8. (a) Explain, with the aid of a sketch, how the piston of a hydraulic ram can
Question:
8. (a) Explain, with the aid of a sketch, how the piston of a hydraulic ram can be mechanically linked to an input servo valve to obtain a negative feedback servomechanism. Describe how a position demand is met.
(b) Assume that you are employed by a company that manufactures hydraulic servomechanisms. You have been asked to recommend an electrical method of providing position feedback rather than the mechanical method used at present. The demand signal has been chosen to be a d.c. voltage. Cost-effectiveness and reliability are essential. Examine position sensor options and select a cost-effective and reliable solution. Justify your choice. Sketch a closed-loop block diagram of the modified hydraulic servomechanism, identifying the sensor, its signal conditioning and the form of error detector. You can assume that the servo valve will be operated by a progressive solenoid that receives its operating current from a voltage-to-current converter.