2015 2nd Asia-Pacific World Congress on Computer Science and Engineering (APWC on CSE), 2015
In this paper we propose a new solution to the findpath problem of a point-mass robot which is re... more In this paper we propose a new solution to the findpath problem of a point-mass robot which is required to move safely to a designated target in a 3-dimensional workspace. We consider a priori known workspace cluttered with obstacles of arbitrary position and size. The novelty of the solution is three-fold. Firstly, a velocity algorithm is used to drive the robot from its initial position to the target position and remain there forever. Secondly, in the presence of obstacles, the control laws are generated by introducing turning angles which ensure that the robot steers safely past the obstacles. Finally, the control laws ultimately guarantee that the equilibrium point of the given system is asymptotically stable. The proposed technique is verified using computer simulations and an application consisting of a cylindrical manipulator is presented.
2015 2nd Asia-Pacific World Congress on Computer Science and Engineering (APWC on CSE), 2015
This paper designs a nonlinear, time-invariant motion planner that guarantees collision-free lane... more This paper designs a nonlinear, time-invariant motion planner that guarantees collision-free lane changing, merging and overtaking maneuvers, whilst considering all practical limitations and constraints due to the system nonholonomy, workspace geometry, and steering specifications. The motion planner derived from the Lyapunov-based Control Scheme works within an overarching leader follower scheme. We note that lane merging is accomplished through a host of strategies, inter alia, the robot from the merging lane is strategically assigned a separate target, and the platoon has its own target. The platoon overtaking is facilitated via virtual-leader technique, whereas single robot overtaking is facilitated via real-leader follower strategy. The effectiveness of the control laws is demonstrated via computer simulations. It also emphasizes the potential contribution to the intelligent vehicle system's discipline.
This paper presents an approach to swarm split and rejoin maneuvers of a system of multi-robots f... more This paper presents an approach to swarm split and rejoin maneuvers of a system of multi-robots formations. A post split formation is split into low-degree sub-swarms when the swarm encounters an obstacle. The sub-swarms reestablish links with other sub-swarms and converge into its pre-split formation after avoiding collisions with the obstacles. The leader-follower control strategy is used for maintaining formation shape in the sub-swarms. A set of artificial potential field functions is proposed for avoiding inter-robot, inter-formation and obstacle collisions and attraction to their designated targets. The Direct Method of Lyapunov is then used to establish stability of the given system. The effectiveness of the proposed nonlinear acceleration control laws is demonstrated through a computer simulation.
In this paper, we propose a new solution to motion planning and control problem for a flock of 1-... more In this paper, we propose a new solution to motion planning and control problem for a flock of 1-trailer systems. A set of artificial potential field functions is proposed for the flock of 1-trailer robots via the Lyapunov-based control scheme for the avoidance of swarm of boids and attraction to their designated targets. The dynamic environment for the first time includes a swarm of boids, which is governed separately by a system of ODE’s. The swarm exhibits collective emergent behaviors in the vicinity of the workspace while the flock of 1-trailer systems safely maneuver from their initial configuration to designated targets. The effectiveness of the control laws is demonstrated via computer simulations. The novelty of the paper lies in the simplicity of the controllers and the ease in the treatment of the dynamic environment.
2015 IEEE Conference on Control Applications (CCA), 2015
This research presents a Lagrangian swarm model for the control of a planar swarm model that has ... more This research presents a Lagrangian swarm model for the control of a planar swarm model that has a target. The Direct Method of Lyapunov is used to ensure cohesion of the swarm and stability at the target point. The model proposed can address obstacle-free and obstacle-cluttered environments. Emergent patterns such as split/rejoin, tunnelling maneuver and emergent leader are some of the achievable results, which we apply to nonholonomic planar vehicles.
In this paper, we develop a planar Lagrangian swarm model using the Direct Method of Lyapunov to ... more In this paper, we develop a planar Lagrangian swarm model using the Direct Method of Lyapunov to construct the instantaneous velocity of each individual in the swarm. The velocity controllers ensure the cohesion and therefore the stability of the swarm. We introduce novel Lyapunov functions which allow the swarm to navigate in obstacle-free and obstacle-cluttered environments. We apply the methodology to a swarm of planar nonholonomic vehicles. Via computer simulations, we illustrate several self-organizations such as parallel formation, emergent leader, split/rejoin maneuver, and tunnelling for obstacle avoidance.
