Storage and retrieval machine control system having an encoder and an optical distance meter

A storage and retrieval machine comprising:

• a base, said base being movable in a horizontal direction,
• a carriage, said carriage being moveable in a vertical direction,
• a control system, said control system controlling movement of said base in said horizontal direction and movement of said carriage in said vertical direction, said control system further including
• a first rotary distance meter,
• a first optical distance meter, said first optical distance meter cooperating with said first rotary distance meter to provide information to said control system, said information pertaining to said movement of said base,
• a second rotary distance meter,
• a second optical distance meter, said second optical distance meter cooperating with said second rotary distance meter to provide information to said control system, said information pertaining to said movement of said carriage.

A method of controlling movement of a warehouse vehicle from a start point to an end point of a trajectory, said method comprising the steps of:

• A. ascertaining the location of said start point;
• B. generating information pertaining to said movement of said warehouse vehicle using a rotary distance meter;
• C. repetitively determining, based on said generating step (B), the current position of said warehouse vehicle along said trajectory as said warehouse vehicle traverses said trajector;
• D. implementing a feedback control system which controls said movement of said warehouse vehicle from said start point to said end point, said feedback control system being implemented based on said movement information generated by said rotary distance meter;
• and
• E. generating information pertaining to said movement of said warehouse vehicle using an optical distance meter, said optical distance meter comprising a laser and a laser beam sensor;
• F. ascertaining that the moveable object has reached said end point based on said generating step (E), said ascertaining step further comprising the steps of
• 1. emitting a laser beam from said laser, and
• 2. measuring a laser beam travel time, said laser beam travel time being the amount of time required for the laser beam to travel from said laser to said laser beam sensor.

A method of calibrating an optical distance meter with a rotary distance meter, said optical distance meter and said rotary distance meter being adapted for monitoring movement of a warehouse vehicle, said vehicle being one of a base of a storage and retrieval machine and a carriage of said storage and retrieval machine, said method comprising the steps of:

• advancing said vehicle along a trajectory;
• generating a first distance measurement, said first distance measurement being generated by said rotary distance meter;
• generating a second distance measurement, said second distance measurement being generated by said optical distance meter, said first and second distance measurements representing substantially the same location of said vehicle;
• and
• storing information pertaining to said second distance measurement in a look-up table as a function of said second distance measurement, said information relating to said first distance measurement.

A storage and retrieval machine comprising:

• a base, said base being movable in a horizontal direction;
• a carriage, said carriage being moveable in a vertical direction;
• a control system;
• said control system further including
• a horizontal control system which controls movement of said base along a horizontal trajectory, said horizontal control system including
• a first rotary distance meter, said first rotary distance meter providing information to said horizontal control system at a middle portion of said horizontal trajectory,
• a first optical distance meter, said first optical distance meter providing absolute position information to said horizontal control system at an endpoint of said horizontal trajectory, and
• a vertical control system which controls the movement of said carriage along a vertical trajectory, said vertical control system including
• a second rotary distance meter, said second rotary distance meter providing relative position information to said vertical control system at a middle portion of said vertical trajectory, and
• a second optical distance meter, said second optical distance meter providing absolute position information to said vertical control system at an endpoint of said vertical trajectory.

A method of controlling movement of a warehouse vehicle along a trajectory, said vehicle being one of a base of a storage and retrieval machine and a carriage of said storage and retrieval machine, said method comprising the steps of:

• A. determining the position of said vehicle, said determining step including the steps of
• 1. generating a first distance measurement with an optical distance meter,
• 2. generating a second distance measurement with a rotary distance meter, and
• 3. determining said position of said vehicle based on said first and second distance measurements;
• B. repeating step (A) such that said position of said vehicle is repetitively determined (1) as said vehicle traverses said trajectory and (2) based on respective repetitively generated first and second distance measurements;
• and
• C. implementing a feedback control system which controls said movement of said vehicle along said trajectory, said feedback control system being implemented based on the repetitive determinations of said position of said vehicle determined during step (B).