1. A method of controlling a stepping motor comprising the step of:
magnetising at least one of a number of teeth within the stepping motor to move a rotor of the stepping motor into a position such that it contacts or maintains contact with a mechanical stop, wherein a first tooth is generally aligned with the mechanical stop and at least one of the teeth is magnetised such that a rotational force acts to urge the rotor in only a direction towards the mechanical stop, thereby resetting the position of the rotor; and
providing n teeth in the stepping motor, wherein n is an even number and the n teeth are arranged in two sets such that a first tooth of a first set is offset by an angle from a first tooth of a second set.
2. A method according to claim 1, wherein the mechanical stop is at a known position.
3. A method according to claim 1, further comprising a start-up step in which a number of the teeth are magnetised to provide the rotor of the motor with momentum.
4. A method according to claim 1, wherein when magnetised teeth of the first set have alternating polarities, and teeth of the second set have alternating polarities.
5. A method according to claim 4, wherein the stepping motor is controlled in half-step mode and the method further comprises a start-up step in which a number of the windings are excited to provide the rotor of the motor with momentum.
6. A method according to claim 5, wherein the start-up step comprises the following steps carried out in sequential order:
magnetising the first tooth of the first set of teeth, the first tooth being generally aligned with the mechanical stop, to form the first pole and magnetising a second tooth of the first set of teeth to form the second pole;
magnetising a first tooth of the second set of teeth, positioned to one side of the first tooth of the first set of teeth, to form a third pole of the same polarity of as the first pole and magnetising a second tooth of the second set of teeth, positioned between the first and second teeth of the first set of teeth and on the opposing side of the first tooth of the first set of teeth to that of the first tooth of the second set of teeth, to form the fourth pole;
ceasing to magnetise the first and second teeth of the first set of teeth;
magnetising the first tooth of the first set of teeth to form the first pole with a polarity opposite to that of the third pole and magnetising the second tooth of the first set of teeth to form the second pole;
ceasing to magnetise the first and second teeth of the second set of teeth; and
magnetising the first tooth of the second set to form the third pole with polarity opposite to that of the second pole and magnetising the second tooth of the second set to form the fourth pole.
7. A method according to claim 6, wherein the start-up step further comprises the following sequential steps:
ceasing to magnetise the first and second teeth of the first set of teeth; and
magnetising the first tooth of the first set of teeth to form the first pole with polarity opposite to that of the third pole and magnetising the second tooth of the first set of teeth to form the second pole.
8. A method according to claim 5, wherein the resetting step comprises the following sequential steps:
magnetising the first tooth of the first set of teeth to form the first pole and magnetising a second tooth of the first set of teeth to form a second pole;
magnetising the first tooth of the second set of teeth, positioned to one side of the first tooth of the first set of teeth, to form the third pole with a polarity opposite to that of the second pole and magnetising a second tooth of the second set of teeth, positioned between the first and second teeth of the first set of teeth and on the opposing side of the first tooth of the first set of teeth to that of the first tooth of the second set of teeth, to form the fourth pole; and
ceasing to magnetise the first and second teeth of the first set of teeth.
9. A method according to claim 8, wherein the first sequential step is repeated a number of times.
10. A method according to claim 9, wherein the first sequential step is repeated twice.
11. A method according to claim 1, wherein the stepping motor is controlled in full step mode.
12. A method according to claim 1, wherein the stepping motor is controlled in micro-step mode.
13. A method according to any one of claim 1, wherein the motor is controlled in half step mode.
14. A method according to claim 1, wherein there are two or more poles on a rotor of the stepping motor.
15. A method according to claim 1, wherein the teeth of the stator are magnetised by using current carrying coils or windings in the motor.
16. A method according to claim 1, wherein the stepping motor is attached to one or more gears.
17. A method according to claim 1, wherein if a first tooth of a first set of teeth is magnetised all of a first sub-set of the first set of teeth are magnetized in a corresponding manner to the first tooth of the first set of teeth, if a second tooth of a first set of teeth is magnetised all of a second sub-set of the first set of teeth are magnetised in a corresponding manner to the second tooth of the first set of teeth, if a first tooth of a second set of teeth is magnetised all of a first sub-set of the second set of teeth are magnetised in a corresponding manner to the first tooth of the second set of teeth, and if a second tooth of a second set of teeth is magnetised all of a second sub-set of the second set of teeth are magnetised in a corresponding manner to the second tooth of the second set of teeth.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device at a cleat for a sailing boat for detachably locking a line of a sail or a rigging, where the line runs over a sheave on an elevated level and the cleat for locking the line is situated at a distance from a deck of the boat, comprising the sheave having a ratchet back stop on the external sheave surface and a movably actuatable mechanism external to the sheave that includes at least one pivotably mounted main arm and that is arranged to activate the ratchet back stop when the line run over the sheave is under fixed load, the line directly engages the movably actuatable mechanism and thereby the movably actuatable mechanism contacts the ratchet back stop and prevents the sheave from rotating backward toward the sail or the rigging.
2. The device of claim 1, wherein the main arm is divided and formed of two arm parts that co-operate with each other.
3. The device of claim 2, wherein an outer spring force-actuated arm part is turnably mounted with an inward turned end portion around a shaft around which an inner arm part is turnably mounted, the outer arm part being arranged to enable, upon overcoming a force of the spring, the inner arm part to form ratchet back stop with the inward turned end portion thereof.
4. The device of claim 1, wherein the main arm is spring force-actuated in a downward hoisting direction of the line.
5. The device of claim 1, wherein the main arm is divided and formed of two arm parts that co-operate with each other.
6. The device of claim 5, wherein an outer spring force-actuated arm part is turnably mounted with an inward turned end portion around a shaft around which an inner arm pant is turnably mounted, the outer arm part being arranged to enable, upon overcoming a force of the spring, the inner arm part to form ratchet back stop with the inward turned end portion thereof.
7. The device of claim 1, wherein an outer end of the main arm has an abutment part that has a form of a concave plate or reel.
8. The device of claim 1, wherein the sheave has a number of cogs, recesses, or radially projecting portions distributed along the circumference of the sheave, and the main arm has a ratchet back stop part in a form configured to cooperate with the cogs, recesses, or radially projecting portions.
9. The device of claim 8, wherein the ratchet back stop is arranged to cooperate with the sheave substantially tangentially in relation to a hoisting direction of the sheave.
10. The device of claim 1, wherein the sheave has a wedge-shaped inner line receipt part, and is arranged to be able, in an unactuated state, to rotate freely in two directions, and to be prevented, upon actuation by the ratchet back stop, from rotating in a back direction, thereby acting as a ratchet sheave.