Mobile robot

Abstract

To apply stable and larger force and torque in a robot which carries out work while in contact with a contact surface.SOLUTION: This mobile robot comprises: a body part having a plurality of propulsion units that each generate propulsion force through rotation of a rotary vane; a plurality of support parts provided in the body part and capable of supporting at least a part of the body part in contact with a prescribed contact surface; a work unit that carries out work; and a control unit that drives the propulsion units to generate force for pressing the support parts to the contact surface when the work unit carries out the work.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a mobile robot capable of flight. [Background technology]

[0002] In recent years, unmanned aerial vehicles are used for various purposes, and their development is actively underway. Radio-controlled unmanned helicopters and so-called drones are used as unmanned aerial vehicles. For example, examples of the use of drones for agricultural purposes include spraying pesticides, observing the growth of agricultural crops using an on-board camera, and generating air currents to protect agricultural crops from frost damage (see, for example, Patent Document 1). Furthermore, to enable the unmanned aerial vehicles to be used widely for purposes other than agriculture, arms that perform predetermined tasks and the like are installed on the unmanned aerial vehicles, and flying robots are being developed (see, for example, Patent Document 2).

[0003] Patent Document 3 discloses a mobile robot that flies using a propulsion unit and walks while touching the ground. The mobile robot walks on two legs, and when a sensor detects that the robot body is tilting too much while walking, the robot's posture is controlled using the propulsion unit so that the tilt falls within a predetermined angle range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-000015 A [Patent Document 2] International Publication No. 2016 / 193666 [Patent Document 3] Patent No. 6733965 Summary of the Invention [Problem to be solved by the invention]

[0005] It is conceivable to attach an end effector to a robot to perform work on an object. However, since a flying robot is relatively light, it is easy for the robot to lose its posture due to the reaction force from the object during work. Furthermore, when working while flying, it is not easy to generate a reaction force corresponding to the work force, work torque, and disturbance. As a result, there is a risk that the position and posture of the robot performing work will not match the desired position and posture. Furthermore, in order to maintain the position and posture, the force and torque that can be applied to the object during work are limited.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a robot technology that allows a robot that performs work while coming into contact with a contact surface to stably apply greater force and torque. [Means for solving the problem]

[0007] In the present invention, in order to solve the above problems, a configuration is adopted in which a support part that contacts a contact surface is provided in the mobile robot of the present invention and a propulsion unit is controlled. In addition, a control part is provided in the mobile robot that controls the propulsion unit to press the mobile robot against the contact surface when the working part performs work. With this configuration, a stable work operation of the mobile robot can be realized.

[0008] In detail, the mobile robot according to the present invention includes a main body having a plurality of propulsion units that generate propulsive force by driving rotors, a plurality of support parts that are provided on the main body and can support at least a part of the main body by contacting a predetermined contact surface, a working part that performs a predetermined task, and a front and a control unit that generates a force for pressing the plurality of support parts against the predetermined contact surface by driving the propulsion unit when the working unit performs the predetermined work. Effect of the Invention

[0009] In a robot that performs work while coming into contact with a contact surface, it is possible to stably apply larger forces and torques. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a schematic configuration of a mobile robot according to a first embodiment. [Diagram 2] FIG. 2 is a functional block diagram illustrating functional units formed in the mobile robot according to the first embodiment. [Diagram 3] 5A to 5C are diagrams for explaining changes in stability of the main body when a work operation according to the first embodiment is being performed. [Figure 4] 5 is a diagram showing a schematic diagram of changes in position and magnitude of normal force (sum of normal forces on a contact surface) as viewed from the Y-axis direction according to the first embodiment. FIG. [Diagram 5] FIG. 2 is a diagram showing a schematic diagram of a support region and a target region according to the first embodiment. [Figure 6] 5 is a flowchart showing an example of a process for calculating a rotor thrust force executed by a second control unit according to the first embodiment. [Figure 7] FIG. 11 is a diagram showing a schematic configuration of a mobile robot according to a second embodiment. [Figure 8] FIG. 13 is a diagram showing a schematic configuration of a mobile robot according to a third embodiment. [Figure 9] FIG. 11 is a diagram showing the mobile robot according to the third embodiment as viewed from the Y-axis direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The mobile robot of this embodiment can generate a propulsive force for raising or lowering the main body by using multiple propulsion units provided on the main body side. Each propulsion unit has a rotor, and the propulsive force generated by the propulsion unit is determined by driving the rotor to rotate. The arrangement of multiple propulsion units on the main body can be designed as desired. The mobile robot may be configured to be able to fly (ascend, descend, turn, etc.) depending on the balance of the propulsive forces of the propulsion units provided on the main body. The multiple propulsion units provided on the main body may all be of the same type, or different types may be mixed together. In addition, the propulsive force may be generated by a method other than rotors.

[0012] In the present disclosure, the posture of the mobile robot during work is kept stable by the propulsion unit. That is, the propulsion unit is used to generate a reaction force in the propulsion unit while the mobile robot is working, thereby improving the stability of the posture of the mobile robot during work. Specifically, the propulsion unit presses (pressures) the robot body against the contact surface, thereby keeping the fluctuations in the position and magnitude of the normal force during work within an allowable range. This allows the mobile robot to maintain a desired posture during work.

[0013] The mobile robot is provided with a plurality of support parts, so that the main body part is supported against a predetermined contact surface. The support parts may support the main body part in the vertical direction, or in a direction other than the vertical direction. In the former case, the support parts may be configured as legs that contact the contact surface and enable the main body part to walk on it. In the latter case, the contact surface may be a surface located above the mobile robot. In this case, the contact surface may be, for example, a surface of a ceiling, beam, eaves, etc. of a structure. The contact surface may also be a surface that includes a vertical component. In this case, the contact surface may be, for example, a surface of a wall, pillar, etc. of a structure.

