Patent Publication Number: US-2022231519-A1

Title: Power source switching apparatus, robot, method, and program

Description:
TECHNICAL FIELD 
     The present disclosure relates to a power source switching apparatus, a robot, a method, and a program. In particular, the present disclosure relates to a power source switching apparatus, a robot, a method, and a program that enable switching of a battery (a power source) without stopping electric power being supplied. 
     BACKGROUND ART 
     Many robots are powered by battery. A power source (battery) replacement work for such a robot is often performed after electric power supplied from a power source (a battery) to a robot system is stopped. However, such stoppage of power disrupts a task due to a loss of an actuator power source and requires reboot of the system, and thus becomes a cause of a decrease in operation efficiency of the robot. 
     To avoid a decrease in operation efficiency due to power source replacement, it is effective to replace a battery while electric power continues to be supplied to, for example, a load such as an actuator. As long as the electric power continues to be supplied even during battery replacement, disruption of a task and reboot of a system are not necessary, which makes it possible to reduce a decrease in operation efficiency. 
     It should be noted that replacing a power source without stopping electric power being supplied is referred to as live-line plugging/unplugging, active plugging/unplugging, hot swap, or the like. 
     Examples of a typical technology that discloses a power supply configuration using a plurality of batteries include technologies disclosed in PTL 1 (Japanese Patent Laid-Open No. Hei 9-84273) and PTL 2 (Japanese Patent Laid-Open No. 2011-115031). 
     PTL 1 (Japanese Patent Laid-Open No. Hei 9-84273) discloses a configuration that enables replacing of a battery without shutting off a power source, by the use of diode OR connection and a mechanical battery detection technique. 
     This disclosed configuration, however, has the following problems. 
     (a) Heat loss of a diode is large. 
     (b) A regenerative (charging) current cannot be recovered to a battery since a countercurrent is always prevented. 
     (c) The mechanical battery detection technique makes a detection unit less durable. 
     (d) An inrush current occurs between a power source and a smoothing capacitor. 
     In addition, PTL 2 (Japanese Patent Laid-Open No. 2011-115031) discloses a configuration including a combination of a fuel cell and a battery. In such a configuration, charge and discharge are managed to regulate a depth of discharge of a battery to be shallow such that the battery has a longer life. 
     This disclosed configuration, however, has the following problems. 
     (a) Although the use of the fuel cell and the battery makes it possible to supply electric power in parallel, discharge from the battery and recovery (charging) from the fuel cell to the battery require respective separate circuits. 
     (b) Heat loss of a diode is large. 
     (c) There is no disclosure on battery replacement. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] 
     Japanese Patent Laid-Open No. Hei 9-84273 
     [PTL 2] 
     Japanese Patent Laid-Open No. 2011-115031 
     SUMMARY 
     Technical Problem 
     An object of the present disclosure is to provide a power source switching apparatus, a robot, a method, and a program that enable switching of a battery (a power source) while allowing electric power to continue to be supplied to a system of a robot or the like, in a manner free from, for example, the above problems of the typical technologies. 
     Solution to Problem 
     According to a first aspect of the present disclosure, there is provided a power source switching apparatus including a first switch circuit provided between a first power source port and a load to be supplied with electric power; a second switch circuit provided between a second power source port and the load; and a controller configured to control the first switch circuit and the second switch circuit. The controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states (a) to (c): 
     (a) an ON state that indicates a continuity state; 
     (b) an OFF state that indicates an interruption state; and 
     (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage, 
     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     Further, according to a second aspect of the present disclosure, there is provided a robot including a load including a drive unit, and a power source switching unit configured to perform a control of switching between power sources that supply electric power to the load. The power source switching unit includes a first switch circuit provided between a first power source port and the load to be supplied with the electric power, a second switch circuit provided between a second power source port and the load, and a controller configured to control the first switch circuit and the second switch circuit. The controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states (a) to (c): 
     (a) an ON state that indicates a continuity state; 
     (b) an OFF state that indicates an interruption state; and 
     (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage, 
     thereby performing a process of switching between the power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     Further, according to a third aspect of the present disclosure, there is provided a power source switching control method that is performed on a power source switching apparatus. The power source switching apparatus includes a first switch circuit provided between a first power source port and a load to be supplied with electric power; a second switch circuit provided between a second power source port and the load; and a controller configured to control the first switch circuit and the second switch circuit. The controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states (a) to (c): 
     (a) an ON state that indicates a continuity state; 
     (b) an OFF state that indicates an interruption state; and 
     (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage, 
     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     Further, according to a fourth aspect of the present disclosure, there is provided a robot control method that is performed on a robot. The robot includes a load including a drive unit, and a power source switching unit configured to perform a control of switching between power sources that supply electric power to the load. The power source switching unit includes a first switch circuit provided between a first power source port and the load to be supplied with the electric power, a second switch circuit provided between a second power source port and the load, and a controller configured to control the first switch circuit and the second switch circuit. The controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states (a) to (c): 
     (a) an ON state that indicates a continuity state; 
     (b) an OFF state that indicates an interruption state; and 
     (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage, 
     thereby performing a process of switching between the power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     Further, according to a fifth aspect of the present disclosure, there is provided a program causing a power source switching control process to be performed on a power source switching apparatus. The power source switching apparatus includes a first switch circuit provided between a first power source port and a load to be supplied with electric power; a second switch circuit provided between a second power source port and the load; and a controller configured to control the first switch circuit and the second switch circuit. The program causing the controller to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states (a) to (c): 
     (a) an ON state that indicates a continuity state; 
     (b) an OFF state that indicates an interruption state; and 
     (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage, 
     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     It should be noted that the program of the present disclosure is, for example, a program that can be provided to an information processing apparatus or a computer system capable of execution of a variety of program codes, via a recording medium or a communication medium provided in a computer-readable manner. By providing such a program in a computer-readable manner, a process corresponding to the program is implemented on the information processing apparatus or the computer system. 
     Other objects, features, advantages of the present disclosure will be found by referring to a further detailed description based on later-described embodiments of the present disclosure and the attached drawings. It should be noted that a system herein refers to a logical cluster configuration including a plurality of apparatuses, and the apparatuses in the configuration are not necessarily disposed within the same casing. 
     According to the configuration of an embodiment of the present disclosure, an apparatus and a method capable of performing a power source switching process and a charging process without stopping electric power being supplied to a load are implemented. 
     Specifically, the configuration includes, for example, a first switch circuit provided between a first power source port and a load to be supplied with electric power, a second switch circuit provided between a second power source port and the load, and a controller configured to control each of the switch circuits. The controller is configured to perform, on each of the switch circuits, a process of switching between three states, that is, (a) an ON state, (b) an OFF state, and (c) a diode operating state, thereby performing a process of switching between power sources connected to the respective power source ports without stopping the electric power being supplied to the load. Further, the controller is configured to perform a battery charging with a regenerative energy resulting from a rotation of a motor, which is the load. 
     According to the present configuration, an apparatus and a method capable of performing a power source switching process and a charging process without stopping electric power being supplied to a load are implemented. 
     It should be noted that the effects described herein are merely by way of example without limitation, and an additional effect may be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram for explaining a specific example and a problem of a power source replacement work for a battery-powered robot. 
         FIG. 2  is a diagram for explaining an example of a robot where a battery is replaced while electric power continues to be supplied from the battery. 
         FIG. 3  illustrates diagrams for explaining an example of a battery replacement process using a diode OR circuit. 
         FIG. 4  is a diagram for explaining an example where a regenerative current generated by the rotation of a motor is interrupted by a diode. 
         FIG. 5  illustrates diagrams for explaining an example of an ideal diode circuit. 
         FIG. 6  is a diagram for explaining an example where a regenerative current generated by the rotation of a motor is interrupted by the ideal diode circuit. 
         FIG. 7  illustrates diagrams for explaining respective states of the ideal diode circuit during (a) a live-line plugging/unplugging (hot swap) process for a battery and (b) recovery of a regenerative energy. 
