Energy absorbing means for an autonomous ground vehicle

Energy absorbing means on an autonomous ground robot, which is intended for delivering packages in an uncontrolled and unprotected environment, include elastically deformable padding, crushable material, and spring-loaded or like mechanical devices.

BACKGROUND

The present invention relates to autonomous vehicles, and more particularly to features on an autonomous vehicles for reducing kinetic energy transferred to a person in the event of a contact.

Safety when robots encounter people is, of course, paramount. Accordingly, safety standards, such as ISO TC 184/SC, Robots and Robotic Devices—Collaborative Robots, and ANSI RIA R15.06, Robot and Robot System Safety, have been developed. A collaborative robot is designed for direct interaction with a defined collaborative workspace. A collaborative workspace is the safeguarded space where the robot system and a person (that is, a human being) can perform tasks simultaneously during production operation. The objective of collaborative robots is to combine the repetitive performance of robots with the individual skills and ability of people.

In general, safety procedures for some industrial robots (such as fixed, six access robots in an order fulfillment center) traditionally exclude personnel access to the operations area while the robot it active. Collaborative robots, at least sometimes share the same workspace with a person, and some collaborative robots may function in uncontrolled environments where events are sometimes unpredictable.

Types of collaborative robot operation, while the robot is in automatic operation, include safety-rated monitored stop, hand-guiding operation, speed and separation monitoring, and power and force limiting. In safety-rated monitored stop mode, a person may interact with the robot when it is stopped. Automatic operation resumes when the person is at a safe distance, such as when the person leaves the collaborative workspace. In hand-guiding operation, a person is in direct contact with the robot using hand controls. In speed and separation monitoring, the speed of the robot is reduced the closer an operator is a defined hazard area, and an (emergency) protective stop command is issued when a person is in potential contact. Power and force limiting is based on the principle that reducing the appropriate operating parameters (such as speed, torque, force, and the like) will minimize the harm upon incidental contact between the robot and the person. The latter operation for collaborative operation usually requires a risk assessment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

An autonomous ground vehicle (AGV) is a category of robot that might operate at times in an unprotected, uncontrolled environment. Because the AGV in some embodiments is intended to deliver packages to a residence and/or an intended recipient, the AGV disclosed herein can encounter an operator, and also possibly an untrained person who might not be intending to interact with the robot, in an unprotected, uncontrolled environment. In general, an AGV of the type disclosed herein is a ground vehicle (typically unmanned) that operates, at least in some circumstances, without the need for a human controller, and at least at some times may operate in unprotected and uncontrolled environment. The AGV may use sensors to develop an understanding of the environment (sometimes only a limited understanding), which is then used by control algorithms to determine the next action to take in the context of a human-provided mission goal.

An AGV, both in general and in the context of a delivery AGV disclosed herein, in an uncontrolled, unprotected environment may have the ability to:access information about the environment (such as maps of streets, sidewalks, and buildings, and in some cases building interiors);detect people, obstacles (such as curbs, steps, bumps, slopes, and the like), objects (such as landscaping, gates, and the like), and surfaces (such as lawns, cobblestones, sidewalk cracks and discontinuities, and the like), and then evaluate and take action based on the detection; andtravel under its own power to waypoints, usually by battery power and without human navigation assistance, taking into account the above information and detection.

In some circumstances, an AGV's onboard control system may be able to autonomously learn, such as adjusting strategies based on input about the surroundings, adapt to surroundings without outside assistance, and the like.

A particular subset of autonomous ground vehicles is an AGV that navigates to a desired residential or commercial location to carry an object, such as a package containing a commercial product. For example, United States Patent Application Number 20180024554, titled “Autonomous Ground Vehicles Based At Delivery Locations,” which is assigned to the assignee of the present invention, discloses AGVs that retrieve items from transportation vehicles (e.g., delivery trucks) for delivery to specified locations (e.g., user residences, a commercial business, etc.). In various implementations, the AGVs may be owned by individual users and/or may service a group of users in a given area (e.g., in an apartment building, neighborhood, etc.). The AGVs may travel out (e.g., from a user's residence, apartment building, etc.) to meet a transportation vehicle (e.g., a delivery truck on the street) to receive items, and may be joined by other AGVs that have traveled out to meet the transportation vehicle, and may line up in a particular order (e.g., according to delivery addresses, etc.). After the items are received, the AGVs may travel back (e.g., to the user residences) to deliver the items, and may be equipped to open and close access barriers (e.g., front doors, garage doors, etc.). The AGV may also be equipped with a locked lid that can be opened only by an intended recipient.

The present invention uses the phrase “delivery AGV” or “AGV for package delivery” or other combinations of the terms “AGV” and “delivery” to refer to AGVs having the structure, capabilities and function to navigate to a desired location, such as by navigating public or private sidewalks or neighborhoods, to transport a package to a desired customer or residential or commercial location. Accordingly, a delivery AGW includes an internal chamber for holding a package payload and is limited in speed, such as to 6 mph, 10 mph, or 15 mph, as determined by the particular design guidelines and possibly by state regulation. In this regard, these speed are referred to herein as low speed.

As illustrated in the figures, the delivery AGV10disclosed herein includes a body20, a chassis30, a power supply system40, and a control system50. Body20includes a body has a periphery formed by sidewalls22, including lateral walls23sand end walls23e, that enclose the sides an internal chamber24. Chamber24is suitable for holding an object, such as a conventionally boxed object in intended for delivery to an intended recipient.

In the embodiment of the figures, body20includes a lid26that is hinged to one of the walls22. Lid26preferably is locked in a manner that enables unlocking by the intended recipient, as explained more fully below. Lid26encloses chamber24from above.

A chassis30can include any type of suspension for enabling supporting body20on wheels34. For example, linkages, springs, shock absorbers, and the like may be employed to isolated chamber24from shocks from driving over the ground. A steering mechanism may be employed to move at least a pair of the wheels in the desired direction to facilitate steering. The present invention is not intended to be limited to any type of chassis, steering, suspension, and the like. Six wheels34are shown in the figures, each having a rubberized other otherwise soft tire, and any number and type of wheels are tires are contemplated.

Power system50can include a power supply, such as conventional rechargeable batteries, and an electric motor to provide power to the wheels34. For example, some wheels34may be on fixed axles while a pair of drive wheels—one on each side of AGV10, may each be connected to a motor (not shown in the figures). The control system may power both the left and right motors at equal speed to propel AGV10in a straight line, or may power one motor at a higher speed to turn AGV as needed, or may power the drive wheels in opposing directions to rotate AGV10without translation (that is, rotate in place). The control algorithms for controlling the straight-ahead movement, turning, and rotating AGV10are well known, as will be understood and employed by persons familiar with battery powered vehicles.

Control system50includes sensors60and other components and systems used for navigation and guidance, avoiding objects, image-capture and sensing, power management, communications, security, and other functions inherent in achieving the goals of a delivery AGV. Sensors60can be mounted behind a forward facing panel28F and/or a rearward facing panel28R (not shown). Sensors60can include cameras having images sensors including image signal processing, light sensors, and the like, with corresponding processing including image decoding, lens correction, geometrical transformation, video stream transcoding, video analytics, image capture, and compression to provide obstacle detection and obstacle identification. Sensors for determining speed may also be employed. Panel28F (and28R) can be transparent polymer, such as (for example) acrylic, Plexiglas, or polycarbonate.

Sensors60can include RADAR sensors, such as SRR (Short-range radar) applications and MRR/LRR (mid-range radar, long-range radar) applications; LiDAR sensors, such as infrared LIDAR systems that with the aid of a Micro-Electro-Mechanical System (MEMS), which use a rotating laser, or a solid-state LIDAR. Control system50can also include GPS modules, inertial guidance modules such as an inertial measurement unit (IMU) having gyroscopes and accelerometers (preferably in each of the x, y, and x directions), power management modules to control power, overall consumption, and thermal dissipation. Other modules, components and functions are contemplated.

