Emrah Deniz Kunt

Discrete Sliding Mode Control of Piezo Actuator in Nano-Scale Range

In this paper discrete sliding mode control (SMC) of Piezo actuator is demonstrated in order to achieve a very high accuracy in Nano-scale with the desired dynamics. In spite of the fast dynamics of the Piezo actuator the problem of chattering is eliminated with the SMC control structure. The Piezo actuator suffers from hysteresis loop which is the inherent property and it gives rise to the dominant non-linearity in the system. The proposed SMC control structure has been proved to deliver chattering free motion along with the compensation of the non linearity present due to hysteresis in the system. To further enhance the accuracy of the closed loop system and to be invariant to changes in the plant parameters a robust disturbance observer is designed on SMC framework by taking into consideration the lumped nominal plant parameters. Experimental results for closed loop position and micromanipulation applications are presented in order to verify the Nano-scale accuracy.

Miniaturized modular manipulator design for high precision assembly and manipulation tasks

In this paper, design and control issues for the development of miniaturized manipulators which are aimed to be used in high precision assembly and manipulation tasks are presented. The developed manipulators are size adapted devices, miniaturized versions of conventional robots based on well-known kinematic structures. 3 degrees of freedom (DOF) delta robot and a 2 DOF pantograph mechanism enhanced with a rotational axis at the tip and a Z axis actuating the whole mechanism are given as examples of study. These parallel mechanisms are designed and developed to be used in modular assembly systems for the realization of high precision assembly and manipulation tasks. In that sense, modularity is addressed as an important design consideration. The design procedures are given in details in order to provide solutions for miniaturization and experimental results are given to show the achieved performances.

A workstation for microassembly

In this paper, an open-architecture, reconfigurable microassembly workstation for efficient and reliable assembly of micromachined parts is presented. The workstation is designed to be used as a research tool for investigation of the problems in microassembly. The development of such a workstation includes the design of: (i) a manipulation system consisting of motion stages providing necessary travel range and precision for the realization of assembly tasks, (ii) a vision system to visualize the microworld and the determination of the position and orientation of micro components to be assembled, (iii) a robust control system and necessary mounts for the end effectors in such a way that according to the task to be realized, the manipulation tools can be easily changed and the system will be ready for the predefined task. In addition tele-operated and semi-automated assembly concepts are implemented. The design is verified by implementing the range of the tasks in micro-parts manipulation. The versatility of the workstation is demonstrated and high accuracy of positioning is shown.

Sensorless torque estimation in multidegree-of-freedom flexible systems

This paper presents a sensorless torque estimation algorithm for multidegree-of-freedom flexible systems. The proposed algorithm makes it possible to estimate externally applied torques due to flexible systems interaction with the environment without taking any measurement from the system. The algorithm is based on modifying the disturbance observer in order to decouple the reflected torque waves out of the total disturbance on the actuator. Then Reflected torque waves are used along with the actuators current and velocity to estimate flexible system parameters, dynamics and the external torques or disturbances. Several experimental results are included in order to confirm the validity of the proposed torque estimation algorithm.

Estimation Based PID controller-Sensorless Wave Based Technique ?

Abstract Abstract This paper presents a sensorless estimation algorithm for estimating flexible system parameters, dynamics and externally applied forces or torques due to system interaction with the environment. The proposed algorithm makes it possible to design a chain of observers that require measuring actuators current and velocity along with performing two off-line experiments that do not require any additional measurement from the flexible system. The output of these observers are estimates of the system parameters, estimates of the system dynamics in configuration, motion and acceleration level. Eventually, the estimated positions are used to control the motion and vibration of the flexible lumped system without taking any measurement from the system. Experimental results show the validity of the proposed sensorless estimation algorithm and the possibility of controlling motion and vibration of flexible systems by focusing all the measurements on the actuator side keeping the system free from any attached sensors.

Estimation based control of flexible systems-sensorless wave based technique

This paper presents an algorithm for parameters and positions estimation of lumped flexible systems. As soon as the parameters and the positions are estimated they can be used to design virtual sensors that can be moved along the system to estimate the position of any lumped mass keeping the system free from any attached sensors. The virtual sensors are nothing but a chain of estimators that are connected at the end of each other, starting with two actuators measurements and ending up with system parameters and all the system lumped positions. An estimation Based PID controller is presented based on the feedback of the virtual sensors estimates instead of the actual measurement.

Development of system supervision and control software for a micromanipulation system

This paper presents the realization of a modular software architecture that is capable of handling the complex supervision structure of a multi degree of freedom open architecture and reconfigurable micro assembly workstation. This software architecture initially developed for a micro assembly workstation is later structured to form a framework and design guidelines for precise motion control and system supervision tasks explained subsequently through an application on a micro assembly workstation. The software is separated by design into two different layers, one for real-time and the other for non-realtime. These two layers are composed of functional modules that form the building blocks for the precise motion control and the system supervision of complex mechatronics systems.

A field programmable gate array based modular motion control platform

The expectations from motion control systems have been rising day by day. As the systems become more complex, conventional motion control systems can not achieve to meet all the specifications with optimized results. This creates the necessity of fundamental changes in the infrastructure of the system. Field programmable gate array (FPGA) technology enables the reconfïguration of the digital hardware, thus dissolving the necessity of infrastructural changes for minor manipulations in the hardware even if the system is deployed.