[0014] The predetermined work performed by the working unit includes work that involves contact with an object. When the working unit performs a work while contacting an object, it receives a reaction from the object. These include tasks using an arm, or sensing tasks using a sensor. The posture of the mobile robot may become unstable due to a reaction from an object that accompanies the task. Therefore, it is necessary to ensure an appropriate reaction force when the mobile robot performs a task on an object. For example, it is possible to ensure reaction forces due to gravity and frictional forces by increasing the mass of the mobile robot, but since a mobile robot is required to be lightweight, there is a limit to how much the mass can be increased. On the other hand, in the present disclosure, the mobile robot is pressed against the contact surface by the propulsion unit in order to ensure the reaction force. This makes the mass of the mobile robot appear larger.

[0015] In this way, the reaction force required for the work can be obtained, so that the position and posture of the mobile robot can be kept stable, and the working force and working torque can be further increased.

[0016] In addition, the control unit may set the propulsion force generated by the propulsion unit so that the position of the sum of normal forces at the specified contact surface generated in the multiple support parts by driving the propulsion unit is within a support area corresponding to the contact positions where the multiple support parts contact the specified contact surface.

[0017] Generally, methods for controlling the posture of a mobile robot include controlling the trajectory of the center of gravity of the robot to maintain static and dynamic stability. In methods for controlling the position of the center of gravity to maintain static stability, static stability is determined by whether the projection point of the center of gravity is included in the support area (support polygon) created by the feet. The support area is an area on the contact surface that is defined by the contact points of the support parts that are in contact with the contact surface among multiple support parts. On the other hand, in methods for controlling the trajectory of the center of gravity to maintain dynamic stability, the center of pressure (equal to the zero moment point (ZMP)) within the support area is determined. Dynamic stability is judged by whether the support polygon (support area) formed by the toes is included in the support area. In this disclosure, attention is focused on the relationship between the center of gravity projection point and the center of pressure and the support area.

[0018] That is, by utilizing the propulsion unit to statically and dynamically adjust the trajectory of the pressure center position within the support area while the mobile robot is working, the stability of the posture of the mobile robot while working can be improved. Specifically, by pressing (pressuring) the body against the contact surface with the propulsion unit, the frictional force at the contact part of the contact surface required for work is ensured, and the fluctuation of the position and magnitude of the sum of normal forces within the support area while working is kept within an allowable range. This allows the mobile robot to maintain a desired posture while working.

[0019] The control unit may set a target area within the support area as a target for the position of the sum of the normal forces, and adjust the propulsion force generated by the propulsion unit so that the position of the sum of the normal forces is within the target area. This target area is an area that is set so that the position of the sum of the normal forces does not move outside the support area even if an unexpected force is applied to the mobile robot due to, for example, an external disturbance. By setting such a target area, it is possible to prevent the position of the sum of the normal forces from moving out of the support area even if the mobile robot is affected by, for example, an external disturbance, and therefore the stability of the mobile robot can be further improved.

[0020] Furthermore, when the number of the predetermined support parts in contact with the predetermined contact surface is three or more among the plurality of support parts, the support area may be a polygonal area formed by connecting the contact points of the predetermined support parts and the predetermined contact surface. If the propulsion unit generates a propulsive force such that the position of the sum of the normal forces is within the polygonal area, it is possible to prevent the mobile robot from losing its posture.

[0021] Further, the control unit sets a propulsive force to be generated by the propulsion unit so as to generate a frictional force that causes the plurality of support parts to stop on the predetermined contact surface when the predetermined task is performed. It is possible that the mobile robot may slip on the contact surface due to the reaction force from the object. In response to this, by making the propulsion force generated by the propulsion unit sufficiently large, the frictional force at the contact portion becomes sufficiently large, and it is possible to ensure the frictional force required for the work. This makes it possible to prevent the mobile robot from slipping on the contact surface.

[0022] Furthermore, the plurality of support parts may be a plurality of legs attached to the main body so as to be able to support the weight of the main body. The legs may be configured to be able to walk. As another example, the legs may be configured to only support the weight of the main body but not be able to walk. By having the legs, the mobile robot can perform work in a landed state.

[0023] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, numbers, relative positions, etc. of the components described in the present embodiment are not intended to limit the technical scope of the invention unless otherwise specified.

[0024] First Embodiment Fig. 1 is a diagram showing the external configuration of the mobile robot 10, and Fig. 2 is a diagram showing functional blocks included in the mobile robot 10. A main body 13 of the mobile robot 10 is formed including a portion mainly related to the flying motion of the mobile robot 10, a portion mainly related to the walking motion of the mobile robot 10, and a portion mainly related to the working motion of the mobile robot 10. That is, in this embodiment, the mobile robot 10 is configured to be able to realize flying motion, walking motion, and working motion.

[0025] First, a structure related to flight operation will be described. A plurality of propulsion units 12 are arranged on the main body 13 via a plurality of bridge members 14. In the example shown in FIG. 1, four propulsion units 12 are mounted on the main body 13, but the number of propulsion units 12 is not limited to four as long as the mobile robot 10 can fly. In this embodiment, when the mobile robot 10 is in a reference posture with respect to a contact surface (e.g., the ground) FL, a rotor plane formed by connecting the center points of the rotors 121 of the four propulsion units 12 is parallel to the contact surface FL, and each of the four propulsion units 12 is arranged on the rotor plane in rotational symmetry with the main body 13 as the center. In other words, each of the four propulsion units 12 is arranged on the rotor plane in line symmetry with a predetermined center line in between, or in point symmetry with a predetermined point as the center. In addition, the heights of the four propulsion units 12 from the contact surface FL are all the same. In addition, in the reference posture, all four legs 11, which will be described later, are in a predetermined state so that the main body 13 is not inclined with respect to the contact surface FL.

[0026] The propulsion units 12 each have a rotor, which is a rotor blade, and an actuator for rotating the rotor. All four propulsion units 12 are the same type of unit, but the actuators in each propulsion unit 12 can be controlled independently. Therefore, it is possible to appropriately control the propulsive force obtained by each propulsion unit 12, and thus it is possible to appropriately control the flight attitude, flight speed, and the like of the mobile robot 10. Furthermore, in the pressurization control described below, the actuators in each propulsion unit 12 can be controlled independently. The mobile robot 10 is also equipped with a sensor (flight sensor) 15 required for its flight operation, a sensor (contact sensor 16) required for its walking operation, a battery 17 (see FIG. 2) for supplying driving power to the sensor and the actuators of each propulsion unit 12, and a control device for controlling the power supply from the battery 17 to each actuator. The control device incorporates two control units, a first control unit 100 and a second control unit 200, the details of which will be described below.

[0027] Next, a structure related to walking motion will be described. The mobile robot 10 has four legs 11 configured to be able to walk. The legs 11 are an example of a support part. In the example shown in Fig. 1, four legs 11 are provided on main body 13, but as long as walking motion is possible, the number of legs 11 is not limited to four, and may be two or three, or five or more legs 11.

[0028] As an example of the leg 11, an enlarged view of the leg 11 is shown in FIG. 1. The leg 11 includes a grounding part 111 that comes into contact with the ground when the mobile robot 10 walks by walking, a link part 113 that is connected to the grounding part 111 via a joint 112 so as to be relatively rotatable, a hip joint part 114 that is connected to the link part 113 via the joint 112 so as to be relatively rotatable, and a plurality of actuators (not shown) that drive and control the rotation of each joint 112. The joint 112 related to the link part 113 is designed in a rotation direction (rotation direction around the roll axis and the pitch axis) according to an expected walking motion. Note that the configuration of the leg 11 is not limited to this embodiment. Also, the hip joint part 114 is connected to the lower side of the main body part 13 via a predetermined joint 112 so as to be relatively rotatable. This predetermined joint 112 is configured to be rotatable around the yaw axis. The predetermined joint 112 may also be configured to be rotatable around the roll axis or the pitch axis.

[0029] The legs 11 thus configured are structures that enable the walking motion of the mobile robot 10 while supporting the weight of the mobile robot 10 against the contact surface FL during the walking motion of the mobile robot 10.

[0030] Next, a structure related to a work operation will be described. The mobile robot 10 has one robot arm 30 configured to be able to perform a work operation. The robot arm 30 is an example of a working unit. As an example of the robot arm 30, an enlarged view of the robot arm 30 is shown in FIG. 1. The robot arm 30 includes a hand mechanism 31, an arm mechanism 32, and a base 33. The hand mechanism 31 is attached to one end of the arm mechanism 32, and the other end of the arm mechanism 32 is attached to a base 33 arranged below the main body 13 via a joint 321. The robot arm 30 is connected to the main body 13 so as to be able to rotate relatively. The arm mechanism 32 includes a plurality of link parts 322 connected to each other via the joint 321. The arm mechanism 32 includes a plurality of actuators (not shown) that drive and control the rotation of each joint 321. The hand mechanism 31 includes, for example, two parallel finger parts 311 and an actuator (not shown) that drives the finger parts 311. The arm mechanism 32 can move the hand mechanism 31 to a desired position by changing the angle of each joint 321. As a result, for example, the arm mechanism 32 can move the hand mechanism 31 to a position where the hand mechanism 31 can contact the object W. The joint 321 related to the link part 322 is designed in a rotation direction according to an expected work operation. The configuration of the robot arm 30 is not limited to this embodiment. In the example shown in FIG. 1, one robot arm 30 is provided on the main body part 13, but the number of robot arms 30 is not limited to one, and two or more robot arms 30 may be provided as long as the work operation can be performed. Also, other working units can be attached to the main body part 13 in addition to the robot arm 30.

[0031] <Control Unit of Mobile Robot 10> Next, the control configuration of the mobile robot 10 will be described with reference to Fig. 2. 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 unit and a memory. Each functional unit is formed by executing a predetermined control program in the mobile robot 10.

[0032] First, the first control unit 100 will be described. The first control unit 100 is a functional unit for causing the mobile robot 10 to perform walking and flying movements 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 movements, and further controls the propulsion unit 12 for flying movements. The first control unit 100 controls the propulsive forces of the four propulsion units 12 based on environmental information related to the flight state of the mobile robot 10 and detected by the flight sensor 15. Examples of the environmental information include the angular velocity of the main body 13 detected by a gyro sensor corresponding to three axes (yaw axis, pitch axis, and roll axis) not shown, and information on the inclination of the main body 13 detected by an acceleration sensor corresponding to the same three axes not shown. The first control unit 100 uses the environmental information acquired from these sensors to feedback control the inclination of the main body 13 of the mobile robot 10 so that it is in a state suitable for flight. Furthermore, the environmental information may include an 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, and the azimuth angle can be detected by an azimuth angle sensor.

[0033] Here, when the main body 13 of the mobile robot 10 flies forward, backward, left, or right, the first control unit 100 reduces the rotation speed of the actuator of the propulsion unit 12 in the traveling direction and increases the rotation speed of the actuator of the propulsion unit 12 on the opposite side to the traveling direction, so that the main body of the mobile robot 10 leans forward with respect to the traveling direction and moves in the desired direction. When the main body of the mobile robot 10 turns in the air, the first control unit 100 performs output according to the rotation direction of the rotor 121 based on the turning direction of the main body 13 of the mobile robot 10. For example, when turning the main body 13 of the mobile robot 10 to the right, the first control unit 100 reduces the output of the actuator corresponding to the rotor 121 rotating to the right and increases the output of the actuator corresponding to the rotor 121 rotating to the left.

[0034] Further, the walking action executed by the first control unit 100 will be described. The first control unit 100 is also a functional unit that controls the actuators provided on the four legs 11 for walking when the mobile robot 10 walks. When performing a walking action, the first control unit 100 uses environmental information that indicates whether the ground contact portion 111 of each leg 11 is in contact with the contact surface FL, as detected by the contact sensor 16. In this embodiment, the predetermined walking control program used by the first control unit 100 for walking on the contact surface FL acquires as little information as possible about the surrounding environment of the mobile robot 10, and uses the detection value by the contact sensor 16, in order to make the walking control of the mobile robot 10 easier.

