Patent ID: 12202295

DETAILED DESCRIPTION

Robots and vehicles may move over terrain on wheels. These robots and vehicles may include suspension systems (e.g., shocks, springs, etc.) that absorb impacts experienced by the wheels. For example, the wheels of the robot or vehicle may experience impact forces (e.g., vibrations) when the robot or vehicle move over a rough surface or hit an obstacle (e.g., a curb). The suspension systems absorb these impact forces so that they do not damage other components of the robot or vehicle.

There is an increasing demand, however, for robots and vehicles to be lighter. For example, lighter robots and vehicles may be more fuel efficient and require less maintenance. Suspension systems may be heavy and contribute significant weight to a robot or vehicle. Thus, removing a suspension system from a robot or vehicle may make the robot or vehicle lighter, but the robot or vehicle may also be more prone to damage caused by impact forces.

This disclosure describes a wheel that includes a compliant structure that absorbs impact forces experienced by the wheel. Notably, the compliant structure includes connective elements that elastically deform when experiencing an impact force. The elastic deformation absorbs or disperses the impact force so that other components of the robot or vehicle are not damaged. Thus, the connective elements act as a suspension system for the robot or vehicle. In particular embodiments, a robot or vehicle that includes the wheel and its connective elements may not need to include a separate suspension system to absorb impact forces, which reduces the weight of the robot or vehicle.

In some embodiments, the wheel provides minimum static friction of at least 0.7 on dry concrete and at least 0.45 on wet concrete. Additionally, the wheel allows for at least 3.6 Newton-meters (Nm) of torque transmission for extended periods to climb slopes and at least 30 Nm for short durations to brake. In certain embodiments, the wheel reduces peak acceleration during shock events (e.g., impact forces) and dampens motion due to regular obstacles (e.g., cracks in sidewalks). The wheel may be used on robots or vehicles with a mass between 100 and 120 pounds carrying a payload of 30 pounds.

FIG.1illustrates an example system100. As seen inFIG.1, the system100includes a mobile robot102, which includes a body104, a sensor system106, and wheels108. These components may operate together to control the movement of the robot102. Generally, the robot102may move autonomously over various terrains on wheels108. For example, the robot102may be a delivery robot that delivers packages autonomously to homes or businesses. The wheels108of the robot102include compliant structures that absorb impact forces experienced by the wheels108or the robot102. In particular embodiments, because the wheels108absorb the impact forces, the robot102does not need a separate suspension system to absorb the impact forces, which reduces the weight of the robot102. As a result of its reduced weight, the robot102is more fuel efficient and easier to maintain.

The body104of the robot102protects the internal components of the robot102(e.g., a processor110, a memory112, one or more motors114, and the sensor system106). For example, the body104may shield these internal components from weather or debris. The body104may be made of any suitable material (e.g., metal or plastic). Additionally, the body104may include space to hold a package that the robot102delivers. When the robot102reaches its destination, a cover or lid105on the body104may open to provide access to the package. A recipient at the destination may retrieve the package from the body104, and the robot102may consider the delivery to be complete. The robot102may then return to a central station to be loaded with another package for delivery.

The sensor system106includes one or more sensors (e.g., cameras, light detection and ranging sensors, infrared sensors, vision sensors, three-dimensional sensors, etc.) that detect or sense the environment around the robot102. For example, the sensor system106may capture images or video of the robot's102surrounding environment. Other components of the sensor system106or other components within the body104may process the captured images or video to determine a position or a location of the robot102. The captured images or video may also reveal obstacles that may impede the movement of the robot102. The sensor system106or the other components within the body104may analyze the captured images or video to determine an optimal path that the robot102can take enroute to its destination. The robot102may then navigate itself along this path to avoid obstacles.

The processor110and the memory112are configured to control the operation of the robot102. For example, the processor110and the memory112may control the one or more motors114to rotate the wheels108of the robot102. The processor110and the memory112may operate the motors114at different speeds to navigate the robot102. As another example, the processor110and the memory112may process information from the sensor system106to determine where to navigate the robot102. As yet another example, the processor110and the memory112may determine when the robot102has reached its destination and open the lid105.

The processor110is any electronic circuitry, including, but not limited to microprocessors, application specific integrated circuits (ASIC), application specific instruction set processor (ASIP), and/or state machines, that communicatively couples to memory112and controls the operation of the robot102. For example, the processor110may analyze information from the sensor system106to navigate the robot102to its destination. The processor110may control one or more motors to rotate the wheels108to navigate the robot102. The processor110may be 8-bit, 16-bit, 32-bit, 64-bit or of any other suitable architecture. The processor110may include an arithmetic logic unit (ALU) for performing arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that fetches instructions from memory and executes them by directing the coordinated operations of the ALU, registers and other components. The processor110may include other hardware that operates software to control and process information. The processor110executes software stored on memory to perform any of the functions described herein. The processor110controls the operation and administration of the robot102by processing information (e.g., information received from the sensor system106and the memory112). The processor110may be a programmable logic device, a microcontroller, a microprocessor, any suitable processing device, or any suitable combination of the preceding. The processor110is not limited to a single processing device and may encompass multiple processing devices.

The memory112may store, either permanently or temporarily, data, operational software, or other information for the processor110. The memory112may include any one or a combination of volatile or non-volatile local or remote devices suitable for storing information. For example, the memory112may include random access memory (RAM), read only memory (ROM), magnetic storage devices, optical storage devices, or any other suitable information storage device or a combination of these devices. The software represents any suitable set of instructions, logic, or code embodied in a computer-readable storage medium. For example, the software may be embodied in the memory112, a disk, a CD, or a flash drive. In particular embodiments, the software may include an application executable by the processor110to perform one or more of the functions described herein.

