PIP Control – Matlab Session
Introduction:
You will be using a simple model and testing the design of PIP by Pole-placement and Linear Quadratic Control.
Then you will apply the same process to design a controller for a “real” motor modelled in Simulink.
Exercise Aim:
To practice the design of PIP control systems using matlab.
How to work:
Work either individually or in pairs and keep rough notes for your own future reference in your notebook.
The Tasks to be undertaken
Task 1: First, create a directory in which to work and down load the files for this exercise.
1. Open Ex3.m in the editor. Follow the design process in matlab and run the file. See if you can swap the pole locations and what difference this makes.
2. Modify Ex 3 to do the design by Linear Quadratic Control. Initially use default values for the weights then try modifying them and see what the effect is.
Task 2: DC Motor Control
Now you will use your model of the motor obtained in Lab 2 to design a PIP
Controller and test it on the complete motor system. The design specification for the closed-loop are given below.
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Motor Control Specification
Time response:
- Type-1 Servo performance (the error should be zero in the steady-state)
- For a step input of 100 rad/s the performance must meet:
Rise time <0.1s, Settling-time<0.3s, Overshoot<20%
- A 0.02Nm step load disturbance should be rejected within 0.2s (Note motor max continuous torque is 0.1Nm so this is approx. 20%).
- The peak voltage applied should if possible be less than +/-10V which is the limit of the real motor. If not possible, you can limit it in the PIP control block.
Frequency Domain requirements:
- The system should have adequate stability margins
- The closed-loop bandwidth should be at least 2Hz
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To load your model and get started … .. (suggest using matlab m-file)
>> clear
>> load my_motor_model.mat
Form. the nmssform, design a controller for the motor with LQ and/or Pole- placement.
a. Test it on the TF model (Motor_discrete.slk)
b. Test it on the “real” motor model (motor_real.slk)
* Note: I have provided an emergency model roger_possible_motor_model.mat for use if your system identification exercise was a complete disaster or you have forgotten to bring your model. However, this model is not the “correct” one it is just one of several possible models. So stick with your own if you have one.
Deliverables:
The results will be discussed during the exercise (with support from tutors).
The results will be part of the assessed coursework report that you will write (see separate coursework report guidance).
Once you have successfully completed this Lab, the coursework will be straightforward (i.e. the PIP control design part of it is done, apart from generating graphs, diagrams and reporting).
Files: