US 11,952,247 B1Granted

Control system for an electric pallet jack

AssigneeAmazon Technologies, Inc.

InventorsJames Patrick Dwyer, Robert Matthew Gruendel, Eli Douglas Girod

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Abstract

An electric pallet jack can be configured to include logic controllers that are connected to a drive system and a steering system of the electric pallet jack. The logic controllers can be in communication with one or more sensors that enable determinations of pallet jack velocity, pallet jack acceleration, and a rate of turning for the electric pallet jack. The logic controllers can be configured to provide maximum velocity, maximum acceleration, maximum deceleration, and maximum rate of turning limitations to maintain control over an object transported by the electric pallet jack. The logic controllers can determine whether the maximum thresholds of the electric pallet jack are exceeded by an operating variable and can modulate the amount of power provided by the drive system to reduce the operating variable below the associated threshold.

Claims20

Dependent claims

A system comprising:

a drive wheel encoder that is associated with a drive wheel and is configured to determine a pallet jack velocity and a pallet jack acceleration of an electric pallet jack at a first time;
a load sensor that is configured to determine a load weight of a load, carried by the electric pallet jack, that is travelling at the pallet jack velocity and being accelerated by the pallet jack acceleration at the first time;
a drive motor that is configured to operate the drive wheel such that the load weight travels at the pallet jack velocity and is accelerated by the pallet jack acceleration at the first time;
an acceleration limit controller that is configured to:
receive, from the drive wheel encoder, a first indication of the pallet jack acceleration;
receive, from the load sensor, a second indication of the load weight;
determine, based on the load weight, an acceleration limit that provides a maximum acceleration for the drive wheel;
determine, based on the acceleration limit, that the pallet jack acceleration at the first time meets or exceeds the acceleration limit;
determine, based on the pallet jack acceleration meeting or exceeding the acceleration limit, a rate of power change for the drive motor, the rate of power change configured to limit a rate of acceleration for the load weight below the acceleration limit;
and
determine, at a second time, that the pallet jack acceleration has been reduced below the acceleration limit;
and
a velocity limit controller that is configured to:
receive, from the drive wheel encoder, a third indication of the pallet jack velocity;
receive, from the load sensor, the second indication of the load weight;
determine, based on the load weight, a velocity limit that provides a maximum velocity for the drive wheel;
determine, based on the velocity limit, that the pallet jack velocity at the first time meets or exceeds the velocity limit;
determine, based on the pallet jack velocity meeting or exceeding the velocity limit, a power limit for the drive motor, the power limit configured to limit a maximum velocity for the load weight;
and
determine, at the second time, that the pallet jack velocity has been reduced below the velocity limit.

17 more elements

A method comprising:

receiving, from one or more sensors, one or more indications associated with a drive system and a steering system associated with an electric pallet jack, the one or more indications indicating a load weight of a load being carried by the electric pallet jack;
determining, based at least on the one or more indications, an operating state associated with a pallet jack velocity and a pallet jack acceleration;
determining, based at least on the load weight of the load and the pallet jack velocity, a velocity control that defines a maximum velocity and a minimum velocity associated with the operating state;
determining, based at least on the load weight of the load and the pallet jack acceleration, an acceleration control that defines a set of acceleration limits and a set of deceleration limits;
monitoring the operating state to determine whether the pallet jack velocity satisfies the velocity control and whether the pallet jack acceleration satisfies the acceleration control;
and
determining, based at least on the velocity control or the acceleration control, an updated operating state that is implemented via the drive system.

4 more elements

A system comprising:

one or more processors;
and
a memory storing one or more instructions that are executable by the one or more processors to perform operations comprising:
receiving, from one or more sensors, one or more indications associated with a rotational velocity of one or more wheels of a drive system of an electric pallet jack, the one or more indications indicating a load weight of a load being carried by the electric pallet jack;
determining, based at least on the one or more indications, a pallet jack velocity and a pallet jack acceleration, the pallet jack velocity correlated to the rotational velocity and the pallet jack acceleration correlated to a rate of change for the rotational velocity;
determining, based at least on the one or more indications, the load weight of the load, and an operating state of the drive system, a velocity control that defines a maximum velocity and an acceleration control that defines a maximum acceleration for an object and the electric pallet jack;
determining, based at least on the velocity control and the acceleration control, that at least one of the pallet jack velocity meets or exceeds the maximum velocity or the pallet jack acceleration meets or exceeds the maximum acceleration;
and
providing, to the drive system, an updated operating state that is configured to reduce a power output of the drive system to reduce at least one of the pallet jack velocity or the pallet jack acceleration.

6 more elements

Dependencies are inferred from the claim text.