CN115151175A

CN115151175A - Robotic device with tri-star wheel and actuator arm and method of navigating a surface with a robotic device

Info

Publication number: CN115151175A
Application number: CN202180016622.1A
Authority: CN
Inventors: E.法尼奥利
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2020-02-27
Filing date: 2021-02-19
Publication date: 2022-10-04
Also published as: GB2592405A; WO2021170979A1; GB2592405B; GB202002772D0

Abstract

Certain examples described herein provide a form factor for a robotic device that may be used to navigate a human environment. The form factor consists of a set of three-star wheels and actuated robotic arms. Such a form factor may be used for an autonomous cleaning device. For example, it may enable the robotic cleaning device to navigate stairs and steps and allow for "liftoff" tasks. These "off-the-ground" tasks may include cleaning furniture or areas that the robotic device body cannot enter.

Description

Robotic device with tri-star wheel and actuator arm and method of navigating a surface with a robotic device

Technical Field

The present invention relates to a robot device. The invention can be used for realizing the autonomous household robot.

Background

The human environment presents unique challenges to robotic devices. These environments are designed for human navigation and manipulation; however, humans are extremely complex biological entities that are difficult to replicate using humanoid robots. For example, it has long been desirable to provide a home robotic device that can assist in performing tasks at home. However, houses have discontinuous surfaces, such as stairs and steps, which can cause problems with many robotic devices during navigation. This is often the case even in single-floor apartments, as small level variations between rooms are common. Many domestic robotic devices are low profile devices suitable for navigating a continuous plane.

CN108553030a describes an intelligent corridor cleaning and collecting robot. The intelligent corridor cleaning and collecting robot comprises a robot main body, wherein a partition plate is arranged in the robot main body and used for separating an inner cavity of the robot main body into a garbage collecting cavity and an element mounting cavity. A garbage can is arranged in the garbage collection cavity, and an opening is formed in the top of the robot body.

CN106426083A describes a robot cleaner stair climbing device. The rail laying crawling mechanism is arranged on two sides of the main frame and the auxiliary frame. A bottom plate is arranged below the middle part of the main frame, and a baffle is hinged at the rear end of the bottom plate. When the robot goes upstairs and downstairs, the robot meets the crawling device, and the baffle descends to the ground. The robot climbs up the bottom plate through the baffle, and the baffle is turned up and erected to block the robot. After ascending or descending, the baffle plate descends to the ground, and the robot climbs to the floor through the baffle plate.

CN105996910a describes a domestic stair automatic cleaning robot, which comprises a dust-collecting cleaner with a walking mechanism. The horizontal movement driving mechanism is arranged, and the dust collection cleaner and the mounting frame are driven to move in the longitudinal direction and the horizontal direction by the horizontal movement driving mechanism. There are also provided a telescopic bracket coupled to the link bracket and capable of being unfolded and folded in a vertical direction, and a telescopic driving means for driving the telescopic bracket to be unfolded/folded in the vertical direction.

US2013125338A1 describes a uniquely shaped vacuum cleaner that can be placed in a stable position on stairs while also being suitable for use on flat surfaces (e.g., floors).

KR101016775B1 describes a stair robot cleaner that is provided to enable a user to conveniently clean a group of stairs.

Despite these approaches, it is desirable to develop robotic devices that can easily navigate a human environment and perform various tasks. It is further desirable to develop robotic devices that can be equipped with autonomous navigation systems that can successfully interact with and/or navigate a human environment with minimal human assistance. It is desirable that these robotic devices be robust and not prone to failure.

Disclosure of Invention

According to a first aspect of the present invention there is provided a robotic device comprising an actuated robotic arm comprising an end effector and one or more powered joints, the position of the end effector relative to the robotic device being controllable to perform at least one task, and a propulsion system. The propulsion system includes a drive system and a set of three-star wheels coupled to the drive system.

Thus, the robotic device is able to perform at least one task by actively positioning the actuated robotic arms in space while also being able to navigate discontinuous terrain and obstacles using a set of three-star wheels. The set of three-star wheels further provides stability by providing at least two points of contact with the ground during the mission (e.g., via two of a set of three outer wheels of each three-star wheel), while moving the actuated robotic arm. Thus, the robotic device may easily navigate through the human environment and perform various tasks. The robotic device is able to navigate various surfaces and perform various tasks in a faster, more robust, and less prone to failure than the comparative embodiments described above. Thus, the robotic device may form the basis of an autonomous robotic device.

In certain examples, the robotic device includes a cleaning system, wherein the actuated robotic arm is coupled to the cleaning system and the task includes at least one cleaning task. For example, the robotic device may include an autonomous robot to perform a home cleaning task. While the actuated robotic arm may be configured to move the end effector within space to perform cleaning tasks, it may also be configured to use the actuated robotic arm for auxiliary functions, such as for stabilizing the robotic device during navigation. The set of tri-star wheels enables the robotic device to navigate discrete surfaces in the home, such as stairs, steps, or other level changes, and the robotic device may be configured to perform cleaning tasks while navigating the discrete surfaces. In one case, the robotic device may be configured to perform a cleaning task while also applying a stabilizing force, for example, performing a cleaning task may include applying a force to the surface or object while the robotic device is climbing stairs or steps using the set of tri-star wheels, the force also stabilizing the robotic device.

The cleaning system may include a vacuum system, wherein an aperture at the end effector of the actuated robotic arm may be maintained at a low pressure using the vacuum system. For example, a vacuum tip may be provided at the end effector. In this case, the robotic device may be able to dust a stair while climbing a group of stairs, for example, at home. The action of evacuation can also provide the steady force, the climbing action of helping a set of three-star wheel. This may reduce dumping events while increasing the speed and robustness of climbing stairs.

In some examples, the actuated robotic arm includes a plurality of joints. For example, an actuated robotic arm may have three to six degrees of freedom. For simple embodiments that are easier to configure, the driven robotic arm may have a smaller number of degrees of freedom. In this case, additional positioning, for example rotation perpendicular to the support surface, can be performed by differential driving of the set of three-star wheels. More advanced embodiments, such as where increased flexibility is desired, one or more joints may have a greater number of degrees of freedom and multiple degrees of freedom. For example, robotic devices may be configured with fixtures to perform manual tasks in a home environment.

In some cases, the set of three-star wheels supports the robotic device on a surface, and the actuated robotic arm is configured to perform at least one task above or below the surface. The set of three-star wheels may allow for a compact form factor (form factor) of the robotic device, providing improved navigation capabilities in the home. However, in a human environment, there are often locations to perform tasks (e.g., vacuuming a chair) that are not accessible to the robotic device body. The actuated robotic arms thus allow lift-off tasks to be performed in ways not possible with robotic devices having comparable form factors, such as those described in the background.

In some cases, the robotic device includes a chassis housing at least the propulsion system, wherein the actuated robotic arm is mechanically coupled to the chassis, and wherein the set of tri-star wheels includes a pair of tri-star wheels disposed on either side of the chassis. This provides a particularly compact form factor in which the tri-star wheels can provide stability via two contact points, but are coupled to the propulsion system via a single drive shaft per tri-star wheel. The robotic device may thus be of a size suitable for navigation and storage in a domestic (e.g. home) environment. Such a form factor may also better avoid interfering with the robotic device when a human is present in the surrounding environment.

In certain examples, the end effector includes an interface for removably mounting a plurality of tools. For example, the plurality of tools may include one or more of a clamp, a brush, and a vacuum tip. In this case, the tri-star wheel may provide a stable base while the end effector moves to switch tools among multiple tools. This may then enable a multi-tasking function that increases the utility of the robotic device, for example in a home environment, among other things.

In certain examples, the controller is electrically coupled to the propulsion system and the actuated robotic arm, wherein the controller is configured to control at least the actuated robotic arm. The controller may be configured to control the actuated robotic arm to assist the propulsion system in navigating the discontinuous surface. For example, the controller may be configured to apply a stabilizing force to a surface behind the robotic device using the actuated robotic arms during forward motion using the set of three-star wheels, or may be configured to apply impedance control to adjust one or more powered joints based on the force applied to the end effector. By controlling the actuated robotic arms and propulsion system using a common controller, the form of the robotic device within the space may be controlled. For example, the controller may control the position of the actuated robotic arm while performing tasks to provide a particular center of gravity that affects propulsion of the propulsion system. The controller may thus provide integrated control of the robotic device. In some cases, a neural network architecture may be provided as part of the controller to set the position of the end effector (and/or vice versa) in accordance with the control of the propulsion system.

According to a second aspect of the invention, there is provided a method of navigating a set of discontinuous surfaces with a robotic device, the method comprising driving a set of tri-star wheels of the robotic device to propel the robotic device in a direction of travel along the surface, and applying a force to a portion of the surface with an actuated robotic arm mechanically coupled to the robotic device to assist in the movement during movement along the surface through the discontinuity.

The method thus improves how a robotic device comprising a set of three-star wheels and actuated robotic arms navigates the environment. This may improve navigation of complex home human environments. The actuated robotic arm allows for an active application of force, e.g., via power to one of the plurality of actuators of the actuated robotic arm, and is thus controlled to improve the navigation process. The actuated robotic arm may be primarily designed to perform tasks or functions that do not assist in movement, such as performing cleaning tasks. In these cases, the actuated robotic arm may be actively reused in use to provide stability of the motion.

The robotic device may comprise an autonomous vacuum cleaner and the discontinuity comprises a staircase or a step. The method may thus allow for dust cleaning of many different areas within a domestic environment.

In some cases, applying the force using the actuated robotic arm includes applying the force with the actuated robotic arm in a direction of travel to a second surface located behind the robotic device during contact between the wheel portion of at least one of the set of tri-star wheels and the discontinuous first surface. For example, a tool coupled to an end effector may contact a surface to perform a task such as a cleaning task on the surface, but while also providing a force that stabilizes the robotic device during navigation of the discontinuous surface. This may enable the robotic device to robustly climb a set of stairs. In other cases, the force may be applied to a second surface located in front of the robotic device, for example, while climbing a set of stairs.

In some cases, the method includes performing a cleaning function before, during, or after applying the force. For example, the application of force may form part of the general operation process of the robotic device, with the primary function being to provide a cleaning function. This enables the force to be applied as an auxiliary function performed by the robotic arm. In some cases, the cleaning function may be programmed and/or configured to apply a force without significantly redesigning the cleaning function.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Drawings

Fig. 1A-1C are schematic diagrams illustrating a side view, a front view, and a rear view, respectively, of a first example robotic device;

FIG. 1D is a schematic diagram illustrating a first example robotic device performing a task;

2A-2D are schematic diagrams illustrating a second example robotic device performing a stair climbing procedure;

FIGS. 3A and 3B are schematic diagrams illustrating a side view and a front view, respectively, of a third example robotic device;

FIG. 4 is a schematic diagram illustrating an example planetary gear arrangement for implementing a propulsion unit of a robotic device;

FIG. 5 is a schematic diagram showing degrees of freedom of an example actuated robotic arm;

FIG. 6 is a schematic diagram illustrating an example tool change process;

FIG. 7 is a system diagram illustrating certain example control components for a robotic device;

FIGS. 8A and 8B are schematic diagrams illustrating a side cross-section and a front cross-section, respectively, of a fourth example robotic device;

FIG. 9A is a schematic diagram illustrating an example joint of a robotic device for actuation;

FIG. 9B is a schematic diagram illustrating a side view of a fifth example robotic device;

FIGS. 9C and 9D are schematic diagrams illustrating a side view and a front view, respectively, of a sixth example robotic device; and

FIG. 10 is a flow chart illustrating a method of navigating a set of discontinuous surfaces with a robotic device according to an example.

Detailed Description

Certain examples described herein provide a form factor for a robotic device that may be used to navigate a human environment. The form factor consists of a set of three-star wheels and one actuating arm. Such a form factor may be particularly useful for autonomous cleaning devices. For example, it may enable the robotic cleaning device to navigate stairs and steps and allow for "liftoff" tasks. These "off-the-ground" tasks may include cleaning furniture or areas that the robotic device body cannot enter. As used herein, the term "task" refers to a task to be performed by a robotic device, such as discrete work involving positioning an end effector within space to achieve a desired goal. This goal may be the cleaning and/or manipulation of objects in the environment.

