Bot having high speed stability
First Claim
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1. A method for transporting items in a storage and retrieval system, the method comprising:
- providing an autonomous transport vehicle, the autonomous transport vehicle having a frame;
providing a controller connected to the autonomous transport vehicle;
independently driving at least two drive wheels mounted to the frame;
selectively locking and unlocking swiveling of at least one caster wheel mounted to the frame, the at least one caster wheel having a releasably lockable swivel lock so that when unlocked the releasably lockable swivel lock allows swiveling of the at least one caster wheel relative to the frame and when locked prevents swiveling of the caster wheel relative to the frame; and
effecting, with the controller, locking and unlocking of the releasably lockable swivel lock during a transport of items through the storage and retrieval system based on a predetermined kinematic state that correlates a speed of travel of the autonomous transport vehicle and a turn angle of the autonomous transport vehicle.
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Abstract
An autonomous transport vehicle for transporting items in a storage and retrieval system is provided. The autonomous transport vehicle includes at least two drive wheels and a controller, where each drive wheel is independently driven and a drive wheel encoder is disposed adjacent each drive wheel. The controller, in communication with the drive wheel encoders, is configured to determine a kinematic state of the autonomous transport vehicle within the storage and retrieval system based on incremental data from the drive wheel encoders only and independent of drive wheel slippage.
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Citations
22 Claims
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1. A method for transporting items in a storage and retrieval system, the method comprising:
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providing an autonomous transport vehicle, the autonomous transport vehicle having a frame; providing a controller connected to the autonomous transport vehicle; independently driving at least two drive wheels mounted to the frame; selectively locking and unlocking swiveling of at least one caster wheel mounted to the frame, the at least one caster wheel having a releasably lockable swivel lock so that when unlocked the releasably lockable swivel lock allows swiveling of the at least one caster wheel relative to the frame and when locked prevents swiveling of the caster wheel relative to the frame; and effecting, with the controller, locking and unlocking of the releasably lockable swivel lock during a transport of items through the storage and retrieval system based on a predetermined kinematic state that correlates a speed of travel of the autonomous transport vehicle and a turn angle of the autonomous transport vehicle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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independently driving at least two drive wheels of an autonomous transport vehicle; selectively locking and unlocking swiveling of at least one caster wheel having a releasably lockable swivel lock so that when unlocked the releasably lockable swivel lock allows swiveling of the at least one caster wheel and when locked prevents swiveling of the caster wheel; and estimating, with a controller including a state estimator, a kinematic state that correlates a speed of travel of the autonomous transport vehicle and a turn angle of the autonomous transport vehicle wherein the controller issues control commands to the at least two drive wheels and the releasably lockable swivel lock of the at least one caster wheel based on the estimated kinematic state of the autonomous transport vehicle. - View Dependent Claims (10)
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11. An autonomous transport vehicle for transporting items in a storage and retrieval system, the autonomous transport vehicle comprising:
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a frame; at least two independently driven drive wheels mounted to the frame; a drive wheel encoder disposed adjacent each independently driven drive wheel; at least one caster wheel mounted to the frame and having a releasably lockable swivel lock; and a controller in communication with each drive wheel encoder, wherein the controller is configured to identify a kinematic state of the autonomous transport vehicle within the storage and retrieval system based only on incremental data received by the controller from each drive wheel encoder independent of drive wheel slippage, and wherein the controller is configured to lock and unlock the releasably lockable swivel lock during a transport of items through the storage and retrieval system based on the kinematic state of the autonomous transport vehicle. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification