Mobile robot

Abstract

A mobile robot is provided with: a main body section having a plurality of propulsion units that generate propulsion force by driving a rotary wing; and a plurality of support parts provided on the main body and capable of supporting at least a portion of the main body by coming into contact with a predetermined contact surface, the mobile robot being configured such that, when the main body is supported by the plurality of support parts and movement control is performed, the support control of the movement control is controlled by the plurality of support parts. The plurality of propulsion units are driven to adjust a load applied to a predetermined contact surface via a predetermined support section that is in contact with the predetermined contact surface among the plurality of support sections.

Description

Technical Field

[0001] The present invention relates to a mobile robot capable of flying and performing a moving action. Background Art

[0002] In recent years, unmanned aerial vehicles have been used for various purposes and their development has been in full swing. As unmanned aerial vehicles, remotely controlled unmanned helicopters, so-called drones, are used. For example, as an application example of drones for agricultural purposes, pesticide spraying, breeding observation of crops using a mounted camera, generation of an air current for protecting crops from frost damage, etc. can be exemplified (for example, refer to Patent Document 1). In addition, an arm for performing a prescribed operation is provided on the unmanned aerial vehicle, and a flying robot has been developed so that it can be widely used for other purposes not limited to agricultural purposes (for example, refer to Patent Document 2).

[0003] In addition, Patent Document 3 discloses a mobile robot that performs flight using a propulsion unit and performs a walking action on the ground. In this mobile robot, walking using two legs is performed, and if it is detected by a sensor that the inclination of the robot main body becomes large during the walking action, the propulsion unit is used to control the attitude of the robot so that the inclination is within a prescribed angle range.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-000015

[0007] Patent Document 2: International Publication No. 2016 / 193666

[0008] Patent Document 3: Japanese Patent No. 6733965 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In the case where the robot moves the main body of the robot in a state of contact with a contact surface such as the ground, that is, in the case of moving without the movement caused by flight and moving with contact with the contact surface such as walking (it should be noted that in this application, the movement of the former method is called "flight movement", and the movement of the latter method is called "contact movement"), the main body of the robot needs to be supported by a support portion (for example, a leg) in contact with the contact surface in such a way that the main body does not fall, while realizing the movement of the main body of the robot. Generally, in contact movement, when the moving speed is sharp, it is difficult to maintain the stability of the robot main body and the possibility of falling increases. In addition, the main body of the robot swings with the movement, which hinders the acquisition of information related to the position and posture of the robot required for stable contact movement of the robot, and the possibility of the main body of the robot falling cannot be eliminated.

[0011] The present invention has been completed in view of the above problems, and an object thereof is to provide a robot technology that can minimize the tipping of the main body of a robot performing contact movement in contact with a contact surface and realize stable contact movement.

[0012] Means for Solving the Problem

[0013] In the present invention, in order to solve the above problems, a structure is adopted in which a support portion in contact with a contact surface is provided in the robot of the present invention and the propulsion force of the propulsion unit is controlled. On this basis, in this robot, a first control unit for this contact movement when performing contact movement using the support portion and a second control unit for support control for supporting this contact movement using the propulsion unit are provided. With such a structure, stable contact movement of the robot can be realized.

[0014] Specifically, the mobile robot of the present invention includes: a main body portion having a plurality of propulsion units that generate propulsion force by driving rotary wings; a plurality of support portions provided on the main body portion and in contact with a predetermined contact surface to be able to support at least a part of the main body portion; a first control unit that performs movement control for moving the main body portion on the predetermined contact surface using the plurality of support portions while supporting the main body portion using the plurality of support portions; and a second control unit that uses a part or all of the plurality of propulsion units to perform support control based on the movement control of the first control unit. And, the second control unit drives the plurality of propulsion units in the support control to adjust the load applied to the predetermined contact surface via a predetermined support portion in contact with the predetermined contact surface among the plurality of support portions.

[0015] Advantages of the Invention

[0016] In a mobile robot that performs contact movement in contact with a contact surface, it is possible to avoid the tipping of its main body as much as possible and achieve stable contact movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a diagram showing a schematic configuration of a mobile robot according to an embodiment.

[0018] Figure 2 FIG. is a functional block diagram that visualizes the functional units formed in the mobile robot according to the embodiment.

