Research

Research on Aerial Robotics
Ongoing projects: ANR DACAR (2018-2022), ALCYON Rapid DGA (2017-2020)

Since the last two decades, OSCAR’s members have made significant contributions in the fields of Visual Servo Control, Nonlinear Observer and Nonlinear Control applied to Unmanned Aerial Vehicles (UAV). We have been successful in applying our theoretical results to a wide range of practically motivated problems such as:
  • Path following and trajectory tracking of UAVs (quadrotors, scale-model airplanes);
  • Landing a quadrotor UAV on a moving platform using optical flow;
  • Visual servoing of UAVs;
  • Haptic-based bilateral teleoperation of UAVs;
  • Attitude (i.e. orientation) estimation using an Inertial Measurement Unit (IMU); etc.
In particular, the developed Unified Control Approach to a large family of underactuated vehicles (aerial drones (e.g. quadrotors, ducted fan UAVs), axisymmetric vehicles (e.g. rockets, torpedo-shaped underwater vehicles), scale-model airplanes, motorboats, etc.) is at the heart of recent achievements of OSCAR. The mathematic and geometric elegancy, the simplicity for practical implementation, the enlarged domain of operations and high robustness with respect to external disturbances of the proposed approach are highly supported by successful experimental validations with various robotic platforms either developed by the team (e.g. quadrotors, scale-model airplanes) or by its industrial collaborators (e.g. the ducted-fan UAV of BERTIN Technologies, the Flybox hexacopter of SKYBOTIX, the motorboat of ASCA). We now focus on extending this control approach to Convertible UAVs that exploit both rotary wings and fixed wings for control.
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The quadrotor and the scale-model airplane developed by I3S-OSCAR team
 
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The convertible UAV of I3S-OSCAR team
 

Research on Marine and Underwater Robotics

Ongoing projects: ANR ASTRID CONGRE (2019-2021), FUI GREENEXPLORER (2017-2021)

The focus of this activity direction is to bring our knowledge and techniques in Visual Servo Control, Nonlinear Observer and Nonlinear Control theories (which has been developed for Aerial robotics) to the field of Marine and Underwater Robotics that exhibits new challenges and opportunities. Since 7 years OSCAR team has been active in Marine and Underwater Robotics via its involvement in 4 National and European projects. Some visual servoing solutions for Autonomous Underwater Vehicles (such as stabilization in front of a visual target, pipeline following) have been successfully developed and validated via the collaborations with the team’s industrial partners (CYBERNETIX, ALSEAMAR).
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The Girona-500 AUV (left) used by the company Cybernétix for experimental validations of our vision-based controllers for homography-based stabilization and positioning (middle) and for pipeline following (right)

OSCAR team has recently developed a man-portable underwater robotic vehicle to facilitate experimental validations of the developed control and estimation algorithms. In particular, a novel homography-based visual servoing algorithm without relying on a costly velocity sensor (e.g. DVL) has been successfully validated with this platform for the station keeping application. These experimental demonstrations of this low-cost solution have attracted a number of specialized companies (e.g. ALSEAMAR).
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The AUV platform and Hardware/Software architecture developped by I3S-OSCAR team
 
Nonlinear Control and Sensor-based Control of Autonomous Underwater Vehicles
Autonomous navigation of AUVs in an unknown or partially known and dynamically changing oceanic environment is challenging. Scientific issues are strongly related to the fact that the AUV may navigate in cluttered areas where global acoustic positioning systems are unusable or insufficiently precise for safe navigation. In this case, the AUV must rely on exteroceptive sensors and sensor-based navigation strategies. Although several types of sensors can be used, the video camera remains an excellent candidate as they are considerably cheaper than acoustic sensors and provide rich information at a high update rate. Among many applications related to vision-based control paradigm, we have investigated the two following relevant control problems of AUVs:
Vision-based stabilization and positioning: This functionality is useful for AUV navigation close to underwater infrastructures in the case when high-resolution imaging is needed for inspection or intervention tasks. In the context of monocular-vision, we have recently proposed a homography-based visual servoing (HBVS) control approach for fully-actuated AUVs, using the homography matrix that encodes transformation information between two images of the same planar target. The proposed control approach has been experimentally validated by our industrial collaborator Cybernétix on the Girona-500 AUV. An extension of this work to the case of absence of linear velocity measurements (i.e. DVL is not used) has been recently developed.
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Validation of the proposed HBVS controller using a downward-looking camera: reference image and current images
 
 
Vision-based pipeline following: This problem is highly relevant for inspection of submerged linear infrastructures such as pipelines and cables by AUVs. We have proposed an IBVS controller for fully-actuated AUVs for pipeline/cable following using a monocular camera and using Plücker coordinates for the representation of lines. Experimental validations have been recently carried out by Cybernétix on the Girona-500 AUV.
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Validation of the proposed vision-based controller for pipeline following: Initial image and current images during convergence