# Measuring jump height?

Is it possible to measure jump height with any of the different accelorometers for arduino?
I want to measure the when you jump with a kite board.

Thanks
Magnus

Patience grasshopper.
Good things take time. Miracles take a little longer.

What did you do so far.
Leo..

Hi,

It will tell you what is involved and why it is hard to do.

Tom...

Is this possible?

https://en.wikiversity.org/wiki/User:Fnarmouq2655/ENES100/Project_1

Hi,
That project is possible, they use the accelerometer to just detect the start and top of the jump. that is the point that acceleration spikes and when acceleration = 0.

They use this to start and stop a timer then use a simple physics equation to calculate the height.
They don't directly use the accelerometer figures to calculate the height.

This may be what you need.

The equation is Distance = vi * t + 1/2 * a * t2
Although the code measures time from start of jump to top of jump, the fall time will be the same.

You have to think of the fall of the jump. at the start of the fall..

vi = initial velocity, metres, in this case zero
t = time interval, seconds
a = acceleration, in this case with vertical fall, the force of gravity, 9.81 m/s2

So
Distance (m) = 1/2 * 9,81 * t2

Its worth a try.

Tom...

iggy2:
Is this possible?

User:Fnarmouq2655/ENES100/Project 1 - Wikiversity

Accelerometers in the shoes... when this person jumps, will their legs stay extended after leaving the ground? I.e. will they behave as a box with accelerometer that has been launched? Perhaps center of body would be better unless you want to know how high the feet went.

If they keep their head up you could try putting an ultrasonic sensor in the ceiling and see the difference between standing straight and the closest approach. Those are good to about 14 feet.

TomGeorge:
Distance = vi * t + 1/2 * a * t2

As long as the jumper isn't pulling their feet up as the rest of their mass is coming to zero, that could add 1/4 second or more to the time. Worst part is, they likely won't know anything but "when I do this I jump way higher!".

The exact calculation requires to integrate the measured accelerations over time, to yield the velocity, then integrate the velocity to get the distance. For measuring a height the gravity has to be subtracted from the vertical acceleration, what already may be done inside a calibrated sensor.

If the sensor is rotated during the jump, what will occur at least with a shoe-mounted sensor, the calculations deserve measuring of rotation angles, and higher dimension (3D) and higher degree math.

GoForSmoke:
Accelerometers in the shoes... when this person jumps, will their legs stay extended after leaving the ground? I.e. will they behave as a box with accelerometer that has been launched? Perhaps center of body would be better unless you want to know how high the feet went.

If they keep their head up you could try putting an ultrasonic sensor in the ceiling and see the difference between standing straight and the closest approach. Those are good to about 14 feet.

I agree, you would put it near the centre of mass rather than a swinging appendage.
In a kite board application, it may need refinement due to the body already possibly moving around in a vertical direction.
Tom...

The jumps is between 1m up to 20m.......can you us the force of gravity, 9.81 m/s2 ??..
the kite will act like a parachute..is the any code you can try?

Thanks.
Magnus

Hi,
Yes that will be a problem, hmm your kite will be lifting, so more than just 9.81 m/s2 to use.
So back to using the actual data from the sensor.
And as pointed out by DrDiettrich you will be doing rotations of the body so the orientation of the accelerometer will be changing.

Tom...

Look into how automated quadcopters know their altitude.

This seems a little too obvious but could you not just use an altitude sensor? (barometer) Your resolution would be 0.25m. You could then just use an accelerometer to determine when takeoff happened?