44 accepted papers
This letter focuses on the vibration reduction for Cable-Driven Parallel Robots. A Non-linear Model Predictive Controller (NMPC) is designed and implemented to adapt the control inputs sent to the robot actuators. This NMPC is based on an elasto-dynamic model of the robot, which is discretized and i
In this letter, we present a novel dual-task, closed-loop, visual servoing-based active vision framework in an eye-in-hand configuration. The proposed active vision framework continuously drives the camera motion by coupling continuous Next-Best-View (NBV) planning and visual servo control within a
In this letter, we present a novel dual-task, closed-loop, visual servoing-based active vision framework in an eye-in-hand configuration. The proposed active vision framework continuously drives the camera motion by coupling continuous Next-Best-View (NBV) planning and visual servo control within a …
This paper presents a visual servoing strategy for a clevis and tenon joint assembly as typically performed in aircraft manufacturing. The desired velocity in the image acquired by the cameras observing the parts is extracted from a vector field that guides the motion of the moving part so that it f
This letter proposes a new image-based visual servoing controller for positioning a camera with respect to a cylindrical object. Traditional image-based approaches often rely on estimating planar parameters from the cylinder's projected edges, making them sensitive to noise and modeling errors. In t
In this paper, we present how a proximity array attached as an end-effector can perform a positioning task with respect to a cylinder. We develop the complete modeling of the system from which a classical control law is designed. Positioning with respect to the outside of a cylinder can be used for
In this letter, we present a visual control framework for accurately positioning feature points belonging to the surface of a 3D deformable object to desired 3D positions, by acting on a set of manipulated points using a robotic manipulator. Notably, our framework considers the dynamic behavior of t
In this letter, we consider positioning in congested space within the framework of sensor-based control using vision and proximity sensors. Vision acts as primary sensing modality for performing the positioning task, while proximity sensors complement it by ensuring that the robotic platform does no
This letter proposes a QP-based visual servoing scheme for limiting motion blur during the achievement of a visual task. Unlike traditional image restoration approaches, we want to avoid any deconvolution step by keeping the image sequence acquired by the camera as sharp as possible. To do so, we se
In this letter, we propose a shape visual servoing approach for manipulating a suspended cable attached between two quadrotor drones. A leader-follower control strategy is presented, where a human operator controls the rigid motion of the cable by teleoperating one drone (the leader), while the seco
In this letter, we describe a novel roadmap construction method in unknown environments, which relies on the extraction of the Hamilton-Jacobi skeleton of the free space. This skeleton is used to construct a graph of free-space bubbles, effectively compressing the skeleton information in a sparse da
Cable-Driven Parallel Robots (CDPRs) are well-adapted to large workspaces since they replace rigid links by cables. However, they lack in positioning accuracy and new control methods are necessary to achieve profile-following tasks. This paper presents a control scheme designed for these tasks, rely…
In this paper, we propose a physics-based robot controller to deform a soft object toward a desired 3D shape using a limited number of handling points. For this purpose, the shape of the deformable object is represented using Fourier descriptors. We derive the analytical relation that provides the v…
In this paper we propose a visual servoing approach that controls the deformation of a suspended tether cable subject to gravity from visual data provided by a RGB-D camera. The cable shape is modelled with a parabolic curve together with the orientation of the plane containing the tether. The visua…
In this letter, we discuss the stability analysis of Plane-to-Plane positioning task when the task is designed in proximity sensor space. We utilize a multi-sensor arrangement of proximity sensors that forms a proximity array to obtain the necessary information in sensor space. For the task consider
In this paper, we consider a multi-sensor arrangement of proximity sensors that forms a proximity array. A general modeling methodology is considered within the framework of Sensor-based Control. It incorporates multiple sensor signals from the proximity array by giving primary emphasis on the inter…
In this work we present our results on dynamic visual servoing for the case of moving targets while also exploring the possibility of using such a controller for interaction with the environment. We illustrate the derivation of a feature space impedance controller for tracking a moving object as wel…
Recent Earth observation satellites are now equipped with new instrument that allows image feedback in real-time. Problematic such as ground target tracking, moving or not, can now be addressed by precisely controlling the satellite attitude. In this paper, we propose to consider this problem using…
Robotic systems are increasingly used to work in dynamic and/or unstructured environments and to operate with a high degree of safety and autonomy. Consequently, they are often equipped with external sensors capable of perceiving the environment (e.g., cameras) and the contacts that may arise (e.g.
