Chemical Engineering @ UP wiki - User contributions [en]

Ball and Plate Control Rig

2017-11-16T21:04:54Z

Adrian Russel: Created page with "== Introduction == The ball and plate control rig is a two by two system, consisting of a flat plate on which a ball is balanced. The angle of the plate is manipulated by digi..."

== Introduction ==
The ball and plate control rig is a two by two system, consisting of a flat plate on which a ball is balanced. The angle of the plate is manipulated by digital servo motors while ball position feedback is obtained by processing images taken by a camera mounted above the plate.

==2017 - Adrian Russell==
'''Build'''
[[File:3D_Model.png|500px|left|thumb]]
The rig was designed using the free Design Spark CAD software. The plate of the rig is 400 mm on each side, and is made out of a rigid plastic.

A Raspberry Pi 3 is used to perform all of the input and output operations to and from the process, as well as computational tasks. A Raspberry Pi camera is connected to the dedicated CSI serial port of the Raspberry Pi, allowing for low latency image capturing at up to 200 fps.

All control measurement and control operations are carried out using Python 3 on the Raspberry Pi.

An Adafruit PWM Servo Driver board is used to provide the PWM signals to the servo motors.

High torque digital servo motors are used to manipulated the plate angle.

'''Modelling'''

Since the system is open loop unstable, modelling needs to be carried out with the MVs returning to their steady state position (i.e. zero). Therefore, step tests were conducted in which the duty cycle of the servo motors was stepped up and then down in quick succession, allowing the process to stabilise at a different steady state position, with zero velocity and plate angle.

Linear transfer function models were then fitted to the time domain responses in MATLAB.

'''Control'''

Three controllers have been implemented for the ball and plate system, namely: Proportional-Derivative (PD), Linear Qaudratic Gaussian (LQG) and Linear Quadratic Integral (LQI) control.

The since the system is isolated, the majority of disturbances are Gaussian distributed, and therefore fair controller performance is obtained using the LQG and LQI methods. The PD controller provides the fastest system response, however it is most susceptible to process noise.

A Kalman filter is implemented as a state estimator in order to provide full state feedback for the LQG and LQI controllers.

The fitted linear process models are used in the Kalman filter to estimate the states based on known system dynamics.

File:3D Model.png

2017-11-16T21:03:08Z

Adrian Russel:

PMC Lab

2017-11-16T20:43:03Z

Adrian Russel: /* Rigs */

The Process Modelling & Control lab currently contains five working rigs. The [[Opto 22]] unit is usually refered to as the sixth rig. Equipment on the rigs (and in the lab) is discussed in the lab equipment section. The lab manual is available [http://ragnarok.up.ac.za/documents/labmanual.pdf here]. New users wanting to set up computers and software should have a look at [[PMC Lab Users|this page]].

== Rigs ==
For the rigs in the Tribology labs, see [[Tribology|this page]].

<big>'''[[Acetone Flashing]]'''</big>

The acetone flashing rig is a four by four control problem. You can find the documentation [http://ragnarok.up.ac.za/Rigs/01_Acetone/ here].

<big>'''[[pH Loop]]'''</big>

This rig demonstrates pH control. You can find the documentation [http://ragnarok.up.ac.za/Rigs/02_pH/ here].

<big>'''[[Temperature Control]]'''</big>

The temperature control rig was rebuilt by Ivan and David in 2005. You can find the documentation [http://ragnarok.up.ac.za/Rigs/03_Temperature/ here].

<big>'''[[Level and Flow]]'''</big>

Level and Flow is one of our favourite rigs. You can find the documentation [http://ragnarok.up.ac.za/Rigs/04_Level_and_flow/ here].

<big>'''Distillation Columns'''</big>

There are two distillation columns in the chemical engineering laboratories;
* documentation for the [[small distillation column]] (in the PM&C lab) can be found [http://ragnarok.up.ac.za/Rigs/05_Distillation/ here].
* information on the column [[big distillation column]] (between the 3rd year labs and the PM&C lab) .
<big>'''[[Slug Flow]]'''</big>

This unit, copied from a setup done by Ingvald Bårdsen under supervision of Espen Storkaas and Heidi Sivertsen at [http://www.ntnu.no/indexe.php NTNU], models severe slugging behaviour in a pipeline/riser system.
* the original information is hosted at http://www.nt.ntnu.no/users/skoge/diplom/prosjekt03/bardsen/ (this will, if anything, improve your Norwegian)
* our lab documentation is available [http://ragnarok.up.ac.za/Rigs/Slugflow/ here].

<big>'''[[Dual Fluidised Bed System]]'''</big>

This unit, intended to produce bio-oils from woody biomass, is still under construction by Stephen Swart and Prof. Heydenrych. It is intended to be completed by 2012, with the design outlined in [http://ragnarok.up.ac.za/Rigs/08_DualFluidisedBed/2011/Reference%20Material%20-%20Swart%20(2010)/CRO_700_Project%20Design%20Report.pdf Swart (2010)]. The documentation can be found [http://ragnarok.up.ac.za/Rigs/08_DualFluidisedBed/ here].

<big>'''[[Ball and Plate Control Rig]]'''</big>
This rig is a rapid prototyping and test unit for control systems, consisting of the task of stabilisation and reference tracking of an open loop unstable system.

== Lab equipment ==

Equipment for the rigs are (should be) documented on their respective pages. Some additional equipment in the PMC lab include;
* [[PMC testing equipment|Testing equipment]]

== Contact Details ==

<big>'''[[Burkett Valves]]'''</big>

<big>'''[[Opto Controls]]'''</big>

<big>'''[[Mantech Electronics]]'''</big>