MechatronicsJob/mechanical/electrical

Before that, there is something I would like you to know about the diagram and explanation.  For Question 3, a) Several correct arrangements such as difference amplifier or Instrumentation Amplifier based, provided that the overall system fulfils the functionality described. A discussion on gain Vs stability and why is expected as is the electromechanical reasons for the inevitable steady state error. Question 4 a) standard PWM coupled MOSFET between motor and ground b) A unity gain PA arrangement fed by a DAC internal or external to the micro. d.i) Standard Vcc to ground pot arrangement with wiper operating as a linear voltage to angle sensor. A Low-pass RC filter required to exclude the 50Hz noise, since the arm is slow moving by comparison, at fc -3db anywhere between 40 and 50Hz  d.ii) A mechanical contact or optical incremental sensor is connected such that a pulse is produced for a given angle increment, connected as a poled input or as an interrupt to the micro driving an internal counter or general purpose register set up as a variable. Are you alright with the things I just mentioned above?Those are things I really need for my diagram and explanation.