[0035] Specifically, the actuators provided at the joints 112 of the legs 11 are provided with encoders (not shown) that detect state quantities related to the respective rotational states (such as the rotational position and rotational speed of the actuator's rotation shaft). Note that sensors other than encoders may also be used. Then, the first control unit 100 feedback-controls the actuators of the legs 11 based on the state quantities of the actuators detected by the encoders of the actuators so that the mobile robot 10 can walk in accordance with movement instructions provided to the mobile robot 10.

[0036] Furthermore, during walking control, the contact sensor 16 detects whether or not the ground contact portion 111 of each leg 11 is in contact with the contact surface FL. When the robot arm 30 performs work on an object W, the reaction force from the object W increases the possibility that the legs 11 will slip or the mobile robot 10 will tilt and fall. In order to prevent such slipping of the legs 11 and tilting of the mobile robot 10, in this embodiment, the second control unit 200 performs pressure control. Note that the walking motion described above is not essential in this embodiment. For example, after landing by a flying motion, a working motion can be performed without performing a walking motion.

[0037] <Pressure Control> The pressurization control by the second control unit 200 will be described below. The pressurization control is a control for pressing the mobile robot 10 against the contact surface FL in advance by the rotor thrust of the propulsion unit 12 before the start of a work operation in order to keep the posture of the mobile robot 10 stable during the work. In other words, the pressure control is to press the aircraft against the contact surface FL by the thrust of the propulsion unit 12 (pressure control). By applying pressure to the contact surface FL, the friction force required for the work is secured at the contact portion. In the following, the normal force refers to the sum of the normal forces on the contact surface. The position of the normal force is the position of the center of pressure of the mobile robot 10 with respect to the contact surface FL. The support area SS is an area on the contact surface FL that is defined by the contact parts of the legs 11 that are in contact with the contact surface FL among the multiple legs 11. In other words, the support area SS is defined by connecting the parts of each leg 11 that are in contact with the contact surface FL with straight lines. In the pressurization control according to the first embodiment, the rotor 121 of the propulsion unit 12 is rotated in the opposite direction to that during flight control to apply a downward force to the mobile robot 10 in advance.

[0038] Here, with reference to FIG. 3, a description will be given of changes in the stability of the main body 13 when a task is being performed (when the mobile robot 10 is performing a task using the robot arm 30). FIG. 3 shows an example in which the mobile robot 10 manipulates a cylindrical object W. All four legs 11 are in contact with the contact surface FL. Consider a case in which the mobile robot 10 performs a task o(r, f, t) that requires a task force f and a task torque t at a certain position r. The task o(r, f, t) may include inertial resistance in the sense of D'Alembert's principle. Note that the position r, task force f, and task torque t in the task o(r, f, t) are given in advance.

[0039] In the following description, an XYZ Cartesian coordinate system is set based on the center of gravity of the mobile robot 10. The XY plane is a horizontal plane, and is parallel to the contact surface FL in this case. The direction from the center of gravity of the mobile robot 10 to the object W is the X-axis direction, the vertical direction is the Z-axis direction, and the direction perpendicular to the XZ plane is the Y-axis direction. For simplicity, it is assumed that the rotor plane and the contact surface FL formed by connecting the center points of the four propulsion units 12 are parallel to the XY plane. The direction from the main body 13 toward the contact surface FL is the downward direction. Also, the direction from the main body 13 toward the object W is the forward direction. FIG. 3 shows an example in which the mobile robot 10 pushes the object W in the X-axis direction. Here, FIG. 4 is a diagram showing a schematic diagram of the change in position and magnitude of the normal force fn as viewed from the Y-axis direction.

[0040] 3, when the position of the normal force fn is located inside the support area SS, the mobile robot 10 is stably supported by the four legs 11. On the other hand, when the position of the normal force fn is not located inside the support area SS, the mobile robot 10 is not stably supported by the four legs 11. Therefore, in this case, there is a risk that the mobile robot 10 will fall over.

[0041] In order to prevent the mobile robot 10 from tipping over due to the normal force fn being out of the support area SS, the mobile robot 10 is pressed against the contact surface FL using the four propulsion units 12 in this embodiment. As a result, the actual position of the normal force of the mobile robot 10 relative to the contact surface FL is displaced, and the position of the normal force is displaced into the support area SS to prevent the mobile robot 10 from tipping over. In this embodiment, the second control unit 200 calculates the propulsive force to be applied by the propulsion units 12 and generates the propulsive force in advance during work.

[0042] The support area SS is a closed area formed to include the contact point of the leg 11 whose ground contact portion 111 is actually in contact with the contact surface FL. As an example, the support area SS may be a polygonal area with the contact points as vertices. In that case, in FIG. 3, the support area SS is formed in a quadrangle. From the viewpoint of favorably supporting the mobile robot 10, the support area SS may be formed in a shape that is further reduced inward from the form shown in FIG. 3. This will be described later. Note that the support area SS can be known in advance by configuring each joint 112 of each leg 11 to stop at a predetermined angle during a work operation.

[0043] It is considered that the normal force fn acting on the support area SS fluctuates by dfn, and the position rn of the normal force fn fluctuates by drn, due to the mobile robot 10 pushing the object W (r, f, t). Here, the normal forces fn and (fn+dfn) are set to a magnitude sufficient to generate static friction in the support area SS, and the positional fluctuation drn of the normal force fn is set to a magnitude that prevents the position of the normal force fn from deviating from the support area SS. It is assumed that the static friction force is sufficient for the mobile robot 10 to come to a standstill.

[0044] If a downward force of any magnitude and at any position in the horizontal direction can be applied to the mobile robot 10 while it is performing an operation o(r, f, t), the normal force required for the operation o(r, f, t) can be obtained. In other words, by pressing the mobile robot 10 against the contact surface FL using the rotor thrust, the position of the normal force can be moved, and the posture of the mobile robot 10 can be kept stable.

