Controller Design Of Unicycle Mobile Robot

ABSTRACT: The ability of unicycle mobile robot to stand and move around using one wheel has attracted a lot of researchers to conduct studies about the system, particularly in the design of the system mechanisms and the control strategies. This paper reports the investigation done on the design of the controller of the unicycle mobile robot system to maintain its stability in both longitudinal and lateral directions. The controller proposed is a Linear Quadratic Controller (LQR) type which is based on the linearized model of the system. A thorough simulation studies have been carried out to find out the performance of the LQR controller. The best controller gain, K acquired through the simulation is selected to be implemented and tested in the experimental hardware. Finally, the results obtained from the experimental study are compared to the simulation results to study the controller efficacy. The analysis reveals that the proposed controller design is able to stabilize the unicycle mobile robot. ABSTRAK: Kemampuan robot satu roda untuk berdiri dan bergerak di sekitar telah menarik minat ramai penyelidik untuk mengkaji sistem robot terutamanya didalam bidang rangka mekanikal dan strategi kawalan robot. Kertas kajian ini melaporkan hasil penyelidikan ke atas strategi kawalan robot bagi memastikan sistem robot satu roda dapat distabilkan dari arah sisi dan hadapan. Strategi kawalan yang dicadang, menggunakan teknik kawalan kuadratik sejajar (Linear Quadratic Control) yang berdasarkan model robot yang telah dipermudahkan. Kajian simulasi secara terperinci telah dijalankan bagi mengkaji prestasi strategi kawalan yang dicadangkan. Dari kajian simulasi sistem robot, pemilihan faktor konstan, K yang sesuai di dalam strategi kawalan telah dibuat, agar dapat dilaksanakan ke atas sistem robot yang dibangunkan. Keputusan dari kajian simulasi dan tindak balas oleh sistem robot yang dibangunkan akhirnya dibandingkan bagi melihat kesesuaian faktor kostan, K yang dipilih. Analisa menunjukkan dengan menggunakan strategi kawalan yang dicadangkan dapat menstabilkan robot satu roda. KEYWORDS: unicycle mobile robot; nonholonomic system; LQ

Single wheel robot: gyroscopical stabilization on ground and on incline.

by Loi-Wah Sun.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 77-81).Abstracts in English and Chinese.Abstract --- p.iAcknowledgments --- p.iiiContents --- p.vList of Figures --- p.viiList of Tables --- p.viiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.1.1 --- Literature review --- p.2Chapter 1.1.2 --- Gyroscopic precession --- p.5Chapter 1.2 --- Thesis overview --- p.7Chapter 2 --- Dynamics of the robot on ground --- p.9Chapter 2.1 --- System model re-derivation --- p.10Chapter 2.1.1 --- Linearized model --- p.15Chapter 2.2 --- A state feedback control --- p.16Chapter 2.3 --- Dynamic characteristics of the system --- p.18Chapter 2.4 --- Simulation study --- p.19Chapter 2.4.1 --- The self-stabilizing dynamics effect of the single wheel robot --- p.21Chapter 2.4.2 --- The Tilting effect of flywheel on the robot --- p.23Chapter 2.5 --- Dynamic parameters analysis --- p.25Chapter 2.5.1 --- Swinging pendulum --- p.25Chapter 2.5.2 --- Analysis of radius ratios --- p.27Chapter 2.5.3 --- Analysis of mass ratios --- p.30Chapter 3 --- Dynamics of the robot on incline --- p.33Chapter 3.1 --- Modeling of rolling disk on incline --- p.33Chapter 3.1.1 --- Disk rolls up on an inclined plane --- p.37Chapter 3.2 --- Modeling of single wheel robot on incline --- p.39Chapter 3.2.1 --- Kinematic constraints --- p.40Chapter 3.2.2 --- Equations of motion --- p.41Chapter 3.2.3 --- Model simplification --- p.43Chapter 3.2.4 --- Linearized model --- p.46Chapter 4 --- Control of the robot on incline --- p.47Chapter 4.1 --- A state feedback control --- p.47Chapter 4.1.1 --- Simulation study --- p.49Chapter 4.2 --- Backstepping-based control --- p.51Chapter 4.2.1 --- Simulation study --- p.53Chapter 4.2.2 --- The effect of the spinning rate of flywheel --- p.56Chapter 4.2.3 --- Simulation study --- p.58Chapter 4.2.4 --- Roll up case --- p.58Chapter 4.2.5 --- Roll down case --- p.58Chapter 5 --- Motion planning --- p.61Chapter 5.1 --- Performance index --- p.61Chapter 5.2 --- Condition of rolling up --- p.62Chapter 5.3 --- Motion planning of rolling Up --- p.65Chapter 5.3.1 --- Method I : Orientation change --- p.65Chapter 5.3.2 --- Method II : Change the initial velocities --- p.69Chapter 5.4 --- Wheel rolls Down --- p.70Chapter 5.4.1 --- Terminal velocity of rolling body down --- p.73Chapter 6 --- Summary --- p.75Chapter 6.1 --- Contributions --- p.75Chapter 6.2 --- Future Works --- p.76Bibliography --- p.7

