you have a negative supply in the system?

which kind of help do you need? a resistor to voltage converter seems like a resistive sensor, with the voltage divider and voltage buffer, you track the output voltage. I think if you want a good track, first your supply votlage should be quite stable, or else, you need a Vref. The bipolar transistor may help you to generate the Vref, maybe the buffer as well. The output voltage accuracy depends on the sensitivity requirement of your sensor.