Motion planning and assembly for microassembly workstation

In general, mechatronics systems have no standard operating system that could be used for planning and control when these complex devices are running. The goal of this paper is to formulate a work platform that can be used as a method for obtaining precision in the manipulation of micro-entities using micro-scale manipulation tools for microsystem applications. This paper provide groundwork for motion planning and assembly of the Micro-Assembly Workstation (MAW) manipulation system. To demonstrate the feasibility of the idea, the paper implements some of the motion planning algorithms; it investigates the performance of the conventional Euclidean distance algorithm (EDA), artificial potential fields’ algorithm, and A* algorithm when implemented on a virtual space

A Review of Haptic Feedback Teleoperation Systems for Micromanipulation and Microassembly

International audienceThis paper presents a review of the major haptic feedback teleoperation systems for micromanipulation. During the last decade, the handling of micrometer-sized objects has become a critical issue. Fields of application from material science to electronics demonstrate an urgent need for intuitive and flexible manipulation systems able to deal with small-scale industrial projects and assembly tasks. Two main approaches have been considered: fully automated tasks and manual operation. The first one require fully pre determined tasks, while the later necessitates highly trained operators. To overcome these issues the use of haptic feedback teleoperation where the user manipulates the tool through a joystick whilst feeling a force feedback, appears to be a promising solution as it allows high intuitiveness and flexibility. Major advances have been achieved during this last decade, starting with systems that enable the operator to feel the substrate topology, to the current state-of-the-art where 3D haptic feedback is provided to aid manipulation tasks. This paper details the major achievements and the solutions that have been developed to propose 3D haptic feedback for tools that often lack 3D force measurements. The use of virtual reality to enhance the immersion is also addressed. The strategies developed provide haptic feedback teleoperation systems with a high degree of assistance and for a wide range of micromanipulation tools. Based on this expertise on haptic for micromanipulation and virtual reality assistance it is now possible to propose microassembly systems for objects as small as 1 to 10 micrometers. This is a mature field and will benefit small-scale industrial projects where precision and flexibility in microassembly are required

Enhanced Image-Based Visual Servoing Dealing with Uncertainties

Nowadays, the applications of robots in industrial automation have been considerably increased. There is increasing demand for the dexterous and intelligent robots that can work in unstructured environment. Visual servoing has been developed to meet this need by integration of vision sensors into robotic systems. Although there has been significant development in visual servoing, there still exist some challenges in making it fully functional in the industry environment. The nonlinear nature of visual servoing and also system uncertainties are part of the problems affecting the control performance of visual servoing. The projection of 3D image to 2D image which occurs in the camera creates a source of uncertainty in the system. Another source of uncertainty lies in the camera and robot manipulator's parameters. Moreover, limited field of view (FOV) of the camera is another issues influencing the control performance. There are two main types of visual servoing: position-based and image-based. This project aims to develop a series of new methods of image-based visual servoing (IBVS) which can address the nonlinearity and uncertainty issues and improve the visual servoing performance of industrial robots. The first method is an adaptive switch IBVS controller for industrial robots in which the adaptive law deals with the uncertainties of the monocular camera in eye-in-hand configuration. The proposed switch control algorithm decouples the rotational and translational camera motions and decomposes the IBVS control into three separate stages with different gains. This method can increase the system response speed and improve the tracking performance of IBVS while dealing with camera uncertainties. The second method is an image feature reconstruction algorithm based on the Kalman filter which is proposed to handle the situation where the image features go outside the camera's FOV. The combination of the switch controller and the feature reconstruction algorithm can not only improve the system response speed and tracking performance of IBVS, but also can ensure the success of servoing in the case of the feature loss. Next, in order to deal with the external disturbance and uncertainties due to the depth of the features, the third new control method is designed to combine proportional derivative (PD) control with sliding mode control (SMC) on a 6-DOF manipulator. The properly tuned PD controller can ensure the fast tracking performance and SMC can deal with the external disturbance and depth uncertainties. In the last stage of the thesis, the fourth new semi off-line trajectory planning method is developed to perform IBVS tasks for a 6-DOF robotic manipulator system. In this method, the camera's velocity screw is parametrized using time-based profiles. The parameters of the velocity profile are then determined such that the velocity profile takes the robot to its desired position. This is done by minimizing the error between the initial and desired features. The algorithm for planning the orientation of the robot is decoupled from the position planning of the robot. This allows a convex optimization problem which lead to a faster and more efficient algorithm. The merit of the proposed method is that it respects all of the system constraints. This method also considers the limitation caused by camera's FOV. All the developed algorithms in the thesis are validated via tests on a 6-DOF Denso robot in an eye-in-hand configuration