The robot102may have any number of wheels108. For example, the robot102may have four or six wheels108. To move forward and backward, the robot102may rotate the wheels108on the robot102at the same speed. To turn the robot102left or right, the robot102may rotate the wheels108on one side of the robot102faster than the wheels108on the other side of the robot102. In some embodiments, some of the wheels108have rollers positioned around the circumferences of the wheels108. In the example ofFIG.1, the two back wheels108of the robot102have rollers and the two front wheels108do not have rollers. The rollers rotate about an axis that is orthogonal to the axis of rotation of the wheels108, which allows for lateral movement. The rollers may be angled relative to each other (e.g., a design referred to as a mecanum wheel).

In certain embodiments, the wheels108on the robot102are not identical. For example, to improve traction and reduce uncontrolled lateral sliding, the robot102may have two wheels108with rollers that allow for lateral movement and at least two wheels108with standard traction elements rather than rollers.

The robot102includes one or more motors114that are coupled to the wheels108. For example, there may be one motor114for each wheel108on the robot102. As another example, there may be a motor114for each side of the robot102. The motors114rotate the wheels108to move the robot102.

As seen inFIG.1, the robot102may move over smooth or rough terrain. For example, the robot102may be moving on a sidewalk that includes cracks or grooves. When the wheels108roll over these cracks or grooves, the robot102may experience an impact force. As another example, the robot102may be traveling towards the end of the sidewalk where there is a curb. If the robot102falls off the curb, the robot102may experience an impact force. If these impact forces are not absorbed by an on-board shock absorption system specifically adapted for that purpose, they may cause vibrations that may damage or disrupt other components of the robot102(e.g., the sensor system106, internal circuitry, or other components within the body104). In some instances, the impact force may cause vibrations that damage a package being delivered by the robot102. The wheels108that have rollers may experience additional issues with respect to the impact force. For example, the rollers may be arranged around a carrier structure that surrounds a hub of the wheel. The carrier structure may be made using a rigid material that does not deflect or minimally deflects when experiencing static or dynamic loading so that the rollers can still rotate within the carrier structure. In other words, if the carrier structure were to deform, the deformation may prevent the rollers from rotating. Because the carrier structure does not deform or minimally deforms, however, no energy is dissipated and the impact force travels through the carrier structure and into other components of the wheel108and the robot102, which may damage these components. Even if the robot102is not moving or moving at a steady state, a wheel108may still experience a force. For example, the weight of the robot102may cause the wheels108to experience a force. If the carrier structure does not deform or minimally deforms, however, that force travels through the carrier structure and into other components of the wheel108and the robot102.

As discussed previously, the wheels108of the robot102include a compliant structure that elastically deforms to absorb impact forces experienced by the wheels108or the robot102. The compliant structure may bend, move, stretch, or compress to absorb the impact force. After the impact force is absorbed, the compliant structure may return to its original shape. In particular embodiments, when the compliant structure absorbs the impact force, the compliant structure reduces or eliminates the vibrations caused by the impact force, which protects other components of the robot102or a package being delivered by the robot102. Additionally, even when the robot102is not moving, the compliant structure elastically deforms to support the weight of the robot102. In this manner, the robot102can absorb forces without using a separate suspension system. Furthermore, the carrier structures in the wheels108of the robot can elastically deform different amounts so that all the wheels108of the robot102contact the ground, thereby increasing the contact plane of the robot102(e.g., when the robot102is on uneven terrain). Various embodiments of the wheels108will be described in more detail usingFIGS.2through6.

FIG.2Aillustrates an example wheel108A in the system100ofFIG.1. As seen inFIG.2A, the wheel108A includes a hub202, a compliant structure204A, carrier structures206A and206B, and rollers208. Generally, the compliant structure204A elastically deforms to absorb impact forces experienced by the carrier structures206A and206B. In this manner, the compliant structure204A acts as a suspension system that absorbs impact forces to protect other components. Additionally, the wheel108A may be symmetric across a vertical plane of the wheel108A, which allows for the same wheel108A to be used on the right or the left side of the robot102.

The hub202is positioned at the center of the wheel108A. The hub202includes a central cavity that is shaped and sized to receive an axle that can turn the wheel108A. For example, the axle may attach to a transmission system that turns the axle. When the axel e turns, the hub202and the wheel108A turns with the axle. The hub202may be formed using a rigid material (e.g., metal) that provides structural support for the wheel108A. The hub202may be circular in shape and may attach to the compliant structure204A.

The compliant structure204A may be a circular structure that attaches to the hub202. The compliant structure204A includes a central cavity in which the hub202fits. As seen inFIG.2A, the compliant structure204A includes connective elements205that resemble fins such that the connective elements205achieve a desired flexibility or deformability when the when108A experiences a force component (e.g., a force that is directed towards the hub or tangential to the hub). For clarity, not all of the connective elements205of the compliant structure204A have been labeled inFIG.2A. The connective elements205couple to the hub202at one end and the carrier structures206A and206B at the other end. In certain embodiments, the connective elements205couple directly to the carrier structures206A and206B. In some embodiments, the connective elements205couple directly to a rim, which couples directly to the carrier structures206A and206B. The connective elements205are shaped and sized such that the connective elements205spiral outwards from the hub to the carrier structures206A and206B. The connective elements205may be formed using a material that elastically deforms to absorb impact forces. For example, when the wheel108A is rolling on rough terrain, the carrier structures206A and206B experience impact forces that are absorbed by the connective elements205. The connective elements205elastically deform to absorb the impact forces. Stated differently, the impact force causes the connective elements205to change their shape temporarily. As the connective elements205change shape (e.g., bend, move, compress, or stretch), the connective elements205absorb the impact force. After the impact force has been absorbed, the connective elements205return to their original shape. In this manner, the impact force is absorbed by the compliant structure204A, and the full impact force does not travel through the hub202and into other components coupled to the wheel108A.

