Browsing by Author "Pillai, MB"

Filter results by typing the first few letters
Now showing 1 - 8 of 8
  • Thumbnail Image
    item: Article-Abstract
    Analysis of a dc motor based velocity controller using disturbance observer
    Pillai, MB; Perera, GVAGA; Chinthaka, MKCD; Abeykoon, AMHS
    Motion control incorporates a range of challenges when it comes to the control of mechanical systems. In rotary motion; position, velocity and acceleration control are the tasks required most often for robotics. The achievement of velocity control is one of the popular technical issues in motion control and industrial applications. The traditional approach for velocity control is PID based feedback controllers. PID controllers are not suitable for the applications subjected to higher external disturbances. This paper proposes a Disturbance Observer (DOB) based velocity controller. DOB together with the tuned PID controller can make the system robust. To validate the proposed method, stability analysis and experiments were carried out with and without DOB. The velocity responses of the experiments were analyzed for different modes of disturbances with different observer gains. The performance of the proposed controller shows enhanced results compared to the traditional velocity controllers.
  • Thumbnail Image
    item: Conference-Abstract
    DC Motor inertia estimation for robust bilateral control
    Perera, GVAGA; Pillai, MB; Abeykoon, AMHS
    Identification of system parameters of a small DC motor is a complex and challenging task. This research proposes a disturbance observer (DOB) based novel Change of Inertia Observer (CIOB) to estimate the moment of inertia of a DC motor. Moment of inertia of a small DC motor is estimated using CIOB based velocity test and reaction torque observer (RTOB) based inverse motion acceleration test, and the results are compared with conventional acceleration and deceleration motion tests. These two conventional tests are more suitable for large DC motors and less accurate for small DC motors. DOB is used to estimate the disturbance torques and CIOB is to find the change of inertia. Estimated moments of inertia values using the proposed methods are compared with the conventional methods by applying the values to a bilateral teleoperation system. Proposed methods have produced better results than in the conventional methods. Proposed CIOB method of inertia estimation is much simpler and easier to use compared to conventional methods.
  • Thumbnail Image
    item: Conference-Abstract
    Disturbance rejection analysis of a disturbance observer based velocity controller
    (2016-04-26) Senevirathne, HR; Abeykoon, AMHS; Pillai, MB
    Motion control usually includes the precise control of position/velocity and acceleration control while accurate acceleration control is not useful in many applications. Traditional position/velocity control is derived by feedback based, PID controllers. However the disturbance observer further increases the stability and robustness of the controller. In this paper we assess the effectiveness of the Disturbance Observer working together with a tuned PID controller. Velocity response is compared with and without the disturbance observer. The proposed disturbance observer based velocity controller produce better results than the traditional velocity controller.
  • Thumbnail Image
    item: Conference-Abstract
    Disturbance rejection analysis of a disturbance observer based velocity controller
    (2016-04-26) Senevirathne, HR; Abeykoon, AMHS; Pillai, MB
    Motion control usually includes the precise control of position/velocity and acceleration control while accurate acceleration control is not useful in many applications. Traditional position/velocity control is derived by feedback based, PID controllers. However the disturbance observer further increases the stability and robustness of the controller. In this paper we assess the effectiveness of the Disturbance Observer working together with a tuned PID controller. Velocity response is compared with and without the disturbance observer. The proposed disturbance observer based velocity controller produce better results than the traditional velocity controller.
  • Thumbnail Image
    item: Conference-Abstract
    Frequency response based analysis and designing of bilateral control system
    Jayasekara, GMASM; Jayasingha, PM; Jayalath, PJ; Gomeda, LHC; Menikdiwela, MP; Pillai, MB; Abeykoon, AMHS
    Bilateral control is one of the high-tech control technologies available in transmitting haptics information from one point to another point successfully. In past few years, a fair amount of researches has been carried out with different control strategies, hence bilateral control has been implemented practically in various fields recently. In most of the practical scenarios, time delays, chattering effects and unwanted vibrations lead to deficiencies and inaccuracies which badly affect to the successful implementation of a bilateral control system. Although many researches were carried out to compensate the time delays and chattering effects, eliminating unwanted vibration of a bilateral control has never been discussed. In this study, a method has been proposed to design a bilateral control system which works finely in a particular frequency band. In order to achieve the target, a frequency response analysis to a conventional bilateral control system is carried out showing the effect of system parameters to its operationality, and frequency band is determined for a particular set of system parameters. Finally, the validity of the proposed method is demonstrated through simulation.
  • Thumbnail Image
    item: Article-Abstract
    RTOS based embedded controller implementation of a bilateral control system
    Abeykoon, AMHS; Pillai, MB
    Bilateral tele-operation involves realization of the law of action and reaction between the human and the environment. In this research, an embedded system based bilateral control was developed on a microcontroller based motor driver platform. Bilateral tele-operation needs real-time representation of the forces and positions. This challenge accomplished by incorporating a real-time operating system (RTOS) with a resource limited microcontroller. Sensorless torque detection technique was used to find the external torque while disturbance observer was used as a disturbance rejection tool and also to improve the system’s robustness. When the motion controller was implemented on a microcontroller, 0 - 30 Hz frequency of force bandwidth could be achieved. In an ideal bilateral control, force/position errors should be The experimental results in contact motion showed a force error less than 4 % and a position error less than 6 %. which validates the proposal. This was a significant achievement as the bilateral controllers have never been successfully implemented using a microcontroller.
  • Thumbnail Image
    item: Conference-Abstract
    Simulation of mobile robot navigation with sensor fusion on an uneven path
    Sumanarathna, DMGAIN; Senevirathna, IASR; Sirisena, KLU; Sandamali, HGN; Pillai, MB; Abeykoon, AMHS
    This paper describes the navigation of a two-wheel drive mobile robot along a predefined path under uneven road conditions where it cannot solely rely on encoders, GPS or an accelerometer individually. There are conditions when low friction or slippery ground surfaces such as sandy paths and pits cause one or both encoders to halt or rotate less as the robot moving forward. Areas covered with clouds, trees or structures can block GPS signals. Sudden pickups and halts give false information from accelerometers. Therefore Kalman filter based sensor fusion algorithm is implemented in order to get the best position estimation for the mobile robot using above sensor outputs. The Special feature of this algorithm is that it includes a simple method to overcome the effects of encoder errors due to the slipping of wheels of the mobile robot, which does not require complex computations to additional measurement units to directly measure the slipping of the wheels of the robot. Finally the validity of the proposed algorithm is demonstrated via simulation.
  • Thumbnail Image
    item: Conference-Abstract
    Virtual torsional spring based bilateral control system for soft manipulation
    (2014-06-30) Madawala, MK; Abeykoon, AMHS; Mihiran, BGC; Mohottige, DC; Meththananda, RGUI; Pillai, MB
    In recent years, although there are many researches on bilateral control, there is only little research on improvement of operationality. It will be so effective for operators to improve the operationality of the bilateral control system. In a bilateral control system, the law of action and reaction between master system which the operator manipulates, and the slave system which has contact with the environment is realized. Objective of this research is to eliminate the chattering and to reduce the impact on human operator at contact motion and to introduce controlling force to the slave manipulator to provide more comfort at the human operator's end. In this paper, a new method of improving the operationality which is based on a virtual torsional spring between master and slave system is discussed. Disturbance observer is used as the disturbance compensation tool and also to improve the system robustness. Then proposed method is applied by altering the bilateral control system. Finally the experimental results show the viability of the proposed method.