Motion planning and assembly for microassembly workstation

In general, mechatronics systems have no standard operating system that could be used for planning and control when such devices are running. Our goal is to formulate a work platform that can be used as an environment for obtaining precision in the manipulation of micro-entities using micro-scale manipulation tools of our microsystem applications such as our microassembly workstation. The microassembly workstation setup is made up of the manipulation system, vision system, robust control system and manipulation tools. In this thesis we also provide groundwork for motion planning and assembly of the microassembly workstation manipulation system. We implemented the motion planning algorithms which are tested in the virtual workspace environment in order to demonstrate the functionality of the work platform. Firstly, we investigate the performance of the conventional Euclidean distance algorithm, then, artificial potential field algorithm, and finally A* algorithm when implemented on a virtual space. The physical conditions of the microworld hinder the immediate application of the work platform with the motion planning algorithms on the microassembly workstation. We demonstrate our test results of the motion planning algorithms on the virtual workspace and grid window of the work platform. However, due to object oriented programming nature of the work platform, eventually the work platform can be easily interfaced with the microassembly workstation once the problems which limit the micromanipulation and assembly are attended

Manipulation of nanoparticles by pushing operations using an Atomic Force Microscope (AFM)

This thesis presents new paradigms for a particular class of non-prehensile manipulators of nanoscale objects that are limited to modelling accurately the relative motion of objects using continuous mechanics where the contact area is not presented. This restrictions results in models which have low accuracy and a lack of understanding about the real motion of the nanoscale object. The newly developed paradigms are focused on three topics: characterisation and analysis of forces present during motion at nanoscale in two dimensional space; characterisation and analysis of the quasi-static motion of nanoscale objects using the the instantaneous centre of rotation iCOR; and characterisation and analysis of the quasi-static,impulsive and dynamic motion of nanoscale objects using motion constraints and the iCOR. For characterisation and analysis of forces present on objects being manipulated at nanoscale, new models to characterise rolling and sliding motion are introduced. For the sliding case a relation between friction load (force and torque) and slip motion (displacement and rotation) for rigid nano-object sliding on a flat and a rough surface, where the distribution of the normal contact forces is assumed to be known a priori and the friction is assumed to be independent of slip rate is introduced. Every point of frictional contact is assumed to obey Coulomb’s friction law. A developed set of equations are solved, performing high accuracy integration techniques such as the Bulirsch-Stoer Method implemented on a computing programming language such as FORTRAN. The full relation between the frictional load and the slip motion for a nano-object can thus be described by its iCOR. A new methodology to model the quasi-static motion of nanoscale objects is presented from which are derived equations that can be used to approximate the trii bological parameters of the nano-objects being manipulated for known and unknown contact pressure distributions. The characterisation of the tribological parameters, such as the coefficient of friction μ, is obtained from generated maps using the applied force or the observed iCOR location of the nano-object being manipulated. The approach has several advantages, including simplicity, robustness, and an ability to simulate classes of systems that are difficult to simulate using spatial mechanics. The final part of this thesis introduces a novel constraint-based method in combination with a minimum force principle to locate the iCOR position for nano-objects at quasi-static motion. Furthermore, the iCOR location for impulsive and dynamic motion cases are introduced. The results generated by modelling these cases can describe the full motion of the manipulated nano-object and generate knowledge of their tribological parameters