Recent Question/Assignment

Figure 1 d.c. Motor Position Control
The Technical Specification of the system parameters is:
Motor Armature Resistance 21.2?
Field Constant 20 x 10^-3 Nm/A
Back e.m.f constant 1.8 V / 1000 r.p.m
Step Down Gearbox Ratio 1:300
Load (ref d.c. motor shaft) Inertia 5.9 x 10^-7 kgm^2
Viscous friction 2.9 x 10 ^-6 Nm (rads^1)^-1

Figure 2 Motor Position Control Block Diagram
Task 1
If the controller is to be a simple proportional amplifier of a variable gain k, propose a suitable controller gain based on design calculations and simulations. Use matlab as appropriate. If you prefer to work with a unity negative feedback structure, manipulate the block diagram to achieve this provided it is done correctly. It is not essential to do this, matlab can readily be used to simulate the system with presence of the potentiometer feedback element, or alternatively appropriate closed loop transfer functions can be derived.
[15 marks]
Task 2
Illustrate how additional velocity feedback, from tacho-generator may be incorporated into the closed loop system. Investigate the effect of integrating such a scheme with a proportional controller. Propose a suitable P+D Controller.
[15 marks]
Task 3
Instead of using velocity feedback, improved closed-loop performance may be achieved by introduction of an in series compensator (filter) in the forward path. The compensator may be seen as a replacement for the proportional controller (task 1). Investigate how the parameters of such a compensator maybe designed and how they affect the performance, characteristics of the closed loop system, compared with the results of tasks 2 &3. Propose / design a suitable compensator.
[20 marks]
1. Show all working, derive and explain all steps of working.
2. Embed matlab coding
3. Write report
4. Discuss the graphs generated from matlab and ensure they are sized / zoomed accordingly.