Mobile robot

Abstract

A mobile robot is provided with: a main body section having a plurality of propulsion units for generating propulsion force by driving a rotary wing; and a plurality of support parts provided on the main body and capable of contacting a predetermined contact surface to support at least a portion of the main body, the support parts being configured such that, when movement control is performed while the main body is supported by the plurality of support parts, the support parts support the movement control. When a target pressure position associated with the displacement of the center of gravity of the main body section during the movement control is not within an actual support region in which the main body section is actually supported by a predetermined support section in contact with a predetermined contact surface among the plurality of support sections, some or all of the plurality of propulsion units are driven. In this way, a support support force is generated outside the actual support region, said support force supporting the shortage of the support force required for the movement control.

Description

Technical Field

[0001] The present invention relates to a mobile robot that can fly and perform mobile operations. Background Art

[0002] In recent years, unmanned aerial vehicles have been used for various purposes and their development is in full swing. As unmanned aerial vehicles, radio-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 airflows for protecting crops from frost damage, etc. can be exemplified (for example, refer to Patent Document 1). In addition, arms for performing prescribed operations are provided on unmanned aerial vehicles, and development of flying robots has been carried out so that they 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 flies using a propulsion unit and performs a walking motion on the ground. In this mobile robot, walking using two legs is performed, and when it is detected by a sensor that the inclination of the robot main body becomes large during the walking motion, 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 being in contact with a contact surface such as the ground, that is, in the case of moving while being in contact with the contact surface as in walking without moving by flight (it should be noted that in the present application, the former type of movement is referred to as "flight movement", and the latter type of movement is referred to as "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 tip over while realizing the movement of the main body of the robot. Generally, in contact movement, when the moving speed is rapid, it is difficult to maintain the stability of the main body of the robot and the possibility of tipping over increases. In addition, the main body of the robot swings along 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 tipping over of the main body of the robot 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] Solution to the problem

[0013] In the present invention, in order to solve the above problems, the robot of the present invention adopts a structure in which a support portion in contact with a contact surface is provided and the thrust of a 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 performing 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 thrust by driving rotary wings; a plurality of support portions provided on the main body portion and capable of contacting a predetermined contact surface 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 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 based on the first control unit using a part or all of the plurality of propulsion units. And, in the support control, the second control unit drives a part or all of the plurality of propulsion units when the target pressure position associated with the movement of the center of gravity of the main body portion in the movement control is not inside the actual support area where the main body portion is actually supported by a predetermined support portion in contact with the predetermined contact surface among the plurality of support portions, so as to generate a support thrust outside the actual support area to support the shortage of the support force required for this movement control.

[0015] Effects of the Invention

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

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

[0018] Figure 2 This is a functional block diagram that visualizes the functional parts formed in the mobile robot of the embodiment.

[0019] Figure 3 This is the first diagram for explaining the assist control for assisting the walking of the mobile robot.

[0020] Figure 4 This is a second diagram for explaining the assist control for assisting the walking of the mobile robot.

[0021] Figure 5 This is the third diagram for explaining the assist control for assisting the walking of the mobile robot.

[0022] Figure 6 This is a fourth diagram for explaining the assist control for assisting the walking of the mobile robot.

[0023] Figure 7 FIG. 5 is a fifth diagram for explaining the assist control for assisting the walking of the mobile robot.

[0024] Figure 8 It is a diagram showing the transition of the posture change of the mobile robot according to the presence or absence of the support control in the mobile robot.

[0025] Figure 9 FIG. 6 is a sixth diagram for explaining the assist control for assisting the walking of the mobile robot.

[0026] Figure 10 This is a diagram showing a first method of performing support control for supporting the walking of a mobile robot.

[0027] Figure 11 This is a diagram showing a second method of performing support control for supporting the walking of the mobile robot. DETAILED DESCRIPTION

[0028] The mobile robot according to this embodiment can generate a propulsive force for raising or lowering the main body by using a plurality of propulsion units provided on the side of the main body. 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 capable of flying (ascending, descending, hovering, etc.) by balancing 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.

[0029] Moreover, the mobile robot supports its main body on a prescribed contact surface by having a plurality of support portions. It should be noted that the support of the main body by the support portions can be a support in the vertical direction or can also be a support in a direction other than the vertical direction. In the former case, the support portion can be configured as a leg that can come into contact with 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 come into contact with and hold the contact surface while moving the main body. The structural scheme of the support portion can also adopt a scheme other than these schemes.

[0030] Here, in the mobile robot, contact movement of moving on the contact surface using a plurality of support portions is performed by the first control unit. The first control unit controls the driving of the plurality of support portions so as to perform contact movement in such a manner that the main body does not come into contact with the contact surface due to tipping, that is, while maintaining the state of support by the support portions. Here, when performing 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 preferably the degree of decrease is as small as possible. In particular, in the case where the state of the contact surface with which the support portion comes into contact is difficult to imagine, the possibility of tipping over due to poor movement control based on the first control unit increases.

[0031] Then, when the possibility of such tipping increases, support control for movement control based on the second control unit is performed. In this support control, it is considered that when the target pressure position is not inside the actual support area, the support force generated by the support part required for stable contact movement is insufficient, and the possibility of tipping increases. This target pressure position is the position of the zero moment point (ZMP) of the mobile robot assumed during contact movement based on the first control unit. In addition, the actual support area is an area on the contact surface delimited by the contact parts of the support parts among the plurality of support parts that are in contact with the contact surface. In this way, when the possibility of tipping is considered to be relatively high based on the relationship between the target pressure position and the actual support area, the propulsion force generated by driving a part or all of the plurality of propulsion units is used to generate a support support force outside the actual support area, and the insufficient amount of this support force is supported.

[0032] In this way, when it is determined that the possibility of tipping is relatively high, by using the propulsion force of the propulsion unit to support the insufficient amount of the support force generated by the plurality of support parts, it is possible to reliably provide a support support force for preventing tipping regardless of the action, posture, and position of the support part. This simplifies the structure for preventing tipping in the mobile robot. For example, it is possible to omit the configuration of sensors for smooth contact movement, etc. In addition, even if the state of the contact surface is an unforeseen state, it is possible to reliably generate a support support force by appropriately driving the propulsion unit, and stable contact movement can be achieved.

[0033] 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.

[0034] <Embodiment>

[0035] Here, based on Figure 1 and Figure 2 a 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 13 of the mobile robot 10 is formed to include a part mainly related to the flight action of the mobile robot 10 and a part mainly related to 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.

[0036] First, the structure related to the flight action will be described. A plurality of propulsion units 12 are arranged on the main body 13 via a plurality of bridge members. It should be noted that in Figure 1In 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 the reference posture with respect to the contact surface (for example, the ground, etc.) FL, the rotor plane formed by connecting the centers of the four propulsion units (refer to plane B in Figure 5 described later) is set to be parallel to the contact surface FL, and the four propulsion units 12 are respectively arranged rotationally symmetrically about the main body 13 on the plane B. In other words, the four propulsion units 12 are respectively arranged line-symmetrically across a specified center line or point-symmetrically about 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.

[0037] 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 described later, in the support control when the mobile robot 10 performs a walking action, the actuators in each propulsion unit 12 can also be independently controlled. In addition, the mobile robot 10 is equipped with sensors required for this flight action (flight sensors) 15, sensors required for the walking action (contact sensors 16), a storage battery 17 for supplying driving power to these 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.

[0038] Next, the structure related to the walking action will be described. The mobile robot 10 has four (four) legs 11 configured to be able to perform a walking action. It should be noted that in Figure 1 the example shown, four legs 11 are provided on the main body 13. However, as long as the walking action 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 leg 11, when referring to each leg individually, the reference numerals 11a to 11d are used.

[0039] As an example of the leg 11, in Figure 1An enlarged view of the leg 11 is shown. 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 assumed walking motion. It should be noted that the structure of the leg 11 is not limited to such a solution. In addition, the hip joint portion is rotatably connected to the lower side of the main body portion 13 via a specified joint. The specified joint is configured to be able to rotate around the yaw axis. Regarding the specified joint, it may also be configured to be able to rotate around the roll axis and the pitch axis.

