Automated bot transfer arm drive system

1. A method for operating an automated storage and retrieval system, the method comprising:

providing an autonomous transport vehicle having a transfer arm including at least one finger and a movable finger support member, the at least one finger being movably coupled to the finger support member;

moving the finger support member in a first direction relative to a reference frame of the autonomous transport vehicle and moving the at least one finger linearly relative to the finger support member in a second direction substantially perpendicular to both the first direction in the reference frame of the autonomous transport vehicle and a travel surface on which the autonomous transport vehicle travels;

detecting, with at least one sensor, indexed movement of the at least one finger in the second direction relative to the movable finger support member, where the at least one sensor includes a registration member and a detection member where one of the registration member and detection member is mounted to each of the at least one finger so as to be linearly movable with and by movement of a respective one of the at least one finger and the other one of the registration member and detection member is stationary relative to the at least one finger, where relative position between the registration member and detection member defines more than two indexed positions of the at least one finger; and

determining, with a controller in communication with the at least one sensor, a position of the at least one finger, along the second direction relative to the movable finger support member, based on a proximity of the registration member relative to the detection member.

2. The method of claim 1 , wherein the other one of the registration member and detection member is mounted on the movable finger support.

3. The method of claim 1 , wherein the at least one sensor is an optical, capacitive or inductive sensor.

4. The method of claim 1 , wherein the registration member comprises a reflective flag or a magnetic source.

5. The method of claim 1 , further comprising:

providing the autonomous transport vehicle with a drive unit for each of the at least one finger; and

actuating, with the controller, the drive unit for each of the at least one finger so each of the at least one finger are moved along the second direction substantially in unison.

6. The method of claim 1 , wherein the drive unit for each of the at least one finger includes a stepper motor.

7. The method of claim 1 , further comprising:

providing the autonomous transport vehicle with an inertial sensor coupled to the controller; and

detecting, with the inertial sensor, a tilt of the autonomous transport vehicle relative to a horizontal plane.

8. A method of operating an automated storage and retrieval system, the method comprising:

providing an autonomous transport vehicle having a transfer arm including at least one finger and a movable finger support member, the at least one finger being movably coupled to the finger support member;

moving the finger support member in a first direction and moving the at least one finger relative to the finger support member in a second direction substantially perpendicular to the first direction;

detecting movement of the at least one finger with at least one sensor, the at least one sensor having a registration member and a detection member where one of the registration member and detection member is mounted to each of the at least one finger so as to be movable with a respective one of the at least one finger and the other one of the registration member and detection member is stationary relative to the at least one finger;

determining, with a controller in communication with the at least one sensor, a position of the at least one finger along the second direction based on a proximity of the registration member relative to the detection member; and

selectively moving, with the controller, each of the at least one finger along the second direction depending on a size of a pickface carried by the autonomous transport vehicle.

9. The method of claim 8 , wherein the at least one sensor includes a registration member and a detection member, and one of the registration member and the detection member is mounted to each of the at least one finger and other one of the registration member and detection member is mounted on the movable finger support.

10. The method of claim 8 , wherein the registration member comprises a reflective flag or a magnetic source.

11. The method of claim 8 , wherein the at least one sensor is an optical, capacitive or inductive sensor.

12. The method of claim 8 , further comprising:

providing the autonomous transport vehicle with a drive unit for each of the at least one finger; and

actuating, with the controller, the drive unit for each of the at least one finger so each of the at least one finger are moved along the second direction substantially in unison.

13. The method of claim 12 , wherein the drive unit for each of the at least one finger includes a stepper motor.

14. The method of claim 8 , further comprising:

providing the autonomous transport vehicle with an inertial sensor coupled to the controller; and

detecting, with the inertial sensor, a tilt of the autonomous transport vehicle relative to a horizontal plane.

15. A method of operating an automated storage and retrieval system, the method comprising:

providing an autonomous transport vehicle having a transfer arm that includes at least one finger and a movable finger support member, the at least one finger being movably coupled to the finger support member;

moving the finger support member in a first direction and moving the at least one finger linearly relative to the finger support member in a second direction substantially perpendicular to both the first direction and a travel surface on which the autonomous transport vehicle travels;

detecting, with at least one sensor, indexed movement of the at least one finger, the at least one sensor having a registration member and a detection member where one of the registration member and detection member is mounted to each of the at least one finger so as to be linearly movable with and by movement of a respective one of the at least one finger and the other one of the registration member and detection member is stationary relative to the at least one finger, where relative position between the registration member and detection member defines more than two indexed positions of the at least one finger; and

determining, with a controller in communication with the at least one sensor, a position of the at least one finger, along the second direction, based on a proximity of the registration member relative to the detection member;

wherein the other one of the registration member and detection member is mounted on the movable finger support.

16. The method of claim 15 , wherein the at least one sensor is an optical, capacitive or inductive sensor.

17. The method of claim 15 , wherein the registration member comprises a reflective flag or a magnetic source.

18. The method of claim 15 , further comprising:

providing the autonomous transport vehicle with a drive unit for each of the at least one finger; and

actuating, with the controller, the drive unit for each of the at least one finger so each of the at least one finger are moved along the second direction substantially in unison.

19. The method of claim 15 , further comprising selectively moving, with the controller, each of the at least one finger along the second direction depending on a size of a pickface carried by the autonomous transport vehicle.

20. The method of claim 15 , further comprising:

providing the autonomous transport vehicle with an inertial sensor coupled to the controller; and

detecting, with the inertial sensor, a tilt of the autonomous transport vehicle relative to a horizontal plane.