Demonstrator of advanced controllers Hans Dirne Supervisors prof.dr.ir. J. van Amerongen dr.ir. J.F. Broenink dr.ir. T.J.A. de Vries ir. P.B.T. Weustink May 25 th, 2005 Master of Science assignment

May 25 th, 2005Demonstrator of advanced controllers2 Why this assignment? The Major ‘Mechatronics’ provides several courses in control theory, in which the theory is often supported by simulations. A physical setup might, in addition to simulations, be an enrichment for demonstrating control theory. Such a demonstration setup will be able to make the theory more insightful and will show real limitations in practical setups.

May 25 th, 2005Demonstrator of advanced controllers3 Objectives 1.To design, build and test a mechatronic demonstration setup, with which several control algorithms can be shown in practice 2.To be able to demonstrate performance differences of control algorithms in practice

May 25 th, 2005Demonstrator of advanced controllers4 Overview 1.Demonstration setup options 2.Control systems 3.Design of the new demonstrator 4.Experiments 5.Demonstration 6.Conclusions & recommendations

May 25 th, 2005Demonstrator of advanced controllers5 Demonstration setup options

May 25 th, 2005Demonstrator of advanced controllers6 1.Mechatronic system 2.Portable and easy to set up 3.Robust, safe and failsafe design 4.High level of observability 5.Representable by linear 4 th order model 6.Clear link with well known device Criteria

May 25 th, 2005Demonstrator of advanced controllers7 Three options 1.‘Linix’ laboratory setup 2.Setup of ‘Controllab Products B.V.’ 3.New build

May 25 th, 2005Demonstrator of advanced controllers8 Option 1: ‘Linix’ Laboratory Setup

May 25 th, 2005Demonstrator of advanced controllers9 ‘Linix’ Laboratory Setup motor encoders inertia 2 inertia 1 transmission

May 25 th, 2005Demonstrator of advanced controllers10 ‘Linix’ Laboratory Setup

May 25 th, 2005Demonstrator of advanced controllers11 ‘Linix’ Laboratory Setup Major disadvantage: slip between belt and inertias

May 25 th, 2005Demonstrator of advanced controllers12 Option 2: CLP setup

May 25 th, 2005Demonstrator of advanced controllers13 CLP setup

May 25 th, 2005Demonstrator of advanced controllers14 CLP setup

May 25 th, 2005Demonstrator of advanced controllers15 Sensor positions

May 25 th, 2005Demonstrator of advanced controllers16 Option 3: New Build Advantage Pure design freedom Disadvantage Requires very much time and effort to design

New buildLinixCLP-setup Mechatronic system√√√ Linear 4 th order model√limited linearto be determined Portable, easy to set up√√not in current form Robust, safe, failsafe√√feasible Observability√yes, 2 position Sensors yes, 4 position sensors Link with practical device√transmissionprinter Shows controller differences√no, due to nonlinearities To be determined RemarksTime constraint Overview demonstrators

May 25 th, 2005Demonstrator of advanced controllers18 Control Systems

May 25 th, 2005Demonstrator of advanced controllers19 Mathematical model – 6 th order Viscous PLUS coulomb friction

May 25 th, 2005Demonstrator of advanced controllers20 Focus 1.Linear Quadratic Gaussian (LQG) 2.Proportional, Integral, Differential (PID)

May 25 th, 2005Demonstrator of advanced controllers21 LQG explanation A LQG control algorithm is a combination of 1.Lin. Quad. Regulator (state feedback) 2.Lin. Quad. Estimator (state estimation) 4 th order linear model required!

