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US 2019/0294175 A1Published application
Acceleration controls for a mobile drive unit
AssigneeAmazon Technologies, Inc.
InventorsDragan Pajevic, Gabriel Hebert, Oliver Christoph Purwin
Life of this patent
Estimating the term…
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.
Claims20
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 mid-chassis 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;
- defining a permissible maximum angular acceleration and a maneuver angle based on the prior directional movement and the next directional movement;
- if the next directional movement comprises a turn, causing the motors 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 motors to operate under the permissible maximum linear acceleration.
12 more elements
A mobile drive unit comprising:
- a chassis assembly including a pair of mid-chassis drive wheel assemblies, each mid-chassis 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 mid-chassis drive wheel assemblies;
- and
- memory storing instructions that cause the controller to effectuate operations, the operations comprising:
- determining a prior directional movement of the mobile drive unit;
- determining a next directional movement of the mobile drive unit, the next directional movement comprising a first turn;
- based on the prior directional movement and the first turn, determining an acceleration reduction factor;
- determining an angular acceleration associated with the mobile drive unit;
- determining a reduced angular acceleration based on the angular acceleration and the acceleration reduction factor;
- selecting a maneuver angle based on the prior directional movement and the next directional movement;
- and
- causing the motors to operate in accordance with the next directional movement for the maneuver angle at the reduced angular acceleration.
12 more elements
A motion control system for a mobile drive unit, the motion control system comprising:
- a processor;
- and
- memory storing instructions that cause the processor to effectuate operations, the operations comprising:
- determining a mass of a payload of the mobile drive unit;
- based on a value of the mass, calculating an acceleration ceiling;
- receiving an instruction to cause the mobile drive unit to operate;
- and
- controlling movement of the mobile drive unit to prevent linear acceleration of the mobile drive unit from exceeding the acceleration ceiling.
5 more elements
Dependencies are inferred from the claim text.