Control system50and sensors60may also be employed in controlling the driving and turning of AGV10during normal conditions. For example, a speed sensor on the wheels, sensors on motor current and/or voltage, gps, accelerometer, gyroscope, optical sensors, and the like may be employed to determine a safe straight-ahead speed, safe turning radius and velocity for the vehicle and package (taking into account the possibility of encountering a person who might not see or be expecting the vehicle), safe stopping distance to provide feedback to the controller for determining the speed, and the like.

Control system50may also include a package delivery module and corresponding sensors. For example, a sensor can be associated with a closed position of lid26to assure that a package to be delivered to a residential or commercial destination is secure in chamber24during transport. A means for unlocking a lock on lid26(or unlocking a actuator for lid26or like means) can include a keypad, a wireless communication system (for working with wifi, cellular data, bluetooth, or other communication means to send a signal to the lock upon verification), a facial or fingerprint recognition module, or the like may also be included.

Control system50controls the movement of AGV10to a desired destination, the delivery of a package within chamber24to an authorized recipient, and/or movement of AGV10to a home location. In this regard, the description of control system50and sensors60, and United States Patent Application Number 20180024554 and/or industry practice in view of the present disclosure may inform the functions in this regard.

It is, of course, the goal of control system50to avoid unintentional contact, especially for people, pets, and the like. Contact is referred to herein as transient contact to distinguish it from intentional, low-force contact (such as opening the lid to access a package) and contact over a significant period, such as leaning against or placing a foot on the robot, of the type that is not a risk, or is a low risk, of injuring a person. In the event of transient contact, the energy absorbing means disclosed herein are intended to diminish the magnitude of energy transmitted to a person by an AGV, compared with an unmodified solid or rigid surface of prior art AGVs currently commercialized.

As illustrated inFIG. 1, the energy absorbing means can be an elastic padding180coupled to at least a leading portion of the body. In the illustration ofFIG. 1, padding180extends over the entire leading surface of AGV10, including above and below front sensor window28F, and on the left and right side (as oriented facing the direction of forward movement of AGV10) of sensor window28F. Further, elastic padding180extends on left and right shoulders23L and23R of body20, and extends the fully vertical length of body20such that no unpadded surface on the front projection of AGV10(except as convenient for uncovering the sensors) is exposed. In this regard, the entire forward facing surface consists of panels that are covered by padding180and the sensor window28F. Padding180may also be installed on the rear and sides of AGV10. The sensor window28F is not covered, and recessed relative to a front face of padding180, which recessing diminishes the risk of transient contact directly to sensor window28F

Elastic padding180can be any type for absorbing energy by deflection and then returning to its original shape or near its original shape. For merely illustrative examples, padding180can be one to four inches of eva foam, cross-linked polyethylene foam, pvc nitrile, other foams (such as porous foams), or the like. In general, gels are effective as padding but in some circumstances are relatively heavy; gel performance can also be affected by temperature, and possesses a limited range of compression due to a lack of porosity. Foams often are lighter and more compressible than gels. Thus, a choice between a gel and a foam or other material may be made according to the particular application conditions according to the known parameters of the materials. The term “padding” is used herein to refer to a material that is capable of absorbing mechanical force and/or kinetic energy. The thickness of foam180may be chosen according to the particular characteristics of the foam chosen, the mass and expected speed of the AGV and its payload packages, and the like, understanding that increasing the outside dimensions of the AGV, while possibly increases the chance of transient contact by providing a bigger object. Thus, a tradeoff in padding thickness may be required, with the goal of safety of persons and/or pets remaining most important.