         FIG. 8  is a diagram for explaining a configuration example of a power source switching apparatus of the present disclosure. 
         FIG. 9  is a flowchart for explaining a sequence of a process to be performed by the power source switching apparatus of the present disclosure. 
         FIG. 10  is a flowchart for explaining a sequence of a process to be performed by the power source switching apparatus of the present disclosure. 
         FIG. 11  is a diagram for explaining a configuration example of the power source switching apparatus of the present disclosure. 
         FIG. 12  is a diagram for explaining a configuration example of the power source switching apparatus of the present disclosure. 
         FIG. 13  is a diagram for explaining a configuration example of the power source switching apparatus of the present disclosure. 
         FIG. 14  is a diagram for explaining a configuration example of the power source switching apparatus of the present disclosure. 
         FIG. 15  is a diagram for explaining a hardware configuration example of a traveling robot of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A detailed description will be made below regarding a power source switching apparatus, a robot, a method, and a program of the present disclosure with reference to the drawings. It should be noted that the description will be given in an order of the following items. 
     1. Specific examples and problems of a power source replacement work for a robot 
     2. Power source switching configuration of the present disclosure, power source switching process, and energy regeneration process 
     3. Sequence of a process to be performed by the power source switching apparatus of the present disclosure 
     4. Process sequence for a case where an initial state is different 
     5. Other embodiments 
     6. Hardware configuration example of a robot 
     7. Summary of configurations of the present disclosure 
     1. Specific Examples and Problems of a Power Source Replacement Work for a Robot 
     First, a description will be made regarding specific examples and problems of a power source replacement work for a battery-powered robot with reference to  FIG. 1  and subsequent ones. 
       FIG. 1  illustrates a robot  10  that is powered by a battery (a power source). 
     The robot  10  is a walking robot and moves between a warehouse A, a warehouse B, and a warehouse C, performing a process of transporting packages in the warehouses. 
     The robot  10  is equipped with a removable battery. For example, the robot  10  is attached with a battery 1,  11  at a start point, i.e., the warehouse A, and moves to the warehouse B. Here, for the reason of a fall in a battery level of the battery 1,  11 , the battery 1,  11  is removed from the robot  10 , and a new battery 2,  12  is attached to the robot  10 . 
     For this battery replacement process, it has been typically necessary to remove the battery 1,  11  from the robot  10  after electric power supplied to an actuator of the robot  10  is turned off, then attach the battery 2,  12  to the robot, and, at the end, perform a system reboot process, that is, a reboot process to start supplying electric power again to the actuator of the robot  10  from the new battery 2,  12 . 
     Thus, the battery replacement work disrupts a task due to a loss of an actuator power source and requires reboot of the system, and becomes a major cause of a decrease in operation efficiency of the robot. 
     As measures to avoid such a decrease in operation efficiency due to the battery replacement work, it is effective to replace a battery while electric power continues to be supplied to the system from the battery. 
     By replacement of a battery with power supply maintained, which is what is called live-line plugging/unplugging, active plugging/unplugging, or hot swap, the battery can be replaced without the necessity of performing a power-off process on a system load such as an actuator, the system reboot process, and the like. Therefore, it is possible to avoid a decrease in operation efficiency due to the battery replacement work. 
       FIG. 2  is a diagram illustrating a specific example where a battery is replaced while electric power continues to be supplied from the battery. 
     Similarly to the case in  FIG. 1 , battery replacement is performed at a point of the warehouse B. However, for the robot  10  illustrated in  FIG. 2 , the new battery 2,  12  is attached to the robot  12  while electric power is being supplied from the battery 1,  11 , and the power supplied from the battery 1,  11  to the robot  10  is switched to power supplied from the new battery 2,  12  to the robot  10  after completion of the attachment. The battery 1,  11  is then removed from the robot  10 . 
     Such battery replacement performed while electric power continues to be supplied to the system from the battery eliminates the necessity of performing the power-off process on a system load such as the actuator of the robot  10 , the system reboot process, and the like. Therefore, it is possible to reduce time required for battery replacement and achieve an efficient robot operation. 
     A diode OR circuit is known as a circuit configuration enabling such battery replacement with power supply maintained. 
     A description will be made regarding a battery replacement process using the diode OR circuit with reference to  FIG. 3 . 
       FIG. 3( a )  illustrates a configuration where the battery 1,  11  is connected to a diode D 1  that is one of diodes in the diode OR circuit. 
     In this configuration, electric power is supplied to a system load from the battery 1,  11 . 
       FIG. 3( b )  illustrates a battery replacement work. 
     With the battery 1,  11  connected to the diode D 1  that is the one of the diodes in the diode OR circuit, the battery 2,  12  is connected to a diode D 2  that is the other diode in the diode OR circuit. 
     The battery 1,  11  has been used for a certain period of time, and a voltage thereof is thus lowered. In contrast, the battery 2,  12  has not been used yet, and a voltage thereof is not lowered. In other words, a relation 
         V in1&lt; V in2 
     is true, where Vin1 is the voltage of the battery 1,  11  and Vin2 is the voltage of the battery 2,  12 . 
     When the two batteries having such a difference in voltage are simultaneously connected to the diode OR circuit, a current flows as indicated by arrows on the circuit illustrated in  FIG. 3( b ) . 
     In other words, electric power is supplied from the battery 2,  12  with a higher voltage through the diode D 2  to the system load. A current from the battery 2,  12  with a higher voltage reaches the diode D 1  through the diode D 2  but does not flow further into the diode D 1  by virtue of rectification of the diode D 1 . The battery 1,  11  is removed in this state. 
     The use of the diode OR circuit thus makes it possible to replace the battery with power supply maintained. 
     However, this configuration is disadvantageous in that the battery cannot be charged by recovery of a regenerative energy. 
     For example, a motor is often used as a system load in a robot or the like. When the motor is caused to rotate by an external force, the motor behaves as a power generator, generating electric power. The generated electric power is supplied to a battery, thereby making it possible to charge the battery. 
     Such an energy generated by the load is referred to as regenerative energy, and energy saving can be achieved by efficiently using the regenerative energy. An emphasis has recently been placed on such an efficient use of a regenerative energy. 
     In a case where a motor is connected as a system load, the motor is caused to rotate by an external force, thereby generating a power-generation current (a regenerative current) from the motor toward a power source. However, in the configuration illustrated in  FIG. 3 , the regenerative current generated by the rotation of the motor is interrupted by the diode and is not supplied to the battery. 
       FIG. 4  illustrates a specific example. As illustrated in  FIG. 4 , when a load-side motor  21  rotates and predetermined conditions are satisfied, a load-side voltage Vout becomes higher than the voltage Vin1 of the battery 1,  11  connected to the diode D 1 . In other words, settings are made that satisfies the following expression. 
         V in1&lt; V out 
     If no diode D 1  is provided, a current (a regenerative current) generated by the rotation of the load-side motor  21  is supplied to the battery 1,  11 , enabling charge of the battery 1,  11 , that is, recovery of the regenerative energy. 
     However, in the configuration illustrated in  FIG. 4 , a regenerative current generated by the rotation of the motor is interrupted by the diode D 1  due to the rectification of the diode D 1  and is not supplied to the battery 1,  11 . In other words, the battery 1,  11  cannot be charged with the regenerative current. Further, the regenerative current which is not used to charge the battery and has nowhere to go causes a rapid increase in voltage in a power source line, possibly resulting in damaging of a peripheral device. 
     Thus, in the diode OR circuit, the regenerative current from the motor is also rectified by the diode, so that the regenerative energy cannot be recovered to the battery. 
     It should be noted that, in a configuration using a diode OR circuit, a loss attributed to a forward voltage drop of the diode is often a problem for an intended use with a high current. To solve this problem, in place of a diode itself, a circuit where a transistor is used to emulate rectification properties of a diode, i.e., an ideal diode circuit, is often used. 
     An example of an ideal diode circuit will be described with reference to  FIG. 5 . 
       FIG. 5( a )  illustrates a configuration example of a diode OR circuit including ideal diode circuits  31  and  32 . 
       FIG. 5( b )  is a diagram illustrating an example of a detailed circuit configuration of the ideal diode circuit. 
     As illustrated in  FIG. 5( b ) , the ideal diode circuit may include a plurality of FETs controllable by an ideal diode controller. 
     With the use of the ideal diode circuit as illustrated in  FIG. 5( b ) , a loss attributed to a forward voltage drop of a diode can be reduced. 
     However, even in a case where the diode OR circuit including such an ideal diode circuit is used, a regenerative current generated by the rotation of the motor  21  is interrupted by the diode ideal circuit  31  and is not supplied to the battery 1,  11  as illustrated in  FIG. 6 . In other words, the battery 1,  11  cannot be charged with the regenerative current. Further, the regenerative current which is not used to charge the battery and has nowhere to go causes a rapid increase in voltage in a power source line, possibly resulting in damaging of a peripheral device. 
     One of reasons why a regenerative energy cannot be recovered in a case where a diode OR circuit is used is that, in the diode OR circuit, the diode cannot distinguish between a rise in output-side voltage attributed to a live-line plugging/unplugging operation (hot swap) and a rise in output-side voltage attributed to a regenerative energy. 
     A description will be made regarding this problem with reference to  FIG. 7 . 
       FIG. 7  illustrates diagrams for explaining respective states of the ideal diode circuit during two different processes. 
     (a) During a live-line plugging/unplugging (hot swap) process for a battery 
     (b) During recovery of a regenerative energy 
