And you have the cart before the horse. Find the equations and we can determine the effect of a high impact on the target versus a low impact on the target. I am quite certain the equation will include the distance from the pivot point.
Do you know the force? I don't. Do you know the speed? I don't. On the free floating target you have F=ma and F=1/2mV2. Since you don't want want to use the target you have only F=1/2mV2 where you know neither F nor v. 1 equation, 2 knowns.
No. You are the one putting the cart before the horse. What you're doing right now is similar to building a simulator, and then assuming it will reflect reality without actually comparing it to reality. The fact you have no idea what the numbers should be or what variables you can and cannot ignore is testament to this. In theory, theory matches reality. In reality, it doesn't. Even simple measurements of well known things under controlled conditions at the lab here rarely match up with the math.
I don't care IF the ball hits the target. The ball must hit the target to produce a reading. The reading is acceleration. The only way I have to determine force is from acceleration through the equation that knows seems to know.
Like I said before, speed is tied to the impact force and much easier to measure and interpret directly. You may not want to do it that way for practical reasons involved with the hardware and that's fine. However, I think you are vastly underestimating how reality doesn't always match up with pure math. Mount an accelerometer to the backside of the board and throw a few balls at it at different speeds and angles. I guarantee you the acceleration waveform that you get is a lot messier than you seem to think it will be. So messy it may not even be worth working with, or at least not worth working with on an equation level. If you have already seen the acceleration waveforms for a bunch of kicks, fine, but I somehow don't think you have.
Note that I'm talking about acceleration waveforms here as in a graph unless you have already verified that you can get reliable and consistent peak acceleration readings under most conditions and angles of shots (and soccer balls of different tolerable inflations for that matter). To get a graph of those readings you would either need to scope the accelerometer or have the processor sample and save the data and then spit it out to the PC so you can graph it in a spreadsheet program.
What processor are you planning on using BTW?
How do I use the accelerometer samples values to sum force versus time?
If you try this, you definitely will need to observe the graphs of the acceleration waveforms to know if your results are reliable and to handle any unexpected weirdness in the nature of the curves (like biases, noise, and bandwidth issues). Look up "numerical integration", "numerical methods", and/or numerical methods. These can be processor intensive so you need to make sure your processor can cope.
The target is NEVER going to be horizontal. It will ALWAYS be vertical. As for the rest, ???
Huh? The target is going to be directly above or below the player? I don't think you understood what I was saying. When I say the target is horizontal to the shooter, I don't mean the orientation of the target board. I mean the line between the player and target.
The OP was quite straightforward but for some reason everyone is so hell bent to redesign/design by committee.
That's what happens when you go to a group of people who know what they're doing and ask about how to go about things in the wrong way. We get questions like this all the time.