Data from optical sensors, accelerometers, gyroscopes, motor power draw, and the like may be employed to sense transient contact or less than transient contact. Optionally, proximity sensors and/or contact sensors (not shown in the figures), may be employed to sense when transient contact occurs, even through padding180. A control signal may be sent through a communications module that is part of control system50to signal that transient contact has occurred. Preferably, the control system50disables AGV10upon transient contact until the transient contact can be investigated. Alternatively, or used with padding180in one or more layers, a padding280can be a crushable or plastically deformable material that is suitable for absorbing energy upon impact with a person. For example, padding280can be a crushable material, for example a metal matrix, a polymer matrix, an expanded polystyrene foam (EPS), expanded polypropylene foam (EPP), and/or other plastically deformable foam, or a like material. Examples of a matrix is a honeycomb that is configured to deform and/or fracture in response to an impact while absorbing energy. An example of an aluminum matrix material is Plascore CrushLite™.

Thus, plastically deformable material280can be crushed (deformed) upon transient contact, and during the crushing process absorb kinetic energy for the purpose of reducing force or impact to the person, pet, or the like that is party to the transient contact. The controller50may function as described above with respect to transient impact involving padding180and/or280.

Referring toFIG. 2, an AGV10′ includes a body20′, a chassis30′, a power supply system40′, and a control system50′, which can have the same structure and function as described for first embodiment body20, chassis30, power supply system40, and control system50. AGV10′ includes a strip of elastically deformable padding190′ for absorbing energy upon transient contact with a person.

Strip190′ preferably is at the forward-most portion of body20′ to increase the likelihood of being effective at absorbing kinetic energy upon transient contact with a person, as it is most likely that the forward-most portion of body20′ will be the region of transient contact.

Padding190′ can be of the same material as padding180described for first embodiment AGV10. Alternatively, AGV10′ can include a crushable material290′, as described above for crushable material280. Padding strip190′ and/or290′ may (for merely one example) be employed on AGV configurations and/or environments where it is expected that only the forward-most portion of the AGV (such as the forward-most face of the padding190′/290′) would be the point of transient contact. As padding180/280and190′/290′ may also be provided on the sides are rear of the AGV, in some cases strips190′/290′ can be appropriate for sides and/or rear of an AGV while padding180/280is employed in other portions of the AGV.

Referring toFIGS. 3 and 4, an AGV210is illustrated schematically. AGV210includes a body220, a chassis230, a power supply system240, and a control system250. Body220includes an upper body portion222U and a lower body portion222L. In the operational position, shown inFIG. 3, upper body portion222U is centered on lower body portion222L. Centering of the upper body over the lower body has benefits for stability; it is not required for the operation of the energy absorbing means. Preferably, upper body portion222U overhangs lower body portion222L by an overhang dimension D to promote transient contact with upper body portion222U while diminishing the risk of transient contact with lower body portion222L and the chassis, especially wheels34.

A chamber224may be formed in upper body portion222U or in both the upper and lower portions222U and222L. Power supply system240may be as described above for first embodiment control system40. Because of overhang D, it is less likely that transient contact occurs with lower body portion222U. Thus, where padding180/280and/or190′/290′ is combined with the split configuration of body portions222u/222L, the padding preferably is on upper body portion222U. Other configurations, such as padding also on portions of lower body portion222L, other protections against risk of contact with wheels34, etc., are contemplated.

Control system250may be as described above, plus a sensor that monitors the operational position of upper body portion222U relative to lower body portion222L and provides a signal upon displacement of upper body portion222U relative to lower body portion222L. In embodiments having overhang, D, when AGV210is moving forward, the forward-most portion the AGV210is the forward-most portion of upper body portion222U.

As illustrated schematically in the figures, the entire front face of AGV210is flat, which is not required. Consistent with the schematic, the upper body portion222U (and preferably effectively all of upper body portion222u) projects over lower body portion222L and wheels234. Thus, the most likely place on AGV210for transient contact to occur is on the front face of body222U. If AGV210is moving backwards, or inadvertent transient contact with a person occurs from the rear either while AGV210is stationary or moving forward, the mostly likely place for transient contact to occur is on the rear face of upper body portion222U. Padding, as described above, may be chosen for AGV210accordingly, consistent with the parameters and principles described herein.