[0019] Figure 3 FIG. is a first diagram for explaining support control for supporting the walking of the mobile robot.

[0020] Figure 4 FIG. is a second diagram for explaining support control for supporting the walking of the mobile robot.

[0021] Figure 5 FIG. is a flowchart related to support control for supporting the walking of the mobile robot.

[0022] Figure 6 FIG. is a diagram showing a first mode of support control for supporting the walking of the mobile robot.

[0023] Figure 7 FIG. is a diagram showing a second mode of support control for supporting the walking of the mobile robot. DETAILED DESCRIPTION OF THE INVENTION

[0024] The mobile robot according to the present embodiment can generate a propulsive force for raising or lowering the main body by using a plurality of propulsion units provided on the main body side. Each propulsion unit has a rotary wing, and the propulsive force generated by the propulsion unit is determined by driving the rotary wing to rotate. Preferably, the propulsive force of each propulsion unit can be independently controlled. The arrangement of the plurality of propulsion units on the main body can be designed arbitrarily. The mobile robot can be configured to be able to fly (ascend, descend, rotate, etc.) by the balance of the propulsive forces of the propulsion units provided on the main body. The plurality of propulsion units provided on the main body can all be of the same type or can be a mixture of different types.

[0025] Further, by having a plurality of support portions, the mobile robot supports its main body on a specified contact surface. It should be noted that the support of the main body by the support portions can be vertical support, or can also be support in a direction other than vertical. In the former case, the support portion can be configured as a leg that can contact the contact surface and enable the main body to walk on the contact surface. In the latter case, the support portion can also be configured as an arm that can move the main body while contacting and gripping the contact surface. The structural solutions of the support portions can also adopt solutions other than these.

[0026] Here, in the mobile robot, the first control unit performs contact movement of moving on the contact surface using a plurality of support portions. In order to perform contact movement in such a way that the main body does not contact the contact surface due to tipping, that is, to maintain the state of support by the support portions, the first control unit controls the driving of the plurality of support portions. Here, when performing the control based on the first control unit, there are cases where the contact of a part of the plurality of support portions with the contact surface disappears instantaneously or temporarily, and the stability of the support of the main body by the plurality of support portions decreases. This decrease in stability does not necessarily cause the mobile robot to tip over, but it is preferably minimized. In particular, when it is difficult to imagine the state of the contact surface contacted by the support portions, the possibility of tipping over due to poor movement control based on the first control unit increases.

[0027] Then, when the possibility of such tipping over increases, support control for the movement control based on the second control unit is performed. In this support control, the propulsive force of a plurality of propulsion units is used to adjust the load transmitted to the contact surface via the support portions in contact with the contact surface. That is, by intentionally adjusting the load via each support portion, the position of the center of pressure of the support portion of the mobile robot relative to the contact surface is shifted to a state where tipping is less likely to occur. Thereby, the purpose of avoiding tipping is achieved.

[0028] More specifically, when the target pressure position associated with the shift of the center of gravity of the main body part in the movement control is not inside the actual support area that actually supports the main body part by using the specified support part, the second control part adjusts the load so that the target pressure position is displaced inside the actual support area. In this support control, it is considered that the possibility of tipping over increases due to insufficient support force generated by the support part required for stable contact movement when the target pressure position is not inside the actual support area. The target pressure position is the position of the zero moment point (ZMP) of the mobile robot assumed during the contact movement based on the first control part. In addition, the actual support area is an area on the contact surface divided by the contact parts of the support parts in contact with the contact surface among the plurality of support parts. In this way, when the possibility of tipping over is considered high based on the relationship between the target pressure position and the actual support area, the ZMP of the mobile robot is displaced from the position corresponding to the initial target pressure position (i.e., the position deviating from the actual support area) to the position obtained by load adjustment (i.e., the position within the actual support area) by using the propulsive force generated by driving a part or all of the plurality of propulsion units, thereby avoiding the tipping over of the mobile robot.

[0029] In this way, when it is determined that the possibility of tipping over is high, by using the propulsive force of the propulsion unit to adjust the load, it is possible to reliably provide a support force for preventing tipping over regardless of the action, posture, and position of the support part. This simplifies the structure for preventing tipping over in the mobile robot. For example, the configuration of sensors for smooth contact movement can be omitted. In addition, even if the state of the contact surface is an unanticipated state, it is possible to reliably generate a support force by appropriately driving the propulsion unit, and stable contact movement can be achieved.