Here, we explore the fundamentals of an emerging technique applicable, at least, in principle, to... more Here, we explore the fundamentals of an emerging technique applicable, at least, in principle, to robot navigation, or motion planning. The second method of Lyapunov is currently a powerful mathematical technique used to study the qualitative behaviour of natural or man-made systems that could be modeled, in an approximate way, by differential equations. We review the Lyapunov method and then, in a simple and direct way, we use it to propose a theoretical technique to control the motion of a planar arm in a constrained environment. The controllers are mathematical entities which are nonlinear in nature. Computer simulations are used to illustrate the effectiveness of the proposed controllers.
This paper gives the asymptotic theory of a class of Cramér-von Mises statistics {T ^ N,j , j=1,⋯... more This paper gives the asymptotic theory of a class of Cramér-von Mises statistics {T ^ N,j , j=1,⋯,m} for the m-sample problem pertaining to the empirical processes based on the square residuals from a class of ARCH models. An important aspect is that, unlike the residuals of ARMA models, the asymptotic distribution depends on those of ARCH volatility estimators. Based on the asymptotics of {T ^ N,j , j=1,⋯,m} we numerically assess the relative asymptotic efficiency and ARCH volatility effect for some ARCH residual distributions. Then this aspect of {T ^ N,j , j=1,⋯,m} based on such residual distributions is illustrated numerically. In contrast with the independent, identically distributed or ARMA settings, these studies illuminate some interesting features of ARCH residuals.
Based on an emerging artificial potential field technique that models constraints in a robotic sy... more Based on an emerging artificial potential field technique that models constraints in a robotic system via the second method of Lyapunov, this paper proposes nonlinear controllers to guide the end-effector of a single three-link planar robot arm to the desired target in a structured or constrained environment. Numerical examples show how the controllers provide collision detection and avoidance.
International Journal of Applied Mathematics and Computer Science
Tractor-trailer mobile robots are nonholonomic multibody vehicles that are capable of performing ... more Tractor-trailer mobile robots are nonholonomic multibody vehicles that are capable of performing wide-ranging tasks in either fully known or partially known environments. The paper deals with standard and general 1-trailer robots, controlled via artificial potential field method produced from a Lyapunov-based control scheme. The authors present a set of new artificial potential field functions that improves upon the motion planning and posture control, with theoretically guaranteed point and posture stabilities, convergence and collision avoidance properties. Concept of ghost walls and the distance optimization technique are utilized to strengthen point and posture stabilities of the dynamical model. Simulations demonstrate the effectiveness of the proposed control laws.
Hot swaging experiments were carried out on as-sintered Al composite preforms in order to evaluat... more Hot swaging experiments were carried out on as-sintered Al composite preforms in order to evaluate its pore closure characteristics. The effect of tungsten carbide and iron carbide in plain aluminium has been investigated under triaxial stress state condition. Cylindrical preforms with 0.5 aspect ratio and 88% fractional theoretical density have been produced for pure Al, Al-2WC and Al-2WC-4Fe3C through classical powder metallurgy route. Then, the as-sintered preforms are hot swaged to various height strains to further enclose the residual porosities; thereby to enhance density and mechanical properties. It is observed that induced strain substantially helped to close the porosities; however this largely depends on the reinforcing carbide particles in the Al-matrix.
The Lyapunov-based control scheme is applied to construct new continuous control laws for multi a... more The Lyapunov-based control scheme is applied to construct new continuous control laws for multi agents to perform a number of subtasks integral to the motion planning and control problem, in a priori known environment. The subtasks include navigation in the dynamic environment; respecting kinodynamic constraints; parking; and being aligned to a given final orientation. In this paper, we will incorporate a new subtask classified as the blindman’s problem that will require avoidance of a special category of dynamic obstacles. This category involves dynamic obstacles that are contained within a framework of unique constraints. A requirement of this interesting problem is that the avoidance maneuvers be executed by the mobile robots only and not by the dynamic obstacles. To the authors’ knowledge, this is the first ever attempt to design a one-way avoidance scheme to solve the blindman’s problem. In this work, the Minimum Distance Technique (MDT) coupled with tuning parameters will be i...
