# US 11,029,695 B2 · Acceleration controls for a mobile drive unit

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- Number: US 11,029,695 B2
- Document ID: US11029695B2
- Status: Granted
- Kind: B2
- Application number: 15/934,765
- Filed: 2018-03-23
- Published: 2019-09-26
- Granted: 2021-06-08
- Earliest claimed: 2018-03-23
- Assignees: Amazon Technologies, Inc.
- Applicants: Amazon Technologies, Inc.
- Inventors: Dragan Pajevic; Gabriel Hebert; Oliver Christoph Purwin
- Web page: https://patentgrep.com/patent/US11029695B2

## CPC

- G05D 1/65: Following a desired speed profile
- B25J 5/007: {mounted on wheels}
- B60P 1/649: {Guiding means for the load-transporting element}
- B62D 15/00: Steering not otherwise provided for
- B66F 17/003: {for fork-lift trucks}
- G05B 19/416: characterised by control of velocity, acceleration or deceleration (G05B19/19 takes precedence)
- G05B 19/41895: {using automatic guided vehicles [AGV] (control of position or course of AGV's G05D1/00)}
- G05D 1/00: Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots (drive control systems specially adapted for autonomous road vehicles B60W60/00)
- G05D 1/0214: {in accordance with safety or protection criteria, e.g. avoiding hazardous areas (monitoring the location of vehicles within a certain area, e.g. forbidden or allowed areas, in traffic control systems for road vehicles G08G1/13)}
- G05D 1/0227: {using mechanical sensing means, e.g. for sensing treated area}
- G05D 1/027: {comprising intertial navigation means, e.g. azimuth detector (inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165)}
- G05D 1/0891: {specially adapted for land vehicles}
- G05B 2219/31005: Detect obstacles on path of vehicle
- G05B 2219/43062: Maximum acceleration, limit
- Y02P 90/02: Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
- Y02P 90/60: Electric or hybrid propulsion means for production processes
- G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- B60P: VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS (vehicles with special provisions for transporting patients or disabled persons, or their personal conveyances A61G3/00)
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- B66F: HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD ({invalid lifting devices A61G7/10; } mounting artificial islands on piles or like supports E02B17/00; scaffolding combined with lifting devices E04G1/22; lifting devices for sliding forms E04G11/24; lifting of buildings E04G23/06; shores or struts E04G25/00; lifts or other hoisting devices on ladders E06C7/12; props for mining E21D15/00)
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Motion controls for a mobile drive unit adjust linear acceleration for laden mobile drive units to decrease the likelihood of the payload tipping or bouncing off the mobile drive unit and adjust angular acceleration to reduce the risk of the drive wheels slipping while the casters align with the direction of travel.

## Claims

### Claim 1

A mobile drive unit having a linear acceleration value and an angular acceleration value, the mobile drive unit comprising:
a chassis assembly including a pair of drive wheel assemblies, each drive wheel assembly comprising a motor;
a front caster and a rear caster each connected to the chassis assembly;
a support structure mounted on the chassis assembly;
a payload housing mounted on the support structure, the payload housing comprising a top surface;
a controller communicatively coupled to the pair of drive wheel assemblies; and
memory storing instructions that cause the controller to effectuate operations, the operations comprising:
determining a mass of a payload located on the top surface;
defining a permissible maximum linear acceleration based on the linear acceleration value and the mass of the payload;
determining a prior directional movement of the mobile drive unit, the prior directional movement indicative of a direction of the front caster and the rear caster;
determining a next directional movement of the mobile drive unit, the next directional movement indicative of a travel direction;
defining a permissible maximum angular acceleration and a maneuver angle based on the prior directional movement and the next directional movement, wherein determination of the maneuver angle is based at least in part on the front caster and the rear caster aligned with the travel direction after completion of the maneuver angle;
if the next directional movement comprises a turn, causing the mobile drive unit to operate at the permissible maximum angular acceleration for at least the maneuver angle; and
if the next direction movement comprises a linear movement, causing the mobile drive unit to operate under the permissible maximum linear acceleration.

### Claim 2 (depends on 1)

The mobile drive unit of claim 1, wherein the permissible maximum angular acceleration is at least fifty percent (50%) of the angular acceleration value.

### Claim 3 (depends on 1)

The mobile drive unit of claim 1, wherein the prior directional movement and the next directional movement are both turns in a same direction and the maneuver angle is zero (0) degrees.

### Claim 4 (depends on 1)

The mobile drive unit of claim 1, wherein the prior directional movement is a first turn and the next directional movement is a second turn in an opposite direction as the first turn and the maneuver angle is twenty (20) degrees.

### Claim 5 (depends on 1)

The mobile drive unit of claim 1, wherein the prior directional movement is linear, the maneuver angle is ten (10) degrees.

### Claim 6 (depends on 1)

The mobile drive unit of claim 1, wherein the payload housing comprises a sensor and the determining the mass is based on receiving data from the sensor.

### Claim 7 (depends on 1)

The mobile drive unit of claim 1, wherein the permissible maximum linear acceleration equals the linear acceleration value where the mass does not exceed 270 kilograms.