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ultrasonic sensors for rotation position measurement

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vamsee

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hi,

is that possible to use ultrasonic sensors to measure rotation of ball and its current position when attached to shaft (without attaching anything on it). if not ultrasonic, whatelse will be the better option?

Thanks
 

Ignorant question:

If you rotate a ball, which property allows you to "view" an actual rotation? There must be an uneven surface, marks or whatever. If you intend to use a particular sensor principle, it must be able to recognize these unique surface features and measure their displacement quantitatively.
 

FvM said:
Ignorant question:

If you rotate a ball, which property allows you to "view" an actual rotation? There must be an uneven surface, marks or whatever. If you intend to use a particular sensor principle, it must be able to recognize these unique surface features and measure their displacement quantitatively.
Click to expand...

thank u for the reply.. I dont want to use particularly ultrasonic sensor, is there any other sensor that measures the position of ball?
 

optical mouse does the same thing.....
 

Give us more information : Must it be a non-contact measurement? Are there unique optical features on the ball? Draw us a diagram
 

klystron said:
Give us more information : Must it be a non-contact measurement? Are there unique optical features on the ball? Draw us a diagram
Click to expand...

thank u for the reply.. my project is to measure the position of ball valve without any contact to the ball.. the picture is attached..

important thing is not to place the sensor to the shaft of the ball and the sensor must withstand temperature of 300°C..

Thanks
 

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With the original ball shape, there's no chance to detect the position from the bottom side. With a modified shape, an inductive proximity sensor could work.

The industry standard position sensor solution for ball valves (and similar valves with rotational drive) is mounted on top of the shaft respectively the pneumatic/electrical drive. Why doesn't it work for you?
 

I think the 300°C degree temperature exclude magnetic scanning with hall sensors. Maybe reflective optical scanning could be an option. What kind of material is the ball and is it always a ball(or is it pressed down to open)? Is the function to regulate the flow?

Enjoy your design work?
 

thank u for the reply... generally due to heavy pressure or high torque acted on the shaft (connection between ball and the actuator) sometimes it breaks and we do not know the exact position of the ball inside, it is very important to find the position even after the shaft breaks. so there must be sensor which directly senses the ball position. pls find the attachment...
 

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The only realistic option without modifying the ball would be placing one or multiple inductive proximity sensors at the side, sensing the bore. The high temperature sensors I'm aware of are rather large, thus I don't know if a suitable commercial sensor exists. But 300° seems basically possible for inductive proximity in my view.

Using an actuator with appropriate torque limit seems the better way, however.
 

Maybe it is an option to approach it from the mechanical side by adding at the bottom another shaft signalling to the outside the position. Then theire are many options to pick-up the position outside the 300° environment. An ultrasound approach from outside (with a transimitter and a sensor opposite) and a DSP-analysis might give acceptable results as well. An important question is if the position needs to be identified permanently (e.g feedback to a process controller) or if it just for repair purpose? Also what is the outside temperature on the surface?

Enjoy your design work!
 
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    vamsee

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one idea!
If you would like to measure the orientation (rotation angle) of the ball, perhaps you can add a coded pattern on the ball surface.
this can help to detect the orientation of the ball from one or two points (two points can provide better resolution)

two light detectors in the locations you have mentioned. if the pattern can be designed properly, you can have the absolute position with desired accuracy and resolution.

- - - Updated - - -

another idea!
If you can design the ball in two layers, then you can design the inner ball with some pattern, which can be sensed by proximity sensors.
the pattern again can provide the capability for absolute positioning.

Ofcourse designing in two layers and the material which can be used in the top layer, depends on various parameters, including the material, pressure, friction and etc.
 

HTA said:
Maybe it is an option to approach it from the mechanical side by adding at the bottom another shaft signalling to the outside the position. Then theire are many options to pick-up the position outside the 300° environment. An ultrasound approach from outside (with a transimitter and a sensor opposite) and a DSP-analysis might give acceptable results as well. An important question is if the position needs to be identified permanently (e.g feedback to a process controller) or if it just for repair purpose? Also what is the outside temperature on the surface?

Enjoy your design work!
Click to expand...

thanq for the good one.. ya the measurements are identified permanently and temp outside ll be max 200°C...
 

Dear vamsee,
Non of the sensor will work without mechanical modification. My opinion you can not make drill hole under the ball-valve because it will create leakage...
Yes the heading is somewhat suitable for your application..."ultrasonic sensors for rotation position measurement". you can use high frequency ultrasonic sensor to detect internal & external metal because you have one hollow open window in the ball... but it need painful R&D work & too expensive & can not fix permanently...

I have one idea but it has less accuracy... & it will work only if anything flow into the valve (gas or liquid)
measure the pressure different between inlet & outlet.... Use some differential pressure sensor... do some calculation & assume the percentage of opening...

Regards
Udhay
 
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    vamsee

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A 200°C max. as an outside temperature still could be a problem for attached electronic. Since there is a hot liquate/gas flow there should be a temperature difference depending on the flow. With two temperature sensor you could test what kind of temperature difference is there depending on the open/close position of the valve and whether that is accurate enough.

Enjoy your design work!
 

Use simple angular potentiometer sensor(variable resistor) and connect the POT shaft & Valve extension using thermal isolation material(EX: backlit plastic, wood, etc... )

Regards
Udhay
 

udhay_cit said:
Use simple angular potentiometer sensor(variable resistor) and connect the POT shaft & Valve extension using thermal isolation material(EX: backlit plastic, wood, etc... )

Regards
Udhay
Click to expand...

but it cant be non contact mode of caliberation...
 

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