Dynamics modelling of a multi body unicycle in three-dimensional space

Master of ScienceDepartment of Mechanical and Nuclear EngineeringYouqi WangWarren N. WhiteSelf-balanced unicycle has received the attention of researchers for decades. Over the years, unicycle models with several different assemblies have been introduced by them. A thorough analysis of the dynamics of a unicycle with a frame and a rotating disk is discussed in this research. A torque applied to the rolling wheel maintains the longitudinal stability of the system by moving forward and backward. The rotating disk mounted on the top of the frame maintains the lateral stability of the system by providing a torque. Due to this torque the rolling wheel precess and change its yaw direction. The components of the unicycle assembly are addressed separately for the analysis of the dynamics. First, only the rolling wheel considered. Then, the rolling wheel and the frame are analyzed. Finally, the completed assembly with the rotating disk considered to build the dynamics model. In each of these cases both Newton-Euler and Lagrangian methods are used to obtain the dynamics equations for the unicycle

A framework for safe human-humanoid coexistence

This work is focused on the development of a safety framework for Human-Humanoid coexistence, with emphasis on humanoid locomotion. After a brief introduction to the fundamental concepts of humanoid locomotion, the two most common approaches for gait generation are presented, and are extended with the inclusion of a stability condition to guarantee the boundedness of the generated trajectories. Then the safety framework is presented, with the introduction of different safety behaviors. These behaviors are meant to enhance the overall level of safety during any robot operation. Proactive behaviors will enhance or adapt the current robot operations to reduce the risk of danger, while override behaviors will stop the current robot activity in order to take action against a particularly dangerous situation. A state machine is defined to control the transitions between the behaviors. The behaviors that are strictly related to locomotion are subsequently detailed, and an implementation is proposed and validated. A possible implementation of the remaining behaviors is proposed through the review of related works that can be found in literature

Intelligent Self-Organized Robust Control Design based on Quantum/Soft Computing Technologies and Kansei Engineering

System of systems engineering technology describes the possibility of ill-defined (autonomous or hierarchically connected) dynamic control system design that includes human decision making in unpredicted (unforeseen) control situations. Kansei/Affective Engineering technology and its toolkit include qualitative description of human being emotion, instinct and intuition that are used effectively in design processes of smart/wise robotics and intelligent mechatronics. In presented report the way how these technologies can be married using new types of unconventional computational intelligence is described. System analysis of interrelations between these two important technologies is discussed. The solution of an important problem as robust intelligent control system design based on quantum knowledge base self-organization in unpredicted control situations and information risk is proposed. The background of applied unconventional computational intelligence is soft and quantum computing technologies. Applications of the developed approach in robust integrated fuzzy intelligent control systems are considered using concrete Benchmarks

DEVELOPMENT AND CONTROL OF AN UNDERACTUATED TWO-WHEELED MOBILE ROBOT

Ph.DDOCTOR OF PHILOSOPH

A Practical and Conceptual Framework for Learning in Control

We propose a fully Bayesian approach for efficient reinforcement learning (RL) in Markov decision processes with continuous-valued state and action spaces when no expert knowledge is available. Our framework is based on well-established ideas from statistics and machine learning and learns fast since it carefully models, quantifies, and incorporates available knowledge when making decisions. The key ingredient of our framework is a probabilistic model, which is implemented using a Gaussian process (GP), a distribution over functions. In the context of dynamic systems, the GP models the transition function. By considering all plausible transition functions simultaneously, we reduce model bias, a problem that frequently occurs when deterministic models are used. Due to its generality and efficiency, our RL framework can be considered a conceptual and practical approach to learning models and controllers whe

