1. Active Force Control A Robust Control Technique iCA Introduction
M. Mailah
H. Jamaluddin, I.Z.M. Darus, H.H. Tang, M. Hussein, M.Z.M. Zain
Faculty of Mechanical Engineering
iCA
Intelligent Control & Automation Research Group
Introduction
AFC-Based Systems & Results
Trends & Directions
Background & Motivation
The research on active force control (AFC) is initiated by Johnson (1971) and later Davison (1976) based on the principle of invariance and the classic Newton’s second law of motion. It has been demonstrated that it is possible to design a feedback controller that will ensure the system set point remains unchanged even in the presence of the disturbances or adverse operating and loading conditions provided that the actual disturbances can be modelled effectively. Hewit and Burdess (1981) proposed a more complete package of the system such that the nature of disturbances is oblivious to the system and that it is readily applied to multi-body dynamical systems. Thus, an effective method has been established to facilitate robust motion control of dynamical systems in the presence of various forms of disturbances, parametric uncertainties/changes and undesirable conditions that are prevalent in the real-world environment. Mailah et al. (1996, 1998) extended the usefulness of the method by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller.
AFC Principle & Methodology
A disturbance cancellation control scheme, a.k.a. disturbance rejection control, disturbance observer, robust control
Initiated by Johnson (1971) and Davison (1976); proposed in ‘complete’ form by Hewit and Burdess (1981); embedded AI schemes by Mailah (1998)
Based on principle of invariance and Newton 2nd Law of Motion
Relies on measurement and estimation of parameters
Uses a very simple control algorithm, thereby reducing computational load unlike VSC, sliding mode control, H-infinity, H2 and others
Practical – readily implemented in real-time
AFC loop
Overall control algorithm: [PD+AFC] = Kpe(s) + Kd s e(s) + Q’ W(s)
Ks = 0 PD; Ks = 1 AFC
Robust Navigation and Handling of Mobile Manipulator (2006)
Vehicle Suspension for Improved Ride Comfort (2009)
Complex Manipulation of 3RRR Parallel Manipulator (2011)
Active Vibration Control of a Flexible Plate (2010)
Anti Swing Control of a Sprayer Boom (2014)
Pneumatic Artificial Muscle (PAM) Actuated Robot (2010)
Satellite Pitch Attitude Control (2011)
In-pipe Microrobot (2012)
Current & Future Directions
Biomedical Applications
Tools for OKU/Therapeutic needs
Parkinson’s disease
Robotic surgery
Critical Handling of Materials
Radioactive/Rare/Sensitive materials
Earthquake/Seismic Control
High rise structure/Tower
Space Vehicle Control
Nano Actuation System
Etc.
Satellite attitude control
Microrobot
Active vibration control
Sprayer boom
Automotive brake
Vehicle suspension
Mobile manipulator
Mobile robot
Flexible robot/plate
Rigid/parallel robot
Biomechanics
Tremor suppression
High rise structure
???
PAM actuation system
Space vehicle control
Nano actuation system
Conclusion
AFC is a robust technique based on first principles, relevant and sustainable
Main limitation is the actuator bandwidth to supply the controlled energy for very large scale applications
AFC algorithm is simple, hence computationally efficient
Has a high practical value
Acknowledgements
We would like to thank MOHE, MOSTE and UTM for their continual and unwavering support in accomplishing the research projects.