The carrier structures206A and206B are two separate assemblies that couple to the compliant structure204A. As seen inFIG.2A, the carrier structures206A and206B are similarly-dimensioned circular structures forming a central cavity that is shaped and sized to fit the compliant structure204A and the hub202. The carrier structures206A and206B may be made of a rigid material that rotates with the hub202. The carrier structures206A and206B are positioned adjacent to one another around the compliant structure204A. In some embodiments, the carrier structures206A and206B have a combined width that is less than or equal to the width of the compliant structure204A such that the carrier structures206A and206B do not extend beyond the hub202along an axis of rotation of the wheel108A, which provides for easier rotation of the wheel108A.

As seen in the example ofFIG.2A, the compliant structures206A and206B hold rollers208. Each roller208rotates about an axis of rotation that is orthogonal to the axis of rotation of the wheel108A. In this manner, the rollers208provide for a transverse motion of the wheel108A. Stated differently, if the wheel108A rotates to move forward and backward, the rollers208roll to move the wheel108A in a direction lateral to the forward and backwards motion, thereby allowing for omni-directional movement of the robot102.

As seen inFIG.2A, both carrier structures206A and206B hold rollers208. The rollers208are spaced around the circumference of the carrier structures206A and206B. The rollers208in the carrier structure206A are arranged alternately with the rollers208in the carrier structure206B. In other words, the rollers208in the carrier structures206A and206B are spaced such that a space between two rollers208on the carrier structure206A is positioned adjacent to a roller208on the carrier structure206B, and vice versa. In this manner, each point along a circumference of the compliant structure204A is supported by at least one roller208on the carrier structure206A with a carrier structure206B.

As discussed previously, the rollers208provide a transverse motion for the wheel108A. Returning to the example ofFIG.1, if the mobile robot102includes the wheels108A on both sides of the mobile robot102, the robot102may turn to the left or the right by rotating the wheels108A on the left or right side of the robot102faster than the wheels108A on the other side of the robot102. When the robot102turns in this manner, the rollers108provide for a lateral movement without pulling or skidding the wheels108A on the ground. As a result, the rollers208allow the robot102to turn while protecting the wheels108A, increasing their lifespan. Additionally, the rollers208provide for reduced power consumption for turning operations, smoother or quieter motion, and more deterministic control relative to other, unpredicatble maneuvers (e.g., stick-slip of high friction maneuvers).

FIG.2Billustrates an exploded view of the wheel108A ofFIG.2A. As seen inFIG.2B, the hub202is formed using two portions202A and202B. The portions202A and202B of the hub202may be permanently or removably coupled to each other. For example, threaded fasteners or rivets may be used to couple the portions202A and202B to form the hub202. As another example, the portions202A and202B may be welded together to form the hub202. The portions202A and202B include a central cavity that is shaped and sized to hold an axle. When the axle turns, the wheel108and the hub202turn with the axle.

The compliant structure204A is a circular structure that includes a central cavity shaped and sized to hold the hub202. As seen inFIG.2B, the compliant structure204A includes connective elements205that spiral outwards from the central cavity to the outer circumference of the compliant structure204A. As discussed previously, these connective elements205elastically deform to absorb impact forces so that other components are not damaged by these impact forces. For clarity, not all of the connective elements205of the compliant structure204A are labeled inFIG.2B.

The carrier structures206A and206B include central cavities that are shaped and sized to fit the compliant structure204A and the portions202A and202B of the hub202. The carrier structure206A is positioned adjacent to the carrier structure206B on the compliant structure204A. The carrier structures206A and206B may be coupled to the compliant structure204A using any mechanism. For example, the carrier structures206A and206B may be welded to the compliant structure204A. As another example, the carrier structures206A and206B may be fastened to the carrier structure204A (e.g., using bolts or rivets).

The carrier structures206A and206B hold rollers208. As discussed previously, the rollers208rotate about an axis that is orthogonal to the axis of rotation of the wheel108A, thereby allowing for omni-directional movement of the robot102. In this manner, the rollers208provide for lateral movement of the wheel108A. The rollers208are spaced alternately around a circumference of the carrier structures206A and206B, such that a space between two rollers208on the carrier structure206A is positioned adjacent to a roller208on the carrier structure206B, and vice versa.

FIG.2Cillustrates an example wheel108B in the system100ofFIG.1. The wheel108B is similar to the wheel108A ofFIG.2Aexcept that the wheel108B includes a compliant structure204B′ with two sets of connective elements205A′ and205B′. These two sets of connective elements205A′ and205B′ spiral in opposite directions to balance the impact force absorption, in particular embodiments.

The wheel108B includes a hub202′ that is structurally similar to the hub202of the wheel108A. The hub202′ is positioned a center of the wheel108B. It includes a central cavity that accommodates an axle. When the axle turns, the wheel108B turns with the axle.

