Visp: a Software Environment for Eye-in-hand Visual Servoing 2 Image Based Visual Servoing

In this paper, we describe a modular software that allows fast development of eye-in-hand image-based visual servoing applications (ViSP states for \Visual Servoing Platform"). Visual servoing consists in specifying a task as the regulation in the image of a set of visual features. Various issues have thus to considered in the design of such application: among these issues we nd the control of camera motions and the tracking of visual features. Our environment features a wide class of control skills as well as a library of real-time tracking processes. Some applications that used this modular architecture on a six dof cartesian robot are nally presented. 1 Overview Visual servoing is a very important research area in vision-based robotics (see 4] for an extensive review). Despite all the research in this eld, it seems that there are no software environment that allows fast prototyping of visual servoing tasks. The main reason is certainly that it usually requires speciic hardware (the robot and, most of the time, dedicated image processing boards). The consequence is that the resulting applications are not portable and can be merely adapted to other environment. Today's software design allows to propose elementary components that can be combined to build portable high-level applications. Furthermore , the increasing speed of microprocessors allows the development of real-time image processing algorithms on a simple workstation. Chaumette, Rives and Espiau 3] proposed to constitute a \library of canonical vision-based tasks" for eye-in-hand visual servoing that contents the most classical linkages that are used in practice. Toyama and Hager 9] describe what such a system should be in the case of stereo visual servoing. The proposed system is speciied using the same philosophy as the XVision system 7]. This system (called Servomatic) would have been independent from the robot and the tracking algorithms. Following these ways, ViSP, the software environment we present in this paper features all these capabilities: independence with respect to the hardware, simplicity, extendibility, porta-bility. Moreover, ViSP features a large library of elementary positioning tasks wrt. various basic control features (points, lines, circles, spheres, cylinders, etc.) that can be combined together, and an image processing library that allows the tracking of visual cues (dot, segment, ellipse, spline, etc.). This modular platform has been developed in C++ on Unix Workstations. The remainder of this paper presents the background dealing with the eye-in-hand visual servoing and the tracking algorithms. Software design is then …