Method of mitigating instability of a mobile transport

Abstract

Disclosed is a method of mitigating an instability of a mobile transport including detecting whether the mobile transport is pitching forward and, if so, inducing a torque in the mobile transport in an amount to counter the pitching.

Description

METHOD OF MITIGATING INSTABILITY OF A MOBILE TRANSPORTCROSS REFERENCE TO RELATED APPLICATION(S)

[0001] None.RESERVATION OF COPYRIGHTS

[0002] Portions of the disclosure of this document contain material that is subject to copyright protection. The copyright owner does not object to any reproduction of the document or disclosure as it appears in official records, but reserves all remaining rights under copyright.BACKGROUND

[0003] The present disclosure relates to mobile transports, and more specifically to automated safety controls for mobile transports.

[0004] With legacy software, while descending stairs, there exists the possibility for a mobile transport to enter Cluster Safety Lock (CSL) and continue falling down the stairs in an uncontrolled manner, resulting in the chair pitching forwardly onto the user. CSL occurs when the cluster stops rotating and the system determines that a user may not be able to control the transport if the cluster continued rotating. CSL allows the user to regain proper control of the transport. Since it is possible to detect whether such a fall is likely to occur prior to the center of gravity (CG) of the combination of device and user falling too far forward of the contact wheel or picking up too much momentum, it is possible to force the mobile transport to fall backwardly rather than forwardly. This is preferred because the seat back will absorb the impact of the fall rather than the occupant, and the mobile transport can continue safety sliding down stairs on its back.

[0005] Referring to Figs. 1 and 5, the invention pertains to a mobile transport MT and user, abstractly represented in Fig. 1 and graphically represented in Fig. 5, wherein Fig. 1 center of gravity CG corresponds with Fig. 5 center of gravity 181 , and Fig. 1 wheels W1 and W2 respectively correspond with Fig. 5 wheels 21201 and 20202. Proper stair descent by mobile transport MT depends on providing appropriate feedback to maintain the CG above the grounded wheel W1 . This first requires developing an initial torque T 1 relative to mobile transport MT in the forward direction, achieved by shifting the CG forward of (toward the left side of the page as shown) mobile transport MT, in a sufficient amount to induce mobile transport MT to begin descending, as shown in intervals 1 and 2. Just after beginning descent, averting uncontrolled descent necessitates inducing a torque T2 in an opposite direction to torque T1 , achieved by shifting the CG rearward of (toward the right side of the page as shown) mobile transport MT, inan amount sufficient to reduce but not extinguish rotational momentum of mobile transport MT and prevent descending, as shown in interval 3.

[0006] Referring to Fig. 2, the primary cause of a fall of a mobile transport MT while descending stairs is improper control particularly as the cluster angle <j>c, defined by the axle centerline AC of the base of MT and absolute vertical V relative to gravity, increases from zero, as may be understood transitioning from interval 2 to interval 3. Without sufficient rearward torque T2, the pitch angle ®, defined by the line from the CG to the cluster joint CJ of the cluster, here modeled as the combination of W1 and W2, from the normal N, will remain roughly constant and cause the CG to lead or be in front of grounded wheel W1 , as shown in interval 3, and cause an uncontrolled descent. In this situation, mobile transport MT experiences a positive-feedback condition wherein the cluster is induced to rotate or increase rotation about cluster joint CJ so as to correct for the error. Without negative corrective feedback that would urge the CG rearwardly (toward the right side of the page as shown), the CG being in front of the ground wheel W1 would cause increased and faster cluster rotation that would increase forward momentum. This would likely trigger a Cluster Safety Lock that, in combination with the increasing rotational momentum, would lead to the mobile transport MT falling down the stairs.

[0007] What is needed is a method of recognizing when a mobile transport exhibits an uncontrolled descent condition and causing the mobile transport to fall backwardly or resist falling forwardly.SUMMARY OF THE INVENTION

[0008] The invention is a method of recognizing when a mobile transport exhibits an uncontrolled descent condition and causing the mobile transport to fall backwardly or resist falling forwardly.

[0009] An embodiment configured according to principles of the invention provides a method of mitigating an instability of a mobile transport including detecting whether it is pitching forward and inducing a torque in the mobile transport in an amount to counter the pitching.

[0010] The invention provides improved elements and arrangements thereof, for the purposes described, which are inexpensive, dependable and effective in accomplishing intended purposes of the invention.

[0011] Other features and advantages of the invention will become apparent from the following description of the preferred embodiments, which refers to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention is described in detail below with reference to the following figures, throughout which similar reference characters denote corresponding features consistently, wherein:

[0013] Fig. 1 is a schematic representation of a mobile transport at progressive intervals descending stairs;

[0014] Fig. 2 is a schematic representation of a mobile transport at progressive intervals experiencing uncontrolled descent of stairs;

[0015] Fig. 3 is a schematic representation of a mobile transport at progressive intervals of autotransition configured according to principles of the invention;

[0016] Fig. 4 is a graphical representation pitch rate versus cluster rotation velocity; and

[0017] Fig. 5 is a right side graphical representation of a mobile transport.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] The examples shown in drawings are presented to demonstrate examples of the disclosure. The drawings are illustrative and non-limiting. In the drawings, for illustrative purposes, the size of some of the elements may be exaggerated and not drawn to a particular scale. Additionally, elements shown within the drawings that have the same numbers may be identical elements or may be similar elements, depending on the context.

[0019] Where the term "comprising" is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun, e.g., "a", "an", or "the", this includes a plural of that noun unless something otherwise is specifically stated. Hence, the term "comprising" should not be interpreted as being restricted to the items listed thereafter; it does not exclude other elements or steps, and so the scope of the expression "a device comprising items A and B" should not be limited to devices consisting only of components A and B. Furthermore, to the extent that the terms “includes”, “has”, “possesses”, and the like are used in the present description and claims, such terms are intended to be inclusive in a manner similar to the term “comprising,” as “comprising” is interpreted when employed as a transitional word in a claim.

[0020] Furthermore, the terms "first", "second", "third", and the like, whether used in the description or in the claims, are provided to distinguish between similar elements and not necessarily to describe a sequential or chronological order. It is to be understood that the termsso used are interchangeable under appropriate circumstances (unless clearly disclosed otherwise) and that the aspects of the disclosure described herein are capable of operation in other sequences and / or arrangements than are described or illustrated herein.

[0021] In the following description, numerous specific details are set forth to provide a thorough understanding of various aspects and arrangements. It will be recognized, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well known structures, materials, or operations may not be shown or described in detail to avoid obscuring certain aspects.

[0022] Reference throughout this specification to “an aspect,” “an arrangement,” “a configuration,” or “an example” indicates that a particular feature, structure, or characteristic is described. Thus, appearances of phrases such as “in one aspect,” “in one arrangement,” “in a configuration,” “in some examples,” or the like in various places throughout this specification do not necessarily each refer to the same aspect, feature, configuration, example, or arrangement. Furthermore, the particular features, structures, and / or characteristics described may be combined in any suitable manner.

[0023] To the extent used in the present disclosure and claims, the terms “component,” “system,” “platform,” “layer,” “selector,” “interface,” and the like are intended to refer to a computer-related entity or an entity related to an operational apparatus with one or more specific functionalities, wherein the entity may be either hardware, a combination of hardware and software, software, or software in execution. As an example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and / or a computer. By way of illustration and not limitation, both an application running on a server and the server itself can be a component. One or more components may reside within a process and / or thread of execution and a component may be localized on one computer and / or distributed between two or more computers. In addition, components may execute from various computer-readable media, device-readable storage devices, or machine-readable media having various data structures stored thereon. The components may communicate via local and / or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, a distributed system, and / or across a network such as the Internet with other systems via the signal). As another example, a component can be an apparatus with specific functionality provided by mechanical parts operated by electric or electronic circuitry, which may be operated by a software or firmware application executed by a processor, wherein the processor can be internal or external to the apparatus and executes at least a part of the software or firmware application. As yetanother example, a component can be an apparatus that provides specific functionality through electronic components without mechanical parts; the electronic components can include a processor therein to execute software or firmware that confers at least in part the functionality of the electronic components.