The compliant structure204B′ is positioned around the hub202′. The compliant structure204B′ includes a central cavity shaped and sized to hold the hub202′. As discussed previously, the compliant structure204B′ includes two sets of connective elements205A′ and205B′ that spiral outwards from the hub202′ in opposing directions. The connective elements205A′ in the foreground ofFIG.2Cspiral in a counterclockwise direction. The connective elements205B′ in the background ofFIG.2Cspiral in a clockwise direction. The opposing directions of the two sets of connective elements205A′ and205B′ balance the absorption of impact forces experienced by the wheel108B, in particular embodiments. The connective elements205A′ and205B′ elastically deform (e.g., bend, move, compress, or stretch) to absorb impact forces. After an impact force is absorbed, the connective elements205A′ and205B′ return to their original shape. For clarity, not all of the connective elements205A′ and205B′ in the compliant structure204B′ have been labeled inFIG.2C.

The wheel108B includes the carrier structures206A′ and at206B′, which are similar to the carrier structures206A and206B in the example ofFIG.2A. The carrier structures206A′ and206B′ are positioned around the compliant structure204B′. Both the carrier structures206A′ and206B′ include a central cavity that is shaped and sized to hold the compliant structure204B′ and the hub202′. The carrier structures206A′ and206B′ hold rollers208that are positioned around the carrier structures206A′ and206B′. Like the example ofFIG.2A, the rollers208are positioned alternately around the carrier structures206A′ and206B′. The rollers208rotate about an axis of rotation that is orthogonal to the axis of rotation of the wheel108B, which allows the wheel108B to move laterally on the rollers208.

FIG.2Dillustrates an exploded view of the example wheel108B ofFIG.2C. As seen inFIG.2D, the wheel108B is formed using two portions210A and210B. Each portion210A and210B is molded or formed to include a portion of the hub202′. Each portion210A and210A is molded as a singular structure. The portions210A and210B may be coupled to each other permanently or irremovably. For example, the portions210A and210B may be coupled to each other using threaded fasteners or rivets. As another example, the portions210A and210B may be welded together.

As seen inFIG.2D, the portion210A includes a portion202A of the hub202, a portion204B1of the compliant structure204B, the carrier structure206A′, and the rollers208in the carrier structure206A′. The portion210B includes a portion202B of the hub202′, a portion204B2of the compliant structure204B′, the carrier structure206B′, and the rollers208in the carrier structure206B′. The portions210A and210B are coupled together by coupling the portions202A and202B of the hub202′. For example, the portion202A and202B may be coupled using threaded fasteners or rivets. As another example, the portions202A and202B may be welded together. The portions204B1and204B2of the compliant structure204B may be formed using material that elastically deforms to absorb impact forces. The portions202A and202B of the hub202′ and the carrier structures206A′ and206B′ may be formed using a rigid material.

Additionally, the portion204B1includes the connective elements205A′ of the compliant structure204B′, and the portion204B2includes the connective elements205B′ of the compliant structure204B1′. As seen inFIG.2D, the connective elements205A′ spiral outwards in a counterclockwise direction and the connective elements205B′ spiral outwards in a clockwise direction. The connective elements205A′ and205B′ elastically deform (e.g., bend, move, compress, or stretch) to absorb impact forces. For clarity, not all connective elements205A′ and205B′ of the compliant structure204B′ have been labelled inFIG.2D.

FIG.2Eillustrates an example wheel108C in the system100ofFIG.1. As seen inFIG.2E, the wheel108C is similar to the wheel108A ofFIG.2A, except that the wheel108C includes only one carrier structure206″ that holds one set of rollers208. In particular embodiments, the rollers208of the wheel108C allow for lateral movement of the wheel108C.

The wheel108C includes a hub202″ positioned at a center of the wheel108C. The hub202″ includes a central cavity that accommodates an axle. When the axle turns, the hub202″ and the wheel108C turn with the axle.

The wheel108C includes a compliant structure204A″ coupled to the hub202″ and the carrier structure206″. The compliant structure204A″ may be similar to the compliant structure204A of the wheel108A inFIG.2A. The compliant structure204A″ includes connective elements205″ that spiral outwards from the hub202″. The compliant structure204A″ is formed using material that elastically deforms to absorb impact forces experienced by the carrier structure206″. The connective elements205″ of the compliant structure204A″ deform when experiencing an impact force. After the impact force is absorbed, the connective elements205″ return to their original shape. In this manner, other components, such as the hub202″, do not experience the full impact force.

The carrier structure206″ is positioned around the compliant structure204A″. The carrier structure206″ includes a central cavity that accommodates the compliant structure204A″ and the hub202″. The carrier structure206″ rotates with the hub202″ and the wheel108C.

The carrier structure206″ holds rollers208that span the width of the wheel108C. The rollers208rotate about an axis that is orthogonal to the axis of rotation of the wheel108C, thereby allowing for omni-directional movement of the robot102. As the rollers208rotate, they allow for the wheel108C to move laterally. In this manner, the wheel108C may move laterally without skidding over terrain. As a result, the rollers208improve the lifespan of the wheel108C.

