scholarly journals Visual Servoing of a Moving Target by an Unmanned Aerial Vehicle

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5708
Author(s):  
Ching-Wen Chen ◽  
Hsin-Ai Hung ◽  
Po-Hung Yang ◽  
Teng-Hu Cheng
Keyword(s):  
Visual Servoing ◽  
Feature Vector ◽  
Field Of View ◽  
Control Input ◽  
Predictive Controller ◽  
Aerial Vehicle ◽  
Position And Orientation ◽  
Rotational Motions ◽  
And Performance ◽  
Traditional Image

To track moving targets undergoing unknown translational and rotational motions, a tracking controller is developed for unmanned aerial vehicles (UAVs). The main challenges are to control both the relative position and orientation between the target and the UAV to within desired values, and to guarantee that the generated control input to the UAV is feasible (i.e., below its motion capability). Moreover, the UAV is controlled to ensure that the target always remains within the field of view of the onboard camera. These control objectives were achieved by developing a nonlinear-model predictive controller, in which the future motion of the target is predicted by quadratic programming (QP). Since constraints of the feature vector and the control input are considered when solving the optimal control problem, the control inputs can be bounded and the target can remain inside the image. Three simulations were performed to compare the efficacy and performance of the developed controller with a traditional image-based visual servoing controller.

Visual servoing framework using Gaussian process for an aerial parallel manipulator

2018 ◽  
Vol 233 (9) ◽  
pp. 3408-3425
Author(s):  
Sungwook Cho ◽  
David Hyunchul Shim
Keyword(s):  
Gaussian Process ◽  
Parallel Manipulator ◽  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Flight Test ◽  
Control Input ◽  
Body Velocity ◽  
Aerial Vehicle ◽  
Three Degrees Of Freedom ◽  
Traditional Image

This paper proposes a Gaussian process based visual servoing framework for an aerial parallel manipulator. Our aerial parallel manipulator utilizes the on-board eye-in-hand vision sensor system attached on the end-effector of three-degrees-of-freedom parallel manipulator. There are three major advantages: small, light in weight, and linearity with respect to the host vehicle rather than the serial manipulator, but it has a critical drawback that its workspace is too small to perform the mission itself during the hovering. In order to overcome the limited workspace problem and perform the mission more actively, proposed visual servoing framework is proposed to generate relative body velocity commands of the host vehicle by using the interpolated and extrapolated feature path between the initial and desired features to fed into the underactuated aerial parallel manipulator. It can generate not only numerical stable but also feasible control input. Furthermore, it can overcome the weakness of the traditional image-based visual servoing such as singularities, uncertainties, and local minimums during calculating image Jacobian under the large disparity environment between the target and the unmanned aerial vehicle. As a result of the proposed contribution, we show that our contribution is reliable to perform the picking-and-replacement autonomously, and it shows that it can be applied in the large displacement environments throughout the flight test.

Dynamic Visual Servoing for a Quadrotor Using a Virtual Camera

2017 ◽  
Vol 05 (01) ◽  
pp. 1-17 ◽  
Author(s):  
Geoff Fink ◽  
Hui Xie ◽  
Alan F. Lynch ◽  
Martin Jagersand
Keyword(s):  
Visual Servoing ◽  
Closed Loop ◽  
Field Of View ◽  
Visual Features ◽  
Control Law ◽  
Asymptotically Stable ◽  
Globally Asymptotically Stable ◽  
Virtual Camera ◽  
Aerial Vehicle ◽  
Planar Target

This paper presents a dynamic image-based visual servoing (IBVS) control law for a quadrotor unmanned aerial vehicle (UAV) equipped with a single fixed on-board camera. The motion control problem is to regulate the relative position and yaw of the vehicle to a moving planar target located within the camera’s field of view. The control law is termed dynamic as it’s based on the dynamics of the vehicle. To simplify the kinematics and dynamics, the control law relies on the notion of a virtual camera and image moments as visual features. The convergence of the closed-loop is proven to be globally asymptotically stable for a horizontal target. In the case of nonhorizontal targets, we modify the control using a homography decomposition. Experimental and simulation results demonstrate the control law’s performance.

