Apparatus and method for controllably positioning forks of a material handling vehicle

A material handling vehicle having a frame and a lift mast assembly, said lift mast assembly having a pair of spaced apart uprights connected to the frame, a carriage assembly having a first guide portion oriented transverse to the uprights, said carriage assembly being connected to the uprights and movable along the uprights, first and second forks connected to the carriage assembly and movable relative to the carriage assembly and transverse to the uprights, comprising:

• first detecting means for sensing a location of the first fork and producing a first signal in response to said location of the first fork, said first detecting means including an elongated member having a surface and a plurality of distinguishable spaced apart marks arranged along the surface, said elongated member being substantially parallel to said first guide portion and being connected to the carriage assembly, said surface facing said first and second forks;
• second detecting means for sensing a location of the second fork and producing a second signal in response to said location of the second fork, said second detecting means including said elongated member;
• controlling means for receiving the first signal and responsively producing a first movement signal, and for receiving the second signal and responsively producing a second movement signal;
• first driving means for controllably moving the first fork relative to the carriage assembly in response to said first movement signal;
• second driving means for controllably moving the second fork relative to the carriage assemlby in response to said second movement signal;
• and
• said first detecting means being adapted to deliver electromagnetic radiation in the direction of the surface of said elongated member, receive a reflection of the electromagnetic radiation and deliver said first signal in response to receiving the reflection of the electromagnetic radiation, said second detecting means being adapted to deliver electromagnetic radiation in the direction of the surface of said elongated member, receive a reflection of the electromagnetic radiation and deliver said second signal in response to receiving the reflection of the electromagnetic radiation, the first and second detecting means being connected to the first and second forks, respectively and being movable along the second guide portion in response to movement of the first and second forks, respectively.

A material handling vehicle having a frame and a lift mast assembly, said lift mast assembly having a pair of spaced apart uprights connected to the frame, a carriage assembly having a first guide portion oriented transverse to the uprights, said carriage assembly being connected to the uprights and movable along the uprights, first and second forks connected to the carriage assembly and movable relative to the carriage assembly and transverse to the uprights, comprising:

• first detecting means for sensing a location of the first fork and producing a first signal in response to said location of the first fork;
• second detecting means for sensing a location of the second fork and producing a second signal in response to said location of the second fork;
• controlling means for receiving the first signal and responsively producing a first movement signal, and for receiving the second signal and responsively producing a second movement signal;
• first driving means for controllably moving the first fork relative to the carriage assembly in response to said first movement signal;
• second driving means for controllably moving the second fork relative to the carriage assembly in response to said second movement signal;
• fifth detecting means for sensing a first preselected initial position and delivering a first initial signal in response to said first fork being at said first preselected initial position;
• sixth detecting means for sensing a second preselected initial position and delivering a second initial signal in response to said second fork being at said second preselected initial position, said controlling means being adapted to receive said first and second initial signals and to stop said movement of said first and second forks in response to receiving said signals;
• and
• said fifth and sixth detecting means include first and second initial sensors connected to the carriage assembly and first and second retroreflective strips connected to the first and second forks, respectively, said first and second initial sensors being adapted to deliver electromagnetic radiation in the direction of said first and second retroreflective strips, respectively, receive a reflection of said electromagnetic radiation, and deliver said first and second initial signal in response to receiving said electromagnetic radiation reflection.

An automatic guided vehicle having a frame and a lift mast assembly, said lift mast assembly having a pair of spaced apart uprights connected to the frame, a carriage assembly having a carriage having a first guide portion oriented transverse to the upright and a side shiftable frame having a second guide portion oriented substantially parallel with said first guide portion, said side shiftable frame being connected to the carriage and movable along the first guide portion, said carriage being connected to the uprights and movable along the uprights, first and second forks each having a shank and a load engaging portion extending in a direction generally away from the material handling vehicle, and said shanks being connected to the second guide portion and said first and second forks being movable relative to the carriage assembly along the second guide portion, comprising:

• a first elongated placard having a surface and a plurality of distinguishable spaced apart marks arranged along the surface and being connected to the side shiftable frame, said surface facing the shank of said first fork and substantially parallel to said second guide portion;
• a second elongated placard having a surface and a plurality of distinguishable spaced apart marks arranged along the surface and being connected to the side shiftable frame, said surface facing the shank of said first fork and substantially parallel to said second guide portion;
• first detecting means for delivering electromagnetic radiation in the direction of the surface of said first elongated member, receiving a reflection of the electromagnetic radiation and delivering a first signal in response to receiving the reflection of the electromagnetic radiation, said first detecting means being connected to the first fork and movable along the second guide portion in response to movement of the first fork;
• second detecting means for delivering electromagnetic radiation in the direction of the surface of said second elongated member, receiving a reflection of the electromagnetic radiation and delivering a second signal in response to receiving the reflection of the electromagnetic radiation, said second detecting means being connected to the second fork and movable along the second guide portion in response to movement of the second fork;
• third detecting means for sensing a location of the side shiftable frame with respect to the carriage and delivering a third signal in response to said side shiftable frame being at a preselected transverse position;
• fourth detecting means for sensing first and second elevational edges of a load opening and delivering fourth and fifth signals in response to sensing said first and second elevational edges, respectively;
• first driving means for controllably moving the first fork in a first transverse direction relative to the carriage assembly in response to receiving a seventh signal and to move the first fork in a second transverse direction relative to the carriage assembly in response to receiving an eighth signal;
• second driving means for controllably moving the second fork in said first transverse direction in response to receiving a ninth signal and to move the second fork in said second transverse direction in response to receiving a tenth signal;
• third driving means for controllably moving the side shiftable frame along the first guide edge;
• controlling means for receiving the first and third signals and calculating the location of the first fork relative to the carriage assembly, receiving the second signal and calculating the location of the second fork relative to the carriage assembly, receiving the fourth and fifth signals, delivering a sixth and said ninth signals, stopping movement of said first fork in response to receiving said fourth signal, stopping movement of said second fork in response to receiving said fifth signal, calculating first and second load engaging locations of the first and second forks, respectively, said first and second load engaging locations being substantially centered on said side shiftable frame and enabling said first and second forks to enter said load opening, delivering said seventh, eighth, ninth, and tenth signals, stopping movement of said first and second forks at the first and second load engaging locations, respectively, calculating a location of the side shiftable frame relative said load opening in response to said third signal, said calculated location being substantially aligned with said load opening, and aligning said side shiftable frame with said load opening.

A method for controllably moving first and second forks of a material handling vehicle into alignment with a load having a load opening, said forks having forktip sensors and fork position sensors, said load opening having a centerline and first and second vertical edges spaced substantially equal distances from said centerline, wherein the material handling vehicle includes a pair of uprights, a side shiftable frame movable transverse the uprights, and a microcomputer, comprising:

• positioning the first and second forks at preselected first and second initial positions, respectively;
• moving the first and second forks in respective transverse directions;
• producing first and second position signals in response to sensing the location of the first and second forks, respectively;
• producing a first edge signal in response to sensing the first vertical edge of the load opening;
• producing a second edge signal in response to sensing the second vertical edge of the load opening;
• calculating a location, "X", in response to said first edge signal and said first position signal;
• calculating a location, "Y", in response to said second edge signal and said second position signal;
• positioning said first and second forks in said locations, "X" and "Y", respectively;
• sensing a location of the side shiftable frame with respect to the material handling vehicle;
• and,
• calculating a location of the centerline of the side shiftable frame relative to at least one of the sensed vertical edges.

A material handling vehicle having a frame and a lift mast assembly, said lift mast assembly having a pair of spaced apart uprights connected to the frame, a carriage assembly connected to the uprights and movable along the uprights, first and second forks connected to the carriage assembly and movable relative to the carriage assembly transverse the uprights, comprising:

• first detecting means for sensing a transverse location of the first fork relative to the carriage assembly and producing a first signal in response to said location of the first fork;
• second detecting means for sensing a transverse location of the second fork relative to the carriage assembly and producing a second signal in response to said location of the second fork;
• controlling means for receiving the first and second signals, processing the first and second signals in accordance with a set of preprogrammed instructions, and responsively producing first and second movement signals;
• first driving means for receiving said first movement signal and responsively moving the first fork to a predetermined position relative to said carriage assembly as set forth by said preprogrammed instructions;
• and
• second driving means for receiving said second movement signal and responsively moving the second fork to a predetermined position relative to said carriage assembly as set forth by said preprogrammed instructions.

A material handling vehicle having a frame and a lift mast assembly, said lift mast assembly having a pair of spaced apart uprights connected to the frame, a carriage assembly connected to the uprights and movable along the uprights, first and second forks connected to the carriage assembly and movable relative the carriage assembly transverse the uprights, said carriage assembly includes a carriage having a first guide portion oriented transverse the uprights and a side shiftable frame having a second guide portion oriented substantially parallel with said first guide portion, said side shiftable frame being connected to the carriage and movable along the first guide portion, said first and second forks being connected to said side shiftable frame and movable along said second guide portion, comprising:

• first detecting means for sensing a transverse location of the first fork relative to the side shiftable frame and producing a first signal in response to said location of the first fork;
• second detecting means for sensing a transverse location of the second fork relative to the side shiftable frame and producing a second signal in response to said location of the second fork;
• third detecting means for sensing a location of the side shiftable frame with respect to the carriage and delivering a third signal in response to said side shiftable frame being at a preselected transverse position;
• controlling means for receiving the first, second, and third signals and for producing first, second, and third movement signals in response to said receive signals and a set of preprogrammed instructions;
• first driving means for receiving said first movement signal and responsively moving the first fork to a predetermined position relative the side shiftable frame as set forth by said preprogrammed instructions;
• second driving means for receiving said second movement signal and responsively moving the second fork relative the side shiftable frame as set forth by said preprogrammed instructions;
• and,
• third driving means for receiving said third movement signal and responsively moving said side shiftable frame to a predetermined position relative to said carriage as set forth by said preprogrammed instructions.