FIG.2Fillustrates an example wheel108D in the system100ofFIG.1. As seen inFIG.2F, the wheel108D is similar to the wheel108C, except the wheel108D includes a compliant structure204B′″ that includes two sets of connective elements205A′″ and205B′″. The two sets of connective elements205A′″ and205B′″ spiral outwards from the hub202′″ in opposing directions. For example, the set of connective elements205A′″ in the foreground ofFIG.2Fspiral outwards from the hub202′″ in a counterclockwise direction. The set of connective elements205B′″ in the background ofFIG.2Fspiral outwards from the hub202′″ in a clockwise direction. In this manner, the two sets of connective elements205A′″ and205B′″ balance the absorption of impact forces experienced by the wheel108D. The connective elements205A and205B elastically deform (e.g., bend, move, compress, or stretch) to absorb impact forces. After an impact force is absorbed, the connective elements205A′″ and205B′″ return to their original shape. For clarity, not all of the connective elements205A′″ and205B′″ of the compliant structure204B′″ are labelled inFIG.2F.

Like the wheel108C, the wheel108D includes a hub202′″ positioned at a center of the wheel108D. The hub202′″ includes a central cavity that accommodates an axle. When the axle turns the hub202′″ and the wheel108D turn with the axle.

The compliant structure204B′″ is positioned around the hub202′″. As discussed previously, the compliant structure204B′″ includes two sets of connective elements205A′″ and205B′″ that spiral outwards from the hub202′″ in opposing directions. The connective elements205A′″ and205B′″ of the compliant structure204B′″ are formed using a material that elastically deforms to absorb impact forces. When the connective elements205A′″ and205B′″ of the compliant structure204B′″ experience an impact force, the connective elements205A′″ and205B′″ deform to absorb the impact force. After the impact force is absorbed, the connective elements205A′″ and205B′″ return to their original shape. In this manner, the compliant structure204B′″ absorbs impact forces and other components, such as the hub202′″, experience reduced impact forces, which increases the lifespan of these components, in particular embodiments.

The carrier structure206′″ is positioned around the compliant structure204B′″. The carrier structure206′″ rotates with the hub202′″ and the wheel108D. The carrier structure206′″ holds a set of rollers208. The rollers208are positioned around the carrier structure206′″. The rollers208are spaced around the carrier structure206′″. As discussed previously, the rollers208allow for the wheel108D to move laterally.

FIG.2Gillustrates an example wheel108E in the system100ofFIG.1. As seen inFIG.2G, the wheel108E includes a hub202″″, a compliant structure204A″″ positioned around the hub202″″, and a carrier structure212positioned around the compliant structure204A″″. A difference between the wheel108E and the wheel108A ofFIG.2Ais that the carrier structure212in the wheel108E does not hold rollers208. Rather, the carrier structure212resembles a tire that rotates with the hub202. In certain embodiments, the carrier structure212includes tread that improves the traction or grip of the carrier structure212. The robot102may use the wheel108E as the front wheels.

The compliant structure204A″″ includes connective elements205″″ that spiral outwards from the hub202″″ towards in the carrier structure212in a counterclockwise direction. For clarity, not all of the connective elements205″″ in the compliant structure204A″″ have been labelled inFIG.2G. When the wheel108E experiences an impact force, the connective elements205elastically deform (e.g., bend, move, compress, or stretch) to absorb the impact force. After the impact force is absorbed, the connective elements205″″ return to their original shapes. In certain embodiments, the carrier structure212in the wheel108E may be more flexible than the carrier structures206that hold rollers208. As a result, the carrier structure212may deform more than the carrier structures that hold rollers208.

FIG.2Hillustrates an exploded view of the wheel108E inFIG.2G. As seen inFIG.2H, the carrier structure212may include a central cavity that is shaped and sized to fit the compliant structure204A″″ and the hub202″″. Importantly, an outer rim of the cavity includes grooves or teeth214that are shaped and sized to fit around the contours of the compliant structure204A″″. In certain embodiments, the carrier structure212is over-molded onto the compliant structure204A″″. In some embodiments, the carrier structures206A,206B, and206discussed previously are over-molded onto respective compliant structures204″″ in a similar manner.

FIGS.3A through3Fillustrate various designs for the compliant structure204in the wheels108. Although several designs are shown, this disclosure contemplates any number of designs for the compliant structure204. Generally, each design includes connective elements that extend from the hub202to the carrier structure206. Each of the connective elements are formed using a material that elastically deforms to absorb an impact force. Stated differently, the connective elements change shape when experiencing an impact force. The change in shape absorbs the impact force. After the impact force has been absorbed, the connective elements return to their original shape. In this manner, the connective elements absorb impact forces so that other components, such as the hub202, do not experience the impact forces.

FIG.3Aillustrates an example compliant structure300A in the wheels ofFIGS.2A through2F. As see inFIG.3A, the compliant structure300A includes connective elements306that spiral out from the hub202to the carrier structure206. The design of the compliant structure300A is similar to the designs seen inFIGS.2A through2F. For clarity, not all of the connective elements306of the compliant structure300A have been labeled inFIG.3A.

As seen inFIG.3A, the connective elements306couple to the hub202and the carrier structure206. The connective elements306spiral out from the hub to the carrier structure206in a counterclockwise direction. Alternatively, as discussed previously, the connective elements306spiral outwards from the hub202to the carrier structure206in a clockwise direction. In the design of compliant structure300A, the connective elements306have a consistent thickness along a majority of the length of the connective elements306. As seen inFIG.3A, the connective elements306share this consistent thickness along a majority of their lengths. The thickness of the connective elements306increases slightly near the coupling with the hub202or the carrier structure206. The connective elements306may bend, compress, or stretch along the portion of their lengths that have the consistent thickness to absorb an impact force. After the impact force is absorbed, the connective elements306return to their original shape.