[0045] Next, calculations are made regarding the normal force when performing the task o(ro, fo, to). The symbols in the following equations are defined as follows. Also, the state of the mobile robot 10, excluding the rotor thrust, the support area SS, the working force, and the working torque are assumed to be given. Here, the sum of the rotor thrusts of multiple propulsion units is simply referred to as the rotor thrust. Similarly, the contact surface normal force fn and the contact surface friction force fr are also assumed to mean the sums on the contact surface. Also, for simplicity, the case is shown where the rotor thrust fz only has a downward component on the Z axis. ro:[rox,roy,roz]:Working force position rn:[rnx,rny,-h]:Normal force position rv:[rvx,rvy,rvz]:Rotor thrust position fo:[fox,foy,foz]:Working power fn:[0,0,fnz]: Contact surface normal force fr:[frx,fry,0]:Contact surface friction force fv:[0,0,fvz]:Rotor thrust fi:[fix,fiy,fiz]:Inertia force fg:[0,0,fgz]:Gravity to:[tox,toy,toz]:Working torque ti:[tix,tiy,tiz]: inertia torque tr:[0,0,trz]: Friction torque h: Height from contact surface FL to center of gravity

[0046] First, consider the equations of motion for translational and rotational motion. The equation of motion for parallel motion is as follows: mx””+(ω×v)=fn+fr+fv+fg+fo After transformation, the following formula can be obtained: 0=fn+fr+fv+fg+fo-mx””+(ω×v) Further transformation can be carried out to obtain the following formula: 0 = fn + fr + fv + fg + fo-fi Equation 1

[0047] Moreover, the equation of motion for rotational motion is as follows: Jθ””+(ω×Jω)=(ro×fo)+to+(rn×fn)+(rn×fr)+tr+(rv×fv) After transformation, the following formula can be obtained: 0=(ro×fo)+to+(rn×fn)+(rn×fr)+tr+(rv×fv)-Jθ””-(ω×Jω) Further transformation can be carried out to obtain the following formula: 0=(ro×fo)+to+(rn×fn)+(rn×fr)+tr+(rv×fv) -ti···Eq. 2

[0048] According to the above equation 1, the following relationship holds for translational motion: [0,0,0]=fn+fr+fv+fg+fo-fi Considering each component of XYZ, the following relationship holds: [0,0,0]=[frx+fox-fix,fry+foy-fiy,fvz+foz+fnz-fiz+fgz] Therefore, the following relationship holds: [frx=fix-fox,fry=fiy-foy,fnz=(-fvz)-foz+fiz-fgz]

[0049] From the above, the following relationship can be obtained: Friction force in the x-axis direction: frx=fix-fox···Eq. 3 Friction force in the Y-axis direction: fry=fiy-foy Equation 4 Normal force: fnz=(-fvz)-foz+fiz-fgz...Equation 5

[0050] From the above equation 2, the following relationship holds for rotational motion: [0,0,0]=cpro(rn,fn)+cpro(rn,fr)+cpro(rv,fv)+cpro(ro,fo)+to+tr+ti Here, cpro(x, y) represents the cross product calculation of three-dimensional vectors. Considering each component of XYZ, the following relationship holds: [0,0,0]=[tox-tix+fvz×rvy-foy×roz+foz×roy+((-fvz)-foz+fiz-fgz)rny+(fiy-foy)h,toy-tiy-fvz×rvx+fox×roz-f oz×rox-((-fvz)-foz+fiz-fgz)rnx-(fix-fox)h,trz+toz-tiz-fox×roy+foy×rox-(fix-fox)rny+(fiy-foy)rnx]...Equation 6

[0051] From the above equation 6, the normal force position (rnx) in the X-axis direction is calculated as follows: rnx=-[toy-tiy-fvz×rvx+fox×roz-foz×rox+(fox-fix)h] / [fvz+foz-fiz+fgz]...Formula 7

[0052] Moreover, the normal force position (rny) in the Y-axis direction is given as follows: rny=[tox-tix+fvz×rvy-foy×roz+foz×roy+(fiy-foy)h] / [fvz+foz-fiz+fgz]...Formula 8

[0053] Also, the friction torque (trz) is given by: trz=-[fvz(toz-tiz+fiy×rvx+foy(rox-rvx))+foz(toz-tiz+fiy×rox)+fgz(toz-tiz)+fiz(tiz-toz)+foy(toy-tiy-fiz×rox+fgz×rox)+fiy(tiy-toy) +(fox-fix)tox+(fix-fox)tix+(fox-fix)fvz×rvy+(fix×foy-fiy×fox)roz+((-fox×fvz)-fix×foz+fiz×fox-fgz×fox)roy] / [fvz+foz-fiz+fgz]...Formula 9

[0054] The second control unit 200 determines the rotor thrust fv generated by the four propulsion units 12 at each time so that the normal force position (rnx) in the X-axis direction and the normal force position (rny) in the Y-axis direction, which change during the work operation, always fall within the support area SS. At this time, a certain amount of margin may be provided so that the normal force position rn does not immediately deviate from the support area SS due to disturbances, etc. For example, a target area smaller than the support area SS may be provided within the support area SS. A target region TS may be set, and the rotor thrust fv to be applied by the propulsion unit 12 may be calculated so that the normal force position falls within this target region TS.

[0055] FIG. 5 is a diagram showing a schematic diagram of a support area SS and a target area TS according to the first embodiment. The target area TS is set so as to prevent the position of the normal force from moving outside the support area SS even if it is subjected to a disturbance such as wind. Therefore, the target area TS may be set according to the location where the mobile robot 10 performs the work operation and the work content. For example, the target area TS may be made smaller in a location that is more susceptible to disturbances. The smaller the target area TS, the less likely it is to deviate from the support area SS even if the position of the normal force is displaced. For example, since the outdoor area is more susceptible to wind than the indoor area, the target area TS outdoors may be made relatively small.