Cable-Driven Parallel Robots (CDPRs) are parallel robots with rigid links replaced by cables. As for most parallel robots the determination of the analytical solutions to the direct geometrico-static model (DGSM) is a difficult task that is often not feasible online. However, the knowledge of the mo…
Cable-driven parallel robots (CDPRs) are a type of parallel robots, where cables are used instead of rigid links. This leads to many advantages, such as large workspace, low mass in motion and simple reconfiguration. The drawbacks are accuracy issues and complex cable management. Indeed, it is usual…
In this paper, we propose a novel approach for transferring a deep reinforcement learning (DRL) grasping agent from simulation to a real robot, without fine tuning in the real world. The approach utilises a CycleGAN to close the reality gap between the simulated and real environments, in a reverse r…
Cable-driven parallel robots (CDPRs) are a kind of parallel robots that have cables instead of rigid links. Implementing vision-based control on CDPRs leads to a good final accuracy despite modeling errors and other perturbations in the system. However, unlike final accuracy, the trajectory to the g
This letter focuses on finding robust paths for a robotic system by taking into account the state uncertainty and the probability of collision. We are interested in dealing with intermittent exteroceptive measurements (e.g., collected from vision). We assume that these cues provide reliable measurem
In cable-driven parallel robots (CDPRs), rigid links are substituted by flexible cables. This change in actuation allows for a large workspace with a high payload to weight ratio, among other appealing characteristics. However, the accuracy for such systems needs to be improved to truly outperform c
We present in this paper a modular real-time model-based visual tracker. It is able to fuse different types of measurement, that is, edge points, textured points, and depth map, provided by one or multiple vision sensors. A confidence index is also proposed for determining if the outputs of the trac…
This letter proposes a control framework allowing to position a robot in range and orientation with respect to a sound source from a binaural system. To this end, a sensor-based control framework is developed upon interaural level difference (ILD) cues. ILD is known to be implicitly related to the s
We present a deep neural network-based method to perform high-precision, robust and real-time 6 DOF positioning tasks by visual servoing. A convolutional neural network is fine-tuned to estimate the relative pose between the current and desired images and a pose-based visual servoing control law is…
In this letter, we investigate the online generation of optimal trajectories for target tracking with a quadrotor while satisfying a set of image-based and actuation constraints. We consider a quadrotor equipped with a camera (either down or front-looking) with limited field of view. The aim is to f
In active vision, the camera motion is controlled in order to improve a certain visual sensing strategy. In this paper, we formulate an active vision task function to improve pose estimation. This is done by defining an optimality metric on the Fisher Information Matrix. This task is then incorporat…
This paper presents image-based navigation from an image memory using a combination of line segments and feature points. The environment is represented by a set of key images, which are acquired during a prior mapping phase that defines the path to be followed during the navigation. The switching of…
The determination of the singularity cases in the observation of image features is a complicated problem, which is still open, apart from image points. For the first time, we provide the singularity cases in the observation of three image lines. We show that a concept named the “hidden robot,” which
In this paper, we address the problem of using a camera with limited field of view for controlling the motion of a quadrotor in aggressive flight regimes. We present a minimum time trajectory planning method that guarantees visibility of the image features while allowing the robot to undertake aggre…
In this paper, we show that visual servoing can be formulated as an acceleration-resolved, quadratic optimization problem. This allows us to handle visual constraints, such as field of view and occlusion avoidance, as inequalities. Furthermore, it allows us to easily integrate visual servoing tasks
Apart the use of catadioptric cameras, only few visual servoing works exploit the use of mirror. Such a configuration is however interesting since it allows to overpass the limited camera field of view. Based on the known projection equations involved in such a system, this paper introduces the theo…
We propose in this paper a new active perception scheme based on Model Predictive Control under constraints for generating a sequence of visual servoing tasks. The proposed control scheme is used to compute the motion of a camera whose task is to successively observe a set of robots for measuring th…
This letter presents a method for image-based navigation from an image memory using line segments as landmarks. The entire navigation process is based on 2-D image information without using any 3-D information at all. The environment is represented by a set of reference images with overlapping landm
This paper is a follow-up way to our previous works regarding audio-based control, that is an alternative method for auditory-based robot tasks. Conversely to classic methods oriented towards sound source localization, audio-based control is a sensor-based framework that does not localize the sound…
This paper validates experimentally a novel approach to robot audition, sound-based control, which consists in introducing auditory features directly as inputs of a closed-loop control scheme, that is, without any explicit localization process. The applications we present rely on the implicit bearin
Visual servoing based on photometric data is of great interest since it does not necessitate any image processing or visual tracking steps. A vital issue in such methods is the change in the image resulting from the appearance and disappearance of portions of the scene from the camera field-of-view…
The selection of a suitable set of visual features for an optimal performance of closed-loop visual control or Structure from Motion (SfM) schemes is still an open problem in the visual servoing community. For instance, when considering integral region-based features such as image moments, only heur…
In this paper we experimentally validate and compare three different methods for estimating the 3D parameters of a planar scene from a (possibly time-varying) set of feature points acquired by a moving monocular camera. The first method, based on the classical decomposition of the homography matrix,…
This paper presents a novel approach to robot audition by performing robotic tasks with auditory cues. Unlike many previous works, we propose a control scheme, that does not require any explicit sound source localization. This approach is capable of controlling all the three degrees of freedom in a…
One way to deal with occlusions or loss of tracking of the visual features used for visual servoing tasks is to predict the feature behavior in the image plane when the measurements are missing. Different prediction and correction methods have already been proposed in the literature. The purpose of…