Some examples described herein use one or more "tri-star" wheels. A three-star wheel is a form of positioning unit comprising three rotating wheels equally distributed around a central rotation axis. The outer three wheels can be seen to form a satellite or planetary arrangement about a central axis of rotation. The outer three wheels may be mounted on the ends of a three-spoke hub, with each spoke comprising an elongate member spaced approximately 120 degrees from the other members. A planetary gear arrangement (e.g. in the form of a gear train) may be used to power each of the outer wheels from a common drive shaft.

Examples described herein use actuated robotic arms. In these examples, the term "actuated" is used to indicate that one or more joints of a robotic arm may be moved by one or more actuators, such as joint motors or electroactive polymers. Thus, the actuated robotic arm is configured to move within its environment. Although the term "arm" is used, a robotic arm may be any form of articulated limb or mechanical assembly capable of moving an end effector within space.

In some cases, the combination of one or more tri-star wheels and actuated robotic arms provides a synergistic effect. For example, the tri-star wheel may provide additional stability to the motion of the actuated robotic arm, and the actuated robotic arm may apply additional forces to facilitate navigation over obstacles using the tri-star wheel.

Fig. 1A to 1D show a first example robotic device 100. Fig. 1A shows a side view of a first example robotic device 100. The first example robotic device 100 includes an actuated robotic arm 105 and a propulsion system 110. The actuated robotic arm 105 includes an end effector 112 and one or more powered joints 114. One or more powered joints 114 are used to control the position of the end effector 112 in three-dimensional space. The position of the end effector 112 relative to the robotic device 105 is controllable to perform at least one task.

The propulsion system 110 includes a set of three-star wheels 120 and a drive system 130. In the example of fig. 1A-1D, the set of tri-star wheels 120 includes two tri-star wheels disposed on either side of the body 140 of the robotic device 100. Each tri-star 120 is coupled to a drive system 130, and the drive system 130 provides torque to propel the set of tri-star 120 and move the robotic device 100 along a surface. The drive system 130 may include one or more motors and/or suitable gearing arrangements to effect movement of each tri-star wheel, including, for example, movement of one or more of a hub or wheel assembly and a set of externally rotating wheels.

In the first example robotic device 100, the actuated robotic arm 105 includes three joints: elbow joint 114, wrist joint 150, and shoulder joint 160. Shoulder joint 160 is visible in fig. 1B and 1C. The joints of the actuated robotic arms 105 are coupled by mechanical linkages or "links". Fig. 1A shows forearm link 116 mechanically coupling elbow joint 114 to wrist joint 150 and upper arm link 118 mechanically coupling elbow joint 114 to shoulder joint 160. Each link may comprise a rigid elongate member. Each link may be a single unit or a plurality of coupled sub-units. Each link may have a solid and/or hollow portion. In one instance, the link may comprise a hollow tube and/or a rigid material frame, such as steel, aluminum, or carbon fiber. The three joint examples of fig. 1A-1D may be relatively inexpensive and easy to implement and control, but provide a suitable range of motion to perform rather complex tasks with the required dexterity.

In the first example robotic device 100, the tool 152 is mechanically coupled to the end effector 112. Tool 152 may be moved through wrist joint 150. The tool 152 may be adapted to perform tasks in a human environment. In one case, the task may be a dry or wet cleaning operation or task, such as wiping and/or vacuuming. In one case, the tool may be replaceable, for example as described in the examples that follow.

In the first example robotic device 100, the drive system 130 of the propulsion system 110 drives each of the two tri-star wheels. The drive system 130 may include a single component or multiple components. For example, as shown in fig. 1B and 1C, the drive system includes two lateral portions that couple the body 140 of the robotic device 100 to each of the tri-star wheels 120. These lateral components may include separate drive motors, such as one drive motor for each of the tri-star wheels 120, or a common drive motor that provides torque to each of the tri-star wheels 120 via one or more drive shafts. In some cases, propulsion system 110 may include an electric drive system, where one or more drive motors of drive system 130 are powered by one or more batteries contained within body 140 of robotic device 100. The one or more batteries may be rechargeable, for example, by electrically coupling the robotic device 100 to a power source. In another case, propulsion system 110 may include an electric drive system, wherein one or more drive motors of drive system 130 are powered by one or more wired and/or wireless power sources (e.g., a cable plugged into a mains power source and/or an inductive power source).

In fig. 1A to 1D, each tri-star 120 includes a tri-spider hub 124. The samsung hub 124 may include a single unit or multiple coupling portions. It forms the frame of the tri-star wheel. The spider hub 124 includes three spokes or arms extending from a central portion. Each spoke is equally spaced around the hub, for example at an angle of about 120 degrees. At the end of each spoke is an external rotating wheel 122. Thus, there are three externally rotating wheels 122 in each tri-star wheel. Both the spider hub 124 and the outer wheel 122 are rotatable about respective axes. In one instance, the spider hub 124 may include an assembly that additionally includes gearing to couple the drive system 130 to each externally rotating wheel 122. In normal operation, as shown, for example, in FIG. 1A, an external rotating wheel 122 (e.g., wheels 122-B and 122-C in FIG. 1A) in contact with the ground may be rotated via torque applied by the drive system. As will be described in more detail with reference to fig. 2A-2D, in response to an applied force preventing rotation of one of the outer rotating wheels 122, e.g., the wheel encountering a discontinuity in the surface over which the robotic device 100 is navigating, the tri-star wheel 120 may rotate about the center of the tri-spoke hub 124, e.g., relative to the body 140. In this case, the tri-star 120 may pivot about the axis of a constrained one of the externally rotating wheels. Further details regarding the tri-star arrangement may be found in U.S. patent 3,348,518 and a paper by Bozzini et al entitled "Design of the small mobile robot Eqi. Q-2," both of which are incorporated herein by reference.

It should be noted that the first example robotic device 100 is but one of many potential configurations of a robotic device having a set of tri-star wheels and actuated robotic arms. At a minimum, different joint arrangements, different wheels and joint sizes, different body arrangements and different numbers of wheels are contemplated, and some examples of different arrangements are shown in subsequent figures.