     In the state seen during the live-line plugging/unplugging (hot swap) process for a battery in  FIG. 7( a ) , a relation between voltages at right and left end portions of the ideal diode circuit  31  that is one of the ideal diode circuits in the diode OR circuit, i.e., a relation between the voltage (Vin1) on a battery 1,  11  side and the voltage (Vin2) on a load (motor  21 ) side, is set to the following relation. 
         V in1&lt; V in2 
     In contrast, in the state seen during recovery of a regenerative energy in  FIG. 7( b ) , the relation between the voltages at the right and left end portions of the ideal diode circuit  31 , i.e., the relation between the voltage (Vin1) on the battery 1,  11  side and the voltage (Vout) on the load (motor  21 ) side, is set to the following relation. 
         V in1&lt; V out 
     For the ideal diode circuit  31 , the two states illustrated in  FIGS. 7( a ) and 7( b )  both indicate that the voltage on the battery 1,  11  side is lower than the voltage on an external load side. Thus, from the point of view of the ideal diode circuit  31 , these two states are indistinguishable. 
     Accordingly, the reason why a regenerative energy cannot be recovered in the configuration using a diode OR circuit is that a rise in output-side voltage attributed to the live-line plugging/unplugging operation (hot swap) and a rise in output-side voltage attributed to a regenerative energy are indistinguishable. 
     2. Power Source Switching Configuration of the Present Disclosure, Power Source Switching Process, and Energy Regeneration Process 
     Next, a description will be made regarding a power source switching configuration of the present disclosure, a power source switching process, and an energy regeneration process. 
       FIG. 8  illustrates a configuration example of the power source switching apparatus of the present disclosure. 
     A power source switching apparatus  100   a  illustrated in  FIG. 8  is provided, for example, within the robot  10  described with reference to  FIG. 1  and  FIG. 2 . 
     A load  210  illustrated in  FIG. 8  includes, for example, a CPU that controls the robot, an actuator that performs driving, a motor, and the like. In a case where the load includes the motor, a regenerative energy (a regenerative current) is generated by the rotation of the motor. 
     It should be noted that a smoothing capacitor  103  placed upstream of the load  210  is a capacitive load present in an output line and is a capacitor for reducing and stabilizing (smoothing) a variation in output to the load  210 . 
     As illustrated in  FIG. 8 , the power source switching apparatus  100   a  includes two power source ports, that is, a first power source port  101  and a second power source port  102 . 
     The first power source port  101  is connected to a battery 1,  201 , and the second power source port  102  is connected to a battery 2,  202 . 
     It should be noted that one of the battery 1,  201  and the battery 2,  202  is normally connected to the port, and electric power is supplied to the load  210  from the connected battery. However, during such battery replacement that a battery is replaced with power supply maintained, which is referred to as live-line plugging/unplugging, active plugging/unplugging, or hot swap, the two batteries are temporarily connected to the respective ports. 
     When the battery replacement work is completed, the old battery is removed. 
     The first power source port  101  of the power source switching apparatus  100   a  is connected to the load  210  through a first switch circuit (SW 1 )  110 . 
     Similarly, the second power source port  102  is connected to the load  210  through a second switch circuit (SW 2 )  120 . 
     The first switch circuit (SW 1 )  110  connected to the first power source port  101  includes two FETs, i.e., an FET ( 1 A)  111  and an FET ( 1 B)  112 . 
     The FET ( 1 A)  111  is an FET for controlling electrical continuity of the battery 1,  201  and controls electric power supplied to the outside from the battery 1,  201  through the first switch circuit  110 . 
     Specifically, an FET controller  130  controls a gate-source voltage of the FET ( 1 A)  111 , thereby controlling continuity and interruption for a current in a direction from input (a battery side) to output (a load side). 
     Further, a gate voltage of the FET ( 1 A)  111  is controlled by the FET controller  130 , which makes it possible to control a continuity/interruption speed of the FET ( 1 A)  111 . This makes it possible to reduce an inrush current to the output-side capacitive load (the smoothing capacitor  103 ). 
     The load-side FET ( 1 B)  112  of the first switch circuit (SW 1 )  110  is an FET for preventing a countercurrent. Specifically, the FET controller  130  controls a gate-source voltage of the FET ( 1 B)  112 , thereby controlling continuity and interruption for a current in a direction from output (the load side) to input (the battery side). 
     Controlling the two FETs of the first switch circuit (SW 1 )  110 , i.e., the FET ( 1 A)  111  and the FET ( 1 B)  112 , enables the first switch circuit (SW 1 )  110  to be set in the following three states. 
     (a) an ON state 
     (b) an OFF state 
     (c) an ideal diode operating state 
     It should be noted that setting and transition between these three states are controllable by the FET controller  130 . 
     (a) The ON state is a state where the first switch circuit (SW 1 )  110  is brought into electrical continuity. 
     It is a state where a current in the direction from input (the battery side) to output (the load side) through the first switch circuit (SW 1 )  110  and a current in the direction from output (the load side) to input (the battery side) through the first switch circuit (SW 1 )  110  are both carried. 
     (b) The OFF state is a state where the first switch circuit (SW 1 )  110  is interrupted. 
     It is a state where a current in the direction from input (the battery side) to output (the load side) through the first switch circuit (SW 1 )  110  and a current in the direction from output (the load side) to input (the battery side) through the first switch circuit (SW 1 )  110  are both interrupted. 
     (c) The ideal diode operating state is an operating state depending on diode properties, more specifically, in a case where an input-side (battery-side) voltage of the first switch circuit (SW 1 )  110  is larger than an output-side (load-side) voltage, the current in the direction from input (the battery side) to output (the load side) through the first switch circuit (SW 1 )  110  is carried, and 
     in a case where the output-side (load-side) voltage exceeds the input-side (battery-side) voltage of the first switch circuit (SW 1 )  110 , the current in the direction from output (the load side) to input (the battery side) is interrupted. 
     It should be noted that, in (a) the ON state, the first switch circuit (SW 1 )  110  is always in a continuity state without dependence on the input-side (battery-side) and output-side (load-side) voltages of the first switch circuit (SW 1 )  110 . 
     In contrast, in (b) the OFF state, the first switch circuit (SW 1 )  110  is always in an interruption state without dependence on the input-side (battery-side) and output-side (load-side) voltages of the first switch circuit (SW 1 )  110 . 
     Similarly, the second switch circuit (SW 2 )  120  connected to the second power source port  102  includes two FETs, i.e., an FET ( 2 A)  121  and an FET ( 2 B)  122 . 
     The FET ( 2 A)  121  is an FET for controlling electrical continuity of the battery 2,  202  and controls electric power supplied to the outside from the battery 2,  202  through the second switch circuit  120 . Specifically, the FET controller  130  controls a gate-source voltage of the FET ( 2 A)  121 , thereby controlling continuity and interruption for a current in a direction from input (a battery side) to output (a load side). 
     Further, a gate voltage of the FET ( 2 A)  121  is controlled by the FET controller  130 , which makes it possible to control a continuity/interruption speed of the FET ( 2 A)  121 . This makes it possible to reduce an inrush current to the output-side capacitive load (the smoothing capacitor  103 ). 
     The load-side FET ( 2 B)  122  of the second switch circuit (SW 2 )  120  is an FET for preventing a countercurrent. Specifically, the FET controller  130  controls a gate-source voltage of the FET ( 2 B)  122 , thereby controlling continuity and interruption for a current in a direction from output (the load side) to input (the battery side). 
     Controlling the two FETs of the second switch circuit (SW 2 )  120 , i.e., the FET ( 2 A)  121  and the FET ( 2 B)  122 , enables the second switch circuit (SW 2 )  120  to be set in the following three states. 
     (a) the ON state 
     (b) the OFF state 
     (c) the ideal diode operating state 
     It should be noted that setting and transition between these three states are controllable by the FET controller  130 . 
     (a) The ON state is a state where the second switch circuit (SW 2 )  120  is brought into electrical continuity. 
     It is a state where a current in the direction from input (the battery side) to output (the load side) through the second switch circuit (SW 2 )  120  and a current in the direction from output (the load side) to input (the battery side) through the second switch circuit (SW 2 )  120  are both carried. 
     (b) The OFF state is a state where the second switch circuit (SW 2 )  120  is interrupted. 
     It is a state where a current in the direction from input (the battery side) to output (the load side) through the second switch circuit (SW 2 )  120  and a current in the direction from output (the load side) to input (the battery side) through the second switch circuit (SW 2 )  120  are both interrupted. 
     (c) The ideal diode operating state is an operating state depending on diode properties, more specifically, 
     in a case where an input-side (battery-side) voltage of the second switch circuit (SW 2 )  120  is larger than an output-side (load-side) voltage, the current in the direction from input (the battery side) to output (the load side) through the second switch circuit (SW 2 )  120  is carried, and 
     in a case where the output-side (load-side) voltage exceeds the input-side (battery-side) voltage of the second switch circuit (SW 2 )  120 , the current in the direction from output (the load side) to input (the battery side) is interrupted. 
     It should be noted that, in (a) the ON state, the second switch circuit (SW 2 )  120  is always in a continuity state without dependence on the input-side (battery-side) and output-side (load-side) voltages of the second switch circuit (SW 2 )  120 . 
     In contrast, in (b) the OFF state, the second switch circuit (SW 2 )  120  is always in an interruption state without dependence on the input-side (battery-side) and output-side (load-side) voltages of the second switch circuit (SW 2 )  120 . 
     The FET controller  130  controls the gate-source voltages of the four FETs: the two FETs of the first switch circuit (SW 1 )  110 , i.e., the FET ( 1 A)  111  and the FET ( 1 B)  112 , and the two FETs of the second switch circuit (SW 2 )  120 , i.e., the FET ( 2 A)  121  and the FET ( 2 B)  122 . 
     The FET controller  130  includes the following three voltage detection units.
         (1) Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 )   (2) Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 )   (3) Vout: the output-side voltage of each of the switch circuits  110  and  120         

     The FET controller  130  compares these three voltages, i.e., Vin1, Vin2, and Vout, and controls the gate voltages of the four FETs of the first switch circuit (SW 1 )  110  and the second switch circuit (SW 2 )  120  on the basis of a comparison result. 
     Specifically, the three states (the ON state, the OFF state, and the ideal diode operating state) of each of the switch circuits  110  and  120  are switched on the basis of the comparison result of Vin1, Vin2, and Vout. Through this switching, a switching control for the following three types of processes is performed. 
     (Process 1) normal process: a process of supplying electric power from the battery to the load 
     (Process 2) live-line plugging/unplugging process (hot swap): a battery switching process performed while electric power continues to be supplied to the load 
     (Process 3) regeneration process: a process of charging the battery by supplying the battery with a regenerative energy (a regenerative current) resulting from the rotation of the motor of the load 
     3. Sequence of a Process to be Performed by the Power Source Switching Apparatus of the Present Disclosure 
     Next, a description will be made regarding a sequence of a process to be performed by the power source switching apparatus of the present disclosure. Specifically, a description will be made regarding a sequence of a process to be performed by the FET controller  130 . 
       FIG. 9  is a flowchart for explaining the sequence of the process to be performed by the FET controller  130 . The FET controller  130  performs the process according to, for example, a program stored in a memory inside the FET controller  130  or in an external memory. The FET controller  130  holds a processor having a program execution function and performs the process based on a flow described below according to control performed by the processor. 
     It should be noted that, in the flow illustrated in  FIG. 9 , an initial state (a start state) is a normal process state where electric power is supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110  in the configuration illustrated in  FIG. 8 . 
     In other words, in the initial state, as a result of a gate voltage control performed on the FETs of each of the switches by the FET controller  130 , the following state is set. 
     first switch circuit (SW 1 )  110 =ON 
     second switch circuit (SW 2 )  120 =OFF A description will be made below regarding a process in each step of the flow illustrated in  FIG. 9 . 
     (Step S 101 ) 
     First, in Step S 101 , the FET controller  130  detects the following three voltages. 
     (1) Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) 
     (2) Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ) 
     (3) Vout: the output-side voltage of each of the switch circuits  110  and  120   
     (Step S 102 ) 
     Next, in Step S 102 , the FET controller  130  performs a process of comparing Vin1 and Vout, determining whether or not the expression 
         V in1 +Vtha&lt;V out 
     is true, where 
     Vin1 is the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ), 
     Vout is the output-side voltage of each of the switch circuits  110  and  120 , and 
     Vtha is a predetermined threshold value. 
     The threshold value Vtha can be set as desired by a user. 
     The threshold value Vtha can be set to any value equal to or more than 0. However, for example, in a case where the threshold value Vtha=0 and where Vin1 and Vout are substantially the same in value, the operation is likely to be frequently switched and become unstable. 
     For a stable operation, it is favorable that a value slightly larger than 0 be set. 
     The process proceeds to Step S 103  in a case where it is determined in Step S 102  that the following expression is true. 
         V in1 +Vtha&lt;V out 
     In contrast, in a case where it is determined that the above expression is not true, the process proceeds to Step S 111 . 
     (Step S 111 ) 
     First, a description will be made regarding a process in Step S 111  for the case where the expression 
         V in1 +Vtha&lt;V out 
     is determined to be not true in Step S 102 . 
         V in1 +Vtha&lt;V out 
     In the case where the above expression is not true, the following relation is satisfied. 
         V in1 +Vtha≥V out 
     In other words, 
     a value given by adding the threshold value Vtha to Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) is equal to or more than 
     Vout: the output-side voltage of each of the switch circuits  110  and  120 . 
     In this case, in Step S 111 , a present operating state, that is, the normal process state where electric power is supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110 , is continued. 
     The process of supplying electric power from the battery 1,  201  to the load  210  is a process performed when the FET controller  130  sets (maintains) the respective switch circuits in the following operating states. 
     first switch circuit (SW 1 ) 110=ON 
     second switch circuit (SW 2 ) 120=OFF 
     As a result of the above settings, the electric power continues to be supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110  which is set in the ON state. 
     (Step S 103 ) 
     In contrast, in the case where it is determined in Step S 102  that the expression 
         V in1 +Vtha&lt;V out 
     is true, the process proceeds to Step S 103 . 
     In Step S 103 , the FET controller  130  performs a process of comparing Vin1 and Vin2, determining whether or not the expression 
         V in1 +Vthb&lt;V in2 
     is true, where 
     Vin1 is the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ), 
     Vin2 is the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ), and 
     Vthb is a predetermined threshold value. 
     The threshold value Vthb can be set as desired by a user. 
     Similarly to Vtha described above, the threshold value Vthb can be set to any value equal to or more than 0. However, for example, in a case where the threshold value Vthb=0, the operation is likely to be frequently switched and become unstable. For a stable operation, it is favorable that a value slightly larger than 0 be set. 
     The process proceeds to Step S 104  in a case where it is determined in Step S 103  that the following expression is true. 
         V in1 +Vthb&lt;V in2 
     In contrast, in a case where it is determined that the above expression is not true, the process proceeds to Step S 121 . 
     It should be noted that, in the case where the expression 
         V in1 +Vthb&lt;V in2 
     is true in Step S 103 , the battery 2,  202 , which is higher in voltage than the battery 1,  201 , is connected to the input-side second power source port  102  of the second switch circuit (SW 2 )  120 . In other words, an unused battery for replacement is connected to the input-side second power source port  102 . 
     Thus, the determination process in Step S 103  corresponds to a process of determining whether or not the unused battery 2,  202  for replacement is connected to the input-side second power source port  102  of the second switch circuit (SW 2 )  120 . 
     In the case where the expression 
         V in1 +Vthb&lt;V in2 
     is true in Step S 103 , the unused battery 2,  202  for replacement is determined to be connected to the input-side second power source port  102  of the second switch circuit (SW 2 )  120 , and, in Step S 104  and subsequent steps, a live-line plugging/unplugging (hot swapping) process for a battery is performed. 
     In contrast, in the case where the above expression is determined to be not true, the unused battery 2,  202  for replacement is determined to be not connected to the input-side second power source port  102  of the second switch circuit (SW 2 )  120 , and, in Step S 121  and subsequent steps, a charging process for the battery 1,  201 , that is, a process of charging the battery 1,  201  with a regenerative energy (a regenerative current) generated by the motor of the load  210 , is performed. 
     (Step S 104 ) 
     The process in Steps S 104  to S 107  corresponds to the live-line plugging/unplugging (hot swapping) process for a battery. 
     The live-line plugging/unplugging (hot swapping) process for a battery in Steps S 104  to S 107  is performed in a case where it is determined in Step S 102  and Step S 103  that the following two expressions are true. 
         V in1 +Vtha&lt;V out 
         V in1 +Vthb&lt;V in2 
     In other words, the live-line plugging/unplugging (hot swapping) process for a battery is performed in a case where the following conditions are satisfied: 
     a value given by adding the threshold value Vtha to Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) is less than 
     Vout: the output-side voltage of each of the switch circuits  110  and  120 ; and 
     a value given by adding the threshold value Vthb to Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) is less than 
     Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ). 
     In the case where these conditions are satisfied, the FET controller  130  determines that the new unused battery 2,  202  for replacement is connected to the input-side second power source port  102  of the second switch circuit (SW 2 )  120 , and, in Step S 104  and subsequent steps, performs the live-line plugging/unplugging (hot swapping) process for a battery. 
     First, in Step S 104 , the FET controller  130  changes the first switch circuit (SW 1 )  110  from the ON state to the ideal diode operating state. 
     This state change process is performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the first switch circuit (SW 1 )  110 , that is, the FET ( 1 A)  111  and the FET ( 1 B)  112 , so as to switch the continuity/interruption state of each of the FETs. 
     As described above, the ideal diode operating state is an operating state depending on diode properties. Specifically, in a case where the input-side (battery-side) voltage of the first switch circuit (SW 1 )  110  is larger than the output-side (load-side) voltage, the current in the direction from input (the battery side) to output (the load side) through the first switch circuit (SW 1 )  110  is carried, and 
     in a case where the output-side (load-side) voltage exceeds the input-side (battery-side) voltage of the first switch circuit (SW 1 )  110 , the current in the direction from output (the load side) to input (the battery side) is interrupted. 
     (Step S 105 ) 
     Next, in Step S 105 , the FET controller  130  changes the second switch circuit (SW 2 )  120  from the OFF state to the ON state. 
     This state change process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the second switch circuit (SW 2 )  120 , that is, the FET ( 2 A)  121  and the FET ( 2 B)  122 , so as to switch the continuity/interruption state of each of the FETs. 
     (Step S 106 ) 
     Next, in Step S 106 , the FET controller  130  changes the first switch circuit (SW 1 )  110  from the ideal diode operating state to the OFF state. 
     This state change process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the first switch circuit (SW 1 )  110 , that is, the FET ( 1 A)  111  and the FET ( 1 B)  112 , so as to switch the continuity/interruption state of each of the FETs. 
     (Step S 107 ) 
     In Step S 107 , as a result of the above-described process in Steps S 104  to S 106 , electric power starts being supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120 . 
     In other words, 
     a process of a change from 
     a start state=a state where electric power is supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110 , to 
     Step S 107 =a state where electric power is supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120   
     is performed without stopping the electric power being supplied to the load  210 . 
     That is, the live-line plugging/unplugging (hot swapping) process for a battery is completed. 
     This live-line plugging/unplugging (hot swapping) process for a battery is a process performed when the FET controller  130  sets the respective switch circuits in the following operating states in sequence. 
     (S 104 ) first switch circuit (SW 1 )  110 =from the ON state to the ideal diode operating state 
     (S 105 ) second switch circuit (SW 2 )  120 =from the OFF state to the ON state 
     (S 106 ) first switch circuit (SW 1 )  110 =from the ideal diode operating state to the OFF state 
     By performing the above operating state change processes for the switch circuits in sequence, it is possible to perform the live-line plugging/unplugging (hot swapping) process for a battery without stopping electric power being supplied to the load  210 . 
     In other words, first, (S 104 ) the first switch circuit (SW 1 )  110 =from the ON state to the ideal diode operating state is achieved, and thus, electric power continues to be supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110 . 
     As described above, the ideal diode operating state is an operating state where, in a case where the input-side (battery-side) voltage of the first switch circuit (SW 1 )  110  is larger than the output-side (load-side) voltage, a current in the direction from input (battery side) to output (load side) through the first switch circuit (SW 1 )  110  is carried. 
     Next, (S 105 ) the second switch circuit (SW 2 )  120 =from the OFF state to the ON state is achieved, and thus, electric power starts being supplied from the battery 2,  202 , which is connected to the input side (battery side) of the second switch circuit (SW 2 )  120 , to the load  210  through the second switch circuit (SW 2 )  120 . 
     It should be noted that, although the output-side (load-side) voltage is likely to exceed the input side (battery side) of the first switch circuit (SW 1 )  110  at this point of time, a current in the direction from output (load side) to input (battery side) of the first switch circuit (SW 1 )  110  is interrupted since the first switch circuit (SW 1 )  110  is set in the ideal diode operating state. Therefore, occurrence of a countercurrent state where a current flows into the battery 1,  201  is prevented. 
     At the end, the switching process is performed such that (S 106 ) the first switch circuit (SW 1 )  110 =from the ideal diode operating state to the OFF state is achieved, and thus, electrical continuity between the battery 1,  201  and the load  210  is completely interrupted. Thereafter, the battery 1,  201  can be removed from the first power source port  101 . 
     By performing the above-described processes, a regenerative energy (a regenerative current) generated by the motor of the load  210  flows into the battery 1,  201  through the first switch circuit (SW 1 )  110 , and a charging process for the battery 1,  201  is performed. 
     (Step S 121 ) 
     Next, a description will be made regarding a process in Steps S 121  to S 123 . 
     The process in Steps S 121  to S 123  is a charging process for the battery 1,  201 , that is, a process of charging the battery 1,  201  with a regenerative energy (a regenerative current) generated by the motor of the load  210 . 
     This battery regeneration process is performed in a case where it is determined in Step S 102  and Step S 103  that the following two expressions are true. 
         V in1 +Vtha&lt;V out 
         V in1 +Vthb≥V in2 
     In other words, the battery regeneration process is performed in a case where the following conditions are satisfied: 
     a value given by adding the threshold value Vtha to Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) is less than 
     Vout: the output-side voltage of each of the switch circuits  110  and  120 ; and a value given by adding the threshold value Vthb to 
     Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) is equal to or more than 
     Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2, 
     It should be noted that the FET controller  130  confirms in Steps S 102  and S 103  that the two expressions 
         V in1 +Vtha&lt;V out 
         V in1 +Vthb z V in2 
     are true, determines that a rise in the load-side voltage (Vout) is based on generation of a regenerative energy, and then performs the process in Step S 121  and subsequent steps, that is, the process of charging the battery 1,  201  with the regenerative energy (the regenerative current) generated by the motor of the load  210 . 
     In other words, in a case where the expression 
         V in1 +Vtha&lt;V out 
     is satisfied in Step S 102 , 
     a cause for a rise in the load-side voltage (Vout) is supposed to be one of the following two reasons. 
     (Reason 1) a rise in voltage (Vout) based on the output voltage of the battery 2,  202   
     (Reason 2) a rise in the voltage (Vout) based on generation of the regenerative energy of the load  210   
     Then, it is further confirmed in Step S 103  that the following expression is satisfied. 
         V in1 +Vthb≥V in2 
     This expression is satisfied in a case where 
     the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ) is lower than 
     the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  102 )+the threshold value (Vthb). 
     If it is confirmed in Step S 103  that the expression 
         V in1 +Vthb≥V in2 
     is satisfied, then it is determined that the above-described (Reason 1), which is supposed to be the cause for the rise in the load-side voltage (Vout), is not a possible cause. As a result, it can be determined that 
     the cause for the rise in the load-side voltage (Vout) is the above-described (Reason 2), that is, a rise in the voltage (Vout) based on generation of the regenerative energy of the load  210 . 
     In such a manner, the FET controller  130  confirms in Steps S 102  and S 103  that the two expressions 
         V in1 +Vtha&lt;V out 
         V in1 +Vthb≥V in2 
     are true, and determines that a rise in the load-side voltage (Vout) is based on generation of a regenerative energy. Then, the FET controller  130  performs the process in Steps S 121  to S 123 , that is, the process of charging the battery 1,  201  with the regenerative energy (the regenerative current) generated by the motor of the load  210 . 
     First, in Step S 121 , the FET controller  130  maintains the ON state of the first switch circuit (SW 1 )  110 . 
     This state maintenance process is performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the first switch circuit (SW 1 )  110 , that is, the FET ( 1 A)  111  and the FET ( 1 B)  112 , so as to maintain the continuity/interruption state of each of the FETs at a present state. 
     (Step S 122 ) 
     Next, the FET controller  130  maintains the OFF state of the second switch circuit (SW 2 )  120  in Step S 122 . 
     This state maintenance process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the second switch circuit (SW 2 )  120 , that is, the FET ( 2 A)  121  and the FET ( 2 B)  122 , so as to maintain the continuity/interruption state of each of the FETs at a present state. 
     (Step S 123 ) 
     In Step S 123 , as a result of the above-described process in Steps S 121  to S 122 , the charging process for the battery 1,  201 , that is, the process of charging the battery 1,  201  with the regenerative energy (the regenerative current) generated by the motor of the load  210 , is performed. 
     This charging (regeneration) process for the battery 1,  201  is a process performed when the FET controller  130  sets the respective switch circuits in the following operating states. 
     first switch circuit (SW 1 )  110 =ON 
     second switch circuit (SW 2 )  120 =OFF 
     The above settings allow a regenerative energy (a regenerative current) generated by the motor of the load  210  to flow into the battery 1,  201  through the first switch circuit (SW 1 )  110 , so that the charging process for the battery 1,  201  is performed. 
     As described above, in the power source switching apparatus  100   a  illustrated in  FIG. 8 , the FET controller  130  controls the switch circuits  110  and  120  connected to the batteries  201  and  202 , respectively, that is, performs a switching control between the following three states. 
     (a) the ON state 
     (b) the OFF state 
     (c) the ideal diode operating state 
     These controls performed by the FET controller  130  allow the power source switching apparatus  100   a  illustrated in  FIG. 8  to reliably perform the following three processes. 
     (Process 1) normal process: a process of supplying electric power from the battery to the load 
     (Process 2) live-line plugging/unplugging process (hot swap): a battery switching process performed while electric power continues to be supplied to the load 
     (Process 3) regeneration process: a process of charging the battery by supplying the battery with a regenerative energy (a regenerative current) resulting from the rotation of the motor of the load 
     4. Process Sequence for a Case where an Initial State is Different 
     Next, a description will be made regarding a process sequence for a case where an initial state is different from that in the process previously described with reference to  FIG. 8 . 
     In the flow illustrated in  FIG. 9 , the initial state (the start state) is a normal process state where electric power is supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110  in the configuration illustrated in  FIG. 8   
       FIG. 10  illustrates a process sequence to be performed by the FET controller  130  in a case where the initial state (the start state) is a normal process state where electric power is supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120 . 
     The flow illustrated in  FIG. 10  corresponds to a flow where the following elements in the flow illustrated in  FIG. 9  are replaced with each other:
         the battery 1 and the battery 2;   the switch  1  (SW 1 ) and the switch  2  (SW 2 ); and Vin1 and Vin2.       

