod68by the axial actuator73shown inFIG. 11. Therefore, for example, even if the robot1′ to be charged is erroneously positioned, and the position sensor65detects that the power receiving connector4and the power supplying connector22are spaced apart from each other, the positions of the connectors can be adjusted by the axial actuator73. Furthermore, the axial actuator73enables the power supplying connector22and the guide pins60to be exposed to the outside of the charging station20′ when the robot1′ comes close to the charging station20′ for charging and to be housed in the charging station20′ when charging of the robot1′ is not performed. Furthermore, since the axial actuator73can move the power supplying connector22toward the power receiving connector4, the robot1′ can be charged in the upright position, rather than leaning against the charging station20′.

While the guide sleeves50are provided on the side of the power receiving connector4, and the guide pins60are provided on the side of the power supplying connector22according to the second embodiment, the present invention is not limited thereto, and the guide pins60may be provided on the side of the power receiving connector4, and the guide sleeves50may be provided on the side of the power supplying connector22. In addition, while the locking mechanism is constituted by the engaging pins61on the guide pins60and the guide slits51formed in the guide sleeves50according to the second embodiment, a fitting latch8may be used as in the embodiment described above.

Furthermore, while the moving means is constituted by the first rubber floating66and the second rubber floating67according to the second embodiment, either one of the rubber floatings may be omitted if a single rubber floating suffices for movement of the power supplying connector22and the guide pins60in the radial direction of the guide pins60.