[0030] Hereinafter, specific embodiments of the present invention will be described based on the drawings. The dimensions, materials, shapes, the number thereof, relative arrangements, etc. of the structural components described in this embodiment are not intended to limit the technical scope of the invention only to these without special description.

[0031] <Embodiment>

[0032] Here, based on Figure 1 and Figure 2 the general situation of the mobile robot 10 of this embodiment will be described. Figure 1 is a diagram showing the external structure of the mobile robot 10, Figure 2 is a diagram showing the functional blocks included in the mobile robot 10. The main body part 13 of the mobile robot 10 is formed to include a part mainly associated with the flight action of the mobile robot 10 and a part mainly associated with the walking action of the mobile robot 10. That is, in this embodiment, the mobile robot 10 is configured to be able to perform flight actions and walking actions.

[0033] First, the structure associated with the flight motion will be described. A plurality of propulsion units 12 are arranged on the main body 13 via a plurality of bridge members 14. It should be noted that, in Figure 1 the example shown, four propulsion units 12 are mounted on the main body 13. However, as long as the mobile robot 10 can fly, the number of mounted propulsion units 12 is not limited to four as long as it is plural. In addition, in the present embodiment, when the mobile robot 10 is in a reference posture with respect to the contact surface (e.g., the ground, etc.) FL, the rotor plane formed by connecting the center points of the four propulsion units is set to be parallel to the contact surface FL, and the four propulsion units 12 are respectively arranged in a rotationally symmetric manner around the main body 13 on the rotor plane. In other words, the four propulsion units 12 are respectively arranged in a line-symmetric manner across a specified center line or in a point-symmetric manner around a specified point on the plane B. It should be noted that this reference posture is a state in which all four legs 11 described later are set to a specified state to avoid the main body 13 from tilting with respect to the contact surface FL. It should be noted that, for the propulsion unit 12, when referring to each propulsion unit individually, the reference numerals 12a to 12d are used.

[0034] The propulsion unit 12 has a propeller as a rotary wing and an actuator for driving the propeller to rotate. All four propulsion units 12 are of the same type, but the actuators in each propulsion unit 12 can be independently controlled. Therefore, the propulsion force obtained by each propulsion unit 12 can be appropriately controlled, and thus the flight attitude, flight speed, etc. of the mobile robot 10 can be appropriately controlled. And, as will be described later, in the support control during the walking motion of the mobile robot 10, the actuators in each propulsion unit 12 can also be independently controlled. In addition, the mobile robot 10 is equipped with sensors (flight sensors) 15 required for the flight motion, sensors (contact sensors 16) required for the walking motion, a storage battery 17 for supplying driving power to the sensors and the actuators of each propulsion unit 12 (refer to Figure 2 ), and a control device for controlling the power supply from the storage battery 17 to each actuator. Two control units, a first control unit 100 and a second control unit 200, are assembled in this control device, and the details will be described later.

[0035] Next, the structure associated with the walking motion will be described. The mobile robot 10 has four (four) legs 11 configured to be able to perform a walking motion. It should be noted that, in Figure 1In the example shown, four legs 11 are provided on the main body 13. However, as long as the walking motion can be performed, the number of legs 11 is not limited to four, and can also be two, three, or five or more legs 11 can be provided. It should be noted that for the legs 11, when referring to each leg individually, the reference numerals 11a to 11d are used.

[0036] As an example of the leg 11, an enlarged view of the leg 11 is shown in Figure 1 The leg 11 has: a grounding portion that grounds when the mobile robot 10 walks by a walking motion; a link portion that is rotatably connected to the grounding portion via a joint; a hip joint portion that is rotatably connected to the link portion via a joint; and a plurality of actuators (not shown) that drive and control the rotation of each joint. The joints related to the link portion are designed with their rotation directions (rotation directions around the roll axis and the pitch axis) according to the envisaged walking motion. It should be noted that the structure of the leg 11 is not limited to such a scheme. In addition, the hip joint portion is rotatably connected to the lower side of the main body 13 via a prescribed joint. The prescribed joint is configured to be able to rotate around the yaw axis. Regarding the prescribed joint, it can also be configured to be able to rotate around the roll axis and the pitch axis.

