Visual Servoing of a Conventional CNC Machine Using an External Axis Controller (original) (raw)
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Visual Servo Control of Industrial Robot Manipulator
IFAC Proceedings Volumes, 2002
This paper presents an image-based visual servo controller for an industrial robot. The simple structure controller is based on a transposed Jacobian which feeds back directly the image feature errors and the joint velocities. Under these hypotheses, the control algorithm does not need to use the inverse kinematics and the inverse jacobian matrix. Experimental results in two different industrial robots are also presented to illustrate the controller's performance.
International Journal of Machine Tools and Manufacture, 2008
Machine-tool axis dynamics is an important factor that has influence in the machining finishing and interferes with wear machine and actuators. The parameters that describe this dynamics are: position, speed, acceleration, and jerk; these parameters are useful to make decisions on the trajectory planning, control, and machine performance. The contribution of this work is the development of a dynamics reconstruction method that consists of a combination of finite differences and a filter based on the application of discrete wavelet transform, where Daubechies function basis is used. The method objective is to obtain the dynamics parameter from a machine-tool axis, starting from an encoder for a sensorless approach. Results of the simulations and experimentation applied to computerized numerical control (CNC) lathe show the efficiency of the method, since the axis dynamics reconstruction of the machine tool is achieved by processing the position signal generated from the encoder.
Robotical Automation in CNC Machine Tools, A Review
2023
Robotics and automation have significantly transformed CNC machining operations, enhancing productivity, precision, and efficiency. Robots are employed to load and unload raw materials, workpieces, and finished parts onto CNC machines. They can efficiently handle heavy and bulky components, reducing the demand of manual labor and minimizing the risk of injuries. Robots can also be used in CNC machine tools to perform tasks such as automatic tool changing system, part inspection, and workpiece positioning. Automation technologies, including in-line inspection systems and non-destructive testing methods, can be integrated into CNC machining cells to enhance accuracy and reduce scrap and rework in machining operations. These systems collect real-time data on process parameters and machine tool performance to predict maintenance, optimize machining parameters, and improve overall efficiency. In the study, applications of robotics and automation in modification of CNC machine tools are reviewed and discussed. Different applications of robotics and automations in CNC machine tools such as automated material handling, automatic tool changing, robotic work cells, adaptive machining, machine tending, quality inspection, data monitoring and analysis and production line integration are discussed. Thus, by analyzing recent achievements in published papers, new ideas and concepts of future research works are suggested. As a result, accuracy as well as productivity in process of part production can be enhanced by applying the robotics and automation in CNC machining operations.
Position Control of an Industrial Robot Using an Optical Measurement System For Machining Purposes
A series of mechanical properties and disturbances limit the accuracy achievable in robotic applications. External control of the end effector position is commonly known as being an appropriate mean to increase accuracy. This paper presents an approach for position control of industrial robots using the pass-through between an industrial CNC and servomotors. A CNC-controlled robot is used together with an external optical measurement system to close the feedback loop of robot end effector and robot controller in order to improve robot accuracy. For short cycle times and implementation reasons a PLC is used for signal processing and control implementation. The relevance of the approach is outlined in experiments. The robot behaviour in free space motion and in machining application is analysed with the optical measurement system and a CMM.
COMPARISON OF VISUAL SERVOING TECHNIQUES: EXPERIMENTAL RESULTS
In visual servoing applications, two main approaches were deened by Sanderson and Weiss at the beginning of the eighties: Position Based Control and Image Based Control. The aim of this article is to present diierent control laws using these approaches, and discuss the main advantages and disadvantages of both approaches through experimental results. The target object is composed of four non-coplanar characteristic points. From the projection of these four points in the image frame, the estimate of the Pose of the object in the sensor frame is computed using the Dementhon algorithm.
