P11011: Modular Motion Tracking Knee Flexion Unit V1

ADC Resolution

ADC Resolution

The analog-to-digital converter (ADC) has 2^10 bits of resolution and can operate from 0 V to Vcc, which is 5 V in the case of the knee flexion sensor. The output of the potentiometer ranges from 0 V to 5 V and has an operating range of 312 degrees. The values of least significant bit are determined by dividing the input range of the ADC and thus the degree range of the potentiometer by the number of bits.

V_LSB = (5V - 0V)/1024bits = 4.88 mV/bit
a_LSB = 312deg/1024bits = 0.305 deg/bit

The buffer amplifier reduces the voltage range 0.025 V to 4.975 V, effectively losing 1% of the range. Amplification could be used to get full use of the ADC but with this small loss, it is not required. The sensor still has 309 deg of range and can measure within 0.305 deg of accuracy, which exceeds the specifications.

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