     A description will be made regarding a process based on the flow illustrated in  FIG. 10 . 
     In the initial state, as a result of a gate voltage control performed on the FETs of each switch by the FET controller  130 , the following state is set. 
     first switch circuit (SW 1 )  110 =OFF 
     second switch circuit (SW 2 )  120 =ON 
     (Step S 201 ) 
     First, in Step S 201 , the FET controller  130  detects the following three voltages. 
     (1) Vin1: the input-side voltage of the first switch circuit (SW 1 )  110  (=the output voltage of the battery 1,  201 ) 
     (2) Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ) 
     (3) Vout: the output-side voltage of each of the switch circuits  110  and  120   
     (Step S 202 ) 
     Next, in Step S 202 , the FET controller  130  performs a process of comparing Vin1 and Vout, determining whether or not the following expression is true. 
         V in2 +Vtha&lt;V out 
     The process proceeds to Step S 203  in a case where it is determined in Step S 202  that the following expression is true. 
         V in2 +Vtha&lt;V out 
     In contrast, in a case where it is determined that the above expression is not true, the process proceeds to Step S 211 . 
     (Step S 211 ) 
     First, a description will be made regarding a process in Step S 211  for the case where the expression 
         V in2 +Vtha&lt;V out 
     is determined to be not true in Step S 202 . 
         V in2 +Vtha&lt;V out 
     In the case where the above expression is not true, the following relation is satisfied. 
         V in2 +Vtha≥V out 
     In other words, 
     a value given by adding the threshold value Vtha to Vin2: the input-side voltage of the second switch circuit (SW 2 )  120  (=the output voltage of the battery 2,  202 ) is equal to or more than 
     Vout: the output-side voltage of each of the switch circuits  110  and  120 . 
     In this case, in Step S 211 , a present operating state, that is, the normal process state where electric power is supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120 , is continued. 
     The process of supplying electric power from the battery 2,  202  to the load  210  is a process performed when the FET controller  130  sets (maintains) the respective switch circuits in the following operating states. 
     first switch circuit (SW 1 )  110 =OFF 
     second switch circuit (SW 2 )  120 =ON 
     As a result of the above settings, the electric power continues to be supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120  which is set in the ON state. 
     (Step S 203 ) 
     In contrast, in the case where it is determined in Step S 202  that the expression 
         V in2 +Vtha&lt;V out 
     is true, the process proceeds to Step S 203 . 
     In Step S 203 , the FET controller  130  performs a process of comparing Vin1 and Vin2, determining whether or not the following expression is true. 
         V in2 +Vthb&lt;V in2 
     The process proceeds to Step S 204  in a case where it is determined in Step S 203  that the following expression is true. 
         V in2 +Vthb&lt;V in1 
     In contrast, in a case where it is determined that the above expression is not true, the process proceeds to Step S 221 . 
     It should be noted that, in the case where the expression 
         V in2 +Vthb&lt;V in1 
     is true in Step S 203 , the battery 1,  201 , which is higher in voltage than the battery 2,  202 , is connected to the input-side first power source port  101  of the first switch circuit (SW 1 )  110 . In other words, an unused battery for replacement is connected to the input-side first power source port  101 . 
     Thus, the determination process in Step S 203  corresponds to a process of determining whether or not the new and unused battery 1,  201  for replacement is connected to the input-side first power source port  101  of the first switch circuit (SW 1 )  110 . 
     In the case where the expression 
         V in2 +Vthb&lt;V in1 
     is true in Step S 203 , the unused battery 1,  201  for replacement is determined to be connected to the input-side first power source port  101  of the first switch circuit (SW 1 )  110 , and, in Step S 204  and subsequent steps, a live-line plugging/unplugging (hot swapping) process for a battery is performed. 
     In contrast, in the case where the above expression is determined to be not true, the unused battery 1,  201  for replacement is determined to be not connected to the input-side first power source port  101  of the first switch circuit (SW 1 )  110 , and, in Step S 221  and subsequent steps, a charging process for the battery 2,  202 , that is, a process of charging the battery 2,  202  with a regenerative energy (a regenerative current) generated by the motor of the load  210 , is performed. 
     (Step S 204 ) 
     The process in Steps S 204  to S 207  corresponds to the live-line plugging/unplugging (hot swapping) process for a battery. 
     This live-line plugging/unplugging (hot swapping) process for a battery in Steps S 204  to S 207  is performed in a case where it is determined in Step S 202  and Step S 203  that the following two expressions are true. 
         V in1 +Vtha&lt;V out 
         V in1 +Vthb&lt;V in2 
     First, in Step S 204 , the FET controller  130  changes the second switch circuit (SW 2 )  120  from the ON state to the ideal diode operating state. 
     This state change process is performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the second switch circuit (SW 2 )  120 , that is, the FET ( 2 A)  121  and the FET ( 2 B)  122 , so as to switch the continuity/interruption state of each of the FETs. 
     (Step S 205 ) 
     Next, in Step S 205 , the FET controller  130  changes the first switch circuit (SW 1 )  110  from the OFF state to the ON state. 
     This state change process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the first switch circuit (SW 1 )  110 , that is, the FET ( 1 A)  111  and the FET ( 1 B)  112 , so as to switch the continuity/interruption state of each of the FETs. 
     (Step S 206 ) 
     Next, in Step S 206 , the FET controller  130  changes the second switch circuit (SW 2 )  120  from the ideal diode operating state to the OFF state. 
     This state change process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the second switch circuit (SW 2 )  120 , that is, the FET ( 2 A)  121  and the FET ( 2 B)  122 , so as to switch the continuity/interruption state of each of the FETs. 
     (Step S 207 ) 
     In Step S 207 , as a result of the above-described process in Steps S 204  to S 206 , electric power starts being supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110 . 
     In other words, 
     a process of a change from 
     a start state=a state where electric power is supplied from the battery 2,  202  to the load  210  through the second switch circuit (SW 2 )  120 , to 
     Step S 207 =a state where electric power is supplied from the battery 1,  201  to the load  210  through the first switch circuit (SW 1 )  110   
     is performed without stopping the electric power being supplied to the load  210 . 
     That is, the live-line plugging/unplugging (hot swapping) process for a battery is completed. 
     (Step S 221 ) 
     Next, a description will be made regarding a process in Steps S 221  to S 223 . 
     The process in Steps S 221  to S 223  is a charging process for the battery 2,  202 , that is, a process of charging the battery 2,  202  with a regenerative energy (a regenerative current) generated by the motor of the load  210 . 
     This battery regeneration process is performed in a case where it is determined in Step S 202  and Step S 203  that the following two expressions are true. 
         V in2 +Vtha&lt;V out 
         V in2 +Vthb≥V in1 
     The FET controller  130  confirms in Steps S 202  and S 203  that the two expressions 
         V in2 +Vtha&lt;V out 
         V in2 +Vthb≥V in1 
     are true, determines that a rise in the load-side voltage (Vout) is based on generation of a regenerative energy, and then performs the process in Step  3221  and subsequent steps, that is, the process of charging the battery 2,  202  with the regenerative energy (the regenerative current) generated by the motor of the load  210 . 
     First, in Step S 221 , the FET controller  130  maintains the ON state of the second switch circuit (SW 2 )  120 . 
     This state maintenance process is performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the second switch circuit (SW 2 )  120 , that is, the FET ( 2 A)  121  and the FET ( 2 B)  122 , so as to maintain the continuity/interruption state of each of the FETs at a present state. 
     (Step S 222 ) 
     Next, the FET controller  130  maintains the OFF state of the first switch circuit (SW 1 )  110  in Step S 222 . 
     This state maintenance process is likewise performed as a result of the gate voltage control performed by the FET controller  130  on the two FETs of the first switch circuit (SW 1 )  110 , that is, the FET ( 1 A)  111  and the FET ( 1 B)  112 , so as to maintain the continuity/interruption state of each of the FETs at a present state. 
     (Step S 223 ) 
     In Step S 223 , as a result of the above-described process in Steps S 221  to S 222 , the charging process for the battery 2,  202 , that is, the process of charging the battery 2,  202  with the regenerative energy (the regenerative current) generated by the motor of the load  210 , is performed. 
     As described above, irrespective of whether the initial state is the state where electric power is supplied to the load  210  through the battery 1,  201  or the state where electric power is supplied to the load  210  through the battery 2,  202 , the power source switching apparatus  100   a  illustrated in  FIG. 8  performs, in either case, a control of the switch circuits  110  and  120 , that is, a control of the following three states. 
     (a) an ON state 
     (b) an OFF state 
     (c) an ideal diode operating state 
     This makes it possible to reliably perform the following three processes. 
     (Process 1) normal process: a process of supplying electric power from the battery to the load 
     (Process 2) live-line plugging/unplugging process (hot swap): a battery switching process performed while electric power continues to be supplied to the load 
     (Process 3) regeneration process: a process of charging the battery by supplying the battery with a regenerative energy (a regenerative current) resulting from the rotation of the motor of the load 
     5. Other Embodiments 
     Next, a description will be made regarding other embodiments. 
     The power source switching apparatus  100   a  illustrated in  FIG. 8  is a configuration example of the power source switching apparatus of the present disclosure, The power source switching apparatus of the present disclosure can be implemented by a variety of configurations in addition to the configuration illustrated in  FIG. 8 . 
     A plurality of modification examples will be described in sequence as follow. 
     Modification example 1. Configuration example with separate FET controllers corresponding one-to-one to the switch circuits 
     Modification example 2. Configuration example with a microcomputer (MCU) 
     Modification example 3. Configuration example with a comparator 
