Alina Voda

Task Planning Algorithm in Hybrid Assembly/Disassembly Process

Abstract A model of a mechatronic assembly/disassembly line served by a robotic manipulator mounted on mobile platform, in order to perform disassembly, is proposed in this paper. The model is a hybrid one in which the mechatroninc line is the discrete system and the wheeled mobile robot (WMR) together with the robotic manipulator (RM) is considered the continuous system. The mobile platform is used only in disassembling operations in order to transport the components from the disassembling locations to the storage locations. The cycle performed by the WMR equipped with RM is the continuous part of the hybrid system. Therefore, a Hybrid Petri Net (HPN) is used in modeling and control. This hybrid system takes into consideration the distribution of the necessary tasks to perform the hybrid disassembly of a component, using robot synchronization with flexible line process. The ultimate goal is to make completely reversible the assembly line, that is to execute full disassembly.

New approach in control of assembly/disassembly line served by robotic manipulator mounted on mobile platform

The new idea of this paper is to make reversible an assembly line, i.e. to allow complete disassembly, by using a mobile platform equipped with robotic manipulator. The approach is a hybrid one in which the assembly/disassembly line is the discrete system whilst the wheeled mobile robot (WMR) together with the robotic manipulator (RM) is considered the continuous one. The mobile platform is used only in disassembling operations, in order to transport the components from the disassembling locations to the storage locations. Therefore, Synchronized Hybrid Petri Nets (SHPN) approach is used in modeling and control. This hybrid system takes into consideration the distribution of the necessary tasks to perform the hybrid disassembly of the components, using robot synchronization with flexible line process. The ultimate goal is to make completely reversible the assembly line. The SHPN model is transposed into LabView platform, thus getting a control structure of the mechatronic line and of WMR.

Hybrid modeling, balancing and control of a mechatronics line served by two mobile robots

This paper presents hybrid model for an assembly/disassembly mechatronics line serviced by two mobile robotics systems, working in parallel. The aim is to reverse an assembly line using these mobile platforms. For this purpose, an assembly/disassembly line balancing (A/DLB) and synchronized hybrid Petri nets (SHPN) will be used to model and control an assembly/disassembly mechatronics line (A/DML), with a fixed number of workstations, served by two wheeled mobile robots (WMRs) one of them equipped with a robotic manipulators (RM). The WMR with RM is used for part manipulation and the other for transporting. Moreover, the model operates in synchronized mode with signals from sensors. The SHPN model is hybrid type, where A/DML is the discrete part, and WMRs are the continuous parts. Disassembly starts after the assembly process and after the assembled piece fails the quality test, for recovering the parts. The WMRs are used only during disassembly, to manipulate and transport the parts from the disassembling locations to the storage warehouse locations.

Robust digital control of flexible structures using the combined pole placement/sensitivity function shaping method

The paper presents a methodology for designing robust digital controllers for flexible mechanical structures. The method proposed combines pole placement with sensitivity function shaping in the frequency domain. It is illustrated by its application to the control of a very flexible robot arm and of a very flexible transmission system. Experimental results are given.

Fractional order PID controller with online tuning based on FRIT and RLS

This paper presents a new strategy for online robust control-based fractional order PID controller (FPID). The technique suggests an online parameters tuning of the FPID using fictitious reference iterative tuning (FRIT) approach. This approach enables us to track the desired optimal FPID parameters online using experimental data without any plant model identification. After having set the optimal non-integer orders α and β, the gains of the FPID are then estimated in a recursive manner using the so-called recursive least squares (RLSs) algorithm with forgetting factor, which can cope with variation of plant characteristics adaptively. The performances of this technique are compared with other results already existing in the literature through some typical examples; the results of the proposed approach show significant performance improvement.

Temperature control of a greenhouse heated by renewable energy sources

The paper proposes a system developed to provide heat for a greenhouse using parabolic trough collectors (GHPTC). The GHPTC control system has the goal to maintain the temperature inside the greenhouse at a desired level, with the actuating variable the flow of the conducting fluid through collector pipes. Considering this aspect, the proposed model takes into account as an output variable the internal temperature of the greenhouse as it influences directly the growth of the plants. The GHTPC model consists of two individual parts: the greenhouse model and the collectors model. Both were validated using real data, considering the maxim error between the real and simulated data on a period of one day. A nonlinear and linear model were deducted for the complex GHPTC system. Based on the linearized model, a PID controller was tuned and used to control the internal temperature in the greenhouse. The control method is suited for the system according to the obtained stationary and transient response performances.

Creep modeling for piezoelectric actuators using fractional order system of commensurate order

This paper focuses on the creep modelling for the piezoelectric actuators (PEAs) using fractional system of commensurate order. The proposed fractional system of commensurate order is derived from another fractional system of non commensurate order through an identification method based on the recursive least squares algorithm. The choice of the fractional system of commensurate order representation is due mainly to the ability to use this representation to implement the PEA using analogue circuits through rational function approximation of its irrational transfer function, to represent the PEA using a fractional order state space representation, to easily study the PEAs stability and to derive its closed form responses. The proposed PEA model has been validated in simulation and on an experimental set-up from Gipsa-lab.

Control-based observer for unknown input disturbance estimation in magnetic levitation process

In this paper, an unknown input observer design is proposed for input disturbance estimation in a magnetic levitation process. The observer is designed using a control-based strategy which has been recently introduced. The method is shown to be very efficient for this estimation problem, with results both in simulation and in real time.

Experiments and analysis for fractional order modelling of an EEG recording process

In this study, an original experimental setup is proposed to analyze the transfer function of an electroencephalographic(EEG) measurement chain: this setup allows to control electrodes inserted into an electrolyticmedium, and observe the electrical potentials at different points with electrodes connected to an electroencephalographicrecording system. Experimental transfer functions are obtained that enable to characterize theinfluence of the electrolyte, the electrode-electrolyte interfaces, and the medium itself. A theoretical modelcontaining so-called constant phase elements is then proposed and analysed to understand the behaviour ofthe transfer function in Bode or Nyquist representations. Experimental and theoretical systems are finallycompared.

Adaptive hysteresis compensation on an experimental nanopositioning platform

ABSTRACT This paper presents a novel adaptive approach for hysteresis compensation applied to a piezoelectric actuator in one axis of an STM-like lab-made micro-/nanopositioning platform. The idea is to identify a compensating static parametric model, which imitates directly the inverse model of the nonlinearity. In this way, the approach is less complex than those based on model inversion. In addition, the identification is made online, allowing to consider a simple polynomial model, and to adapt its parameters according to the actual hysteresis curve which is faced (ascending or descending path, varying input amplitude, etc.). In order to be able to track possibly fast parameter variations, an original adaptation algorithm is proposed within the Bayesian framework, and including an exponential forgetting factor with optimal data-driven tuning. Illustrative experimental results are finally presented for tracking both triangular and sinusoidal reference signals with varying amplitude.