[0040] The leg 11 configured in this way is a structure that can perform the walking motion of the mobile robot 10 while supporting the self-weight of the mobile robot with respect to the contact surface FL during the walking motion of the mobile robot 10. Therefore, the four legs 11 function as the supporting portions of the present invention for the walking motion included in the type for realizing the moving action. In addition, different from the flying action, the walking motion is performed with at least one of the four legs 11 in contact with the contact surface FL and supporting the main body portion 13. Therefore, the walking motion is also a way of the action included in the contact movement.

[0041] <Control Unit of Mobile Robot 10>

[0042] 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 and a second control unit 200. The control device is a computer having an arithmetic processing device and a memory, and the second control unit 200 has an acquisition unit 210, a setting unit 220, and an execution unit 230 as functional units. Each functional unit is formed by executing a specified control program in the mobile robot 10.

[0043] 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 on the legs 11 for walking actions and controls the propulsion unit 12 for flying actions. Also, 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 in 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. Also, in the environmental information, the azimuth angle, which is the orientation of the main body 13 in the absolute coordinate system (i.e., the orientation of the main body of the mobile robot 10) based on the orientation of the earth's axis, can be included, and this azimuth angle can be detected by an azimuth sensor.

[0044] 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. Additionally, 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 clockwise, the first control unit 100 reduces the output of the actuator corresponding to the propeller that rotates clockwise and increases the output of the actuator corresponding to the propeller that rotates counterclockwise.

[0045] Also, 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 on 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.

[0046] Specifically, an encoder (not shown) for detecting a state quantity related to the respective rotation states (such as the rotational position and rotational speed of the rotation axis of the actuator) 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. And, the first control unit 100 feedback-controls the actuator 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, the environmental information outside the robot is not utilized as much as possible. As a result, the sensors arranged on the mobile robot 10 can be omitted as much as possible and the walking control itself can be simplified.

[0047] And, 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.

[0048] <Support Control>

[0049] Hereinafter, the support control based on the second control unit 200 will be described. The second control unit 200 includes an acquisition unit 210, a setting unit 220, and an execution unit 230, and realizes the support control through the cooperation of these functional units. Here, based on Figure 3 , the change in the stability of the main body portion 13 during walking control (when the mobile robot 10 performs a walking motion) will be described. Figure 3 The upper part (a) of represents the state where the four legs 11 of the mobile robot 10 are in contact with the contact surface FL, and the lower part (b) represents the state where one leg 11a among the four legs 11 has left the contact surface FL. The state where the leg 11a has left the contact surface FL is detected by the contact sensor 16 of the leg 11a. Here, the mobile robot 10 performs a walking motion while carrying the workpiece W.

[0050] Here, for the leg 11 whose grounding portion is actually in contact with the contact surface FL, the closed region formed in a manner including its contact point is defined as the actual support region SS. As an example, the actual support region SS can be a polygonal region with the contact point as a vertex. In this case, in Figure 3In (a) thereof, the actual support area SS is formed as a quadrilateral. In Figure 3 In (b) thereof, the actual support area SS is formed as a triangle. In addition, from the viewpoint of appropriately supporting the mobile robot 10, the actual support area SS may also be formed into a shape that is further reduced to the inside of the forms shown in (a) and (b) of Figure 3 respectively. It should be noted that the second control unit 200 can grasp the positions of the contact points of the respective legs 11 based on the detection values of the respective contact sensors 16 and the states (positions) of the actuators of the respective legs 11 when the contact state is detected.

[0051] Moreover, when the mobile robot 10 performs walking control using four legs 11, the position 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 the respective legs 11 are driven in a manner to follow this position command. At this time, the position of the ZMP that should exist, which is calculated based on the trajectory of the mobile robot 10 and the like, 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.