[0056] 5, when the position of the normal force is P1 outside the target region TS, the second control unit 200 may adjust the rotor thrust fv by targeting, for example, point P2 where a line connecting the position P1 of the normal force and the center of gravity P0 of the target region TS meets the boundary line of the target region TS. For example, the normal force positions according to the above formulas 7 and 8 may be partially differentiated with respect to the rotor thrust fv and the rotor thrust position rv, respectively, to examine the direction of change, and the rotor thrust fv and the rotor thrust position rv may be determined by repeating a process of increasing or decreasing a small amount so as to move in a desired direction.

[0057] During the operation, the mobile robot 10 may receive a reaction from the object W, which may cause the legs 11 to slip on the contact surface FL. In response to this, the frictional force at the contact portion is set sufficiently high, thereby preventing the legs 11 from slipping. Therefore, the second control unit 200 may set the normal force so that the frictional force at the contact portion is greater than the frictional force obtained by Equation 3 and Equation 4. The friction coefficient at the contact surface FL is assumed to be given in advance. For example, since the frictional force at the contact portion is proportional to the static friction coefficient and the normal force, the second control unit 200 may set the normal force so that the frictional force determined by the static friction coefficient and the normal force is greater than the frictional force obtained by Equation 3 and Equation 4. Similarly, the normal force may be set so that the frictional torque around the Z axis is greater than the frictional torque obtained by Equation 9.

[0058] FIG. 6 is a flowchart showing an example of a process for calculating a rotor thrust executed by the second control unit 200 according to the first embodiment. The routine shown in FIG. 6 is executed by the second control unit 200 at a predetermined timing before the mobile robot 10 performs a work operation. In step S101, the second control unit 200 calculates a force and a torque corresponding to the work. The force and the torque corresponding to the work may be stored in advance in a memory included in the second control unit 200. Also, information related to the work may be input by an operator. Next, in step S102, the second control unit 200 calculates a friction force and a normal force to be generated. At this time, the second control unit 200 calculates a friction force and a normal force to be generated based on Equation 3, Equation 4, Equation 5, and Equation 9.

[0059] In step S103, the second control unit 200 calculates a normal force for generating the friction force calculated in step S102. The second control unit 200 calculates the normal force so that the friction force determined by the static friction coefficient and the normal force is greater than the friction force obtained from Equation 3 and Equation 4. Furthermore, in step S104, the second control unit 200 calculates a rotor thrust for generating the normal force. The second control unit 200 calculates a rotor thrust capable of generating both the normal force calculated in step S102 and the normal force calculated in step S103.

[0060] In step S105, the second control unit 200 determines whether the position of the normal force is within the target region TS. The position of the normal force is calculated based on Equations 7 and 8. If the determination in S105 is affirmative, the rotor thrust calculated in step S104 is finalized. On the other hand, if the determination in step S105 is negative, the process proceeds to step S106. Then, in step S106, the second control unit 200 adjusts the position of the normal force. At this time, the second control unit 200 adjusts the rotor thrust, for example, by targeting a point P2 where a straight line connecting the calculated position P1 of the normal force and the center of gravity P0 of the target area TS touches the boundary line of the target area TS. After that, the second control unit 200 ends this routine.

[0061] 6 is executed before the start of actual work. Then, at the time of starting actual work, the second control unit 200 controls the propulsion unit 12 so that the rotor thrust is the one calculated in step S104 or step S106. Note that if the influence of disturbance is not taken into consideration, the processes in steps S105 and S106 may be omitted.

[0062] The second control unit 200 may determine whether the normal force is within an allowable range for the mechanical strength of the mobile robot 10, and if it is outside the allowable range, may output, for example, a warning without carrying out the pressurization control. The second control unit 200 may also perform feedback control of the rotor thrust by sensing the floor reaction force, the body attitude angle, the relative speed with respect to the support area, and the like while performing the work operation. For example, a suitable sensor may be used to detect slippage of the contact portion and feedback control the rotor thrust. This makes it possible to dynamically respond to unexpected disturbances and environmental changes. For example, a suitable sensor may be used to measure the position and magnitude of the normal force within the actual support area SS and feedback control the rotor thrust. This makes it possible to dynamically respond to unexpected disturbances and environmental changes, such as by appropriately adjusting the position and magnitude of the normal force.

[0063] As described above, according to the first embodiment, the mobile robot 10 can be pressed against the contact surface FL by the thrust of the propulsion unit 12 while the mobile robot 10 is working. This makes it possible to obtain the reaction force required for the work, and therefore the mobile robot 10 can be prevented from slipping on the contact surface FL or losing its posture while working. Therefore, the working force and the working torque can be further increased. In addition, since highly accurate positioning and posture determination is possible, the accuracy of the work can be improved. In addition, since the use of environmental information and the like is suppressed as much as possible for the pressure control of the mobile robot 10, stable work operations can be realized despite the use of fewer sensors. In addition, since the control of the robot arm 30 itself may be the same as the conventional control, development costs can be reduced.

[0064] <Second embodiment> In the second embodiment, an example will be described in which the contact surface FL is located above the mobile robot 10, such as the ceiling of a structure. FIG. 7 is a diagram showing a schematic configuration of the mobile robot 10 according to the second embodiment. The mobile robot 10 according to the second embodiment is configured to have a symmetrical shape with respect to the XY plane compared to the mobile robot 10 according to the first embodiment. That is, the mobile robot 10 according to the second embodiment has a shape obtained by turning the mobile robot 10 according to the first embodiment upside down. The mobile robot 10 according to the second embodiment performs a work operation while performing a flying operation. In the second embodiment, the rotation direction of the rotor 121 is the same when performing a flying operation and when performing a work operation.

[0065] In FIG. 7, an XYZ Cartesian coordinate system is set with the center of gravity of the mobile robot 10 as the reference. The XY plane is a horizontal plane, which is parallel to the contact surface FL in this case. The direction from the center of gravity of the mobile robot 10 to the object W is the X-axis direction, the vertical direction is the Z-axis direction, and the direction perpendicular to the XZ plane is the Y-axis direction. The object W according to the second embodiment protrudes downward in the Z-axis direction (vertical direction) from the contact surface FL. The propulsion unit 12 generates rotor thrust so that the legs 11 of the mobile robot 10 are pressed against the contact surface FL during a work operation. The contact surface FL is perpendicular to the vertical The rotor plane is perpendicular to the direction, and is formed by connecting the center points of the rotors 121 of the four propulsion units 12, and is parallel to the contact surface FL.