Multi-cameras visual servoing for dual-arm coordinated manipulation

Robotica ◽  
2017 ◽  
Vol 35 (11) ◽  
pp. 2218-2237 ◽  
Author(s):  
Jiadi Qu ◽  
Fuhai Zhang ◽  
Yili Fu ◽  
Shuxiang Guo
Keyword(s):  
Visual Servoing ◽  
Field Of View ◽  
End Effector ◽  
Visual Constraints ◽  
Position And Orientation ◽  
Dual Arm Robot ◽  
Pose Alignment ◽  
Alignment Errors ◽  
Object Features ◽  
Dual Arm

SUMMARYAlthough image-based visual servoing (IBVS) provides good performance in many dual-arm manipulation applications, it reveals some fatal limitations when dealing with a large position and orientation uncertainty. The object features may leave the camera's field of view, and the dual-arm robot may not converge to their goal configurations. In this paper, a novel vision-based control strategy is presented to resolve these limitations. A visual path planning method for dual-arm end-effector features is proposed to regulate the large initial poses to the pre-alignment poses. Then, the visual constraints between the position and orientation of two objects are established, and the sequenced subtasks are performed to attain the pose alignment of two objects by using a multi-tasks IBVS method. The proposed strategy has been implemented on a MOTOMAN robot to perform the alignment tasks of plug–socket and cup–lid, and results indicate that the plug and socket with the large initial pose errors 145.4 mm, 43.8○ (the average errors of three axes) are successfully aligned with the allowed pose alignment errors 3.1 mm, 1.1○, and the cup and lid with the large initial pose errors 131.7 mm, 20.4○ are aligned with the allowed pose alignment errors −2.7 mm, −0.8○.

Position and Attitude Control by Rotor Tilt and Rotor Speed Synchronization for Single Axis Tilting-Rotor Quadcopter

2017 ◽  
Author(s):  
Rumit Kumar ◽  
Alireza Nemati ◽  
Manish Kumar ◽  
Kelly Cohen ◽  
Franck Cazaurang
Keyword(s):  
Attitude Control ◽  
Pd Controller ◽  
Servo Motor ◽  
Rotor Speed ◽  
Tilt Rotor ◽  
Rotor Design ◽  
Aerial Vehicle ◽  
Simulation Results ◽  
Position And Orientation ◽  
And Performance

In this paper, the control maneuvering, and performance analysis of a tilting-rotor quadcopter during autonomous flight is presented. Unlike traditional quadcopters, a tilting-rotor quadcopter provides additional actuated controls as the propeller motors are actuated for tilt which can be utilized to improve efficiency of the aerial vehicle during flight. The tilting-rotor quadcopter design is accomplished by using an additional servo motor for each rotor that enables the rotor to tilt about the axis of quadcopter arm. Here, a detailed control strategy has been discussed to use the propeller tilts for position and orientation control during completely autonomous flights of the quadcopter. In conventional quadcopters, the variation in rotational speeds of the four propellers is utilized for maneuvering. This work incorporates use of varying propeller rotational speeds along with tilting of the propellers for maneuvering the quadcopter during flight. A PD controller is developed to achieve various modes of flight and numerical simulation results are presented demonstrating the performance of the controller. Furthermore, the performance of the tilt-rotor design is compared with respect to the conventional quadcopter in the presence of wind disturbances and uncertainties in the system.

