Alexandru Dumitrache

A Heuristic Approach for Constrained Real Time Motion Planning of a Redundant 7-DOF Mechanism for 3D Laser Scanning

Abstract This article presents a heuristic algorithm for motion planning of a short range 7-DOF Laser Scanning System consisting of a 6-DOF vertical robot arm and a rotary table holding the workpiece. The redundancy of the mechanism is exploited for specifying certain constraints such as imposing a smooth motion of the rotary table while respecting the acceleration and speed limits and avoiding undesirable configurations of the robot arm such as the kinematic singularities, out-of-range conditions and collisions between the mechanical elements of the system (robot, table, workpiece and laser probe). The paper also presents the control system of the rotary table, and a communication protocol which allows the integration of the above-mentioned planning algorithm into the 3D scanning system.

IMS10-image-based milling toolpaths with tool engagement control for complex geometry

This paper presents a NC toolpath generation strategy with tool engagement control for arbitrarily complex discrete part geometry, which reduces machining time and tool wear and can be used in high speed machining. The toolpath computation is based on image models for design part, raw stock and cutting tool, and involves pixel-based simulation of the milling process. Simulation results and comparison with existing methods are presented.

Robotic 3D Surface Laser Scanning for Feature-Based Quality Control in Holonic Manufacturing

The paper describes an on line geometry control technique which uses a laser sensor hand-held by a 6 d.o.f.-vertical articulated robot and displaced along predefined scanning paths. The 3D surface of manufactured part is digitally reconstructed after the robot drives the laser sensor along a scanning motion pattern corresponding to the part type (prismatic, revolute) and geometric features to be checked (direct measurements: lengths, angles, signatures, depth map evaluation: local and global indicators) against reference part models. The robotized laser scanning system is integrated with a 2D vision platform allowing thus to perform an extended set of geometry inspection tasks on manufactured parts (processed on CNC machine tools, assembled by robots). The described quality control technology is applied to holonic manufacturing by including in the order holon the inspection sequence retrieved from the product holon and the laser scanner robot enabled by the resource holon. Implementing solutions and experimental results are reported.

Robot Arms with 3D Vision Capabilities

The use of industrial robots in production started a rapid expansion in the 1980s, since they had the possibility of improving productivity, being able to work for extended periods of time with good repeatability, therefore making the quality of products stable. However, since the first robots worked “blindly”, on a pre-programmed trajectory, dedicated equipment had to be prepared only for supplying the workpieces to the robots (Inaba & Sakakibara, 2009). Also, human operators had to manually align the workpieces before the robot was able to manipulate them. The intelligent robots appeared later in 2001 in order to solve this problem. An intelligent industrial robot is not a humanoid robot that walks and talks like a human, but one that performs complex tasks, similar to a skilled worker. This is achieved with sensors (vision, force, temperature etc) and artificial intelligence techniques. Today, solutions to problems like picking parts placed randomly in a bin (bin picking), which were considered difficult a few years ago, are now considered mature: (Hardin, 2008) and (Iversen, 2006). A similar problem is auto racking, where robots have to pick parts which are presented one at a time, although the exact location and 3D orientation varies. These applications are made possible using 3D vision sensors.

Automatic Generation of Milling Toolpaths with Tool Engagement Control for Complex Part Geometry

Abstract This paper presents a NC toolpath generation strategy with tool engagement control for arbitrarily complex discrete part geometry, which reduces machining time and tool wear and can be used in high speed machining. Simulations and comparison with existing methods are presented.

Collision and proximity avoidance for robust behaviour of real-time robot applications

This paper proposes a set of techniques for predictive collision avoidance, which ensure robust operation of robot applications. Implementation issues for applying the techniques to state-of-art robots are presented, including integration with manual and automatic operation modes.

Flexible 3D Trajectory Teaching and Following for Various Robotic Applications

Abstract This paper addresses an actual problem regarding complex industrial robot applications. Based on the fact that no CAD model for the processed parts is available, the application presented here consists in a 3D accurate path following, applicable in various robot tasks. Using a sensor-based 3D path learning procedure available in automatic or manual mode, the 6 d.o.f industrial robot will be able to reproduce in real-time the learned trajectory. Calibration and synchronization aspects are presented, and experimental results are provided and analyzed.

Knowledge-Based Adaptive Machining Concept for Service Oriented Architectures

This chapter presents a new architecture for intelligent CNC machining in the context of a service-oriented manufacturing system involving material processing and robotized assembly operations. The proposed approach is a knowledge-based adaptive machining concept (KBAMC), which encompasses four modules: management, observation, prediction and strategy.

Open Source Framework for Real-Time Robot Simulation and Collision Avoidance

Abstract This paper presents a portable simulation environment for robotics, implemented with open source components and aimed at research, offline programming and educational usage. The simulation employs rigid body dynamics, collision detection, customizable robot environments and real-time 3D graphics. A case study presents an application for collision detection and avoidance in physical robots, outside the simulation environment, with experimental results showing benchmarks and real-time monitoring issues.

AUTOMATIC GENERATION OF 3D MACHINING SURFACES WITH TOOL COMPENSATION FROM GRAYLEVEL IMAGE MODELS

Abstract The paper presents a theoretical approach and implementing issue for automatic CNC toolpath generation using morphological image processing operators applied to depth map images. This method allows computing cutter compensation for various end mill shapes. Roughing is made using zigzag cuts with a flat end mill, and finishing is done with isoparametric toolpaths using various rounded end mills. An AI-based algorithm and image processing software create CNC machining instructions from depth map image models. The paper also describes a graphical user interface and includes experimental results.