FIGS. 5 and 6schematically shown AGV210from a side view. As illustrated in the figures, each side face of AGV210is flat, and thus the entire side face of upper body portion222U projects laterally over lower body portion222L and laterally outwardly over and beyond wheels234. Thus, the most likely place on AGV210for transient contact to occur from the side is on the side face of body222U. Padding, as described above, may be chosen accordingly, consistent with the parameters and principles described herein.

An AGV, such as AGV10may also have its front wall, end wall, and/or sidewall formed entirely of padding, such as any type and material described above. For merely one example, a sidewall formed of a crushable, aluminum or plastic matrix, such as a honeycomb or like material, may be structurally sound for the desired purpose of delivering packages while preventing unauthorized access to the chamber, while providing the energy absorbing characteristics described herein.

FIGS. 7 and 8illustrate an energy absorbing mechanism270that also is a center biasing mechanism that retains upper body portion222U in an operational position relative to lower body portion222L that, in the embodiment shown in the figures, is a centered position. Mechanism270includes a pair of longitudinal springs271and a pair of transverse springs272. Each one of the springs271and272has one end coupled to a bracket273that is affixed to and protrudes from upper body portion222U and another end that is coupled to a bracket274that is affixed to and protrudes from the lower body portion222L. Brackets273and274can take any form, and are shown in the figures as pins or studs. The springs are illustrated as helical springs, and any type of spring, with straightforward and corresponding changes to the mounting brackets, may be employed.

Upper body portion222U is biased into its center position (FIGS. 3 and 5) longitudinally by springs271fand271rand laterally by springs272L and272R. The designations “f” and “r” refer to front and rear ones on springs271and “R” and “L” to right and left ones of springs272. For example, rearward movement of upper body portion222U relative to lower body portion222L elongates the front spring271rand compresses the rear one of springs271r, which causes each spring to provide a force that resists rearward movement (although applying a restoring force by each opposing spring is not required, as the springs can be configured and/or preloaded so that only one spring provides a restoring force in some instances). Similarly, a rightward displacement of upper body portion222U relative to lower body portion222L, right spring272R compresses and left spring272L elongates, created a centering force in each spring272rand272L. The springs may also be include a pre-load, as desired. The springs may have spring constants chosen for the configuration, each of the spring constants may be the same or vary according to the desired application, and number of springs may be increased or decreased, as desired.

For small forces applied to and small displacement of upper body portion222U from lower body portion222L below a predetermined threshold, such as might occur from vibration from normal motorized rolling, minor impact from a pothole or irregularity in pavement, forces inherent in traveling up or down an incline, and the like, springs271and272can retain upper body portion222U in its operational, centered position. Mechanism270can be configured to absorb energy even for small forces that create the minor displacement below the predetermined threshold described herein. Position sensors (of any type, not shown in the figures) may be employed to provide a signal to controller250that upper body portion222U is in its operational position.

For a transient contact or other contact that is more than a predetermined threshold, springs271and272can be chosen (such as by length and spring constant) to permit displacement of the upper body portion222urelative to lower body portion222L, thus promoting energy absorption by mechanism270from the transient impact. Further, a sensor (not shown in the figures) can be provided to produce a control signal to the controller that a transient contact has occurred, which may cause AGV210to be disabled or shut down until an operator can investigate the transient contact, and/or take other appropriate action.

The magnitude of the energy absorption, the displacement of upper body portion222U relative to lower body portion222, and the predetermined force threshold that can be chosen according to known parameters, such as expected speed of AGV210, whether other energy absorption means (such as the padding described above) is employed on the AGV, mass of AGV210and upper body portion222U, maximum and minimum weights of the payload (in the case of delivery robot, the expected weight of the packages), and like parameters that are intended to be optimized to promote safety of people.

