dknguyen said:
I have a accelerometer that outputs an analog voltage that outputs with a scale factor of say, 500mV/g. I want to integrate the output (or double integrate the output) so that I can get the velocity (and displacement).
You are going to suffer alot with this, double integration will cause you alot of problems any slight offset will be integrated to a slope after the 1st integrator and then into a quadratic by the next so if you are not careful you can get it running away very easily
dknguyen said:
I can do it through digitally sampling the output voltage, but was wondering if there was an analog circuit or device capable of doing it (since then method could inherently filter out noise without the use of filters, remove a lot of quantization noise, and would offload a lot time-sensitive of work from the processor).
Yes there is an analogue cct it is called an "integrator"
**broken link removed**
Why do you say "inherently filter" an integrator is effectively a low-pass filter and even if it was implemented in digital it would filter as well.
You wont really be removing quantization noise since I guess some where down the line you will still be passing this signal through an ADC.
IF anything it will be more stable in the digital domain due to OPAMP offsets and noise outputs. IF it was a single integrator then sure analogue will do nicely (equally digital), but cascading integrator after integrator will cause problems since the output of the 1st integrator will contain the integrated signal+OPAMP noise+OPAMP offset (this offset will then get integrated by the 2nd)
Sure you can put a nice arrangement of variable resistors down to tune the offset but there is alot of time involved in calibrating it to remove the offsets - 2 off as oposed to only one calabration for the digital domain. Equally any variations in temp or other variables (the state of solder-points) will increase noise injected into the analogue implementation
The only real arguement for having it in the time-domain is limitations in the digital (space,polling etc)
dknguyen said:
The basic process I was going to use whether it was analog or digital was to time-integrate the voltage (once or twice) and then digitizing the result and digitally multiply the result by the scale factor (once or twice) to give me real-world phenomena (velocity or displacement) being measured.
I also have a rate gyroscope that outputs a velocity as an analog voltage which I would also like to time-integrate so that can get the total angular movement. Its the same idea as above.
The only integrators I have been able to find work by integrating a current and outputting the result as a voltage. I need a circuit that integrates a voltage and outputs the result as a voltage so that I can cascade them together to achieve multiple-integrations.
Why do you need a "current" ?