1. Control Theory in Industry, Robotics and Infrastructure
Lachlan Blackhall and Tyler Summers

2. Motivating Example
You walk into your classroom and turn your air conditioning on to a temperature of 24 degrees.
The air conditioner turns on until the internal thermostat registers that the air temperature is 24 degrees then shuts off the air conditioner until the temperature rises again.
A simple controller is responsible for keeping you cool!

3. Systems Modelling

4. Control Components A system
Possibly a mathematical model of that system.
A control goal
A sensor to observe the system
An actuator to influence the system
A control algorithm that tells the actuator how to behave based on the observations of the sensor.
A computer or analog circuit to link it together.

5. Differential Equations
Control is primarily concerned with systems that can be written as differential equations.
Almost everything can be written in this form so control really applies to any physical systems.
It all started with trying to apply external control to simple differential equations.

6. Industrial Applications
Control emerged as a way to automate:
Manufacturing
Assembly
Processing and Refinement
Has since been used successfully in additional areas:
Robotics
Infrastructure

7. Revisiting our Example
The thermostat is one of the simplest controllers you can create.
This type of controller is known as a bang-bang controller.
A bang–bang controller (on–off controller) is a feedback controller that switches abruptly between two states.

8. Bang-Bang Control
They are routinely used to control a plant that accepts a binary input, for example a heater or air conditioner.
Bang–bang controls are actually optimal controls in some cases, although they are also often implemented because of simplicity or convenience.

9. PID Control PID stands for proportional–integral–derivative.
PID is a generic control loop feedback mechanism used in industrial control systems.
The control signal has three components based on the error between the observed operation and the nominal set point:
A proportional component
An integral component
A derivative component

10. PID Control (cont.) Some history Developed in the late 1800s
Initially trialled as a way to control US Navy ship steering.
Can be implemented mechanically, using analog electronics and now using digital electronics like FPGAs
Most commonly implemented in industry these days using programmable logic controllers.

11. PID Control (cont.)
used with permission from

12. PID Control (cont.) Heuristically:
P depends on the present error
I on the accumulation of past errors
D is a prediction of future errors, based on the current rate of change.
The weighted sum of these three actions is used to adjust the process via a control element or actuator.

13. PID Control (cont.)
In the absence of knowledge of the underlying process, a PID controller is the best controller.
The response of the controller can be described in terms of the responsiveness of the controller to an error, the degree to which the controller overshoots the set-point and the degree of system oscillation.
Note that the use of the PID algorithm for control does not guarantee optimal control of the system or system stability.

14. PID Control (cont.)
Some applications may require using only one or two actions to provide the appropriate system control.
This is achieved by setting the other parameters to zero.
A PID controller will be called a PI, PD, P or I controller in the absence of the respective control actions.
– P vs PID Control

15. Demonstration
LEGO Mindstorms Line Following Robot – Bang-Bang vs P Controller
LEGO Mindstorms Segway Robot – PID Control

16. Applications of PID
Assembly
Robotics
SCADA
Building Control

17. Assembly
PID Controllers are vitally important to robots used for automated assembly.
Precision control was the technological breakthrough that allowed robotic assembly to become so commonplace.
Demonstrations:
Car Assembly Footage
– BMW Assembly Plant Footage

18. Robotics
Beyond assembly industrial robots can perform a great many tasks including:
Welding
painting,
pick and place (such as packaging, palletizing and SMT)
product inspection, and testing
There are lots of other robots out there using PID control.

19. Robotics (cont.) Demonstrations:
- Catching balls and darts (Lund)
– ABB Challenge
- ASIMO
– BIG DOG

20. SCADA
How do you control a number of systems, and a number of controllers that are possibly spread out on a factory floor or over a large geographic footprint?

21. SCADA
SCADA (supervisory control and data acquisition) are industrial control systems (ICS) that monitor and control industrial, infrastructure, or facility-based processes.
Industrial processes include:
Manufacturing / production / assembly
Power generation, transmission and distribution
Wastewater collection and treatment
Oil and gas pipelines and refineries

22. SCADA (cont.)

23. SCADA (cont.)
A SCADA system usually consists of the following subsystems:
A human–machine interface or HMI
A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to the process.
Remote terminal units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system.
Programmable logic controller (PLCs) for implementing PID control through actuators.
Communication infrastructure connecting the supervisory system to the remote terminal units.

24. SCADA (cont.) Demonstration Videos

25. Building Control Modern buildings have a variety of control systems:
HVAC
Energy
Security
Structural stability
- Siemens Future Buildings

26. Group Task Forms groups of 8-10. Briefly discuss:
Areas where you think control could or should be used in your society.
Are there systems in your society that could be controlled that are currently not?
Present to the group.