Acceleration sensor calibrated hoist positioning

1. A hoist positioning system comprising:

an accelerometer attached to a hoist;

a control unit for processing signals from the accelerometer and comparing the processed signals with calibration data to determine a position of the hoist, wherein in a calibration mode, the control unit calibrates readings from the accelerometer to different vertical positions of the hoist as the calibration data;

a drive system for moving the hoist up and down; and

a relay that is switched ON or OFF by a control signal from the control unit, wherein when the relay is switched ON, power is supplied to the drive system and when the relay is switched OFF, power to the drive system is cut off.

2. The hoist positioning system according to claim 1 , further comprising an infrared receiver for receiving a destination floor input from a remote infrared transmitter, wherein the control unit sends a control signal to switch OFF the relay when the control unit determines that the destination floor has been reached.

3. The hoist positioning system according to claim 1 , further comprising a wireless transceiver for communicating with a base unit in a control room.

4. The hoist positioning system according to claim 1 , further comprising a wireless receiver for communicating with a base unit in a control room, wherein when a destination floor input is received from the base unit through the wireless receiver, the control unit sends a control signal to switch OFF the relay when the control unit determines that the destination floor has been reached.

5. The hoist positioning system according to claim 1 , wherein the control unit is mounted to the hoist.

6. The hoist positioning system according to claim 1 , wherein the control unit is operable in the calibration mode and an operation mode.

7. The hoist positioning system according to claim 1 , wherein the relay is an SCR.

8. A hoist positioning system comprising:

an accelerometer attached to a hoist;

a drive system for moving the hoist up and down; and

a control unit for issuing signals to control the drive system, the control unit operable in a calibration mode and an operation mode,

wherein, in the calibration mode, the control unit calibrates first readings from the accelerometer to different vertical positions of the hoist as calibration data, in the operation mode, the control unit moves the hoist to a particular vertical position based on second readings from the accelerometer and the calibration data.

9. The hoist positioning system according to claim 8 , further comprising an infrared receiver for receiving a destination floor input from a remote infrared transmitter, wherein the control unit moves the hoist to the destination floor based on the second readings from the accelerometer and the calibration data.

10. The hoist positioning system according to claim 8 , further comprising a high-voltage power source for the drive system.

11. The hoist positioning system according to claim 8 , further comprising a relay that is switched ON or OFF by a control signal from the control unit, wherein when the relay is switched ON, power is supplied from the high-voltage power source to the drive system and when the relay is switched OFF, power from the high-voltage power source to the drive system is cut off.

12. The hoist positioning system according to claim 8 , wherein the relay is an SCR.

13. The hoist positioning system according to claim 8 , further comprising a wireless transceiver for communicating with a base unit in a control room.

14. The hoist positioning system according to claim 8 , further comprising a wireless receiver for communicating with a base unit in a control room, wherein when a destination floor input is received from the base unit through the wireless receiver, the control unit sends a control signal to switch OFF the relay when the control unit determines that the destination floor has been reached.

15. A hoist positioning method comprising:

controlling a hoist to different vertical positions and calibrating first readings from the accelerometer to different vertical positions of the hoist as calibration data;

receiving a destination vertical position for the hoist; and

moving the hoist to the destination vertical position based on second readings from the accelerometer and the calibration data.

16. The hoist positioning method according to claim 15 , wherein moving the hoist to the destination vertical position includes switching ON a relay to cause power from a high voltage power source to be supplied to a drive system for the hoist.

17. The hoist positioning method according to claim 15 , wherein moving the hoist to the destination vertical position includes switching ON a relay to cause power from a high voltage power source to be supplied to a drive system for the hoist, and switching OFF the relay when the destination vertical position has been reached.

18. The hoist positioning method according to claim 15 , wherein moving the hoist to the destination vertical position includes determining if the destination vertical position has been reached based on a comparison of the second readings from the accelerometer with the calibration data.

19. The hoist positioning method according to claim 15 , wherein the destination vertical position for the hoist is received from an input device operated on the hoist.

20. The hoist positioning method according to claim 15 , wherein the destination vertical position for the hoist is received from an input device operated in a control room remote from the hoist.