FIG.3Billustrates an example compliant structure300B in the wheels108ofFIGS.2A through2F. As seen inFIG.3B, the compliant structure300B include connective elements306′ that are coupled to the hub202and the carrier structure206. For clarity, not all of the connective elements306′ in the compliant structure300B have been labeled inFIG.3B. The connective elements306′ spiral outwards from the hub202to the carrier structure206in a counterclockwise direction. Alternatively, as discussed previously, the connective elements306′ spiral outwards from the hub202to the carrier structure206in a clockwise direction.

The connective elements306′ have a thickness that tapers from the carrier structure206to the hub202. As seen inFIG.3B, the connective elements306′ are thicker near the carrier structure206than near the hub202. As a result, the thicknesses of the connective elements306′ changes along the length of the connective elements306′, which improves the strength of the connective elements306′ in certain embodiments. The connective elements306′ bend, compress, or stretch to absorb impact forces. After the impact forces are absorbed, the connective elements306′ return to their original shape. In this manner, the connective elements306absorb impact forces so that other components, such as the hub202, do not experience those impact forces.

FIG.3Cillustrates an example of compliant structure300C in the wheels108ofFIGS.2A through2F. As seen inFIG.3C, the compliant structure300C includes connective elements306″ that couple to the hub202and the carrier structure206. For clarity, not all of the connective elements306″ in the compliant structure300C have been labeled inFIG.3C. Generally, the connective elements306″ include multiple angled portions between the hub202and the carrier structure206.

As seen inFIG.3C, the connective elements306″ include three portions,308A,308B, and308C between the hub202and the carrier structure206. The portion308A connects to the hub202and extends in a first direction towards the carrier structure206. The portion308B connects to the portion308A. The portion308B extends in a second direction from the portion308A towards the carrier structure206. The portion308B extends in a direction that is different from the direction in which the portion308A extends. The portion308C connects to the portion308B and the carrier structure206. The portion308C extends in a third direction from the portion308B to the carrier structure206. As seen inFIG.3C, the portion308C extends in a direction that is different from the directions in which the portions308A and308B extend. In this manner, the connective elements306″ include bends that are formed by the portions308A,308B, and308C. For example, a first bend is formed using the portions308A and308B, and a second bend is formed using the portions308B and308C. Generally, the connective elements306″ may bend, stretch, or compress at these bends to absorb impact forces. After the impact forces are absorbed, these bends return to their original shapes. In this manner, the connective elements306″ absorb impact forces so that other components, such as the hub202, do not experience those impact forces. The connective elements306″ may include any number of portions308and any number of bends. In certain embodiments, because the connective elements306″ are made with portions308A,308B, and308C, the weight of the compliant structure300C is reduced. Additionally, it is more difficult for debris to become stuck between the connective elements306″.

FIG.3Dillustrates an example compliant structure300D in the wheels108ofFIGS.2A through2F. As seen inFIG.3D, the compliant structure300D includes connective elements306′″ coupled to the hub202and the carrier structure206. For clarity, not all of the connective elements306′″ have been labeled inFIG.3D.

Like the compliant structure300C inFIG.3C, the connective elements306′″ in the compliant structure300D include multiple portions308between the hub202and the carrier structure206. In the example ofFIG.3Dthe connective elements306′″ include three portions,308A,308B, and308C. The portion308A connects to the hub202and extends in a first direction from the hub202towards the carrier structure206. The portion308B connects to the portion308A and extends in a second direction from the portion308A towards the carrier structure206. The direction in which the portion308B extends is different from the direction in which the portion308A extends. The portion308C connects to the portion308B and the carrier structure206. The portion308C extends from the portion308B towards the carrier structure206in a third direction. The direction in which the portion38C extends is different from the directions in which the portions308A and308B extend.

As seen inFIG.3D, the portions308A,308B, and308C form bends in the connective elements306′″. For example, a first bend is formed using portions308A and308B, and a second bend is formed using portions308B and308C. Generally, the connective elements306′″ bend, compress, or stretch at these bends to absorb impact forces. After the impact forces are absorbed, the connective elements306′″ return to their original shapes. This disclosure contemplates the connective elements306′″ including any number of portions308and any number of bends.

The compliant structure300D differs from the compliant structure300C in that the connective elements306′″ in the compliant structure300D overlap another connective element306′″ in the compliant structure300D. As seen inFIG.3D, each connective element306′″ includes a portion308B that overlaps with another portion308B of another connective element306′″ between the hub202and the carrier structure206. The connective elements306′″ may or may not couple to each other at these points of overlap. In certain embodiments, because the connective elements306′″ are made with portions308A,308B, and308C, the weight of the compliant structure300D is reduced. Additionally, it is more difficult for debris to become stuck between the connective elements306′″. Furthermore, the symmetry of the compliant structure300D improves the torsional load experienced by the compliant structure300D in some embodiments.

FIG.3Eillustrates an example compliant structure300E in the wheels108ofFIGS.2A through2F. As seen inFIG.3E, the compliant structure300E includes connective elements306″″ that couple to the hub202and the carrier structure206. For clarity, not all of the connective elements306″″ have been labeled inFIG.3E.