Adaptive Visual Servoing of Contour Features
IEEE/ASME Transactions on Mechatronics, 2018
In vision-based robotic manipulation, it is usually required that the object should present a desired shape or be viewed at a specific angle to facilitate subsequent operations such as object crawling and component inspection. To implement this kind of visual servoing tasks, image features that describe shape information of objects need to be designed. This paper proposes methods based on the general contour of an object. The Bezier curve and the Non-Uniform Rational B-Spline (NURBS) curve are respectively used to fit the contour of the object. Based on contour curve parameters, image contour features are designed. Visual measurements of the image features are used to provide feedback on the shape information of the object to the eye-in-hand visual servoing system. Based on the visual feedback, the motion of the robot is controlled to make the image features converge to the desired values. In this way, it is implemented that the object presents the desired shape or is viewed at the desired angle. Moreover, by using adaptive laws to estimate curve parameters online, the proposed method does not require a priori knowledge of the 3D position of the object. The stability of the proposed controller is analyzed by Lyapunov theory. This method has substantially expanded the application domain of not only the image feature-based visual servoing, but also the B-spline curves. The feasibility of the proposed method is validated by experiments. Index Terms-visual shape servoing, curve image feature, Bezier curve, B-spline curve Ⅰ. INTRODUCTION Visual servoing is widely used because of the high reliability, the wide availability and the low-cost feature of visual sensors. It can be used for many practical tasks like detection, robot inspection and trajectory tracking. One of the key problems of visual servoing is the selection of image features, which can be used to describe the environment and to define control tasks. The most commonly used image features are point features such as feature points [1, 2], hole points [3], mass center [4] and other artificially marked points [5, 6]. Other geometric features, such as line features [7] and ellipse features
The objective of this work is the proposal of a new strategy for controlling the position of a cutting tool relative to a machined part. This works starts with the comparison between manual machine tools and the numerically controefled (NC) machine tools. Despite the high eficciency in terms of accuracy and speed, NC machine requires a considerable time to preparing it, i.e., it requires time for generating the cutting path and then, programming the machine, by using specif programming codes. Besides, the prepared program must be debuged. On the other hand, manual conventional machine tool, although having an elevate flexibility -it does not require programming, has low efficiency, compared with NC machines, since fine positionings must be executed manually, by moving handles carefully. The final goal of this work is the development of a machine tool that has a characteristic intermediate between a NC machine and a manual machine tool, i.e., a machine in which, the motion of the cutting tool is defined by the human operator and a servo system helps the operator to reach the desired positioning faster. For this goal, this work presents a positioning strategy composed of: a) a manually driven sliding table, b) a position sensor that monitores the table position, c) a magnetic brake that locks the handle when the table reaches the desired position and d) a computer that executes the control algorith. The control strategy is presented considering a motion in only one direction. A prototype is developed and constructed. By positioning tests, the effectiveness of the strategy is demonstrated. The system enables a fast and precise positioning of the table, with the operator driving the table through handles. Comparison with completely manual positioning shows that by the proposed strategy, a faster positioning is possible.
A Brief Comparative Study of Visual Servoing Systems
IJSRD - International Journal for Scientific Research & Development, 2018
This paper presents an overview of visual servoing systems. The basic structure of a visual servoing system, various controller techniques used and the comparison of the techniques being used is a matter of concerned of the paper. The paper concentrates on different visual servoing techniques like: image based, position based and hybrid visual servo control, for different issues concerning both hardware and software requirements.
Motion control of medium size CNC machine-tools - A hands-on approach
Proceedings of the 2012 7th IEEE Conference on Industrial Electronics and Applications, ICIEA 2012, 2012
This paperwork presents an integrated approach based upon simulation and experimental work for reducing the positioning errors of a small to medium size CNC machine-tools. The approach is intended to be used at the shop-floor level and therefore it is based upon a straight-forward model of the feed drive. The model was particularized with specific data from a CNC milling machine and simulation techniques were used to predict the behavior of the system. Only the control parameters of the feed drive which may be altered by the user, without modifying the structure of the CNC controller were taken into consideration and tuned. Simulation results and experimental data gathered before and after the tuning process were compared.