[0037] The leg 11 configured in this way is a structure that supports the self-weight of the mobile robot 10 with respect to the contact surface FL during the walking motion of the mobile robot 10 and can perform the walking motion of the mobile robot 10. Therefore, the four legs 11 function as a support portion of the present invention for the walking motion included in the type for realizing the moving motion. In addition, different from the flying motion, the walking motion is performed in a state where at least one of the four legs 11 is in contact with the contact surface FL and supports the main body 13. Therefore, the walking motion is also a mode of the motion included in the contact movement.

[0038] <Mobile Robot 10's Control Unit>

[0039] Next, based on Figure 2 the control structure of the mobile robot 10 will be described. The mobile robot 10 has a control device including a first control unit 100, a second control unit 200, and a detection unit 300. The control device is a computer having an arithmetic processing device and a memory. Each functional unit is formed by executing a prescribed control program in the mobile robot 10.

[0040] First, the first control unit 100 will be described. The first control unit 100 is a functional unit for performing walking actions and flying actions in the mobile robot 10 using the legs 11 and the propulsion unit 12. That is, the first control unit 100 controls the actuators provided in the legs 11 for walking actions and controls the propulsion unit 12 for flying actions. Further, the first control unit 100 controls the propulsion force of the four propulsion units 12 based on the environmental information detected by the flight sensor 15 among the information related to the flight state of the mobile robot 10. As this environmental information, information such as the angular velocity of the main body 13 detected by a gyro sensor corresponding to three axes (yaw axis, pitch axis, roll axis, not shown) and the inclination of the main body 13 detected by an acceleration sensor corresponding to the same three axes (not shown) can be exemplified. The first control unit 100 performs feedback control using the environmental information obtained by these sensors so that the inclination of the main body 13 of the mobile robot 10 becomes a state suitable for its flight. Further, the environmental information may include the azimuth angle that is the orientation of the main body 13 in the absolute coordinate system with reference to the orientation of the earth axis (that is, the orientation of the main body of the mobile robot 10), and this azimuth angle can be detected by an azimuth angle sensor.

[0041] Here, when the main body 13 of the mobile robot 10 flies forward, backward, left, or right, the first control unit 100 reduces the rotational speed of the actuator of the propulsion unit 12 in the traveling direction and increases the rotational speed of the actuator of the propulsion unit 12 on the side opposite to the traveling direction, so that the main body of the mobile robot 10 assumes a posture that is inclined forward with respect to the traveling direction and travels in the desired direction. Further, when the main body of the mobile robot 10 rotates and flies, the first control unit 100 outputs the propellers 21 according to the rotation direction based on the rotation direction of the main body 13 of the mobile robot 10. For example, when the main body 13 of the mobile robot 10 rotates to the right, the first control unit 100 reduces the output of the actuator corresponding to the propeller that rotates to the right and increases the output of the actuator corresponding to the propeller that rotates to the left.

[0042] Next, the walking action performed by the first control unit 100 will be described. The first control unit 100 is also a functional unit for controlling the actuators provided in the four legs 11 for walking when the mobile robot 10 walks. The first control unit 100 uses the environmental information detected by the contact sensor 16 indicating whether the grounding portion of each leg 11 is in contact with the contact surface FL during the walking action. It should be noted that in the present embodiment, the specified walking control program used by the first control unit 100 for walking on the contact surface FL minimizes the acquisition of information related to the surrounding environment of the mobile robot 10 and uses the detection values detected by the contact sensor 16.

[0043] Specifically, an encoder (not shown) for detecting a state quantity (such as the rotational position and rotational speed of the rotational axis of the actuator) related to the respective rotational states is provided in the actuator of each joint provided in the leg 11. It should be noted that sensors other than the encoder can also be used. Further, the first control unit 100 feedback-controls the actuators of the leg 11 based on the state quantities of the respective actuators detected by the encoders of the respective actuators, so as to realize the walking motion of the mobile robot 10 in accordance with the movement instruction given to the mobile robot 10. Thus, in the present embodiment, in the feedback control of the actuator, environmental information outside the robot is not used as much as possible. As a result, sensors provided in the mobile robot 10 can be omitted as much as possible and the walking control itself can be simplified.

