
5ba6d0be22fdfa513bae0a5e30835060.ppt
- Количество слайдов: 47
Master of Science assignment Demonstrator of advanced controllers Hans Dirne May 25 th, 2005 Supervisors prof. dr. ir. J. van Amerongen dr. ir. J. F. Broenink dr. ir. T. J. A. de Vries ir. P. B. T. Weustink
Why this assignment? The Major ‘Mechatronics’ provides several courses in control theory, in which 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 theory more insightful and will show real limitations in practical setups. May 25 th, 2005 Demonstrator of advanced controllers 2
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, 2005 Demonstrator of advanced controllers 3
Overview 1. 2. 3. 4. 5. 6. Demonstration setup options Control systems Design of the new demonstrator Experiments Demonstration Conclusions & recommendations May 25 th, 2005 Demonstrator of advanced controllers 4
Demonstration setup options May 25 th, 2005 Demonstrator of advanced controllers 5
Criteria 1. 2. 3. 4. 5. 6. Mechatronic system Portable and easy to set up Robust, safe and failsafe design High level of observability Representable by linear 4 th order model Clear link with well known device May 25 th, 2005 Demonstrator of advanced controllers 6
Three options 1. ‘Linix’ laboratory setup 2. 2. Setup of ‘Controllab Products B. V. ’ 3. 3. New build May 25 th, 2005 Demonstrator of advanced controllers 7
Option 1: ‘Linix’ Laboratory Setup May 25 th, 2005 Demonstrator of advanced controllers 8
‘Linix’ Laboratory Setup encoders motor inertia 2 transmission May 25 th, 2005 Demonstrator of advanced controllers inertia 1 9
‘Linix’ Laboratory Setup May 25 th, 2005 Demonstrator of advanced controllers 10
‘Linix’ Laboratory Setup Major disadvantage: slip between belt and inertias May 25 th, 2005 Demonstrator of advanced controllers 11
Option 2: CLP setup May 25 th, 2005 Demonstrator of advanced controllers 12
CLP setup May 25 th, 2005 Demonstrator of advanced controllers 13
CLP setup May 25 th, 2005 Demonstrator of advanced controllers 14
Sensor positions May 25 th, 2005 Demonstrator of advanced controllers 15
Option 3: New Build Advantage • Pure design freedom Disadvantage • Requires very much time and effort to design May 25 th, 2005 Demonstrator of advanced controllers 16
Overview demonstrators New build Linix CLP-setup Mechatronic system √ Linear 4 th order model √ Portable, easy to set up √ √ not in current form Robust, safe, failsafe √ √ feasible Observability √ yes, 2 position yes, 4 position Sensors sensors Link with practical device √ transmission Shows controller differences √ no, due to To be nonlinearities determined Remarks Time constraint √ √ limited linear to be determined printer
Control Systems May 25 th, 2005 Demonstrator of advanced controllers 18
Mathematical model – 6 th order Viscous PLUS coulomb friction May 25 th, 2005 Demonstrator of advanced controllers 19
Focus 1. Linear Quadratic Gaussian (LQG) 2. Proportional, Integral, Differential (PID) May 25 th, 2005 Demonstrator of advanced controllers 20
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, 2005 Demonstrator of advanced controllers 21
4 th order linear model Required steps: 1. Downsize system order 2. Linearize system: discard coulomb friction Result: linear 4 th order model (e. g. State Space) May 25 th, 2005 Demonstrator of advanced controllers 22
LQG controlled system May 25 th, 2005 Demonstrator of advanced controllers 23
PID May 25 th, 2005 Demonstrator of advanced controllers 24
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 error May 25 th, 2005 controller output Demonstrator of advanced controllers 25
Tuning (2) Tuning procedure: 1. Set Q and R 2. Minimize criterion J by optimizing 3. controller gains (KLQG and KP, KI, KD) May 25 th, 2005 Demonstrator of advanced controllers 26
Tuning (3) Optimization results KP = 15. 7 KI = 42 KD = 1. 6 KLQG = [3. 7, 74, 8. 2, 70]T May 25 th, 2005 Demonstrator of advanced controllers 27
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, 2005 Demonstrator of advanced controllers 28
PID vs LQG (2) The LQG control algorithm leads to an unacceptable position error with the nonlinear process May 25 th, 2005 Demonstrator of advanced controllers 29
LQG+ May 25 th, 2005 Demonstrator of advanced controllers 30
LQG+ vs LQG Effect of integrator: Static error is minimized! Interesting to see the performance of LQG+ in practice… May 25 th, 2005 Demonstrator of advanced controllers 31
Design of the new demonstrator May 25 th, 2005 Demonstrator of advanced controllers 32
Procedure Goal: to test a control algorithm on a physical setup How? May 25 th, 2005 Demonstrator of advanced controllers 33
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, 2005 Demonstrator of advanced controllers 34
System overview (2) May 25 th, 2005 Demonstrator of advanced controllers 35
Realization Mechatronics Embedded PC + I/O Power (CPU) Power (motor) Motor amplifier May 25 th, 2005 Demonstrator of advanced controllers 36
Experiments May 25 th, 2005 Demonstrator of advanced controllers 37
Experiments • Comparison of PID/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, 2005 Demonstrator of advanced controllers 38
May 25 th, 2005 Demonstrator of advanced controllers 39
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, 2005 Demonstrator of advanced controllers 40
Demonstration May 25 th, 2005 Demonstrator of advanced controllers 41
Demonstration What will be shown: 1. 2. ‘Homing’ of the demonstrator 1. Determining absolute position PID controller in practice with various controller gains Furthermore: 1. 2. 3. Online adjustment of parameters Real-time variable monitoring Real-time animation of demonstration setup May 25 th, 2005 Demonstrator of advanced controllers 42
Conclusions & Recommendations May 25 th, 2005 Demonstrator of advanced controllers 43
Conclusions 1. 2. 3. The new mechatronic demonstration setup is a compact, integrated machine that forms a versatile development environment for testing various control algorithms in practice 2. 3. The new demonstrator allows for easy comparison of different control algorithms 3. 1. 2. 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 1. 2. 3. 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, 2005 Demonstrator of advanced controllers 44
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, 2005 Demonstrator of advanced controllers 45
Questions…? May 25 th, 2005 Demonstrator of advanced controllers 46
THANK YOU FOR YOUR ATTENTION you are all invited for DRINKS at ‘De Tombe’, floor 0 May 25 th, 2005 Demonstrator of advanced controllers 47