May 25 th, 2005Demonstrator of advanced controllers22 4 th order linear model Required steps: 1.Downsize system order 2.Linearize system: discard coulomb friction Result: linear 4th order model (e.g. State Space)

May 25 th, 2005Demonstrator of advanced controllers23 LQG controlled system

May 25 th, 2005Demonstrator of advanced controllers24 PID

May 25 th, 2005Demonstrator of advanced controllers25 Tuning (1) For proper comparison of the PID with the LQG controlled system, tuning with the same criteria is required. 1.Avoid actuator saturation 2.Minimization of criterion: position errorcontroller output

May 25 th, 2005Demonstrator of advanced controllers26 Tuning (2) Tuning procedure: 1.Set Q and R 2.Minimize criterion J by optimizing controller gains (K LQG and K P,K I,K D )

May 25 th, 2005Demonstrator of advanced controllers27 Tuning (3) Optimization results K P = 15.7 K I = 42 K D = 1.6 K LQG = [3.7, 74, 8.2, 70] T

May 25 th, 2005Demonstrator of advanced controllers28 PID vs LQG (1) The PID controlled system consumes twice the power of the LQG system The maximum frame movement in the PID controlled system is twice compared to LQG

May 25 th, 2005Demonstrator of advanced controllers29 PID vs LQG (2) The LQG control algorithm leads to an unacceptable position error with the nonlinear process

May 25 th, 2005Demonstrator of advanced controllers30 LQG+

May 25 th, 2005Demonstrator of advanced controllers31 LQG+ vs LQG Effect of integrator: Static error is minimized! Interesting to see the performance of LQG+ in practice…

May 25 th, 2005Demonstrator of advanced controllers32 Design of the new demonstrator

May 25 th, 2005Demonstrator of advanced controllers33 Goal: to test a control algorithm on a physical setup Procedure How?

May 25 th, 2005Demonstrator of advanced controllers34 System overview (1) Client: Runs MS Windows Generating models Model control (start/stop/upload/delete) Setting parameters of controlled system real-time View parameters of controlled system real-time Server: Runs Linux, with real-time kernel Runs control system Performs I/O

May 25 th, 2005Demonstrator of advanced controllers35 System overview (2)

May 25 th, 2005Demonstrator of advanced controllers36 Realization Mechatronics Embedded PC + I/O Power (CPU) Power (motor) Motor amplifier

May 25 th, 2005Demonstrator of advanced controllers37 Experiments

May 25 th, 2005Demonstrator of advanced controllers38 Experiments Comparison of PID/LQG/LQG+ performance on the new demonstration setup Same controller parameters used as in simulation (after tuning) Performance comparison on: 1.Static error 2.Frame vibration 3.Power usage

May 25 th, 2005Demonstrator of advanced controllers39

May 25 th, 2005Demonstrator of advanced controllers40 Results The LQG+ controlled system outperforms the PID controlled system: Maximum frame movement differs factor 3 Total power consumption differs a factor 2 Both control algorithms minimize the static error, but the LQG controlled system is faster More performance increase is expected with a better model Differences in performance between 2 nd order PID and 4 th order LQG have now been demonstrated in practice

May 25 th, 2005Demonstrator of advanced controllers41 Demonstration

May 25 th, 2005Demonstrator of advanced controllers42 Demonstration What will be shown: 1.‘Homing’ of the demonstrator 1.Determining absolute position 2.PID controller in practice with various controller gains Furthermore: 1.Online adjustment of parameters 2.Real-time variable monitoring 3.Real-time animation of demonstration setup

May 25 th, 2005Demonstrator of advanced controllers43 Conclusions&Recommendations

May 25 th, 2005Demonstrator of advanced controllers44 Conclusions 1.The new mechatronic demonstration setup is a compact, integrated machine that forms a versatile development environment for testing various control algorithms in practice 2.The new demonstrator allows for easy comparison of different control algorithms 3. Non-linear friction elements in the process will lead to lower performance in position control of a 4 th order LQG-controlled system compared to a 2 nd order PID control algorithm 4.Addition of an integrating term leads to an ‘LQG+’ control algorithm that can compensate for differences between process and reference model.

May 25 th, 2005Demonstrator of advanced controllers45 Recommendations Hardware Expand safety system Reduce weight of the demonstrator (next version) Add parallel processing (e.g. distributed control) Software / control Experiment with more control systems (MRAS, (L)FF, ILC etc) Perform system identification General 1.Set up lab work assignments for student

May 25 th, 2005Demonstrator of advanced controllers46 Questions…?

May 25 th, 2005Demonstrator of advanced controllers47 THANK YOU FOR YOUR ATTENTION you are all invited for DRINKS at ‘De Tombe’, floor 0