Intelligent motorized lifting device

1. An apparatus comprising:

a drum to draw in or let out a line from the drum, the drum comprising a helical groove formed in an outer surface thereof to accommodate the line,

the helical groove dividing the outer surface into multiple segments of peaks and valleys;

a passive guide mounted on a slide adjacent the drum comprising a plurality of teeth tracking and extending into the helical groove between at least two of the peaks, wherein the passive guide pushes the line into the helical groove;

the passive guide further comprising an opening through one of the teeth, the opening being connected to a channel running through the passive guide to an opening in a top surface thereof to guide passage of the line through the passive guide and onto the drum;

a motor and transmission coupled to the drum to apply a torque thereto;

a tracking module to track a current amount of line let out from the drum;

a servo control unit to receive the current amount, compare the current amount to a desired amount of line to let out from the drum, and generate an error signal reflecting a difference between the current amount and the desired amount;

a modulation module to generate, from the error signal, a control signal to control the motor to bring the current amount into better alignment with the desired amount;

a set point module to enable a user to establish at least one intermediate set point between a low set point and a high set point, each set point reflecting a preselected amount of line to be let out from the drum, stored in persistent memory.

2. The apparatus of claim 1 , wherein the set point module establishes a set point for a current amount of line let out from the drum.

3. The apparatus o claim 1 , further comprising a smart lift module to cause the desired amount to be set in accordance with a set point immediately below the current amount of the line let out from the drum.

4. The apparatus of claim 1 , further compromising a smart lower module to cause the desired amount to be set in accordance with a set point immediately below the current amount of line let out from the drum.

5. The apparatus of claim 1 , wherein the control signal varies in accordance with the error signal.

6. The apparatus of claim 1 , wherein the control signal is a pulse-width-modulated signal.

7. The apparatus of claim 1 , wherein tracking a current amount of line let out from the drum comprises tracking an angular position of the drum and a number of rotations of the drum.

8. The apparatus of claim 7 , further comprising an absolute position encoder to measure the angular position of the drum.

9. The apparatus of claim 7 , further comprising a counter to keep track of the number of rotations of the drum.