[0052] Then, in order to suppress the tipping that may occur due to the target pressure position PP departing from the actual support area SS, in the present embodiment, four propulsion units 12 are used to generate an additional amount of support force (supporting support force) required to suppress this tipping. An explanation of Figure 4 the generation of this supporting support force will be given. Figure 4 The state of the mobile robot 10 shown in Figure 3The state shown in Fig. (b) is the same, and the target pressure position PP is located at a position separated from the actual support area SS. Here, when supporting the supporting force, the load to be supported by the legs 11b, 11c, and 11d that are actually in contact with the contact surface FL is set. This load becomes the load that should be shared by the legs 11b, 11c, 11d and the propulsion unit 12 for all the loads required for the movement of the mobile robot 10 to be supported. Therefore, it can be appropriately set in consideration of the propulsion force generated by the propulsion unit 12 and the supporting force of the legs 11 (the output of the actuators assembled in the legs 11b, 11c, 11d, the strength of the structure, etc.). Usually, in order to make the mobile robot 10 stand stably on the contact surface FL, it is preferable to apply a certain degree of load through the legs 11b, 11c, 11d to generate appropriate frictional force. Therefore, it is not preferable to arbitrarily reduce the load to be supported by the legs 11b, 11c, 11d. And, the position where the resultant force F2 of the load formed by the legs 11b, 11c, 11d is generated is defined as the support generation position P2. The support generation position P2 is determined to be an arbitrary position within the actual support area SS formed by the legs 11b, 11c, 11d.

[0053] And, the support supporting force F1 is generated at the imaginary support position P1 located outside the actual support area SS. This imaginary support position P1 is a position where the target pressure position PP is included in the interior of the enlarged support area S1 when an area equivalent to the actual support area formed when it is assumed that there are legs 11 at the imaginary support position P1 and a supporting force is generated, that is, when the enlarged support area S1 is formed by the contact points of the legs 11b, 11c, 11d and the imaginary support position P1. Based on Figure 5 And Figure 6 The determination of the imaginary support position P1 and the calculation of the support supporting force F1 will be described. Figure 5 The state of the mobile robot 10 in Figure 4 is the same as the state shown.

[0054] In Figure 5 , three planes A to C are set for illustration. Plane A is a plane that includes the target pressure position PP and the support generation position P2 and extends in the vertical direction (the direction perpendicular to the contact surface FL). Plane B is a plane that includes the centers of the 4 propulsion units 12 and is parallel to the contact surface FL. Plane C is a plane that includes the center of gravity of the mobile robot 10 and is parallel to the contact surface FL. According to Figure 6 it can be understood that the propulsion force generated by the propulsion unit 12 acts on plane B. With this propulsion force, the support supporting force F1 for supporting the loads required for the movement of the mobile robot 10 accompanying the walking motion is generated. At this time, the plane B formed by the propulsion unit 12 supports in a manner parallel to the contact surface FL.

[0055] Here, the imaginary support position P1 generated by the support force F1 is located on the straight line connecting the support generation position P2 generated by the resultant force F2 of the loads formed by the legs 11b, 11c, and 11d and the target pressure position PP. This is because when the three points are arranged on the straight line in this way, it is difficult to break the balance of the mobile robot 10 when the support force is supported by the propulsion unit 12. Therefore, as long as the balance of the mobile robot 10 can be maintained within the allowable range, it is not necessary to necessarily arrange the three points on a straight line. It should be noted that in the present embodiment, the three points are arranged on a straight line, the line segment between the imaginary support position P1 and the target pressure position PP is set as line segment A, and the line segment between the support generation position P2 and the target pressure position PP is set as line segment B. In such a case, F1 can be calculated according to the following formula 1.

[0056] F1:F2 = the length of line segment B: the length of line segment A ··· (Formula 1)

[0057] According to Formula 1, the longer the length of line segment A is set, the more the support of the mobile robot 10 can be supported while reducing the support force. Therefore, in order to reduce the output of the propulsion unit 12 for generating the support force, it is preferable to make line segment A the longest, that is, set at the position farthest from the target pressure position. Here, as Figure 7 shown, in the mobile robot 10, four propulsion units 12 are arranged via the bridge member 14 from the main body portion 13. With this bridge member 14, the distance from the center of gravity position of the mobile robot 10 to the propulsion unit 12 can be appropriately ensured. The resultant force of the propulsion forces generated by the propulsion units 12 is directly below each propulsion unit 12 at the position farthest from the center of gravity position. Therefore, the method of arranging the propulsion units 12 via the bridge member as described above helps to ensure that the length of line segment A in Formula 1 is longer.

[0058] Here, the support of the support force is studied from a physical aspect. For the sake of simplicity of explanation, it is assumed here that the body is in a stationary state and is not in contact with objects other than the contact surface FL. When considering the motion state, in addition to the gravity acting on the mobile robot 10, the forces required for the desired motion also need to be considered. In addition, the contact force also needs to be considered when in contact with objects other than the contact surface FL. In Figure 6 , the sum of the reaction force (resultant force F2) transmitted from the contact surface to the leg 11 and the imaginary support force (support force F1) regarded as being generated by the propulsion unit 12 on the contact surface FL is equal to the gravity. Therefore, the following formula 2 holds.

[0059] [Mathematical formula 1]

[0060] ··· (Formula 2)

[0061] fRi represents the reaction force transmitted to each leg 11, and fVi represents the above-mentioned imaginary supporting force.

[0062] Moreover, the sum of the moments generated by the reaction force (resultant force F2) transmitted from the contact surface to the contacting leg 11 and the moment generated by the imaginary supporting force (supporting force F1) regarded as being generated by the propulsion unit 12 on the contact surface FL becomes zero, so the following Equation 3 holds.

[0063] [Mathematical formula 2]

[0064] ··· (Equation 3)

[0065] rRi represents the position of the grounding part of each leg, rVi represents the position where the above-mentioned imaginary supporting force is generated (imaginary supporting position P1), and rri represents the position of each propulsion unit 12. In addition, frVi represents the propulsion force of the propulsion unit 12 required to generate the supporting force.

[0066] Moreover, Figure 2 The setting unit 220 shown sets the reaction force fRi transmitted to each leg 11 that satisfies Equation 1, Equation 2, and Equation 3. And the execution unit 230 calculates the supporting force F1 that satisfies Equation 1, Equation 2, and Equation 3, and adjusts the output of each propulsion unit in order to generate the supporting force F1 at the imaginary supporting position P1. In addition, the acquisition unit 210 acquires the target pressure position PP during the walking control of the mobile robot 10. The acquired target pressure position PP is used for the determination of whether it is inside the actual support area SS, the calculation according to Equation 1, etc. as described above.

[0067] In Figure 8 shows the change trend of the inclination of the main body 13 of the mobile robot in the case of performing the support control based on the second control unit 200 (upper figure (a)) and the case of not performing the support control (lower figure (b)) when the mobile robot 10 actually walks. The roll axis and pitch axis of the mobile robot 10 are axes included in a plane parallel to the contact surface FL. According to Figure 8 it can also be known that by performing the support control based on the second control unit 200, the change in the inclination of the main body 13 is suppressed compared with the case of not performing the support control, and the stability of the walking motion of the mobile robot 10 is improved. In addition, as described above, for the walking control of the mobile robot 10, although fewer sensors are used to try to suppress the use of environmental information, a stable walking motion is also achieved as Figure 8 shows.

[0068] <Variation 1>

[0069] Based on Figure 9A modification example of the mobile robot 10 disclosed in the present application will be described. As described based on Figure 6 As described above, the support bearing force F1 is a force for supporting the main body 13 of the mobile robot 10 in such a manner that the plane B is parallel to the contact surface FL. However, depending on the attitude of the mobile robot 10, the output responsiveness of the propulsion unit 12, etc., as shown in the upper part (a) of Figure 9 , there is a possibility that the attitude of the mobile robot 10 deviates greatly. Thus, in this modification example, for example, the angles and angular velocities of the mobile robot 10 around the roll axis and the pitch axis can also be fed back to correct the target pressure position PP. The angles and angular velocities of each axis are detected by a sensor (such as a gyro sensor) capable of detecting angles and angular velocities.

[0070] Through this correction, for example, the target pressure positions that originally shifted as PP0, PP1, and PP2 shift as PP0, PP1', and PP2' (refer to the lower part (b) of Figure 9 ). In this case, although the path that the mobile robot 10 actually advances deviates from the path that it should originally advance, on the other hand, the attitude of the mobile robot 10 is maintained in a more stable state. Therefore, the above feedback process can be said to be a useful process when there is relatively some leeway in the setting of the walking path.

[0071] <Modification Example 2>

[0072] In the mobile robot 10, in addition to generating the support bearing force, the output of the propulsion unit 12 can also be feedback-controlled to control the attitude of its main body 13. In this case, the propulsion unit 12 overlaps and outputs the generation of the support bearing force and the propulsion force required for attitude control, and the propulsion force required for this attitude control is called the attitude control propulsion force. Also, for the purpose of achieving the stability of the attitude during the walking motion by applying an appropriate load to the contact surface FL and utilizing its frictional force, or conversely reducing the frictional force with the contact surface FL to reduce the energy required for the walking motion, the mobile robot 10 additionally drives the propulsion unit 12 to further overlap and output the propulsion force. In this way, the propulsion force of the propulsion unit 12 for adjusting the load relative to the contact surface FL is called the self-weight compensation propulsion force, and the load generated on the contact surface FL thereby is called the self-weight compensation target.

[0073] Thus, the following Equation 4 holds.

[0074] [Mathematical Formula 3]

[0075] ··· (Equation 4)

[0076] fcorri represents the propulsive force for attitude control of each propulsion unit 12, fcompadi represents the propulsive force for self-weight compensation of each propulsion unit 12, and fweight represents the self-weight compensation target. Additionally, Δf represents the disturbance force.

[0077] Moreover, based on the relationship of the moment about the center of gravity, the following Equation 5 holds.

[0078] [Mathematical Equation 4]

[0079] ··· (Equation 5)

[0080] ΔM represents the disturbance moment.

[0081] It can be understood from Equations 1 to 5 that the support control for generating the support bearing force based on Equations 1 to 3 can additionally perform attitude feedback control and self-weight compensation control. Therefore, in the mobile robot 10, it is possible to easily select the implementation of this control according to the purpose of each control. However, when attitude feedback control and self-weight compensation control are added to the support control, note that the actual imaginary support position P1, support bearing force F1, support generation position P2, and resultant force F2 change.

[0082] <Other Embodiment>

[0083] First, an explanation will be given based on Figure 10 a first aspect of the support state formed by the legs 11 during the walking motion of the mobile robot 10. It should be noted that in Figure 10 , a walking motion is performed on a contact surface in a state of being a so-called uneven ground rather than a flat surface. In Figure 10 , the state of supporting the main body 13 of the mobile robot 10 using all four legs 11 is disclosed in the upper part (a). Additionally, in the middle part (b), the state of supporting the main body 13 of the mobile robot 10 using three of the four legs 11 is disclosed. Specifically, the leg 11a leaves the contact surface, and the other legs 11b, 11c, and 11d support the main body 13. Additionally, in the lower part (c), the state of supporting the main body 13 of the mobile robot 10 using two of the four legs 11 is disclosed. Specifically, the legs 11a and 11c leave the contact surface, and the main body 13 is supported by the other legs 11b and 11d.

[0084] The state supported by the four legs 11 is the most stable state. However, in a case where the contact surface is in an uneven ground state as in this embodiment, there is also 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. If that is the case, the support control of 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.

[0085] Here, as shown in (c) of Figure 10 , in 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 straight line, it is determined that the target pressure position PP is inside the actual support area SS, and when the target pressure position PP is off this straight 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 of the walking control based on the second control unit 200 described above can be executed.

[0086] In addition, for the walking motion of the mobile robot 10, it is not necessarily required to walk using the four legs 11. For example, depending on 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 the legs, it is sufficient to execute the support control of the walking control based on the second control unit 200 described above.

[0087] Next, based on Figure 11 , 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 Figure 11 , a state is disclosed in which, in addition to all of the four legs 11, the 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 the expansion of 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 realized. 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.