The present invention is not limited to energy absorbing means that are or that use springs, as it will be clear to persons familiar with the mechanics of AGVs in view of the present disclosure that the springs can be replaced with a dashpot (such as an air cylinder or hydraulic cylinder) having the desired displacement characteristics. Horizontal and/or vertical cantilevered member (not shown in the figures) that bend under the minor displacement described above may be employed. The cantilevered members can absorb energy while deflecting, deflect enough to permit movement of upper body portion222U relative to lower body portion222L such that the displacement sensor sends a displacement signal to the controller, and (optionally) fracture upon sufficient force.

Moreover, the function of absorbing energy upon displacement of upper body portion222U relative to lower body portion222L can be performed by a wide variety of materials and structures, such as any that which can elastically and/or plastically deforms to absorb energy. In this regard, the materials described above for padding180or190′ (for the exterior of the AGV) may be installed between upper and lower body portions222U and222L. The material may be formed into connectors or spacers between body portions222U and222L that deform to absorb energy upon relative displacement of the body portions.

FIG. 9illustrates a detent320for retaining upper body portion222U at a desired position, which is centered in the figures, relative to lower body portion222L. Detent320may be employed with any energy absorbing means and can affect the properties of the energy absorbing means, as the detent mechanism may perform some or all of the function of retaining the body portions222uand222L in registration during the application of the small forces to the AGV (that is, forces not associated with transient contact with a person), described above.

Detent320, as illustrated in the figures, includes a dimple recess322in upper body portion222U, and a plunger assembly330in lower body portion222L and installed in a cylindrical recess324therein. Plunger assembly330includes a body332, a spring334, and a ball336. Spring334biases ball336upwardly (in the orientation of theFIG. 9) against stops that retain ball336within body332. Accordingly, ball336can be moved downwardly upon sufficient force to overcome the biasing force of spring334.

As illustrated, ball336protrudes into the dimple322of upper body portion222u. According to the normal function of a detent, the detent320requires a minimum force to horizontally displace upper body portion222ufrom lower body portion222L. Detent320can aid in the centering of body portions222U and222L during assembly and/or operation, may aid in indicating when a sufficient magnitude of displacement has occurred, and may require a minimum force for the displacement to overcome the retaining force of the detent.

For example, detent320can be employed with a corresponding sensor for indicating that AGV210is in an operational mode with upper body portion222U aligned with lower body portion222L. The sensor can be calibrated with the alignment, or the position of detent320itself may be incorporated into the control system. And detent320can provide sensory information to an assembler, by providing an audible click or resisting sliding movement between the upper and lower body portions during assembly. During operation, detent320will resist displacement of upper body portion222U relative to lower body portion222L during some of the small forces described above. In this regard, the force required to overcome detent320may be chosen to be below a force that is capable of injuring a person or pet. Thus, detent320may perform the function of retaining the desired position of upper body portion222U relative to lower body portion222L and/or verifying the appropriate position thereof in an operational position.

When combined with the energy absorbing means (180,280,190′,290′, and/or270, or the like) described herein, detent320enables the AGV to receive a minimum threshold force without any displacement of upper body portion222U relative to lower body portion222L, while maintaining safety to people and pets. Then, upon enough force to dislodge ball336from dimple322, the energy absorbing means can perform its function of absorbing force to mitigate risk of injuring a person. Any combination of signals indicating dislodging of ball336from dimple322, minimum threshold of displacement of upper body portion222ufrom lower body portion322L, and/or activation of the energy absorbing means may be used to send an alarm, disable the AGV operation, contact an operator or investigator, or like action.

The present invention has been illustrated by using examples of possible embodiments. The present invention is not limited to the structure, function, and/or materials set out herein. Rather, it is intended that the invention be given its broadest appropriate scope. For merely some examples, examples of elastically deformable padding and plastically deformable padding is for illustration only, as it will be clear to persons familiar with padding materials that many suitable substitutions are well known and can be used herein, according to known parameters for choosing the materials. The mechanical means (springs, dashpots, etc.) that may be employed as the energy absorbing means can be designed in any configuration, and are provided to illustrate the concepts generally disclosed herein.