You must determine your desired resolution/accuracy to make a good selection. All technologies have their weaknesses and you can only choose when you know when the those weaknesses are beyond your tolerance.
Regarding Capacitive Sensors:
I would say capacitive sensors are also relative...
I would say your largest problem right now is the 5mm sensing area. The electric field from the electrode is somewhat conical so the spot size is about 130% of sensing area diameter. This means that the field is wrapping over the edges of your beam and the sensor is already not operating in its...
I'm sorry, but I don't understand "connecting the load cell to the motor" with a cable.
"On the ground" means there is no "load" on the load cell. Are you connecting the frame/chassis/housings of the load cell and motor with a cable?
If not sinusoidal, what does it look like? What exactly is...
You do not have a grounding issue as that nearly always results in line frequency noise.
I don't know where you are seeing this noise. Is it in the output of the load cell? the displacement sensor? What technology is used in each?
Please say more about "disconnecting the cable from load cell to...