Fig. 1D illustrates an example of how the first example robotic device 100 performs a task in an environment. In one instance, the first example robotic device 100 may include a cleaning system, wherein the actuated robotic arm 105 is coupled to the cleaning system and arranged to perform at least one cleaning function. For example, the cleaning system may include a vacuum system, wherein an aperture at the end effector 112 of the actuated robotic arm 105 may be maintained at a low pressure using the vacuum system. In this case, the tool 152 may comprise a vacuum cleaner head, and the robotic device 105 may comprise an autonomous vacuum cleaner. The vacuum system may comprise a cyclonic vacuum system and/or the robotic device may comprise an autonomous cyclonic vacuum cleaner.

Fig. 1D shows a piece of furniture 180. The furniture 180 may be a chair, shelving unit, countertop, table, or the like. Furniture 180 is placed on floor surface 170. The first example robotic device 100 also rests on the same surface 170 via two externally rotating wheels 122-B, 122-C within each tri-star 120. The tri-star is arranged to provide stability for performing tasks above surface 170. For example, in fig. 1D, the actuated robotic arm 105 is used to perform a task on the furniture 180. This may be described as an "off-plane" or "off-ground" task, as tool 152 is located above surface 170. Although the example of fig. 1D shows an example of a task performed above the surface 170, the task may also be performed below the surface, for example as shown in fig. 2A-2D. Where the tool 152 comprises a vacuum cleaner head, the actuated robotic arm 110 may be manipulated to allow the tool 152 to cover an area of furniture 180, which may involve vacuuming a chair or sofa. The primary purpose of the actuated robotic arm may therefore not include providing a stability function for the robotic device. However, in certain described examples, an actuated robotic arm may provide such stability function as an auxiliary purpose, e.g., in addition to one or more defined tasks.

In a coordinate system in which surface 170 defines an x-y plane, the position of end effector 112 may be determined by controlling the rotation of one or

more joints

114, 150, and 160, at least in the vertical z-axis (e.g., vertical in FIG. 1D). In one case, the position of wrist joint 150 in the z-axis is controlled by changing the angle of one or more of elbow joint 114 and shoulder joint 160, where wrist joint 150 changes the orientation of the plane of tool 152 within the environment. In this case, there may be three degrees of freedom. In other cases, one or more joints may also be capable of rotating about an axis parallel to the z-axis, and thus may also control the position of end effector 112 within the x-y plane. In the latter case, the shoulder joint 160 may comprise a ball joint or a double joint assembly that allows rotation about an axis parallel to the z-axis and the y-axis, respectively. This may allow, for example, positioning of end effector 112 in six degrees of freedom. Where the movement of the end effector 112 is constrained to a movement plane (e.g., the plane of fig. 1D), the robotic device 100 may rotate on the surface 170 to move the end effector 112 within an x-y plane. For example, the drive system 130 may provide a differential torque to each of the three-star wheels 120 to allow the robotic device to rotate about the center of the body 140. One or more joints of the actuated robotic arm may be rotated using one or more electric motors. In one case, the control system of the robotic device 100 may determine one or more of joint angles and torques to apply to move the actuated robotic arm 105 within the environment.

Fig. 2A-2D illustrate a second example robotic device 200 performing a stair climbing process. The second example robotic device 200 is shown as a variation of the first example robotic device 100, but may equally include one of the other example robotic devices described herein. Unless otherwise noted, the described features including other examples of the first example robotic device 100 apply to the second example robotic device 200. As described with reference to fig. 1A to 1D, the robotic device 200 has a set of three-star wheels and actuated robotic arms. The robotic device 200 is shown navigating over a discontinuous surface; in this example, the discontinuous surface is a set of stairs 205. The set of stairs 205 has a step change in height. For example, the stairs 205 are comprised of a substantially vertical planar portion 272 and a substantially horizontal planar portion 274. Other forms of discontinuities may also be navigated in a similar manner, including obstructions on the surface, uneven terrain, steps (e.g., one or more changes in surface orientation), curbs, and differences in surface height in different rooms (e.g., due to room geometry and/or floor construction). In general, the form factor of the robotic device 200 enables navigation of a large number of different environments having non-planar floor surfaces.

In fig. 2A, the robotic device 200 rests on a horizontal surface 274 of the stair 205. The two outer rotating wheels of each tri-star provide stability and contact the horizontal surface 274. While in this position, the end effector 210 may move to perform tasks on one or

more surfaces

272, 274 of the stair 205. For example, the end effector 210 may perform a cleaning function such as vacuuming or wiping stairs. In performing a task, the drive system of the propulsion system may be deactivated, for example, to make the outer wheels of the spider or spider non-rotating.

In response to the robotic device 200 being ready to proceed up the stairs 205, for example, the drive system may be engaged once the tasks associated with one or more of the

sub-surfaces

272 and 274 are completed. The robotic device 200 may move forward until the substantially vertical surface 272 prevents the front outer wheel of each tri-star from moving further. At this point, the tri-star wheel may begin to rotate about the center of each tri-spoke hub. This may occur, for example, in response to local friction between the front outer wheels and an obstacle (e.g., surface 272) exceeding a threshold, e.g., sufficient to prevent forward movement of the outer wheels. As shown in fig. 2B, rotation of the spider about the center of each spider hub and pivoting about the front outer wheel causes the body of the robotic device 200 to move up and over discontinuities in the surface.

As also shown in fig. 2B, during the stair-climbing motion of the tri-star, the end effector 210 may apply a force to one of the

surfaces

272 or 274 to help push the robotic device 200 upward. The force applied by the end effector 210 may also (or alternatively) stabilize the robotic device 200 during the stair climbing process so that it does not fall back or topple to the side. For example, the force applied by the end effector 210 may help the set of spider wheels rotate about the center of each spider hub and compensate (at least partially) for the weight of the body of the robotic device 200. In one instance, the end effector 210 may perform tasks and provide propulsion and/or stabilization functions, for example, while the tri-star wheel of the robotic device 200 is navigating at discontinuities in the surface, a dust extraction operation may be performed on the horizontal surface 274 of the stairs.