[0066] The pressurization control according to this embodiment is a control that secures a frictional force at the contact portion of the contact surface FL required for work that cannot be obtained by gravity by pressing (pressurizing) the aircraft against the contact surface FL with the thrust of the propulsion unit 12, and further, keeps the position of the normal force during work within the support area SS. The support area SS is an area on the contact surface FL that is defined by the contact portion of the leg 11 that is in contact with the contact surface FL among the multiple legs 11. In the pressurization control, an upward force is applied to the main body 13 in advance by the propulsion unit 12. Note that the calculation formula for the normal force is omitted because the gravity component is simply reversed from that in the first embodiment. As in the first embodiment, a target area TS may be set within the support area SS, and the normal force may be set so that the normal force falls within the target area TS.

[0067] In this way, a desired normal force can be obtained by pressing the mobile robot 10 against the upper contact surface FL. In other words, since the reaction force required for the work can be obtained, it is possible to prevent the mobile robot 10 from slipping on the contact surface FL or losing its posture during the work.

[0068] <Third embodiment> In the third embodiment, an example in which the contact surface FL is located, for example, in front of the mobile robot 10, such as a wall of a structure, will be described. FIG. 8 is a diagram showing a schematic configuration of the mobile robot 10 according to the third embodiment. In the following description, an XYZ orthogonal coordinate system is set based on the center of gravity of the mobile robot 10. The YZ plane is a horizontal plane, and is a plane perpendicular to the contact surface FL here. The vertical direction is the X-axis direction. The contact surface FL is parallel to the vertical direction (X-axis direction). The Z axis is perpendicular to the contact surface FL, and the XY plane is parallel to the contact surface FL. Here, FIG. 9 is a diagram showing the mobile robot 10 as viewed from the Y-axis direction. The rotor plane B formed by connecting the center points of the rotors 121 of the four propulsion units 12 is inclined by an angle A1 with respect to the contact surface FL. The mobile robot 10 according to the third embodiment does not need to include the legs 11. On the other hand, the mobile robot 10 according to the third embodiment has an extended bridge member 14. A contact portion 141 is disposed at the end of the bridge member 14. The contact portions 141 are arranged such that a line connecting the contact portions 141 arranged on adjacent bridge members 14 is positioned outside the rotor 121 of the propulsion unit 12. Two protective portions 142 are arranged on each contact portion 141 to prevent the rotor 121 from contacting the contact surface FL.

[0069] In addition, a support shaft 40 is disposed on the upper part of the main body 13, which contacts the contact surface FL to support the mobile robot 10 when the mobile robot 10 performs work. A support portion 41, which is a member that contacts the contact surface FL, is disposed on the tip of the support shaft 40. In FIG. 8, the support shaft 40 is disposed so as to extend diagonally upward from the upper part of the main body 13 in parallel with the XZ plane. The support portion 41 of the support shaft 40 contacts the contact surface FL together with two contact portions 141 disposed on the contact surface FL side when the robot arm 30 performs work. At this time, the lengths of the bridge member 14 and the support shaft 40 and the angle of the support shaft 40 with respect to the main body 13 are set so that the rotor 121 of the propulsion unit 12 does not contact the contact surface FL.

[0070] It is assumed that the mobile robot 10 configured in this manner moves horizontally, for example in the Z-axis direction, toward the contact surface FL. At this time, flight control is performed by the first control unit 100. Then, for example, when the two contact portions 141 come into contact with the contact surface FL, the mobile robot 10 tilts around the contact portions 141. At this time, the main body portion 13 rotates upward around the contact portions 141. This rotation causes the support portion 41 to come into contact with the contact surface FL. In this state, Even if an attempt is made to move the mobile robot 10 further in the horizontal direction, the reaction force acting on the support portion 41 and the two contact portions 141 causes the mobile robot 10 to hover in that position.

[0071] Here, as in the first embodiment, the support area SS is considered. The support area SS according to the third embodiment is formed into a triangle defined by the contact areas of the support part 41 and the two contact parts 141, as shown in Fig. 8. If the position of the normal force is within the support area SS, the mobile robot 10 can hover stably. Even during work by the robot arm 30, the posture can be stabilized by performing pressure control to increase the normal force in advance.

[0072] As in the first embodiment, the normal force fn and normal force position rn are calculated based on the equation of motion. The symbols in the following equations are defined as follows. In addition, the state of the mobile robot 10, except for the rotor thrust, the support area SS, the working force, and the working torque are assumed to be given. ro:[rox,roy,roz]:Working force position rn:[rnx,rny,-h]: normal force position (corresponding to r above) rv:[rvx,rvy,rvz]:Rotor thrust position fo:[fox,foy,foz]:Working power fn:[0,0,fnz]:Normal force on contact surface (corresponding to f above) fr:[frx,fry,0]:Contact surface friction force fv:[fvx,0,fvz]: rotor thrust fi:[fix,fiy,fiz]:Inertia force fg:[fgz,0,0]:Gravity to:[tox,toy,toz]:Working torque ti:[tix,tiy,tiz]: inertia torque tr:[0,0,trz]: Friction torque h: Height from contact surface FL to center of gravity The rotor thrust position rv is a point on the rotor plane B, and the rotor thrust fv is a vector perpendicular to the rotor plane and having the rotor thrust position rv as its starting point.