Locomotion system for ground mobile robots in uneven and unstructured environments

One of the technology domains with the greatest growth rates nowadays is service robots. The extensive use of ground mobile robots in environments that are unstructured or structured for humans is a promising challenge for the coming years, even though Automated Guided Vehicles (AGV) moving on flat and compact grounds are already commercially available and widely utilized to move components and products inside indoor industrial buildings. Agriculture, planetary exploration, military operations, demining, intervention in case of terrorist attacks, surveillance, and reconnaissance in hazardous conditions are important application domains. Due to the fact that it integrates the disciplines of locomotion, vision, cognition, and navigation, the design of a ground mobile robot is extremely interdisciplinary. In terms of mechanics, ground mobile robots, with the exception of those designed for particular surroundings and surfaces (such as slithering or sticky robots), can move on wheels (W), legs (L), tracks (T), or hybrids of these concepts (LW, LT, WT, LWT). In terms of maximum speed, obstacle crossing ability, step/stair climbing ability, slope climbing ability, walking capability on soft terrain, walking capability on uneven terrain, energy efficiency, mechanical complexity, control complexity, and technology readiness, a systematic comparison of these locomotion systems is provided in [1]. Based on the above-mentioned classification, in this thesis, we first introduce a small-scale hybrid locomotion robot for surveillance and inspection, WheTLHLoc, with two tracks, two revolving legs, two active wheels, and two passive omni wheels. The robot can move in several different ways, including using wheels on the flat, compact ground,[1] tracks on soft, yielding terrain, and a combination of tracks, legs, and wheels to navigate obstacles. In particular, static stability and non-slipping characteristics are considered while analyzing the process of climbing steps and stairs. The experimental test on the first prototype has proven the planned climbing maneuver’s efficacy and the WheTLHLoc robot's operational flexibility. Later we present another development of WheTLHLoc and introduce WheTLHLoc 2.0 with newly designed legs, enabling the robot to deal with bigger obstacles. Subsequently, a single-track bio-inspired ground mobile robot's conceptual and embodiment designs are presented. This robot is called SnakeTrack. It is designed for surveillance and inspection activities in unstructured environments with constrained areas. The vertebral column has two end modules and a variable number of vertebrae linked by compliant joints, and the surrounding track is its essential component. Four motors drive the robot: two control the track motion and two regulate the lateral flexion of the vertebral column for steering. The compliant joints enable limited passive torsion and retroflection of the vertebral column, which the robot can use to adapt to uneven terrain and increase traction. Eventually, the new version of SnakeTrack, called 'Porcospino', is introduced with the aim of allowing the robot to move in a wider variety of terrains. The novelty of this thesis lies in the development and presentation of three novel designs of small-scale mobile robots for surveillance and inspection in unstructured environments, and they employ hybrid locomotion systems that allow them to traverse a variety of terrains, including soft, yielding terrain and high obstacles. This thesis contributes to the field of mobile robotics by introducing new design concepts for hybrid locomotion systems that enable robots to navigate challenging environments. The robots presented in this thesis employ modular designs that allow their lengths to be adapted to suit specific tasks, and they are capable of restoring their correct position after falling over, making them highly adaptable and versatile. Furthermore, this thesis presents a detailed analysis of the robots' capabilities, including their step-climbing and motion planning abilities. In this thesis we also discuss possible refinements for the robots' designs to improve their performance and reliability. Overall, this thesis's contributions lie in the design and development of innovative mobile robots that address the challenges of surveillance and inspection in unstructured environments, and the analysis and evaluation of these robots' capabilities. The research presented in this thesis provides a foundation for further work in this field, and it may be of interest to researchers and practitioners in the areas of robotics, automation, and inspection. As a general note, the first robot, WheTLHLoc, is a hybrid locomotion robot capable of combining tracked locomotion on soft terrains, wheeled locomotion on flat and compact grounds, and high obstacle crossing capability. The second robot, SnakeTrack, is a small-size mono-track robot with a modular structure composed of a vertebral column and a single peripherical track revolving around it. The third robot, Porcospino, is an evolution of SnakeTrack and includes flexible spines on the track modules for improved traction on uneven but firm terrains, and refinements of the shape of the track guidance system. This thesis provides detailed descriptions of the design and prototyping of these robots and presents analytical and experimental results to verify their capabilities