[0044] Further, during walking control, the contact sensor 16 detects whether the grounding portion of each leg 11 is in contact with the contact surface FL. The fact that the leg 11 is not in contact with the contact surface FL means that the main body portion 13 of the mobile robot 10 is not supported by the reaction force from the contact surface FL via the leg 11. When the main body portion 13 of the mobile robot 10 is not supported by the leg 11, the stability of the main body portion 13 may change, and in some cases, the possibility of the main body portion 13 tipping over increases. In such a case, in the present embodiment, support control based on the second control unit 200 (corresponding to the "support control for walking control" of the present invention) is implemented.

[0045] <Support Control>

[0046] Hereinafter, the support control based on the second control unit 200 will be described. Here, Figure 3 A description will be given of changes in the stability of the main body portion 13 during walking control (when the mobile robot 10 performs a walking motion). For simplicity of description, it is assumed that the mobile robot 10 is in a stationary state. When the mobile robot 10 is in a moving state, that is, in the case of being accompanied by acceleration and deceleration motions, external disturbances, etc., in addition to gravity, the required forces and / or torques are also considered. Figure 3 The upper part (a) of Figure 3 shows the state in which the four legs 11 of the mobile robot 10 are in contact with the contact surface FL, and

[0047] Here, for the leg 11 where the grounding part actually contacts the contact surface FL, a closed area formed in a manner including its contact point is defined as the actual support area SS. As an example, the actual support area SS can be a polygonal area with the contact point as the vertex. In this case, in Figure 3 in (a), the actual support area SS is formed as a quadrilateral, and in Figure 3 in (b), the actual support area SS is formed as a triangle. Additionally, from the perspective of appropriately supporting the mobile robot 10, the actual support area SS can also be formed into a shape that is further reduced to the inside of the manner shown in Figure 3 in (a) and (b). It should be noted that the second control unit 200 can grasp the position of the contact point of each leg 11 based on the detection value of each contact sensor 16 and the state (position) of the actuator of each leg 11 when the contact state is detected.

[0048] Moreover, when the mobile robot 10 performs walking control using four legs 11, the trajectory where the center of gravity of the mobile robot 10 should exist during this walking motion is given to the above-mentioned first control unit 100 as a position command, and each leg 11 is driven in a manner to follow this position command. At this time, the position of the ZMP that should exist, calculated based on the trajectory of the mobile robot 10, etc., is defined as the target pressure position PP. The target pressure position PP also takes into account the load of the workpiece W carried by the mobile robot 10. And during walking control, as Figure 3 shown in (a) of Figure 3 , when the target pressure position PP is located inside the actual support area SS, the mobile robot 10 is stably supported by the four legs 11. On the other hand, as Figure 3 shown in (b) of Figure 3 , when the target pressure position PP is not located inside the actual support area SS, the mobile robot 10 does not become a state of being stably supported by the three legs 11b, 11c, and 11d. Therefore, in this case, there is a possibility that the mobile robot 10 will tip over.

[0049] Then, in order to suppress the tipping that may occur due to the deviation of the target pressure position PP from the actual support area SS, in the present embodiment, the four propulsion units 12 are used to adjust the load via the legs 11 in contact with the contact surface FL. As a result of the load adjustment, the position of the center of pressure of the mobile robot 10 substantially with respect to the contact surface FL is displaced, and the target pressure position PP is displaced toward the inside of the actual support area SS, thereby achieving the suppression of tipping. An explanation of this load adjustment is based on Figure 4 this. Figure 4 The state of the mobile robot 10 shown in the upper part (a) of Figure 3The state shown in (b) is the same, where the legs 11b, 11c, and 11d are in contact with the contact surface FL, and the actual support area SS in the shape of a triangle is formed by connecting the respective contact points 11b1, 11c1, and 11d1. Moreover, the target pressure position PP is located at a position deviated from the actual support area SS.