Fig. 2C shows how after contact is made between the new front outer wheel and the horizontal surface, the new front outer wheel begins to propel the robotic device further forward (via friction between the wheel and the surface). The previous front outer wheel may also rotate and push the robotic device 200 upward via friction between the wheel and the vertical surface 272. The end effector 210 may be additionally applied as before. Fig. 2D shows that once the previous front outer wheel has passed the stair edge, the two outer wheels that contact the ground can again be used to propel the robotic device forward. The end effector 210 may complete the task on the stairs and then lift upward to begin performing the task on the uppermost surface on which the robotic device 200 is now located.

The tri-star device may be configured to provide stair climbing functionality as known in the art. In some cases, a cylindrical body may be used that may allow rotation of the robotic device 200 without rotating about the center of the spider hub of the tri-star wheel, e.g., the robotic device 200 may rotate to a new position while navigating discontinuities in the surface. In the example depicted in fig. 2A to 2D, the rotation around the center of the spider hub of the tri-star wheel allows to maintain the orientation of the body of the robotic device during the stair climbing procedure. Although horizontal surface 274 accommodates two outer rotating wheels in fig. 2A, in other stair configurations, horizontal surface 274 may be narrower in the dimensions of the figure and thus may accommodate only one outer wheel. In this case, a similar process may still be performed, for example with a motion similar to that shown in fig. 2B and 2C. Indeed, in these cases, the additional force provided by end effector 210 may provide additional stability and upward propulsion.

Fig. 3A and 3B illustrate a third example robotic device 300. The third example robotic device 300 may be considered a variation of the first example robotic device 100 shown in fig. 1A-1D. The third example robotic device 300 includes an actuated robotic arm 305 and propulsion system 310 similar to the example of fig. 1A-1D. However, in this example, the external rotator wheel 322 is different in size; i.e. they are larger and extend towards each other. The configuration shown in fig. 3A and 3B may be more suitable for rough terrain and/or more robust to rollover motions. In one case, the outer wheels of the tri-star may be interchanged. In this case, the robotic device 300 may include the robotic device 100 but with an alternative set of coupled external rotating wheels 322.

In one case, the radius r of the external rotator wheel may be chosen _w And/or the length l of each spoke in a three-spoke hub _s To provide different climbing capabilities. Bozzini et al provide more information in the above-mentioned publication. In general, if l is increased _s /r _w Ratio, the robotic device is able to climb over higher obstacles based on movements in the form of limbs using spokes as a stepping motion. If l is _s /r _w The ratio is reduced, the robot device is more suitable for movement using two outer wheels, and the gear arrangement may be more protected. The lower limit of this ratio may be: 1/cos (30 °), for example, in the case where the externally rotatable wheel is in the interference limit state. The described example tri-star wheel, e.g. with three spoke hubs and a set of three equidistant outer wheels, allows efficient stair climbing, whose design can be achieved with a small number of moving parts, increasing robustness and reducing malfunctions. The three-spoke design further enables one or more of the spoke size and the outer wheel size to be configured to suit the use environment, allowing different designs to be easily configured for different environments.

Fig. 4 shows an example of a gear arrangement 400 that may be used for a tri-star. The gear arrangement 400 of fig. 4 is a so-called planetary gear arrangement comprising a central sun gear 410 and a plurality of outer planet gears 420, 430. The central sun gear 410 may be driven by the drive system described herein. The spider hub assembly may be configured to rotate independently of the drive shaft of the central sun gear 410. Thus, the spider hub acts as a planet carrier. In this example, each spoke of the three-star device has two planet gears: a first inner planetary gear 420 and a second outer planetary gear 430. The outer rotating wheel of each spoke may be driven by a second outer planetary gear 430. Although two planetary gears are shown, other gear train configurations having more or fewer gears may alternatively be used. The dimensions of the sun gear 410 and the planet gears 420, 430 can be determined based on design considerations. This arrangement provides simple drive control of the tri-star, for example: propulsion may be provided to the three externally rotatable wheels by a single drive shaft. This then provides a simple form factor, allowing compact size and re-use robustness for home applications.

In some examples described herein, including the example of fig. 4, each tri-star has two degrees of freedom, including one degree of freedom for the outer rotating wheel and one degree of freedom for the tri-spoke hub. In the device of fig. 4, by selectively locking and/or unlocking the degrees of freedom, a single transmission system (e.g., driven by a drive system) may be used to achieve the different motions. In climbing stairs as shown in fig. 2A to 2D, the robotic device can passively modify its motion from a forward mode using two externally rotating wheels to a climbing mode climbing over a discontinuity. In the forward mode, the spider hub may be free to rotate mechanically about its axis, but the weight of the robotic device and the contact force between the external rotating wheel and the ground plane limit the angular position of the robotic device. In the climbing mode, local friction between the front outer wheel and the obstacle impedes rotation of the wheel and causes the spider hub to rotate. The robotic device thus rotates about the front outer wheel to clear the obstacle.

Fig. 5 shows three degrees of freedom of an example actuated robotic arm 500. First degree of freedom-theta ₁ Provided by the shoulder joint 560. The shoulder joint 560 may extend around the circumference of the body of the robotic device or may be positioned on top of the body. The former case may allow for omnidirectional operation of the robotic device, while the latter case uses a preferred orientation of the robotic device body. The shoulder joint 560 may allow rotation through a limited angular range, for example, 120 or 180, or a full 360 rotation. Second degree of freedom-theta ₂ Provided by the elbow joint 514. Third degree of freedom-theta ₃ Provided by wrist joint 550. As previously described, the third degree of freedom may allow for rotation of the plane of the end effector and/or attachment tool 552. Similar to shoulder joint 560, each of elbow joint 514 and wrist joint 550 may have a defined range of rotation. The elbow joint 514 may provide the maximum possible range of rotation for the three joints, for example around most of the circumference of the joint within the constraints imposed by the presence of the linkage members. Wrist joint 550 may provide a relatively large range of motion or be limited to a predetermined range of motion.

In some cases, one or more of elbow joint 514, wrist joint 550, and shoulder joint 560 may include a ball joint or a double joint assembly to allow further rotation in at least a plane perpendicular to the plane of freedom shown in the figures. For example, if desired, the wrist joint 550 and shoulder joint 560 may be implemented as ball joints to increase the range of motion. However, a limited range of motion, e.g., three degrees of freedom, may be easier to control, e.g., in an autonomous implementation.