The connective elements306″″ in the compliant structure300E are linear and coupled to the hub202such that the connective elements306″″ are tangential to the hub202. The connective elements306″″ extend from the hub202to the carrier structure206. As seen inFIG.3E, each of the connective elements306″″ extend in a different direction from the hub202. Generally, the connective elements306″″ bend, compress, or stretch along the lengths of the connective elements306″″ to absorb impact forces. After the impact forces are absorbed, the connective elements306″″ return to their original linear shape. In certain embodiments, because the connective elements306″″ are tangential to the hub202, there is more space between the connective elements306″″ and the weight of the compliant structure300E is reduced. Additionally, it is more difficult for debris to become stuck between the connective elements306″″.

FIG.3Fillustrates an example compliant structure300F in the wheels108ofFIGS.2A through2F. As seen inFIG.3F, the compliant structure300F includes connective elements306′″″ that couple to the hub202and the carrier structure206. For clarity, not all of the connective elements306′″″ have been labeled inFIG.3F.

As seen inFIG.3F, the connective elements306′″″ spiral outwards from the hub202towards the carrier structure206in a counterclockwise direction. Alternatively, the connective element306′″″ spiral outwards from the hub202towards the carrier structure206in a clockwise direction. The connective elements306′″″ have a consistent thickness along the majority of the length of the connective elements306′″″. The thickness of the connective elements306′″″ increases around the coupling to the hub202or the carrier structure206. The compliant structure300F differs from the compliant structure300A in that the compliant structure300F has a denser arrangement of connective elements306′″″. In other words, the compliant structure300F has more connective elements306′″″ than the compliant structure300A. The connective elements306′″″ may bend, stretch, or compress along the length of the connective elements306′″″ to absorb impact forces. After the impact forces are absorbed, the connective elements306′″″ return to their original shapes. In this manner, the connective elements306′″ absorb impact forces so that other components, such as the hub202, do not experience these impact forces. In certain embodiments, because of the increased density of the connective elements306′″″, the strength and stiffness of the compliant structure300F is improved.

FIG.4Aillustrates an example carrier structure2061in the wheels108ofFIGS.2A through2D. As seen inFIG.4A, the carrier structure2061includes a central cavity that is configured to hold a compliant structure204and a hub202. The carrier structure2061holds rollers208that are arranged around an outer edge of the carrier structure2061. As discussed previously, these rollers208rotate about an axis orthogonal to an axis of rotation of the wheel108, thereby allowing for omni-directional movement of the robot102. In this manner, the rollers208allow the wheel108to move laterally on the rollers208.

As seen previously, the carrier structure2061inFIG.4Ais positioned adjacent a similar carrier structure2061around a compliant structure204. The rollers208on these carrier structures2061may be spaced such that the rollers208are arranged alternately. For example, the space between two rollers208in a carrier structure2061may be positioned adjacent to a roller208in the other carrier structure2061. In this manner, every point along a circumference of a compliant structure204may be supported by a roller208of one of the two carrier structures2061.

FIG.4Billustrates an example carrier structure2063in the wheels108ofFIGS.2E and2F. As seen inFIG.4B, the carrier structure2063is circular and includes a central cavity that is sized and shaped and sized to hold a compliant structure204and a hub202. The carrier structure2063holds rollers208that are arranged around an outer edge of the carrier structure2063. The rollers208rotate about an axis orthogonal to the axis of rotation of the wheel108, thereby allowing for omni-directional movement of the robot102. In this manner, the rollers108allow the wheel108to move laterally on the rollers208.

The carrier structure2063in the example ofFIG.4Bmay not be paired with another carrier structure2063. As a result, the rollers208in the carrier structure2063ofFIG.4Bare arranged closer to each other than the rollers208in the carrier structure2061ofFIG.4A. Additionally, the rollers208in the example ofFIG.4Bare wider than the rollers208in the example ofFIG.4A.

FIGS.5A,5B,5C, and5Dillustrate rollers208in the carrier structure206ofFIG.4A. As seen inFIG.5A, a rod502extends through a central cavity of a roller208. The roller208rotates about the rod502. The rod502is positioned within the carrier structure206so that the roller208rotates in the carrier structure206. As seen inFIG.5B, the rod502is secured within the carrier structure206by coupling two halves of the carrier structure206together. In this manner, the rod502is sandwiched between these two portions of the carrier structure206, thus holding the rod502in place while allowing the roller208to rotate on the rod502.

FIGS.5C and5Dillustrate the roller208without the rod502. As seen inFIGS.5C and5D, the roller208includes a central cavity504through which the rod502extends. The central cavity504also allows the roller208to rotate on the rod502. In some embodiments, the cavity504includes bearings that help the rod502rotate within the cavity504. The roller208may be made using any process. For example, the roller208may be made using a molding process. As another example, the roller208may be made using a three-dimensional printing process.

FIGS.5E and5Fillustrate an example roller208in the carrier structure206ofFIG.4B. As seen inFIGS.5E and5F, the roller208is wider than the roller208in the examples ofFIGS.5A through5D. The roller208includes a central cavity504through which the rod502extends. The roller208rotates on the rod502. In some embodiments, the cavity504includes bearings that help the rod502rotate within the cavity504. The roller208may be made using any process. For example, the roller208may be made using a molding process. As another example, the roller208may be made using a three-dimensional printing process.

