Lab #4 – Velocity and Position

Control of a Servomotor

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Introduction:

This report covers the methods, procedures and results of lab #4. During this lab, an understanding of the velocity and position control of a servomotor was developed. Matlab-Simulink was used to represent the transfer functions used during this lab.

Results:

This section of the report goes over the results of the lab questions, including the procedure and how the results were obtained.

We were presented with a linear and non-liner motor model for this lab. The non-linear model accounted for the friction and is more realistic when compared to the linear model. Both Matlab-Simulink Models (block diagrams) can be seen in Figures 1 and 2. For the purpose of this lab, the various motor parameters were taking from the Pittman S232S003 DC data sheet.

The system parameters are expressed below in Table 1.

Table 1: System Parameters for Servomotor (with friction, non-linear)

Velocity Control:

1A. In Figure 3, we implemented a proportional controller (Kp) and used the model to determine the motor velocity, wm, as a function of time for a Vd = 2V u(t). Table 1-2 below summarizes the systems parameters used for this analysis, and the results for this process can be seen in Table 2.

Table 1-2: System Parameters for Velocity Control.

1B. A proportional-integral control was them implemented, alongside the adjustment of Kp and Tr to minimize the settling time within a tolerance of 2% and as well, the steady-state error. The transfer function for a PI controller is given by :

The results can be seen in Table 3 below. Through trial and error, we obtained optimal values were Tr = 19, KP = 2, that accounted for a lower steady state error and settling time when compared to other combinations.

Position Control:

2A. The position control system can be modeled by the