[0050] In addition, Figure 4 The lower part (b) shows a view of the contact surface FL observed from above and the relationship between the actual support area SS and the target pressure position PP. In the load adjustment for assist control, the drive control of the four propulsion units 12 is performed such that the target pressure position PP deviated from the actual support area SS is received within the actual support area SS. In Figure 4 the (b), the target pressure position after the load adjustment is indicated by PP1. It should be noted that, at this time, in order to prevent the adjusted target pressure position PP1 from immediately deviating from the actual support area due to external disturbances or the like, it is preferable to set a certain margin (stability margin). That is, the load adjustment is performed such that the partition itself having a certain breadth centered on the target pressure position is received within the actual support area SS.

[0051] More specifically, the sum of the reaction force transmitted from the contact surface to the leg 11 and the load increased or decreased by the propulsion unit 12 is equal to the gravity, and thus the following Equation 1 holds. The load increased or decreased by the propulsion unit 12 is regarded as an increase or decrease in the weight (mass) of the imaginary mobile robot 10 and is referred to as the "gravity load based on the imaginary mass".

[0052] [Equation 1]

[0053] ··· (Equation 1)

[0054] fRi represents the reaction force transmitted to each leg 11, fVgAi represents the gravity load based on the above-mentioned imaginary mass, and fri represents the rotor thrust.

[0055] Moreover, based on the balance of the moments about the center of gravity of the mobile robot 10, the following Equation 2 holds.

[0056] [Equation 2]

[0057] ··· (Equation 2)

[0058] rRi represents the position of the grounding part of each leg, and rri represents the position of each propulsion unit 12. In addition, rVgAi represents the position of the imaginary mass.

[0059] Moreover, when the mobile robot 10 is in a stationary state, the average of the center of gravity of the original mobile robot 10 (the center of gravity corresponding to the target pressure position PP) and the position of the imaginary mass becomes the center of gravity of the mobile robot after load adjustment. The point where the center of gravity of the mobile robot after load adjustment is projected onto the contact surface FL becomes the target pressure position PP1 after load adjustment. Moreover, the load applied to the target pressure position PP1 becomes the sum of the gravitational loads generated by the self-weight of the mobile robot 10 and the imaginary mass. Based on the above, the gravitational load generated by the imaginary mass and the position of the imaginary mass that satisfy Equation 1 and Equation 2 and where the target pressure position PP1 after load adjustment falls within the actual support area are calculated. Furthermore, based on Equation 2, the rotor thrust that can achieve the imaginary mass is calculated, and a drive command is issued to each propulsion unit 12. Thereby, the support control based on the second control unit 200 is executed, and as a result, the stability of the walking motion of the mobile robot 10 is improved compared to the case where the support control is not performed. In addition, as described above, for the walking control of the mobile robot 10, although fewer sensors are used to minimize the use of environmental information, a stable walking motion is achieved.

[0060] Next, the detection unit 300 will be described. The detection unit 300 is a functional unit that detects the friction condition on the contact surface FL. For example, by performing image processing of the contact surface FL captured by the camera provided in the mobile robot 10, the degree of dryness of its surface, the condition on the surface of the contact surface FL, etc. are grasped, and the friction condition is detected. Generally, when the contact surface FL is wet due to rain, snow, etc., the friction coefficient with the mobile robot 10 decreases, which may have some impact on the stable walking motion. On the contrary, when there is a substance with high viscosity on the contact surface FL, affected by the substance and the friction coefficient becomes too high, it may still have some impact on the stable walking motion.

[0061] Then, based on Figure 5 the support control based on the friction condition detected by the detection unit 300 will be described. Figure 5 The support control shown is repeatedly executed by the second control unit 200 at a prescribed time interval. First, in S101, it is determined whether the target pressure position PP at that moment is within the actual support area SS. When an affirmative determination is made in this determination, the process of S103 is performed, and when a negative determination is made in this determination, the process of S102 is performed. It should be noted that as an example of the case of a negative determination is Figure 4 the state shown in (a) of Figure 4 And in S102 after a negative determination is made, as described above, load adjustment using the propulsion unit 12 is performed, and the target pressure position PP1 adjusted as shown in (b) of

[0062] Next, in S103, the detection unit 300 detects the friction condition on the contact surface FL. For the detection of the friction condition, as described above, through the image processing of the shooting result taken by the camera, the following judgments are made, for example, whether there is no attachment of water, snow, etc. that causes the robot to tip over on the contact surface FL, or whether there is no attachment of substances that cause an increase in friction. Then, next, in S104, based on the friction condition obtained from the shooting result, a determination is made as to whether another load adjustment is required. That is, when the difference between the friction condition detected by the detection unit 300 and the assumed friction condition exceeds a specified threshold, it is considered that this difference may have a non-negligible impact on the walking motion of the mobile robot 10. Therefore, in such a case, not only the load adjustment in S102 but also another load adjustment is determined to be required (a positive determination is made).

[0063] When a positive determination is made in S104, the process proceeds to S105, and another load adjustment using the propulsion unit 12 is performed. The load adjustment performed in S105 is an additional load adjustment to the load adjustment performed in S102. For example, based on the result detected by the detection unit 300 and the difference in the obtained friction condition, the gravitational load based on the imaginary mass and the position of the imaginary mass that should be increased to ensure the friction force that conforms to the assumption are calculated. At this time, attention is paid to the fact that the target pressure position after the re-adjustment is within the actual support area SS. When S105 ends, the support control shown from the beginning is repeated. Figure 5 Shown support control. In this way, according to Figure 5 Shown support control, the support for the walking control of the mobile robot 10 considering the condition of the contact surface FL is performed, resulting in a further improvement in the stability of the walking motion of the mobile robot 10.

[0064] <Example of Variation 1>

[0065] Based on Figure 6 A first aspect of the support state formed by the legs 11 during the walking motion of the mobile robot 10 will be described. It should be noted that in Figure 6 , the action of walking on a contact surface in a state of being in a so-called uneven ground rather than a flat surface is performed. In Figure 6The upper part (a) discloses a state in which the entire body part 13 of the mobile robot 10 is supported by all of the four legs 11. Additionally, the middle part (b) discloses a state in which the body part 13 of the mobile robot 10 is supported by three of the four legs 11. Specifically, the leg 11a is separated from the contact surface, and the other legs 11b, 11c, and 11d support the body part 13. Further, the lower part (c) discloses a state in which the body part 13 of the mobile robot 10 is supported by two of the four legs 11. Specifically, the legs 11a and 11c are separated from the contact surface, and the other legs 11b and 11d support the body part 13.

[0066] The state supported by the four legs 11 is the most stable state. However, in a case where the contact surface is uneven as in this embodiment, there is a possibility that the target pressure position PP deviates from the actual support area SS due to the inclination of the mobile robot 10 or the like. In such a case, the support control for the walking control based on the second control unit 200 described above can be executed. The same applies to the case of being supported by three legs 11.

[0067] Here, as Figure 6 shown in (c) of, for the case of being supported by two legs 11, the actual support area SS formed by the legs 11b and 11d in contact with the contact surface becomes a linear area connecting the respective contact points. In such a case, when the target pressure position PP is located on this line, it is determined that the target pressure position PP is inside the actual support area SS, and when the target pressure position PP deviates from this line, it is determined that the target pressure position PP is not inside the actual support area SS. And in the latter case, the support control for the walking control based on the second control unit 200 described above can be executed.

[0068] Furthermore, regarding the walking motion of the mobile robot 10, it is not necessarily required to be walking using the four legs 11. For example, according to the shape and inclination of the contact surface, two of the four legs 11a and 11c can always be separated from the contact surface and the remaining two legs 11b and 11d can be used for walking. That is, when performing a walking motion using the number of legs in the state most suitable for the contact surface and the mobile robot 10 cannot be stably supported by these legs, it is sufficient to execute the support control for the walking control by the second control unit 200 described above.

[0069] <Deformation Example 2>

[0070] Next, based on Figure 7, a second embodiment of the support state formed by the legs 11 during the walking motion of the mobile robot 10 will be described. In the upper part (a) of FIG. 11, a state is disclosed in which, in addition to all of the four legs 11, an end effector 20 having a gripping mechanism originally used for gripping an object is used to support the main body portion 13 of the mobile robot 10. By the contact of the end effector 20 with the contact surface, the number of contact points for supporting the main body portion 13 increases, and an increase in the actual support area SS can be achieved. As a result, the chance that the target pressure position PP is included in the actual support area SS increases, and a more stable walking motion is achieved. In such a case, when the target pressure position PP also deviates from the actual support area SS, the support control of the walking control based on the second control unit 200 described above can be executed.

[0071] In addition, in the middle part (b), a state is disclosed in which, in addition to all of the four legs 11, an object 20a gripped by the end effector 20 is also used to support the main body portion 13 of the mobile robot 10. In this case, the actual support area SS is formed by the contact points of the object 20a gripped by the end effector 20 with the contact surface. For example, when the mobile robot 10 walks while carrying the object 20a, a stable walking motion can be achieved by using this object. Assuming that, in such a case, the target pressure position PP also deviates from the actual support area SS, the support control of the walking control based on the second control unit 200 described above can be executed.

[0072] In addition, in the lower part (c), a state is disclosed in which, in addition to two of the four legs 11, i.e., legs 11c and 11d, an auxiliary support portion 11e that is not directly used for the walking motion like the legs 11 but is configured to be able to support the main body portion 13 during its walking motion is used to support the main body portion 13 of the mobile robot 10. The auxiliary support portion 11e does not have joints and actuators for driving the joints like the legs 11, but is configured as a structure that can apply a certain degree of load to the contact surface and maintain contact. In this case, the actual support area SS is also formed by the contact points of the auxiliary support portion 11e with the contact surface. The supporting force generated by the auxiliary support portion 11e may be weaker than the supporting force generated by the legs 11 in some cases. However, for example, when comparing the case of walking using two legs 11c and 11d with the case of adding the auxiliary support portion 11e to walk, the actual support area SS can be expanded, and thus a stable walking motion is achieved. Assuming that, in such a case, the target pressure position PP also deviates from the actual support area SS, the support control of the walking control based on the second control unit 200 described above can be executed.

[0073] Description of Reference Numerals

[0074] 10: Mobile robot, 11, 11a, 11b, 11c, 11d: Legs, 11e: Auxiliary support portion, 12, 12a, 12b, 12c, 12d: Propulsion unit, 13: Main body portion, 14: Bridge member, 15: Flight sensor, 16: Contact sensor, 17: Battery, 20: End effector, 20a: Object, 100: First control unit, 200: Second control unit, FL: Contact surface, PP: Target pressure position, SS: Actual support area.

Claims

1. A mobile robot, wherein, the mobile robot includes: a main body portion having a plurality of propulsion units that generate propulsion force by driving rotary wings; a plurality of support portions provided on the main body portion and capable of supporting at least a part of the main body portion by contacting a specified contact surface; a first control unit that performs movement control of moving the main body portion on the specified contact surface using the plurality of support portions while supporting the main body portion using the plurality of support portions; and a second control unit that performs support control for the movement control of the first control unit using a part or all of the plurality of propulsion units, in the support control, the second control unit drives the plurality of propulsion units to adjust the load applied to the specified contact surface via a specified support portion that contacts the specified contact surface among the plurality of support portions.

2. The mobile robot according to claim 1, wherein, when a target pressure position associated with the shift of the center of gravity of the main body portion in the movement control is not inside an actual support area where the main body portion is actually supported by the specified support portion, the second control unit adjusts the load so that the target pressure position is displaced inside the actual support area.

3. The mobile robot according to claim 2, wherein, the mobile robot further includes a detection unit that detects a friction condition on the specified contact surface, the second control unit further adjusts the load based on the friction condition detected by the detection unit.

4. The mobile robot according to any one of claims 1 to 3, wherein, when the number of specified support portions that contact the specified contact surface among the plurality of support portions is 3 or more, the actual support area is a polygonal area formed by connecting contact points where each of the specified support portions contacts the specified contact surface, when the number of specified support portions that contact the specified contact surface among the plurality of support portions is 2, the actual support area is a linear area formed by connecting contact points where the 2 specified support portions each contact the specified contact surface.

5. The mobile robot according to any one of claims 1 to 3, wherein, the plurality of propulsion units are arranged linearly symmetrically or point symmetrically with respect to the main body portion when viewed from the direction of gravity of the main body portion.

6. The mobile robot according to any one of claims 1 to 3, wherein, the plurality of support portions are a plurality of legs mounted on the main body portion in a manner capable of supporting the weight of the main body portion.

7. The mobile robot according to claim 6, wherein, the plurality of support portions further include a gripping portion capable of gripping an object, or the object gripped by the gripping portion and capable of contacting the specified contact surface.

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