6 research outputs found
Enhanced vision-based localization and control for navigation of non-holonomic omnidirectional mobile robots in GPS-denied environments
New Zealand’s economy relies on primary production to a great extent, where use of the technological
advances can have a significant impact on the productivity. Robotics and automation
can play a key role in increasing productivity in primary sector, leading to a boost in national
economy. This thesis investigates novel methodologies for design, control, and navigation
of a mobile robotic platform, aimed for field service applications, specifically in agricultural
environments such as orchards to automate the agricultural tasks.
The design process of this robotic platform as a non-holonomic omnidirectional mobile
robot, includes an innovative integrated application of CAD, CAM, CAE, and RP for development
and manufacturing of the platform. Robot Operating System (ROS) is employed for
the optimum embedded software system design and development to enable control, sensing,
and navigation of the platform.
3D modelling and simulation of the robotic system is performed through interfacing ROS
and Gazebo simulator, aiming for off-line programming, optimal control system design, and
system performance analysis. Gazebo simulator provides 3D simulation of the robotic system,
sensors, and control interfaces. It also enables simulation of the world environment, allowing
the simulated robot to operate in a modelled environment. The model based controller for kinematic
control of the non-holonomic omnidirectional platform is tested and validated through
experimental results obtained from the simulated and the physical robot.
The challenges of the kinematic model based controller including the mathematical and
kinematic singularities are discussed and the solution to enable an optimal kinematic model based controller is presented. The kinematic singularity associated with the non-holonomic
omnidirectional robots is solved using a novel fuzzy logic based approach. The proposed
approach is successfully validated and tested through the simulation and experimental results.
Development of a reliable localization system is aimed to enable navigation of the platform
in GPS-denied environments such as orchards. For this aim, stereo visual odometry (SVO) is
considered as the core of the non-GPS localization system. Challenges of SVO are introduced
and the SVO accumulative drift is considered as the main challenge to overcome. SVO drift is
identified in form of rotational and translational drift. Sensor fusion is employed to improve
the SVO rotational drift through the integration of IMU and SVO.
A novel machine learning approach is proposed to improve the SVO translational drift
using Neural-Fuzzy system and RBF neural network. The machine learning system is formulated
as a drift estimator for each image frame, then correction is applied at that frame to avoid
the accumulation of the drift over time. The experimental results and analyses are presented
to validate the effectiveness of the methodology in improving the SVO accuracy.
An enhanced SVO is aimed through combination of sensor fusion and machine learning
methods to improve the SVO rotational and translational drifts. Furthermore, to achieve a
robust non-GPS localization system for the platform, sensor fusion of the wheel odometry
and the enhanced SVO is performed to increase the accuracy of the overall system, as well as
the robustness of the non-GPS localization system. The experimental results and analyses are
conducted to support the methodology
Singularity-free state-space representation for non-holonomic, omnidirectional undercarriages by means of coordinate switching
Non-holonomic, omnidirectional undercarriages that are composed of steered standard wheels seem to provide a solid compromise between versatility, flexibility and high robustness against various ground conditions. However, such undercarriages are characterized by the occurrence of a number of singular configurations. To avoid these singular configurations most control-approaches restrict the admissible configuration-space thus eventually reducing the mobility and flexibility of the undercarriage. Within this work a state-space representation that forms a locally singularity-free atlas of the admissible configurationspace is presented. Based on this state-space description a switching based controller is developed that incorporates the former singular regions into the used configuration space and thus allows to exploit the full flexibility of non-holonomic, omnidirectional undercarriages. The implemented controller is quantitatively and qualitatively evaluated and compared to one approach that avoids the singular regions and one that completely neglects the non-holonomic bindings
15th Conference on Dynamical Systems Theory and Applications DSTA 2019 ABSTRACTS
From Preface: This is the fifteen time when the conference „Dynamical Systems – Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and the Ministry of Science and Higher Education. It is a great pleasure that our invitation has been accepted by so many people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to
participate in the conference for the first time. With proud and satisfaction we welcome nearly 255 persons from 47 countries all over the world. They decided to share the results of their research and many years experiences in the discipline of dynamical systems by submitting many very interesting papers. This booklet contains a collection of 338 abstracts, which have gained the acceptance of referees and have been qualified for publication in the conference edited books.Technical editor and cover design: Kaźmierczak, MarekCover design: Ogińska, Ewelina; Kaźmierczak, Mare