Method of operating a stepper motor especially adapted for use with a data storage library picker assembly

A method applied to a picker device confined to a tape library, the method comprising:

• providing a tape cartridge, a slot wherein the tape cartridge is adapted to be disposed, and the picker device, wherein the picker device comprises a stepper motor, a pair of jaws operable to be moved towards or away from each other via the stepper motor, and at least one pressure sensor directly influenced by at least one of the jaws;
• a) opening the jaws to a separation greater than the width of the tape cartridge;
• b) moving the picker device in a position where the jaws are capable of clamping the tape cartridge;
• c) energizing the stepper motor at a first slow speed to establish a detent position and a rotational direction of the stepper motor;
• d) ramping up the stepper motor to a first high speed in the rotational direction thereby causing the jaws to close;
• e) sensing a first pressure at a first pressure threshold via the pressure sensor when at least one of the jaws contacts the tape cartridge;
• f) ramping down the stepper motor in the rotational direction to a first medium speed in response to sensing the first pressure attaining the first pressure threshold;
• g) sensing a second pressure at a second pressure threshold via the pressure sensor;
• h) slowing the stepper motor to a second slow speed in the rotational direction in response to sensing the second pressure attaining the second pressure threshold;
• i) sensing a third pressure at a third pressure threshold via the pressure sensor wherein the jaws fully clamp on the tape cartridge;
• j) stopping the stepper motor in response to sensing the third pressure attaining the third pressure threshold;
• and
• k) if the pressure sensed by the pressure sensor varies from the third pressure threshold, rotating the stepper motor in the rotational direction or an opposite rotational direction to maintain the third pressure to hold the fully clamped jaws on the tape cartridge.