[0073] According to Equation 1 derived in the first embodiment, the following relationship holds in translational motion. [0,0,0]=fn+fr+fv+fg+fo-fi Considering each component of XYZ, the following relationship holds: [0,0,0]=[fvx+frx+fox-fix+fgz,fry+foy-fiy,fvz+foz+fnz-fiz] Therefore, the following relationship holds: [frx=-fvx-fox+fix-fgz,fry=fiy-foy,fnz=- fvz-foz+fiz]

[0074] From the above, the following relationship can be obtained: Friction force in the X-axis direction: frx=-fvx-fox+fix-fgz Equation 10 Friction force in the Y-axis direction: fry = fiy - f oy Equation 11 Normal force: fnz=-fvz-foz+fiz...Equation 12

[0075] From Equation 2 derived in the first embodiment, the following relationship holds in rotational motion. [0,0,0]=cpro(rn,fn)+cpro(rn,fr)+cpro(rv,fv)+cpro(ro,fo)+to+tr-ti Here, cpro(x, y) represents the cross product calculation of three-dimensional vectors. Considering each component of XYZ, the following relationship holds: [0,0,0]=[tox-tix+fvz×rvy-foy×roz+foz×ro y+(-fvz-foz+fiz)rny+(fiy-foy)h,toy-tiy+fvx×rvz-fvz×rvx+fox×roz-foz×rox-(-fvz-foz+fiz)rnx-(-fv x-fox+fix-fgz)h,trz+toz-tiz-fvx×rvy-fox×roy+foy×rox-(-fvx-fox+fix-fgz)rny+(fiy-foy)rnx] Formula 13

[0076] From the above equation 13, the normal force position (rnx) in the X-axis direction is given as follows: rnx=[toy-tiy+fvx×rvz-fvz×rvx+fox×roz-foz×rox+(fvx+fox-fix+fgz)h] / [fvz+foz-fiz]...Formula 14

[0077] Moreover, the normal force position (rny) in the Y-axis direction is given as follows: rny=[tox-tix+fvz×rvy-foy×roz+foz×roy+(fiy-foy)h] / [fvz+foz-fiz]...Formula 15

[0078] Also, the friction torque (trz) is given by: trz=-[fvz(toz-tiz+fiy×rvx+foy(rox-rvx))+foz(toz-tiz+fiy×rox)+fiz(tiz-toz)+foy(toy-tiy+fvx×rvz-fiz×rox)+fiy(-toy+tiy-fvx rvz)+(fvx+fox-fix+fgz)tox+(-fvx-fox+fix- 16

[0079] The second control unit 200 then determines the rotor thrust fv to be generated by the four propulsion units 12 at each time point so that the normal force position in the X-axis direction (rnx) and the normal force position in the Y-axis direction (rny), which change during the work operation, fall within the support area SS. Note that, similarly to the first embodiment, a target area TS may be set within the support area SS, and the rotor thrust fv to be applied by the propulsion units 12 may be calculated so that the normal force position falls within this target area TS.

[0080] Also, similarly to the first embodiment, the second control unit 200 may set the normal force so as to obtain a frictional force larger than the frictional force obtained by Equation 10 and Equation 11. Similarly, the normal force may be set so that the friction torque around the Z axis is also larger than the friction torque obtained by Equation 16.

[0081] In the third embodiment, an example in which one support shaft 40 is disposed has been described, but the number of support shafts 40 is not limited to one, and may be two or more. In addition, even if there are multiple support shafts 40, it is not necessary for all of the support shafts 40 to be in contact with the contact surface FL. It is sufficient that the support area SS can be formed. In addition, in the third embodiment, the bridge member 14 is extended to dispose the contact portion 141, but instead, three or more support shafts 40 may be disposed, thereby making it possible to configure the bridge member 14 without being extended. In other words, the support area SS may be formed only by the multiple support shafts 40. In addition, when the mobile robot 10 has multiple robot arms 30, the main body 13 may be supported by any one of the robot arms 30.

[0082] As described above, according to the third embodiment, even if the contact surface FL is located, for example, in front of the mobile robot 10, the mobile robot 10 can be pressed against the contact surface FL by the rotor thrust of the propulsion unit 12 while the mobile robot 10 is flying. Since the necessary reaction force can be obtained, it is possible to prevent the mobile robot 10 from slipping on the contact surface FL or losing its posture during work. Therefore, the working force and working torque can be further increased. In addition, since it is possible to determine the position and posture with high accuracy, the accuracy of the work can be improved. [Explanation of symbols]

[0083] REFERENCE SIGNS LIST 10 mobile robot, 11 legs, 12 propulsion unit, 13 main body, 14 bridge member, 15 flight sensor, 17 battery, 30 robot arm, W object, 100 first control unit, 200 second control unit, FL contact surface, SS support area, TS target area

Claims

1. A main body having a plurality of propulsion units that generate propulsive force by driving rotors; A plurality of support parts provided on the main body part and capable of supporting the main body part by contacting a predetermined contact surface; A working unit that performs a predetermined work; a control unit that generates a force for pressing the plurality of support units against the predetermined contact surface by driving the propulsion unit when the working unit performs the predetermined work; A mobile robot comprising:

2. the control unit sets a propulsive force generated by the propulsion unit such that a position of a sum of normal forces on the predetermined contact surface generated on the plurality of support parts by driving the propulsion unit is within a support region corresponding to contact positions at which the plurality of support parts contact the predetermined contact surface. The mobile robot of claim 1 .

3. the control unit sets a target area, which is a target for a position of the sum of the normal forces, within the support area, and adjusts the propulsion force generated by the propulsion unit so that the position of the sum of the normal forces is within the target area. The mobile robot according to claim 2.

4. When the number of the predetermined support parts in contact with the predetermined contact surface among the plurality of support parts is three or more, the support area is a polygonal area formed by connecting the contact points between each of the predetermined support parts and the predetermined contact surface. The mobile robot according to claim 2.

5. the control unit sets a propulsive force generated by the propulsion unit so as to generate a frictional force that causes the plurality of support parts to come to rest on the predetermined contact surface when the predetermined task is performed. The mobile robot of claim 1 .

6. The plurality of support parts are a plurality of legs attached to the main body part so as to be able to support the weight of the main body part. The mobile robot of claim 1 .

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