FIGS.5G,5H, and5Iillustrate example rollers208in the carrier structures206ofFIGS.4A and4B. Generally,FIGS.5G,5H, and5Iillustrate rollers208with tread506. The tread506includes any suitable tread pattern. In the examples ofFIGS.5G and5H, the tread pattern includes ridges that run around a circumference of the rollers208. Multiple ridges are arranged along the length of the roller208. In this manner, the tread506is symmetric about the axis of rotation of the roller208. In the example ofFIG.51, the tread506includes bumps formed on the surface of the roller208. In this manner, the tread506may be symmetric about an axis orthogonal to the axis of rotation of the roller208. In each of these examples the tread506improves the grip or traction provided by the rollers208. The tread506may make it more difficult for the rollers208to skid or slide on terrain.

FIGS.6A and6Billustrate example compliant structures602and608in the wheels108ofFIGS.2A through2F. Generally,FIGS.6A and6Billustrate how compliant structures602and608deform to absorb an impact force through elastic deformation. For example, connective elements in the compliant structures602and608may elastically buckle or bend to absorb impact forces.

As seen inFIGS.6A, the compliant structure602includes connective elements604that spiral outwards from a hub202in a clockwise direction. The compliant structure602is experiencing an upwards impact force from the bottom of the compliant structure602. The connective element604elastically deforms to absorb this impact force. For example, the compliant element604deforms to form a bend606along the length of the connective element604. The impact force may act on the connective element604to cause the connective element604to form the bend606. By forming the bend606, the connective element604absorbs the impact force. After the impact force is absorbed, the connective element604returns to its original shape, which still includes a bend that is smaller in magnitude than the bend606. The wheel108in the example ofFIG.6Amay include a carrier structure (e.g., the carrier structure212shown inFIGS.2G and2H), which is more flexible than carrier structures206that hold rollers208. As a result, the carrier structure may deform more when experiencing an impact force.

FIG.6Billustrates a compliant structure608that includes connective elements610that spiral outwards from a hub202in a counterclockwise direction. The connective elements610may experience an upwards impact force from the bottom of the compliant structure608. As seen inFIG.6B, the connective elements610deform to form bends612along the length of the connective elements610to absorb the impact force. The impact force may act on these connective elements610to form the bends612. After the connective elements610absorb the impact force, the connective elements610return to their original shapes, which still include bends that are smaller in magnitude than the bends612.

FIGS.6C and6Dillustrate an example compliant structure614in the wheels108ofFIGS.2A through2D. The wheel108includes a compliant structure614and a carrier structure206that holds rollers208.FIG.6Cshows the wheel108under no load, andFIG.6Dshows the wheel108under a load (e.g., a 2000 Newton load). As seen in these figures, the connective elements616in the compliant structure614elastically deform under load to absorb some of the force experience by the wheel108. Specifically, in this example, the connective elements616form bends618to absorb the load. In certain embodiments, because the compliant structure614absorbs some of the load experienced by the wheel108, the roller208does not deform (e.g., compress) so as to prevent the roller208from rotating in the carrier structure206. Although some deformation of the roller208or the carrier structure206may occur, the deformation is minimal and does not prevent the carrier structure206and the roller208from operating as desired. In an example, under load (e.g., a 2000 Newton load), the roller208deflects by three millimeters, which represents a 15% deflection. A rod within the roller208deflects by two millimeters, which represents a 10% deflection. The connective elements616deflect by fifteen millimeters, which represents a 75% deflection.

FIG.7is a flowchart of an example method700in the system100ofFIG.1. The robot102may perform the method700. In particular embodiments, the robot102absorbs impact forces using a compliant structure of a wheel108to protect other components of the robot102. Additionally, the robot102absorbs these impact forces without a separate suspension system.

In block702, the robot102rotates wheels108to move. The wheels108may be arranged on two sides of the robot102. Rotating the wheels108causes the robot102to move forwards or backwards. By rotating the wheels108on one side of the robot102at a different speed than the wheels108on the other side of the robot102, the robot102turns to the left or to the right. The wheels108include one or more rollers208that allow the wheels108to move laterally without skidding and damaging the wheels108when the robot102turns. The robot102uses a sensor system106to capture images or video of the environment around the robot102. The robot102analyzes the images or video to determine how to navigate the robot (e.g., around obstacles or towards a destination). The robot102then rotates the wheels108accordingly to navigate the robot102.

In block704, the robot102experiences an impact force. For example, the robot102may move over rough terrain that causes the impact force. As another example, the robot may fall (e.g., off a curb), causing the impact force. The impact force may cause vibrations in the robot102. These vibrations may damage components of the robot102or a package being carried by the robot102. For example, the vibrations may damage or disrupt a sensor system106of the robot102. As another example, the vibrations may damage internal circuitry of the robot102.

In block706, the robot102absorbs the impact force by elastically deforming a compliant structure204in the wheel108. The compliant structure204includes several connective elements306that are formed using a material that elastically deforms when experiencing an impact force. For example, the connective elements may bend, move, compress, or stretch when experiencing an impact force. These deformations in the connective elements absorb the impact force. After the impact force is absorbed, the connective elements return to their original shapes in block708. In this manner, the connective elements protect other components of the robot102from being damaged by the impact force. As a result the robot102absorbs impact forces without using a separate suspension system, which reduces the weight of the robot102in particular embodiments.

The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

In the preceding, reference is made to embodiments presented in this disclosure. However, the scope of the present disclosure is not limited to specific described embodiments. Instead, any combination of the features and elements described herein, whether related to different embodiments or not, is contemplated to implement and practice contemplated embodiments. Furthermore, although embodiments disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the scope of the present disclosure. Thus, the aspects, features, embodiments and advantages described herein are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

Aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.”

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.