[0024] To the extent used in the subject specification, terms such as “store,” “storage,” “data store,” data storage,” “database,” and the like refer to memory components, entities embodied in a memory, or components comprising a memory. It will be appreciated that the memory components described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory.

[0025] In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A, X employs B, or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. Moreover, articles “a” and “an” as used in the subject disclosure and claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.

[0026] The words “exemplary” and / or “demonstrative,” to the extent used herein, mean serving as an example, instance, or illustration. For the avoidance of doubt, the subject matter disclosed herein is not limited by disclosed examples. In addition, any aspect or design described herein as “exemplary” and / or “demonstrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs, nor is it meant to preclude equivalent exemplary structures and techniques. Furthermore, to the extent that the terms “includes,” “has,” “contains,” and other similar words are used in either the detailed description or the claims, such terms are intended to be inclusive, in a manner similar to the term “comprising” as an open transition word, without precluding any additional or other elements.

[0027] As used herein, the term “infer” or “inference” refers generally to the process of reasoning about, or inferring states of, the system, environment, user, and / or intent from a set of observations as captured via events and / or data. Captured data and events can include user data, device data, environment data, data from sensors, application data, implicit data, explicit data, etc. Inference can be employed to identify a specific context or action or can generate a probability distribution over states of interest based on a consideration of data and events, for example.

[0028] The disclosed subject matter can be implemented as a method, apparatus, or article of manufacture using standard programming and / or engineering techniques to produce software,firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. The term "article of manufacture," to the extent used herein, is intended to encompass a computer program accessible from any computer-readable device, machine- readable device, computer-readable carrier, computer-readable media, or machine-readable media. For example, computer-readable media can include, but are not limited to, a magnetic storage device, e.g., hard disk; floppy disk; magnetic strip(s); an optical disk (e.g., compact disk (CD), digital video disc (DVD), Blu-ray Disc (BD)); a smart card; a flash memory device (e.g., card, stick, key drive); a virtual device that emulates a storage device; and / or any combination of the above computer-readable media.

[0029] Generally, program modules include routines, programs, components, data structures, etc., that perform particular tasks or implement particular abstract data types. The illustrated aspects of the subject disclosure may be practiced in distributed computing environments where certain tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules can be located in both local and remote memory storage devices.

[0030] Computing devices can include at least computer-readable storage media, machine- readable storage media, and / or communications media. Computer-readable storage media or machine-readable storage media can be any available storage media that can be accessed by the computer and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer-readable storage media or machine- readable storage media can be implemented in connection with any method or technology for storage of information such as computer-readable or machine-readable instructions, program modules, structured data, or unstructured data.

[0031] Computer-readable storage media can include, but are not limited to, random access memory (RAM), read only memory (ROM), electrically erasable programmable read only memory (EEPROM), flash memory or other memory technology, compact disk read only memory (CD ROM), digital versatile disk (DVD), Blu-ray disc (BD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, solid state drives or other solid state storage devices, or other tangible and / or non-transitory media that can be used to store desired information. In this regard, the terms “tangible” or “non-transitory” herein as applied to storage, memory, or computer-readable media, are to be understood to exclude only propagating transitory signals per se as modifiers, and do not exclude any standard storage, memory, or computer-readable media that are not only propagating transitory signals per se.

[0032] Computer-readable storage media can be accessed by one or more local or remote computing devices, e.g., via access requests, queries, or other data retrieval protocols, for a variety of operations with respect to the information stored by the medium.

[0033] A system bus, as may be used herein, can be any of several types of bus structure that can further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and a local bus using any of a variety of commercially available bus architectures. A database, as may be used herein, can include basic input / output system (BIOS) that can be stored in a nonvolatile memory such as ROM, EPROM, or EEPROM, with BIOS containing the basic routines that help to transfer information between elements within a computer, such as during startup. RAM can also include a high-speed RAM such as static RAM for caching data.