Disturbance observer-based visual servoing for multirotor unmanned aerial vehicles

2018 ◽  
Vol 66 (3) ◽  
pp. 258-267 ◽  
Author(s):  
Hui Xie ◽  
Zhen He ◽  
Darryl Veitch
Keyword(s):  
Disturbance Observer ◽  
Visual Servoing ◽  
Visual Target ◽  
Feedforward Control ◽  
Field Of View ◽  
External Disturbances ◽  
Saturation Control ◽  
Controller Performance ◽  
Aerial Vehicle ◽  
Control Part

Abstract This paper presents a disturbance observer based input saturated visual servoing law for a quadrotor unmanned aerial vehicle (UAV). The controller regulates the 4D relative pose, i. e., 3D translational and yaw motion, between the vehicle and a planar horizontal visual target in an environment with external disturbances. A feedforward control is used to compensate the lumped disturbance consisting of both system uncertainties and external disturbances. The feedback control part is based on a nested saturation control, which is used to bound the orientation of the UAV and therefore helps to keep the visual target in the camera’s field of view. Simulation results are provided to demonstrate controller performance.

A Novel Gripping System for Delivery of Packages via Unmanned Aerial Vehicles

2020 ◽  
Author(s):  
Trigun Dinesh Maroo ◽  
Andrew B. Wright
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Unmanned Aerial Vehicle ◽  
Control Input ◽  
Ground Vehicle ◽  
Aerial Vehicles ◽  
Aerial Vehicle ◽  
Position And Orientation ◽  
End Effectors

Abstract An Unmanned Aerial Vehicle (UAV) can carry packages to locations that are unreachable by a ground vehicle using a gripper that can handle standard sized packages. This paper presents a UAV-mounted system for grasping corrugated boxes. The proposed gripping system uses two pairs of end effectors which are arranged perpendicular to each other. All four grippers are geared so that they can be actuated by a single control input. The mechanism is designed to handle position and orientation errors of the box relative to the gripper. The gripper was experimentally validated using a test box that was misaligned in position and orientation.

An auto-landing strategy based on pan-tilt based visual servoing for unmanned aerial vehicle in GNSS-denied environments

2021 ◽  
pp. 106891
Author(s):  
Chengbin Chen ◽  
Sifan Chen ◽  
Guangsheng Hu ◽  
Baihe Chen ◽  
Pingping Chen ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Visual Servoing ◽  
Aerial Vehicle

scholarly journals Observer-based robust integral of the sign of the error control of class I of underactuated mechanical systems: Theory and real-time experiments

2021 ◽  
pp. 014233122110313
Author(s):  
Afef Hfaiedh ◽  
Ahmed Chemori ◽  
Afef Abdelkrim
Keyword(s):  
Real Time ◽  
Error Control ◽  
Degrees Of Freedom ◽  
Sliding Mode ◽  
Mechanical Systems ◽  
Class I ◽  
Control Input ◽  
Underactuated Mechanical Systems ◽  
Control Scheme ◽  
And Performance

In this paper, the control problem of a class I of underactuated mechanical systems (UMSs) is addressed. The considered class includes nonlinear UMSs with two degrees of freedom and one control input. Firstly, we propose the design of a robust integral of the sign of the error (RISE) control law, adequate for this special class. Based on a change of coordinates, the dynamics is transformed into a strict-feedback (SF) form. A Lyapunov-based technique is then employed to prove the asymptotic stability of the resulting closed-loop system. Numerical simulation results show the robustness and performance of the original RISE toward parametric uncertainties and disturbance rejection. A comparative study with a conventional sliding mode control reveals a significant robustness improvement with the proposed original RISE controller. However, in real-time experiments, the amplification of the measurement noise is a major problem. It has an impact on the behaviour of the motor and reduces the performance of the system. To deal with this issue, we propose to estimate the velocity using the robust Levant differentiator instead of the numerical derivative. Real-time experiments were performed on the testbed of the inertia wheel inverted pendulum to demonstrate the relevance of the proposed observer-based RISE control scheme. The obtained real-time experimental results and the obtained evaluation indices show clearly a better performance of the proposed observer-based RISE approach compared to the sliding mode and the original RISE controllers.

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