Due to their robustness and cost effectiveness, double fed induction generator (DFIG) based wind turbines are becoming very popular in wind energy conversion systems. Robustness of any implemented ...control structure can easily be lost due to nonlinearities, variations in the DFIG parameters and network voltage failures. In this study, machine parameter dependent terms will be estimated with the first order low pass filter disturbance observer, and stator voltage orientation will be applied in the experimental test bed. DSP ACE DS1103 platform is used as a digital controller.
FPGA based control of a walking piezo motor Uzunovic, Tarik; Golubovic, Edin; Sabanovic, Asif
2014 IEEE 13th International Workshop on Advanced Motion Control (AMC),
03/2014
Conference Proceeding
This paper describes FPGA based control system for a piezoelectric motor, commercially available Piezo LEGS motor. Driving voltages waveforms are defined as a combination of linear functions. This ...definition provides possibility for easy implementation on very simple hardware. Linear functions parameters allow forming of the driving voltages according to desired trajectory of motor's legs. Considering that FPGA technology offers many advantages over the classical microprocessor based systems, it is used as control system implementation hardware. Realized control system can be very easily expanded to control multiple motors, if hardware resources are big enough. Also modularity is provided, making the future application very simple. In the paper control system structure is described in detail along with a very simple control algorithm for Piezo LEGS motor positioning control. Experimental results are given to validate designed control system. They showed satisfying control performance, responses with no overshoot and expected steady state error.
This paper presents a compact and low cost digital signal controller (DSC) based implementation for power control of a doubly fed induction generator (DFIG) based wind energy setup for micro-grid ...applications. The experimental setup consists of a back to back converter, a 1.1 kW DFIG and two low cost, industry standard DSCs. Stator active power and reactive power are controlled by means of the rotor currents. Decoupled components of the rotor current in a rotating frame are controlled by a robust, disturbance observer based control structure. The proposed controller was validated through experiments.
This paper describes configuration space control of a Delta robot with a neural network based kinematics. Mathematical model of the kinematics for parallel Delta robot used for manipulation purposes ...in microfactory was validated, and experiments showed that this model is not describing "real" kinematics properly. Therefore a new solution for kinematics mapping had to be investigated. Solution was found in neural network utilization, and it was used to model robot's inverse kinematics. It showed significantly better mapping between task space coordinates and configuration (joint) space coordinates than the mathematical model, for the workspace of interest. Consequently positioning accuracy improvement is expected. Neural network is then used as a part of the control system. Applied control strategy was configuration space acceleration control with disturbance observer.
In this paper implementation of a control system for high precision applications is presented. The control system is developed for a Piezo LEGS motor, which is a walking piezo motor that can be ...employed in nanometric precision applications. In the control system structure, two main components are digital signal controller which executes control algorithm and power driver that is generating driving voltages for the motor. The waveforms of the driving voltages are designed using a recently presented coordinate transformation. This transformation enables synthesis of driving waveforms according to design requirements regarding force imposed to the motor's rod and rod's x-direction trajectory profile. In this work, the waveforms are selected to ensure no relative motion between the motor's legs and rod, and constant velocity of the rod within one step. Control algorithm is named as virtual time control. Despite its simplicity, the algorithm allows high precision positioning which is very close to theoretically achievable one.
In this paper a novel design for three-dimensional (3-D) contour controller is proposed. This design relies on dynamics projection to the moving Frenet-Serret frame defined for each point on ...reference trajectory. Contour controller consists of independent joint controller and additional sliding mode controller, added as corrective term. Control task is defined as contour tracking with constant tangential velocity. Contour controller was compared with independent joint controller designed as acceleration controller with first order disturbance observer. Reference trajectory is generated using time based spline approximation to provide smooth reference trajectory. Experimental results showed significant improvement that contour controller provides over independent joint control with relatively high velocity references.
This work presents functional description of a walking piezoelectric motor and its control in bending mode. For this purpose a dynamical model of the actuator is derived based on simple mass spring ...damper system. Identification experiments are conducted to verify the theoretical kinematics of the bimorph legs presented in previous works. These experiments demonstrate approximately linear relation between the legs displacement in x and y planes to the applied voltages. Based on these results a PI controller followed by Hadamard transformation is proposed as a controller scheme. Experimental results for staircase and sinusoidal tracking references reveal precise positioning down to few nano-meters.
This work focuses on the design of adaptive controller for high precision positioning purposes using PiezoLegs actuator. Actuator is driven with the set of periodical sine shaped voltages with known ...frequency, amplitude and phase shift between the phases. Clear relationships between the amplitude and phase shifts between the phases and actuator step size have been established. Based on these relationships adaptive controller has been designed. Controller is a linear, cascaded type of feedback controller that uses position feedback from an encoder. Based on the information of the absolute error controller performs the adaptive step size modulation by changing amplitude or phase shift of the driving voltages. Proposed algorithm is validated experimentally. Experimental results show satisfactory level performance, controller achieves fast settling time, no overshoot response and high accuracy of positioning with small steady state errors.
This paper presents a methodological approach for the practical realization of high precision laser micromachining over shapes of arbitrary geometry. The scheme presented throughout the paper ...includes an easy-to-use way of reference generation via image processing for shapes that is mathematically difficult to represent. The necessary constraint of tracking the constant reference tangential velocity for high precision laser production is enabled via the so called spline polynomial interpolation method. The description of algorithmic steps for the acquisition of reference cartesian trajectory from an image is followed by the presentation of spline method and the controller used for the realization. The proposed approach is tested in experiments and the validity of the methodology is verified for practical implementation.