[0088] In addition, the middle section (b) discloses a state in which the main body 13 of the mobile robot 10 is supported by the object 20a held by the end effector 20 in addition to all of the four legs 11. In this case, the actual support area SS is formed by the contact point between the object 20a held by the end effector 20 and the contact surface. For example, when the mobile robot 10 walks while carrying the object 20a, the object can be used to achieve a stable walking motion. Assuming that the target pressure position PP also deviates from the actual support area SS in such a case, the above-mentioned support control of the walking control based on the second control unit 200 can be performed.

[0089] In addition, the lower section (c) discloses a state in which the main body 13 of the mobile robot 10 is supported by an auxiliary support part 11e which is not directly used for walking motion like the legs 11 but is configured to support the main body 13 during the walking motion. The auxiliary support part 11e is not provided with a joint and an actuator for driving the joint like the legs 11, but is configured to be a structure capable of applying a certain degree of load to the contact surface and maintaining contact. In this case, the actual support area SS is also formed by the contact point between the auxiliary support part 11e and the contact surface. There may be a case where the support force generated by the auxiliary support part 11e is weaker than the support force generated by the legs 11, but, for example, when the case of walking using the two legs 11c and 11d is compared with the case of walking with the auxiliary support part 11e added thereto, the actual support area SS can be expanded, thereby achieving a stable walking motion. Assuming that the target pressure position PP also deviates from the actual support area SS in such a situation, the above-mentioned assist control of the walking control by the second control unit 200 can be executed.

[0090] Description of Reference Numerals

[0091] 10: mobile robot, 11, 11a, 11b, 11c, 11d: legs, 11e: auxiliary support part, 12, 12a, 12b, 12c, 12d: propulsion unit, 13: main body, 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, P1: imaginary support position, P2: support generation position, F1: support support force, F2: resultant force.

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 contacting a specified contact surface to support at least a part of the main body portion; a first control unit that performs movement control to move the main body portion on the specified contact surface using the plurality of support portions while supporting the main body portion with the plurality of support portions; and a second control unit that uses a part or all of the plurality of propulsion units to perform assist control for the movement control by the first control unit, in the assist control, 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 specified support portions that contact the specified contact surface among the plurality of support portions, the second control unit drives a part or all of the plurality of propulsion units to generate an assist support force outside the actual support area to support a shortage amount of the support force required for the movement control.

2. The mobile robot according to claim 1, wherein, the second control unit has: an acquisition unit that acquires the target pressure position; a setting unit that sets a support generation position where a support force based on the specified support portion is generated inside the actual support area; and an execution unit that determines an imaginary support position on the specified contact surface outside the actual support area where the specified support portion does not contact, based on the target pressure position and the support generation position, calculates the assist support force at the imaginary support position, and drives a part or all of the plurality of propulsion units to generate the assist support force.

3. The mobile robot according to claim 2, wherein, the execution unit determines the imaginary support position such that the target pressure position is included in an enlarged support area defined by the actual support area and the imaginary support position.

4. The mobile robot according to claim 3, wherein, the imaginary support position is arranged on the opposite side of the support generation position across the target pressure position, and the imaginary support position, the target pressure position, and the support generation position are arranged on a straight line.

5. The mobile robot according to claim 4, wherein, the imaginary support position is determined as the position farthest from the target pressure position within a range that can be set based on the arrangement of the plurality of propulsion units.

6. The mobile robot according to any one of claims 1 to 5, wherein, when the number of specified support portions that contact the specified contact surface among the plurality of support portions is three or more, the actual support area is a polygonal area formed by connecting the contact points of each of the specified support portions with the specified contact surface. When the number of the specified support portions that come into contact with the specified contact surface among the plurality of support portions is two, the actual support area is a linear area formed by connecting the contact points of the two specified support portions with the specified contact surface respectively.

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

8. The mobile robot according to any one of claims 1 to 5, wherein the plurality of support portions are a plurality of legs that are mounted on the main body portion in a manner capable of supporting the weight of the main body portion.

9. The mobile robot according to claim 8, wherein the plurality of support portions further include a holding portion capable of holding an object, or the object held by the holding portion so as to be capable of coming into contact with the specified contact surface.

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