Suggestion on a real time information

[amnandu]

Hi All

I was thinking about a project to work on which

- An object ( could be a ball) has circuit built inside and its thrown at some trajectory .

- The circuit inside the ball has sensor to check or speed of the ball its trhown.

- long range RF may be used to send the information in real time to the PC (MATLAB may be) .

- The object will be thrown multiple times so as to see the speed its been thrown at.

- Can an angle also be calculated?

I dunno if its really possible as RF i need to go for UHF and need to power the antenna as well ...
Any suggestions if its really feasible?

Thanks
Nanda

 

[speedEC]

I dunno if its really possible as RF i need to go for UHF and need to power the antenna as well ...

if the range is very low and in open area (since human can throw a ball up to 100 m only), you can use any low cost RF (Ex 433 MHz RF transmitter and receiver). If you want to measure the angle of the trajectory you can use gyroscope ic (cost is high),

pmk

 

[amnandu]

Cheers speedEC

433 MHz RF transceiver works on UHF at 25mW and an OOK modulation should do the transmission part ?

I have no idea about gyroscope, any information on how to implement them?

 

[KlausST]

Hi,

do you know:
as soon as the ball leaves the hand/foot there is about no accelertion measurable inside the ball (free fall, no G).
You can only measure the negative acceleration caused by air. Without air you will measure zero speed and zero acceleration.
If you want to measure speed you need one ore more external (out of the ball) point to refer to. (GPS for example)

What you can do is to measure accleleration and with that (after the ball leaves the hand) the only thing you can do is to calculate its speed taking the known/fixed acceleration of the earth into account (9.81m/s^2).

Klaus

 

[amnandu]

Thanks KlausST

Didnt really think bout the point you mentioned. About GPS i think the tolerance is about +/- 3mtrs which would not give accurate location of the ball. Hope am right in the information??

Nanda

 

[speedEC]

just google for gyrosensor or gyroscope sensor. There are lot of readily available with digital output in the market. The output can be connected to uC through i2c and read the angle of trajectory in the required interval, say 1 ms.

pmk

 

[chuckey]

A different solution could be based on the Doppler effect. if the ball has a transmitter in it then the apparent received frequency will change as the ball changes its speed. 4.7 GHZ systems can detect a burglar creeping about in a house.
Frank