[0034] As employed in the subject specification, the term “processor” can refer to substantially any computing processing unit or device comprising, but not limited to comprising, single-core processors; single-core processors with software multithread execution capability; multi-core processors; multi-core processors with software multithread execution capability; multi-core processors with hardware multithread technology; vector processors; pipeline processors; parallel platforms; and parallel platforms with distributed shared memory. Additionally, a processor can refer to an integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), a programmable logic controller (PLC), a complex programmable logic device (CPLD), a state machine, a discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Processors can exploit nano-scale architectures such as, but not limited to, molecular and quantum-dot based transistors, switches, and gates, in order to optimize space usage or enhance performance of user equipment. A processor may also be implemented as a combination of computing processing units. For example, a processor may be implemented as one or more processors together, tightly coupled, loosely coupled, or remotely located from each other. Multiple processing chips or multiple devices may share the performance of one or more functions described herein, and similarly, storage may be effected across a plurality of devices. A processor may be implemented to reside in a cloud-based network such as, e.g., the Internet.

[0035] The actions of a method or algorithm described in connection with the arrangements disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other known form of storage medium. A storage medium may be coupledto the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in functional equipment such as, e.g., a computer, a robot, a user terminal, a mobile telephone or tablet, a car, or an IP camera. In the alternative, the processor and the storage medium may reside as discrete components in such functional equipment Additionally or alternatively, at least one of the processor and / or the storage medium may reside in a cloud-based network such as, e.g., the Internet.

[0036] Configurations of the present teachings are directed to computer systems for accomplishing the methods discussed in the description herein, and to computer readable media containing programs for accomplishing these methods. The raw data and results can be stored for future retrieval and processing, printed, displayed, transferred to another computer, and / or transferred elsewhere. Communications links can be wired or wireless, for example, using cellular communication systems, military communications systems, and satellite communications systems. Parts of the system can operate on a computer having a variable number of CPUs. Other alternative computer platforms can be used.

[0037] The present configuration is also directed to software / firmware / hardware for accomplishing the methods discussed herein, and computer readable media storing software for accomplishing these methods. The various modules described herein can be accomplished on the same CPU, or can be accomplished on different CPUs. In compliance with the statute, the present configuration has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the present configuration is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the present configuration into effect.

[0038] Methods can be, in whole or in part, implemented electronically. Signals representing actions taken by elements of the system and other disclosed configurations can travel over at least one live communications network. Control and data information can be electronically executed and stored on at least one computer-readable medium. The system can be implemented to execute on at least one computer node in at least one live communications network. Common forms of at least one computer-readable medium can include, for example, but not be limited to, a floppy disk, a flexible disk, a hard disk, magnetic tape, or any other magnetic medium, a compact disk read only memory or any other optical medium, punched cards, paper tape, or any other physical medium with patterns of holes, a random access memory, a programmable read only memory, and erasable programmable read only memory (EPROM), a Flash EPROM, or any othermemory chip or cartridge, or any other medium from which a computer can read. Further, the at least one computer readable medium can contain graphs in any form, subject to appropriate licenses where necessary, including, but not limited to, Graphic Interchange Format (GIF), Joint Photographic Experts Group (JPEG), Portable Network Graphics (PNG), Scalable Vector Graphics (SVG), and Tagged Image File Format (TIFF).

[0039] Various arrangements are described herein. For simplicity of explanation, the methods or algorithms are depicted and described as a series of steps or actions. It is to be understood and appreciated that the various arrangements are not limited by the actions illustrated and / or by the order of actions. For example, actions can occur in various orders and / or concurrently, and with other actions not presented or described herein. Furthermore, not all illustrated actions may be required to implement the methods. In addition, the methods could alternatively be represented as a series of interrelated states via a state diagram or events. Additionally, the methods described hereafter are capable of being stored on an article of manufacture, as defined herein, to facilitate transporting and transferring such methodologies to computers.

[0040] Referring to Figs. 3 and 5, the invention is a method 100 of recognizing when a mobile transport MT exhibits an uncontrolled descent condition and causing mobile transport MT to fall backwardly or resist falling forwardly. Method 100 includes a step 105 of monitoring stability. Step 105 includes determining whether mobile transport MT is pitching forward. If step 105 is true, then method 100 may progress to a step 110 of inducing a rearward torque T2.

[0041] Step 105 includes evaluating the velocity or rate R of mobile transport MT in plane normal to gravity and cluster position 4>c. If the cluster assembly is vertical, <j>cequals 0°, and when horizontal, <|)cequals 90°. The <J)Cvalue is denoted between + / -90 degrees.