It should be noted that the actuated robotic arm may be different than that shown in fig. 5, but still provide multiple degrees of freedom for the end effector in the environment. For example, an electroactive polymer may be disposed around a pivot joint and controlled by an electrical current. In some cases, a camera device may be provided on the robotic device to enable visual feedback of the position of the end effector within three-dimensional space. In one case, one or more neural network architectures can be used to process signals from one or more of a set of joint actuators, position sensors, and cameras and generate signals to control the set of joint actuators.

Fig. 6 shows how a tool attached to an end effector may be replaced. Fig. 6 shows a robotic device 600, which may be an embodiment of the first example robotic device 100 of fig. 1A-1D, and a tool changing unit 610. In fig. 6, the tool change unit 610 comprises a substantially vertical cabinet with

sub-compartments

612, 614, the

sub-compartments

612, 614 being accessible via at least a front aperture. For example, providing the arrangement of fig. 6, other orientations including horizontal may also be used, although a substantially vertical tool change unit 610 may allow for a simpler control procedure for tool change. Within each sub-compartment 612, 614 are a plurality of

replaceable tools

616, 618. In fig. 6, two

interchangeable tools

616, 618 are shown as an example, although in embodiments a different plurality of interchangeable tools may be provided. In FIG. 6, first changeable tool 616 comprises a vacuum chuck and second changeable tool 618 comprises a chuck. The plurality of interchangeable tools may take a variety of forms and may include different fixtures, brushes, vacuum tips, mops, plates or boxes, dusters, wet cleaning attachments such as sprayers, bumper heads for applying motive forces, and the like. Each interchangeable tool may be mounted in a frame or rack within the sub-compartment. In one case, the frame or support may assist in the proper alignment of the replaceable tools within the sub-compartment. The interchangeable tool may be retained within the sub-compartment using a retention force, which may be mechanical (e.g., a spring-loaded detent) and/or magnetic.

To use the replaceable tools within the tool changing unit 610, the end effector of the robotic device 600 includes a tool interface 652. The tool interface 652 may be mechanical and/or magnetic. The tool interface 652 is configured to removably mount one of a plurality of replaceable tools, for example, for performing a task. A tool interface 652 may be coupled to the wrist joint 650 to control orientation, for example, as described above. In use, as shown in fig. 6, the robotic device 600 actuates one or more joints of the actuated robotic arm to move the tool interface 652 into a selected sub-compartment to mount a selected one of the first and second

replaceable tools

616, 618. For example, in fig. 6, robotic device 600 may be attempting to mount vacuum head 616, or may have just placed vacuum head 616 and is moving to attach fixture 618. The movement is shown by arrow 620 in fig. 6. One or more of the sub-compartments 612, 614 and the interface 652 may include locking features that actuate to lock and/or unlock the interchangeable tool in place. These locking components may be electronically controlled (e.g., by robotic means and/or by sub-compartments based on sensor data). The interface 652 may provide mechanical and electrical coupling with the robotic device 600. The electrical coupling may be provided by electrical contacts (e.g., in a plug and socket arrangement) and may provide one or more of power and control signals. For example, one or more actuators on the clamp 618 may be powered and controlled by the robotic device 600 via the interface 652. Electrical coupling to the body of the robotic device may be provided by wired and/or wireless connections extending along the length of the actuated robotic arms. The interchangeable toolset may allow the robotic device to perform a number of different tasks, such as dust extraction and moving objects and dust extraction, using the actuated robotic arms, which further enhances the utility of the robotic device without significantly changing the basic form factor, enabling simpler control (e.g., a generic control program may be reused for different tasks) and scalability.

Fig. 7 illustrates an example control system 700 for a robotic device. The example control system 700 includes certain example control components for a robotic device. The example control system 700 may be used to implement control functions in any of the example robotic devices described herein. The example control system 700 of FIG. 7 relates to an autonomous cleaning apparatus; however, certain control components may also be shared by other examples.

The example control system 700 includes an internal body component 710 that may be provided as part of the body of the robotic device (e.g., may be mounted on or in the body). The inner body member 710 includes a controller 720, a drive control system for the first three-star wheel 730, a drive control system for the second three-star wheel 735, a set of joint control systems 740-744, and a cleaning control system 750. In fig. 7, the set of joint control systems 740 to 744 includes a first joint control system 740 and a set of nth joint control systems 742 to 744, the first joint control system 740 may control a shoulder joint mounted on the robot apparatus main body, and the nth joint control systems 742 to 744 may control a plurality of joints external to the robot apparatus main body, such as an elbow joint and a wrist joint, which are described previously. The set of joint control systems 740-744 may be coupled in a variety of ways known in the art, including in a series daisy-chained arrangement or in parallel. This is indicated by the dashed arrow in fig. 7. The

drive control systems

730, 735 are shown as two separate control systems, for example for two independent motors, but in some cases these may be implemented by a single control system of a set of three-star wheels. The

drive control systems

730, 735 are configured to control a set of three-star wheels, including controlling the speed and/or acceleration of one or more wheels, and in some cases, any rotational locking mechanism. The

drive control systems

730, 735 may control the torque applied by one or more electric motors in response to signals received from the controller 720. The

drive control systems

730, 735 may form part of a propulsion system of the robotic device. The cleaning control system 750 controls the cleaning functions of the robotic device, such as activation of the vacuum unit, vacuum motor control, control of any dry and/or wet cleaning components (including those mounted on the end effector, for example), and cleaning sensor processing.

Controller 720 may include one or more processors, including one or more microprocessors, central processing units, and/or graphics processing units, and a set of memories. The controller 720 is communicatively coupled to the example control components to control actions of the robotic device. In fig. 7, this coupling is accomplished via a system bus 760. The controller 720 in fig. 7 is configured to control at least the actuated robotic arms via a set of joint control systems 740-744. Different levels of control may be provided, for example, in one case, the controller 720 may provide a desired relative three-dimensional position that is translated into joint actuator commands by the set of joint control systems 740 through 744, or in another case, the controller 720 may provide the joint actuator commands themselves, which are then implemented by the set of joint control systems 740 through 744. The controller 720 may also control the

drive control systems

730, 735 to propel the robotic device in the environment. As such, the controller 720 may be configured to control the actuated robotic arms to assist the propulsion system in navigating the discontinuous surface, such as by applying a stabilizing force to the surface behind the robotic device using the set of tri-star wheels during forward motion. In one instance, controller 720 is configured to apply impedance control to adjust one or more powered joints based on the force applied to the end effector. Impedance control may reduce damage to objects and people when the robotic device interacts in the environment.