     Modification example 4. Configuration example with a CPU 
     Modification Example 1. Configuration Example with Separate FET Controllers Corresponding One-to-One to the Switch Circuits 
     First, a description will be made regarding, as a modification example 1, a configuration example with separate FET controllers corresponding one-to-one to the switch circuits, with reference to  FIG. 11 . 
     A power source switching apparatus  100   b  illustrated in  FIG. 11  is a power source switching apparatus having a configuration where the FET controller  130  of the power source switching apparatus  100   a  illustrated in  FIG. 8  is divided into two. 
     The power source switching apparatus  100   b  illustrated in  FIG. 11  includes a first FET controller  141  and a second FET controller  142 . 
     The first FET controller  141  controls the two FETs of the first switch circuit (SW 1 ), i.e., the FET ( 1 A)  111  and the FET ( 1 B)  112 . The first FET controller  141  controls a gate-source voltage of each of the FETs 
     Similarly, the second FET controller  142  controls the two FETs of the second switch circuit (SW 2 ), i.e., the FET ( 2 A)  121  and the FET ( 2 B)  122 . The second FET controller  142  controls a gate-source voltage of each of the FETs 
     As a result of the control performed by the first FET controller  141  and the second FET controller  142 , the first switch circuit (SW 1 ) and the second switch circuit (SW 2 ) are each set in any one of the following three states. 
     (a) the ON state 
     (b) the OFF state 
     (c) the ideal diode operating state 
     The power source switching apparatus  100   b  illustrated in  FIG. 11  can also perform processes similar to the previously described processes based on the flows illustrated in  FIG. 9  and  FIG. 10 . 
     Modification Example 2. Configuration Example with a Microcomputer (MCU) 
     Next, a description will be made regarding a configuration example with a microcomputer (MCU), with reference to  FIG. 12 . 
     A power source switching apparatus  100   c  illustrated in  FIG. 12  is a power source switching apparatus having a configuration where the FET controller  130  of the power source switching apparatus  100   a  illustrated in  FIG. 8  is divided into two components, i.e., an FET controller  150  and a microcomputer (MCU)  160  illustrated in  FIG. 12 . 
     The FET controller  130  of the power source switching apparatus  100   a  illustrated in  FIG. 8  performs, within the FET controller  130 , the process of comparing the voltages (Vin1, Vin2, and Vout), determination of a control mode based on the comparison result, etc. 
     In contrast, in the power source switching apparatus  100   c  illustrated in  FIG. 12 , the microcomputer (MCU)  160  performs a process of comparing the input-side voltage (Vin1) of the first switch circuit (SW 1 )  110 , i.e., a battery 1,  101 -side voltage, and the input-side voltage (Vin2) of the second switch circuit (SW 2 )  120 , i.e., a battery 2,  102 -side voltage. The FET controller  150  controls the FETs of each of the switch circuits  110  and  120  on the basis of a voltage comparison result outputted from the microcomputer (MCU)  160 . 
     The FET controller  150  includes a control information input unit (an Exit control terminal) that receives, as input, the voltage comparison result outputted from the microcomputer (MCU)  160 , and controls the FETs of each of the switch circuits  110  and  120  on the basis of an outputted value from the microcomputer (MCU)  160  that is received as input through the control information input unit (the Exit control terminal). 
     In a case of this configuration, the processes based on the flows illustrated in  FIG. 9  and  FIG. 10  are to be performed by the microcomputer (MCU)  160  and the FET controller  150 . 
     It should be noted that the microcomputer (MCU)  160  may determine the control mode of each of the switches on the basis of the voltage comparison result, and input determined control information to the FET controller  1250 . 
     In this case, the FET controller  150  performs a control according to the control information received as input from the microcomputer  160 . 
     Modification Example 3. Configuration Example with a Comparator 
     Next, a description will be made regarding a configuration example with a comparator, with reference to  FIG. 13 . 
     A power source switching apparatus  100   d  illustrated in  FIG. 13  has a configuration where the FET controller  130  of the power source switching apparatus  100   a  illustrated in  FIG. 8  is divided into two components, i.e., an FET controller  170  and a comparator  180  illustrated in  FIG. 13 . 
     The comparator  180  of the power source switching apparatus  100   d  illustrated in  FIG. 13  performs a process of comparing the input-side voltage (Vin1) of the first switch circuit (SW 1 )  110 , i.e., the battery 1,  101 -side voltage, and the input-side voltage (Vin2) of the second switch circuit (SW 2 )  120 , i.e., the battery 2,  102 -side voltage, and inputs a comparison result to the FET controller  170 . 
     The FET controller  170  includes an information input unit (an Exit control terminal) that receives, as input, the voltage comparison result from the comparator  180 , and controls the FETs of each of the switch circuits  110  and  120  on the basis of the voltage comparison result received as input through the information input unit (the Exit control terminal). 
     In a case of this configuration, the processes based on the flows illustrated in  FIG. 9  and  FIG. 10  are to be performed by the comparator  180  and the FET controller  170 . 
     Modification Example 4. Configuration Example with a CPU 
     Next, a description will be made regarding a configuration example with a CPU, with reference to  FIG. 14 . 
     A power source switching apparatus  100   e  illustrated in  FIG. 14  has a configuration where the FET controller  130  of the power source switching apparatus  100   a  illustrated in  FIG. 8  is divided into two components, i.e., an FET controller  190  and a CPU  195  illustrated in  FIG. 14 . 
     The CPU  195  controls a timing of switching the operating state (ON, OFF, or ideal diode) of each of the switch circuits on the basis of, for example, an operating state of a load. 
     Specifically, the CPU  195  selects a timing at which the load  210  has a less operating amount, and performs a control for causing the operating state (ON, OFF, or ideal diode) of each of the switch circuits to be switched. 
     The CPU  195  acquires an operation plan of the load, specifically, action plan information regarding a robot (program information), from a storage unit not illustrated and detects a timing at which the load  210  has a less processing amount, on the basis of the acquired action plan information (the program information). Control information is outputted to the FET controller  190  such that switching of the operating state (ON, OFF, or ideal diode) of each of the switch circuits is performed at the detected timing. 
     It should be noted that the CPU  195  may perform a process of monitoring a load operating status, detect a timing at which the load  210  has a less processing amount, on the basis of a monitoring result, and output the control information to the FET controller  190  such that switching of the operating state (ON, OFF, or ideal diode) of each of the switch circuits is performed at the detected timing. 
     By performing such a control, it is possible to perform the switch state switching process in which a stress on the FETs of each of the switch circuits is reduced. 
     6. Hardware Configuration Example of a Robot 
     Next, a description will be made regarding an example of a hardware configuration of a traveling robot  300  including the above-described power source switching circuit therein. 
       FIG. 15  is a block diagram illustrating a configuration example of the traveling robot  300  of the present disclosure. 
     As illustrated in  FIG. 15 , the traveling robot  300  includes a control unit  301 , an input unit  302 , an output unit  303 , a sensor group  304 , a drive unit  305 , a communication unit  306 , a storage unit  307 , and a power source switching unit  321 . 
     The control unit  301  performs a control for a process performed in the traveling robot  100 . For example, the control unit  301  performs a process according to a control program stored in the storage unit  307 . The control unit  301  includes a processor having a program execution function. 
     The input unit  302  is an interface to which various pieces of data can be inputted by a user, and includes a touch panel, a code reader unit, a variety of switches, etc. 
     The output unit  303  is a speaker that outputs an alert or a voice, a display that outputs an image, and an output unit that outputs light or the like. 
     The sensor group  304  includes a variety of sensors such as a camera, a microphone, a radar, and a range sensor. 
     The drive unit  305  includes an actuator such as a motor, which serves as a drive unit for a wheel or a leg for causing the traveling robot  100  to move, a direction control mechanism, etc. 
     The communication unit  306  performs a process of communication with, for example, a management server, an external device such as an external sensor, etc. 
     The storage unit  307  stores travel route information, information regarding a program to be performed in the control unit  301 , etc. 
     The power source switching unit  321  has a configuration corresponding to the power source switching apparatus previously described with reference to  FIG. 8 , etc. In other words, the power source switching unit  321  has a configuration that, by switching the operating states (ON, OFF, or ideal diode operation) of the switch circuits, achieves the following processes. 
     (a) the live-line plugging/unplugging (hot swap) process for a battery 
     (b) the recovery of a regenerative energy 
     7. Summary of Configurations of the Present Disclosure 
     The embodiments of the present disclosure are described in detail above with reference to the specific embodiments. However, it is obvious that those skilled in the art would alter or replace the embodiments without departing from the scope of the spirit of the present disclosure. In other words, the present invention is disclosed by way of example and should not be understood as limitations. In order to determine the spirit of the present disclosure, the claims should be taken into account. 
     It should be noted that the technology disclosed herein can be take the following configurations. 
     (1) 
     A power source switching apparatus including: 
     a first switch circuit provided between a first power source port and a load to be supplied with electric power; 
     a second switch circuit provided between a second power source port and the load; and 
     a controller configured to control the first switch circuit and the second switch circuit, in which the controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states including
         (a) an ON state that indicates a continuity state,   (b) an OFF state that indicates an interruption state, and   (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage,       