[0042] When an evaluation (formula 3 below) of a rate change Arate (formula 1 below) per cluster angle change Aciuster (formula 2 below) exceeds a threshold 6, preferably 20 counts / degree, then mobile transport MT is deemed to be in an unstable, uncontrolled falling condition. “Counts” relate to cluster rotation velocity, not in terms of degrees / second, but counts / frame, which roughly converts to 3.83928° / sec. In formula 1 , Ri is the real-time pitch rate of mobile transport MT while descending, and Rmis a minimum rate or lowest value pitch rate that occurs. Referring to Fig. 4, the rates of the rate fields reach minima when the cluster position(x axis) is around vertical, when (|)cis around 0. The lowest point on the rate graph is to what Rmrefers. Arate represents how fast the device pitch is accelerating. For instance, If the device were to fall forward freely, the Arate value would be high as the device accelerates under gravity. In formula 2, CAi is the cluster angle <t>c. is the real-time cluster angle of mobile transport MT while descending, and CAmis the minimum rate that occurs. Formula 1 represents how fast the mobile transport MT pitch isaccelerating. Formula 2 represents how fast the cluster is rotating. Formula 3, which is Formula1 / Formula2, determines how fast mobile transport MT is accelerating against the speed of the cluster. Thus formula 3 determines whether mobile transport MT is falling too fast for it to be called a controlled descent. Thus it helps in deciding if the device is really falling or not. Formula 1 Arate = Ri — RmFormula 2 Acluster = CAi — CAmFormula s 6 = Arate / Acluster

[0043] If the threshold 5 is exceeded, step 110 can be successful when mobile transport also meets certain conditions, namely when Acluster exceeds 20° and cluster position <t>cis less than 45°. When these three conditions are met, step 110 is initiated.

[0044] Step 110 includes a step 115 of computing a gain C that a controller uses to actuate wheels, in this scenario, specifically grounded wheel W1 . Gain C is the product (formula 6) of factors Ci, related to the pitch rate (formula 4), and C2, related to a horizontal offset of the CG and cluster joint (formula 5). In formula 5, Li is the distance between the CG and cluster joint CJ. Formula 4 Ci = (Rj + 1500) / 1500, limited to 0.5 to 2.0Formula 5 C2 = [4000 - (1 / Li)] / 500, limited to 0.5 to 3.0Formula 6 C = Ci * C2, limited to 0.5 to 5.0

[0045] A wheel command WC, the voltage command sent to motor drives to induce motor torque / velocity, is computed according to formula 7 wherein k is a constant gain of the controller and eint is a position error.Formula 7 WC = C * k * eint

[0046] While the principles of the invention have been described herein, the foregoing description is only an example and not a limitation on the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are within the scope of the present invention. The invention is not limited to the particular embodiments described and depicted herein, rather only to the following claims.

Claims

CLAIMSWE CLAIM:

1. Method of mitigating an instability of a mobile transport comprising: detecting pitching forward; and inducing a torque in the mobile transport in an amount to counter the pitching.

2. Method of claim 1 wherein said detecting comprises a ratio of a rate change and a cluster angle change.

3. Method of claim 1 wherein said inducing comprises accelerating the mobile transport.

4. Method of claim 1 wherein said inducing comprises calculating a gain comprising a product of a first factor based on a rate change and a second factor based on distance between a center of gravity and a cluster joint.

5. Method of claim 2 wherein said inducing is contingent on comparing the ratio and a threshold.

6. Method of claim 2 wherein said inducing is contingent on a cluster position.

7. Method of claim 2 wherein said inducing is contingent on a cluster angle change.

8. Method of claim 1 wherein said inducing comprises urging the mobile transport to fall backwardly.

9. Method of claim 1 wherein:the mobile transport comprises a cluster having a first wheel and a second wheel; and said inducing comprises maintaining a center of gravity of the mobile transport above one of the first wheel and the second wheel that contacts a travel surface.

10. Method of claim 1 wherein: the mobile transport comprises a cluster having a first wheel and a second wheel; and said inducing comprises increasing a rotation of one of the first wheel and the second wheel that is foremost in a travel direction of the mobile transport.

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