Yet the elevator arrives at some velocity after not moving, therefore it must experience acceleration in addition to the static acceleration of the of the earth's gravity.

In theory this can be done with a sensitive enough accelerometer. Would you mind describing your accelerometer experiment? Somebody might be able to make a helpful suggestion.

You can get accelerometers sensitive enough to make a digital electronic spirit level.

The ultrasonic option could well be impaired by the noises from the machinery, optical sensors probably wouldn't be reliable because elevator shafts tend to be dirty environments.

For position sensing on the cable drum, Hall effect sensors might be the best option.

One opto that hasn't been mentioned - the opto-gyro which I think was used for navigation when they dug the channel tunnel.

As far as I can understand it - laser pulses are sent round a big reel of fibre-optic cable. The speed of light is a constant (for that fibre-optic medium) so rotating the drum will advance or delay the pulses that emerge from the other end.

 

Yet the elevator arrives at some velocity after not moving, therefore it must experience acceleration in addition to the static acceleration of the of the earth's gravity.

In theory this can be done with a sensitive enough accelerometer. Would you mind describing your accelerometer experiment? Somebody might be able to make a helpful suggestion.

Yes why not.
I tried with 3 axis accelerometer. But the problem with this accelerometer is that it can sense the motion when it is tilted in either X or Y direction.
For Z direction we need to move up & down very fastly. So in lift this motion is not possible to sense.
i attached image for easy understanding.

 

Yes why not.
I tried with 3 axis accelerometer. But the problem with this accelerometer is that it can sense the motion when it is tilted in either X or Y direction.
For Z direction we need to move up & down very fastly. So in lift this motion is not possible to sense.
i attached image for easy understanding.

This suggests that your accelerometer is not sensitive enough, not that using an accelerometer will not work.

If one of the other axes of the accelerometer that you have now is more sensitive you can rotate the accelerometer so that axis is along the Z axis. Otherwise a good option would be to look for a more sensitive accelerometer.

Alternatively, is there a control or display signal that is sent to the elevator that can be used to know when the elevator starts moving?

 

This suggests that your accelerometer is not sensitive enough, not that using an accelerometer will not work.

If one of the other axes of the accelerometer that you have now is more sensitive you can rotate the accelerometer so that axis is along the Z axis. Otherwise a good option would be to look for a more sensitive accelerometer.

Alternatively, is there a control or display signal that is sent to the elevator that can be used to know when the elevator starts moving?

No, there is no such signal sent to elevator.
I agreed that I need more sensitive accelerometer, but still I have doubt about sensing the motion which happens in the lift using high sensitivity accelerometers.
I used Piezo sensor also even this didn't worked shown in the image . Todays Lifts uses VFD's therefore at the start or end of the lift we can not get that much push we can feel which were we got in without VFD's.

 

Yes why not.
I tried with 3 axis accelerometer. But the problem with this accelerometer is that it can sense the motion when it is tilted in either X or Y direction.
For Z direction we need to move up & down very fastly. So in lift this motion is not possible to sense.

You're doing something wrong. If it can detect tilt, that means it can detect in the range of 0-1 g. This would be fine for your application. As Dick noted, perhaps you merely need to use a different axis if there is something wrong with the z-axis.