     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     (2) 
     The power source switching apparatus according to (1), in which 
     the controller is configured to perform a process of charging a battery that is used as a power source and connected to the first power source port or the second power source port, by inputting, to the battery, a regenerative energy generated by a rotation of a motor included in the load. 
     (3) 
     The power source switching apparatus according to (1) or (2), in which 
     the controller compares
         a first switch circuit input-side voltage (Vin1) that is included in a voltage of the first switch circuit on a side of the first power source port,   a second switch circuit input-side voltage (Vin2) that is included in a voltage of the second switch circuit on a side of the second power source port, and   a switch circuit output-side voltage (Vout) that is included in a voltage of the first switch circuit and the second switch circuit on a side of the load, and       

     the controller performs the process of switching between the three states according to a comparison result. 
     (4) 
     The power source switching apparatus according to (3), in which 
     the controller is configured to determine, on the basis of the comparison result of
         the first switch circuit input-side voltage (Vin1),   the second switch circuit input-side voltage (Vin2), and   the switch circuit output-side voltage (Vout),       

     whether a battery replacement execution mode is on or a charging mode is on, 
     the battery replacement execution mode being a mode in which the first power source port and the second power source port are both connected to the respective power sources, 
     the charging mode being a mode in which the process of charging the battery that is used as a power source and connected to the first power source port or the second power source port, by inputting, to the battery, the regenerative energy generated by the rotation of the motor included in the load is performed. 
     (5) 
     The power source switching apparatus according to any one of (1) to (4), in which 
     the first switch circuit and the second switch circuit each include an ideal diode circuit having a plurality of FETs. 
     (6) 
     The power source switching apparatus according to any one of (1) to (5), in which 
     the controller is configured to control a gate-source voltage of each of the FETs provided in the first switch circuit and the second switch circuit. 
     (7) 
     The power source switching apparatus according to any one of (1) to (6), in which 
     the controller includes a plurality of controllers, the plurality of controllers including
         a first controller configured to perform a control of the first switch circuit, and   a second controller configured to perform a control of the second switch circuit.
 
(8)
       

     The power source switching apparatus according to any one of (1) to (7), further including: 
     a microcomputer connected to the controller, the microcomputer being configured to 
     perform a process of comparing
         a first switch circuit input-side voltage (Vin1) that is included in a voltage of the first switch circuit on a side of the first power source port, and   a second switch circuit input-side voltage (Vin2) that is included in a voltage of the second switch circuit on a side of the second power source port, and       

     output a comparison result to the controller. 
     (9) 
     The power source switching apparatus according to any one of (1) to (8), further including: 
     a comparator connected to the controller, the comparator being configured to 
     perform a process of comparing
         a first switch circuit input-side voltage (Vin1) that is included in a voltage of the first switch circuit on a side of the first power source port, and   a second switch circuit input-side voltage (Vin2) that is included in a voltage of the second switch circuit on a side of the second power source port, and       

     output a comparison result to the controller. 
     (10) 
     The power source switching apparatus according to any one of (1) to (9), further including: 
     a processor connected to the controller, the processor being configured to control a timing of the process of switching between the three states (a) to (c). 
     (11) 
     The power source switching apparatus according to any one of (1) to (10), in which 
     the processor is configured to determine a timing of the process of switching between the three states (a) to (c), according to a processing status of the load. 
     (12) 
     A robot including: 
     a load including a drive unit; and 
     a power source switching unit configured to perform a control of switching between power sources that supply electric power to the load, in which 
     the power source switching unit includes
         a first switch circuit provided between a first power source port and the load to be supplied with the electric power,   a second switch circuit provided between a second power source port and the load, and   a controller configured to control the first switch circuit and the second switch circuit, and       

     the controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states including
         (a) an ON state that indicates a continuity state,   (b) an OFF state that indicates an interruption state, and   (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage,       

     thereby performing a process of switching between the power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     (13) 
     The robot according to (12), in which 
     the controller is configured to perform a process of charging a battery that is used as a power source and connected to the first power source port or the second power source port, by inputting, to the battery, a regenerative energy generated by a rotation of a motor included in the load. 
     (14) 
     A power source switching control method that is performed on a power source switching apparatus, in which 
     the power source switching apparatus includes
         a first switch circuit provided between a first power source port and a load to be supplied with electric power,   a second switch circuit provided between a second power source port and the load, and   a controller configured to control the first switch circuit and the second switch circuit, and       

     the controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states including
         (a) an ON state that indicates a continuity state,   (b) an OFF state that indicates an interruption state, and   (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage,       

     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     (15) 
     A robot control method that is performed on a robot, in which 
     the robot includes
         a load including a drive unit, and   a power source switching unit configured to perform a control of switching between power sources that supply electric power to the load,       

     the power source switching unit includes
         a first switch circuit provided between a first power source port and the load to be supplied with the electric power,   a second switch circuit provided between a second power source port and the load, and   a controller configured to control the first switch circuit and the second switch circuit, and       

     the controller is configured to perform, on each of the first switch circuit and the second switch circuit, a process of switching between three states including
         (a) an ON state that indicates a continuity state,   (b) an OFF state that indicates an interruption state, and   (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage,       

     thereby performing a process of switching between the power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     (16) 
     A program causing a power source switching control process to be performed on a power source switching apparatus, the power source switching apparatus including 
     a first switch circuit provided between a first power source port and a load to be supplied with electric power, 
     a second switch circuit provided between a second power source port and the load, and 
     a controller configured to control the first switch circuit and the second switch circuit, 
     the program causing the controller to perform: 
     on each of the first switch circuit and the second switch circuit, a process of switching between three states including
         (a) an ON state that indicates a continuity state,   (b) an OFF state that indicates an interruption state, and   (c) a diode operating state where the electric power is allowed to be supplied only in one direction from a power source port side toward a load side in a case where a power-source-port-side voltage is higher than a load-side voltage,       

     thereby performing a process of switching between power sources individually connected to the first power source port and second power source port without stopping the electric power being supplied to the load. 
     It should be noted that a series of processes described herein can be performed by hardware, software, or the combination of both. In a case where the processes are performed by software, a program in which a process sequence is recorded can be installed in a memory within a computer installed in dedicated hardware and be executed, or a program can be installed in a general-purpose computer capable of performing a variety of processes and be executed. For example, the program can be recorded in advance in a recording medium. In addition to being installed in a computer from the recording medium, the program can be received through a network such as a LAN (Local Area Network) or the Internet and installed in a built-in recording medium such as hard disk. 
     Further, the variety of processes described herein may be performed in parallel or independently depending on an ability of processing of an apparatus that performs the processes or as necessary, instead of being performed in a chronological order based on the description. Further, a system herein refers to a logical cluster configuration including a plurality of apparatuses, and the apparatuses in the configuration are not necessarily within the same casing. 
     INDUSTRIAL APPLICABILITY 
     As described above, with the configuration of an embodiment of the present disclosure, an apparatus and a method capable of performing a power source switching process and a charging process without stopping electric power being supplied to a load are implemented. 
     Specifically, the configuration includes, for example, a first switch circuit provided between a first power source port and a load to be supplied with electric power, a second switch circuit provided between a second power source port and the load, and a controller configured to control each of the switch circuits. The controller is configured to perform, on each of the switch circuits, a process of switching between three states, that is, (a) an ON state, (b) an OFF state, and (c) a diode operating state, thereby performing a process of switching between power sources connected to the respective power source ports without stopping the electric power being supplied to the load. Further, the controller is configured to perform battery charging with a regenerative energy resulting from a rotation of a motor which is the load. 
     With the present configuration, an apparatus and a method capable of performing a power source switching process and a charging process without stopping electric power being supplied to a load are implemented. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10 : Robot 
               11 : Battery 1 
               12 : Battery 2 
               21 : Motor 
               31 ,  32 : Ideal diode circuit 
               100 : Power source switching apparatus 
               101 : First power source port 
               102 : Second power source port 
               103 : Smoothing capacitor 
               110 : First switch circuit (SW 1 ) 
               111 ,  112 : FET 
               120 : Second switch circuit (SW 2 ) 
               121 ,  122 : FET 
               130 : FET controller 
               201 : Battery 1 
               202 : Battery 2 
               210 : Load 
               141 : First FET controller 
               142 : Second FET controller 
               150 : FET controller 
               160 : Microcomputer (MCU) 
               170 : FET controller 
               180 : Comparator 
               190 : FET controller 
               195 : CPU 
               300 : Traveling robot 
               301 : Control unit 
               302 : Input unit 
               303 : Output unit 
               304 : Sensor group 
               305 : Drive unit 
               306 : Communication unit 
               307 : Storage unit 
               321 : Power source switching unit