kai_luo

CONCORDIA UNIVERSITY

DEPARTMENT OF ELECTRICAL ENGINEERING

ELEC_372FUNDAMENTALS OF CONTROL SYSTEMS

LAB REPORT

EXPERIMENT #1FAMILIARIZATION WITH THE BASIC OPERATIONAL PROCEDURESData Performed: 10/1/2012

Data Submitted: 10/6/2012Familiarization With The Basic Operational ProceduresObjectives: In this lab experiment, we will learn the basic operational procedures and try to gain familiarity with the features of the ECP Model 220 system, the default PI+Velocity Feddback configuration.

Introduction:

In this lab experiment, we will try to use the ECP Model 220 system to learn what the difference between open loop systems and closed loop systems. Furthermore, what we need to do in this experience is using different inputs to get various results, such as ramp input, sinusoidal input, sinusoidal sweep input and so on.

Equipment:

----- ECP Model 220 system

----- Photograph of the rotational mechanism

----- PC and Control BoxClosed Loop:

Comments: As we can see from this picture, there are 2 graphs which show the error varies inversely with the output and approaches zero in the steady state. The first graph increases from 0 to 4750 and decrease a little bit until 1second, then there is a sharp reduce until -800 and the tendency reversed to increase until 0. The second graph which shows the error reduces from 4000 to -500 significantly and keeps constant at 0 from 0.5sec to 1 second (from 0.5sec to 1 sec, there is no error), and then there exist huge error again at -4000.Control Effort: Comments: From this graph, we add the Control Effort to the list of available variables and change the Axis Scaling to 1 sec. As we can see from this line chart which is similar to the last one, the only difference is that the error becomes bigger than the previous chart, because of the control effort in the servomotor, which varies in a manner similar to that of the error and makes an output variation with an observable lead time.Responses for other outputs:

Comments: In terms of this graph, we plot both position and velocity at Encoder#1, as we can see from the black graph, the velocity increases from 0 to 4500 and reduce to -500, while the position increasing from 0 to 4800 at 0.25 sec. Furthermore, from 0.6 sec to 1 sec, there is no acceleration of velocity, after 1 sec there is a significant reduce for both position and velocity and then the trend is reversed until it levels off at -3000 and 0 respectively.Response for other inputs:----- Ramp input:

Comments: This is a ramp input with the default parameters of 10000 counts distance, 10000counts/sec velocity, 100msec dwell time and 1 repetition. As we can see from this line chart, the graph of position is similar to the ramp input which rises from 0 to 10000 when the velocity increases from 0 to 10000, after that the position reduces from the peak to 0, while the velocity is decreasing to around -10000 and increases to -2000 because of the inertia. There is a following error occurred, because of the feedback of the closed loop.Sinusoidal input:

Comments: This is graph with the sinusoidal input and the default parameters of 750 counts amplitude, 2.5 Hz frequency. From this chart, the amplitude of the graphs of input, position and velocity stays at around 750 and the period is 1/2.5Hz=0.4s. Now the graph of velocity with sinusoidal input is more similar to the graph of output position than that of ramp input.Axis scaling:

Comments: As we can see from the graph, only the part from 3sec to 4sec of the whole graph is showed, so we can observe those details from the scaling graph and understand easier than that without scaling.The magnitude ratio: input/output=720/900=80%

The phase shift: 3.5-3.4=0.1sec, so the phase shift around 0.1 second.Sinusoidal Sweep input:

Comments: Now we choose the sinusoidal sweep input with the default parameters of 500 counts amplitude, 0.1 to 12 Hz frequency range, linear sweep. As a glance, the frequency for this graph is much higher than the previous one which is 12 Hz per 30 second. The output graph is the logarithmic sweep, so the trend of the graph is decreasing gradually after 5sec from the peak of 590 to20 and the positive part of output depicts the shape of the magnitude frequency response curve of the system.Axis Scaling (from 1.6sec to 15sec):

Comments: According to this graph, we use the axis scaling to change the range from 1.6sec to 15sec, so only the part from 1.6sec to 15sec of the whole graph can be showed, by doing so, we can see more details of the graph which is easier for us to understand. In this case, we can see the peak exits at 5.4sec with the frequency of 2.16Hz and the magnitude ratio at the peak=540/500=1.08, which is 20log1.08=0.67db.

Open Loop Testing:

In the case of open loop, the voltage is only available for the step and sinusoidal inputs.

Step input:

Comments: we choose the step input with 0.5 volts and 5000ms duration. In this case, we can see obviously, when the input increases from 0 to 840000 the velocity shapes as a ramp which rises from 0 to the peak of 158000 and then reversed to reduce to around 0. Sinusoidal input:

Comments: We choose the control effort to be displayed on the left axis and the sinusoidal input of 3Hz, 0.5 volt, 15-20 repetitions.