Linearising a electromechanical control system with Motor, Gear box with stiffness and PWM contoller

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Hello Matlab Experts,
I am trying to model a position control problem with simulink simscape components. The following components are used. 1. PI(s),H Bridge , controlled PWM , a comparator to generate a direction for H bridge, DC motor, Gear box, and spring representing gear box stiffness and a load as inertia ,inertia of the order of 10e6 kg*m^2, and suitable PS-S and S-PS blocks and a ideal rotational reference sensor.
2. When i try to simulate the system the system works and tracks the input with few SS error and with small oscillation. Now i am required to tune the system using PID tunning.
As i understood prior to tuning of the plant I am required to linearize the plant and the only i can apply automated PID Tuning.
I tried the linearization of the plant with system identification using simulutated I/O in the PID tunning tool box. During this i observed the instead of tracking step command the output continuously increase like a ramp. Can any one help to solve the issue ?
Regards Prima Rodrigues

Answers (1)

Arkadiy Turevskiy
Arkadiy Turevskiy on 26 Nov 2014
Please try to follow this example which is very similar to the workflow you are trying to use. If you run into the issues, please provide a clear and detailed explanation of what specifically is not working.
  2 Comments
Prima rodrigues
Prima rodrigues on 27 Nov 2014
Hello.. I attached to plots one with simulation result with P=1 and I=1 and running simulation for 40 sec( tried upto 200 sec) , the observation is that output is trying to track the input value of 0.01 degree , but during the system identification the output looks like a ramp and not settling , the figure pid.png show system identification GUI. Any clue for solving the issue?
Thanks & Regards Prima Rodrigues
Prima rodrigues
Prima rodrigues on 27 Mar 2015
Hello, I am trying to obtain the tf of the plant using bode linear analysis plot using simulink.The obtained tf have very high frequency poles and zeros which is not desirable. Could u suggest to extract the tf of the simulink model for a given frequency range say 0.01 to 1000 Hz.I am tried with bounds option available in bode but it didn't solve the problm Thanks Prima.R

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