In these cases, the stabilizing force may be considered separate from the task to be performed by the actuated robotic arm, e.g. the task is not (primarily) applying the stabilizing force. However, control of the actuated robotic arm may be configured to provide a stabilizing force as a byproduct of performing a task or an auxiliary function. The stabilizing force may be applied before, during, and/or after the task is performed. For example, a force is applied to the stairs by vacuum cleaning the stairs with a vacuum nozzle attached to the end effector. The force may be a stabilizing force and have a stabilizing effect, however, the main task of the robot device is to vacuum clean the stairs. Similarly, after or before vacuuming the stairs, the vacuum may be deactivated, but a force may be applied to the stairs by the end effector that may help "push" the robotic device up the stairs, or provide a counterbalancing force for navigating down the stairs.

The controller device of fig. 7 has the advantage of centralized control, so that different operations of the robotic device, such as propulsion, joint control and cleaning, can be controlled together. For example, one or more forces applied by the end effector may be adjusted based on feedback from one or more propulsion and joint control systems when performing a cleaning task or function. For example, the force may be reduced or increased depending on the manner in which the robotic device is moving in the environment.

Fig. 8A and 8B show cross-sectional views of a side section and a front section, respectively, of a fourth example robotic device 800. Fig. 8A and 8B illustrate how a control system, such as the example control system of fig. 7, may be coupled to physical components of a robotic device. According to the previous example, the two least significant digits of the reference number represent correspondence with features of the first example robotic device 100 shown in fig. 1A-1D. The form factor of the robotic device shown in fig. 8A and 8B is particularly compact and therefore particularly useful in a home environment.

Fig. 8A shows a cross-sectional view behind a three-star wheel. The drive system 830 includes a drive shaft 835 for driving a sun gear of a tri-star, such as the central sun gear 410. The drive system 830 is mounted within the body 840. The main body 840 includes a chassis. A shoulder joint 860 is mounted on the outside of the body 840 to control at least the angular position of the upper arm link 818.

Fig. 8B shows more detail of how the components shown in fig. 8A are arranged relative to the body 840. In this example, there are two drive systems 830 that control the tri-star wheels on either side of the body 840 via drive shafts 835. These drive systems 830 are shown coupled by drive shafts 870, but in other examples a differential drive with separate motors may be provided. Fig. 8B also shows a cleaning system 850 also mounted on the main body 840. For example, the cleaning system 850 may comprise a vacuum system and thus a removable collection unit for dust and particulate matter. A propulsion

system including components

830, 835 and 870 and/or shoulder joint 860 may be arranged to house cleaning system 850. Other components of the fourth example robotic device 800, such as batteries and power supply units, control panels, and the like, are not shown for clarity, but may be designed according to the constraints of each of the presented embodiments.

Fig. 9A to 9D show various variants of a robotic device comprising a set of tri-star wheels and actuated robotic arms.

Fig. 9A shows an example 900 of a shoulder joint 902 mounted on top of a main body 904 of a robotic device. Shoulder joint 902 may be used to implement shoulder joint 160 in fig. 1A-1D. Shoulder joint 902 moves a link 906 (e.g., upper arm link 118 in fig. 1A) in at least one direction 908 (i.e., one rotational degree of freedom). In one case, the shoulder joint 902 may include a ball joint or additional actuator to rotate the joint within the superior plane of the body 904.

Fig. 9B illustrates a fifth example robotic device 920. A fifth example robotic device 920 uses the shoulder joint 902 of fig. 9A and has an elongated body with two

tri-star wheels

922, 924 on each side (four total on both sides). The actuated mechanical arm 926 may move at least via the shoulder joint 902. The fifth example robotic device 920 may be suitable for larger cleaning operations, such as in commercial or industrial buildings, while still retaining the capabilities of the examples described above.

Fig. 9C and 9D are side and front views, respectively, of a sixth example robotic device 930. The sixth example robotic device 930 has two tri-star wheels: front and rear

tri-star wheels

932, 934, and an actuated robotic arm 936. In this case, the

tri-star wheels

932, 934 comprise externally rotating wheels that extend across the width of the body 942 of the sixth example robotic device 930. The

tri-star wheels

932, 934 are mounted between support members 944, the support members 944 extending the length of the body 942. In other examples, the support member 944 may include a plurality of support members. The body 942 also has a shoulder joint 944 for controlling the position of the actuated mechanical arm 936. Shoulder joint 946 is similar to shoulder joint 902 of fig. 9A. Each of the front and rear tri-star wheels may rotate 952, 954 about an axis perpendicular to the support member 944, e.g., in the plane of fig. 9C and out of the plane of fig. 9D. Each spider has two side spider hubs 956 at both ends, for example adjacent to the support member 944. This is best shown in fig. 9D. Three elongated outer wheels 962 extend across the width between the spider hubs 956. These may be driven in one or both spider hubs 956 by gearing similar to that shown in figure 4. A gear train may be provided within the support member 944 to provide torque to the central sun gear, such as 410, from one or more motors mounted within the body 942. The example of fig. 9D also shows how the shoulder joint 946 includes a ball joint to move the upper arm link 966 in a direction 968, e.g., pivoting across the body 942 and along the length of the body 942.

FIG. 10 is a flow diagram illustrating a method of navigating a set of discontinuous surfaces with a robotic device according to an example. The method may be a method for performing a stair climbing procedure as shown in fig. 2A to 2D, or another procedure that allows navigation of obstacles. The method may be implemented by the controller 720 of fig. 7.

At step 1010, a set of tri-star wheels of the robotic device is used to propel the robotic device in a direction of travel along the surface. This may include, for example, applying torque to a set of externally rotating wheels in contact with a substantially horizontal surface such as 170 or 274. Step 1020 then occurs during the movement across the discontinuity along the surface. For example, this may include an obstruction extending upwardly from a surface, such as substantially vertical surface 272. In one case, limited motion may be detected, for example using one or more sensors, such as an accelerometer, gyroscope, torque sensor, and/or rotation sensor. In one case, a limitation of the movement of the front outer wheel or the rotation of the spider hub may be detected. In this case, step 1020 includes applying a force to a portion of the surface with an actuated robotic arm mechanically coupled to the robotic device to assist in the movement. For example, this may include using an actuated robotic arm to push against a nearby surface, as shown in fig. 2A-2D.

The direction of travel may be any direction within the environment, and may include the direction of an "up" or "down" set of stairs. The force may be applied anywhere around the robotic device. For example, the force may be applied in front of the robotic device in the direction of travel, behind the robotic device in the direction of travel, and/or to the side of the robotic device in the direction of travel. The position of the applied force may vary during the movement. This may be performed based on considerations of the task to be performed (e.g. cleaning task) and/or based on kinematic considerations (e.g. how best to stabilize the robotic device). The force may be applied to any surrounding surface, for example to surrounding objects such as stair railings and substantially vertical or non-horizontal surfaces.

In one case, the robotic device comprises an autonomous vacuum cleaner and the discontinuity comprises a staircase or a step. In one instance, applying the force using the actuated robotic arm includes applying the force with the actuated robotic arm in a direction of travel to a second surface located behind the robotic device during contact between the wheel portion of at least one of the set of tri-star wheels and the discontinuous first surface. This may be performed, for example, as the robotic device climbs and cleans a set of stairs. In other cases, such as when descending a group of stairs, a force may be applied to a second surface located in front of or to the side of the robotic device. A cleaning function, such as vacuuming a surface to which a force is applied, may be performed while the force is applied. In one case, impedance control may be used to adjust the applied force, for example by adjusting the torque applied at one or more joints within the actuated robotic arm.

Certain examples described herein provide a form factor for a robotic device that uses a three-star wheel system in combination with a robotic arm. In one case, the robotic device is an autonomous vacuum cleaner, and the vacuum head is mounted on an end effector of a robotic arm. Other tools may also be interchangeably attached. The three-star wheel system provides good performance when climbing large obstacles such as stairs. In the autonomous vacuum cleaner example, the vacuum head may be used to clean stairs while ensuring stability as the robotic device climbs a group of stairs. In addition, the robotic arms may use impedance control to actively assist the robotic device in climbing stairs.

Depending on the specific design, the tri-star wheel may be configured to climb obstacles up to 80% of the height of three wheels, while the comparative non-tri-star wheel is 30% of the height (e.g., diameter). Furthermore, having at least two tri-star wheels on either side of the body or base provides at least four points of contact, which stabilizes the interface with the ground. By virtue of this fact, the robot arm can also be used for "off-ground" operations, such as dusting armchairs or tidying coffee tables. The same principle can also be used for tool changing operations, such as switching between two different types of vacuum nozzles, or replacing a vacuum nozzle with a gripper.

The above examples are to be understood as illustrative. Further examples may be envisaged. Any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other example, or any combination of other examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A robotic device comprising:

an actuated robotic arm comprising an end effector and one or more powered joints, the position of the end effector relative to the robotic device controllable to perform at least one task; and

a propulsion system, comprising:

a drive system, and

a set of three-star wheels coupled to the drive system.

2. The robotic device of claim 1, comprising:

the system is cleaned by the cleaning device and the cleaning device,

wherein the actuated robotic arm is coupled to the cleaning system and the task comprises at least one cleaning task.

3. The robotic device of claim 2,

wherein the cleaning system comprises a vacuum system, and

wherein the aperture at the end effector of the actuated robotic arm is maintained at a low pressure using a vacuum system.

4. The robotic device of any one of the preceding claims, wherein the actuated robotic arm comprises a plurality of joints.

5. The robotic device of any one of the preceding claims, wherein the actuated robotic arm has three to six degrees of freedom.

6. The robotic device of any of the preceding claims, wherein the set of tri-star wheels supports the robotic device on a surface, and the actuated robotic arm is configured to perform at least one task above or below the surface.

7. The robotic device of any one of the preceding claims, comprising:

a chassis housing at least the propulsion system,

wherein the actuated robotic arm is mechanically coupled to the chassis and

wherein the set of three-star wheels comprises a pair of three-star wheels arranged on two sides of the chassis.

8. The robotic device of any one of the preceding claims, wherein the end effector includes an interface for removably mounting a plurality of tools.

9. The robotic device of claim 8, wherein the plurality of tools includes one or more of a gripper, a brush, and a vacuum tip.

10. The robotic device of any one of the preceding claims, comprising:

a controller electrically coupled to the propulsion system and the actuated robotic arm,

wherein the controller is configured to control at least the actuated robotic arm.

11. The robotic device of claim 10, wherein the controller is configured to control the actuated robotic arm to assist the propulsion system in navigating the discontinuous surface.

12. The robotic device of claim 11, wherein the controller is configured to apply a stabilizing force to a surface behind the robotic device using the actuated robotic arm during the forward motion using the set of three-stars.

13. The robotic device of any one of claims 10-12, wherein the controller is configured to apply impedance control to adjust the one or more powered joints based on a force applied to the end effector.

14. A method of navigating a set of discontinuous surfaces with a robotic device, the method comprising:

driving a set of three-star wheels of the robotic device to propel the robotic device in a direction of travel along the surface; and

during movement across the discontinuity along the surface, a force is applied to a portion of the surface by an actuated robotic arm mechanically coupled to the robotic device to assist in the movement.

15. The method of claim 14, wherein the robotic device comprises an autonomous vacuum cleaner and the discontinuity comprises a stair or step.

16. The method of claim 14 or 15, wherein applying the force using the actuated robotic arm comprises applying a force with the actuated robotic arm to a second surface that is behind the robotic device in the direction of travel during contact between the wheel portion of at least one of the set of tri-star wheels and the discontinuous first surface.

17. The method of any one of claims 14 to 16, comprising performing a cleaning function before, during or after applying the force.