Asia-Pacific World Congress on Computer Science and Engineering, 2014
In this paper, we propose a relatively simple approach to solve the motion control problem of a t... more In this paper, we propose a relatively simple approach to solve the motion control problem of a three dimensional articulated manipulator arm. The manipulator arm has two links connected by a revolute joint and is anchored on a rotatable base. The kinematic model is developed and a velocity based algorithm is used to move the end-effector from an initial position to a goal position taking into account the mechanical singularities of the system. For obstacle avoidance, we require every point on the two links to avoid any obstacle that it may encounter. Computer simulations are presented to illustrate the effectiveness of the proposed control laws.
2015 2nd Asia-Pacific World Congress on Computer Science and Engineering (APWC on CSE), 2015
In this paper we propose a new solution to the findpath problem of a point-mass robot which is re... more In this paper we propose a new solution to the findpath problem of a point-mass robot which is required to move safely to a designated target in a 3-dimensional workspace. We consider a priori known workspace cluttered with obstacles of arbitrary position and size. The novelty of the solution is three-fold. Firstly, a velocity algorithm is used to drive the robot from its initial position to the target position and remain there forever. Secondly, in the presence of obstacles, the control laws are generated by introducing turning angles which ensure that the robot steers safely past the obstacles. Finally, the control laws ultimately guarantee that the equilibrium point of the given system is asymptotically stable. The proposed technique is verified using computer simulations and an application consisting of a cylindrical manipulator is presented.
2015 2nd Asia-Pacific World Congress on Computer Science and Engineering (APWC on CSE), 2015
This paper designs a nonlinear, time-invariant motion planner that guarantees collision-free lane... more This paper designs a nonlinear, time-invariant motion planner that guarantees collision-free lane changing, merging and overtaking maneuvers, whilst considering all practical limitations and constraints due to the system nonholonomy, workspace geometry, and steering specifications. The motion planner derived from the Lyapunov-based Control Scheme works within an overarching leader follower scheme. We note that lane merging is accomplished through a host of strategies, inter alia, the robot from the merging lane is strategically assigned a separate target, and the platoon has its own target. The platoon overtaking is facilitated via virtual-leader technique, whereas single robot overtaking is facilitated via real-leader follower strategy. The effectiveness of the control laws is demonstrated via computer simulations. It also emphasizes the potential contribution to the intelligent vehicle system's discipline.
This paper presents an approach to swarm split and rejoin maneuvers of a system of multi-robots f... more This paper presents an approach to swarm split and rejoin maneuvers of a system of multi-robots formations. A post split formation is split into low-degree sub-swarms when the swarm encounters an obstacle. The sub-swarms reestablish links with other sub-swarms and converge into its pre-split formation after avoiding collisions with the obstacles. The leader-follower control strategy is used for maintaining formation shape in the sub-swarms. A set of artificial potential field functions is proposed for avoiding inter-robot, inter-formation and obstacle collisions and attraction to their designated targets. The Direct Method of Lyapunov is then used to establish stability of the given system. The effectiveness of the proposed nonlinear acceleration control laws is demonstrated through a computer simulation.
In this paper, we propose a new solution to motion planning and control problem for a flock of 1-... more In this paper, we propose a new solution to motion planning and control problem for a flock of 1-trailer systems. A set of artificial potential field functions is proposed for the flock of 1-trailer robots via the Lyapunov-based control scheme for the avoidance of swarm of boids and attraction to their designated targets. The dynamic environment for the first time includes a swarm of boids, which is governed separately by a system of ODE’s. The swarm exhibits collective emergent behaviors in the vicinity of the workspace while the flock of 1-trailer systems safely maneuver from their initial configuration to designated targets. The effectiveness of the control laws is demonstrated via computer simulations. The novelty of the paper lies in the simplicity of the controllers and the ease in the treatment of the dynamic environment.
2015 IEEE Conference on Control Applications (CCA), 2015
This research presents a Lagrangian swarm model for the control of a planar swarm model that has ... more This research presents a Lagrangian swarm model for the control of a planar swarm model that has a target. The Direct Method of Lyapunov is used to ensure cohesion of the swarm and stability at the target point. The model proposed can address obstacle-free and obstacle-cluttered environments. Emergent patterns such as split/rejoin, tunnelling maneuver and emergent leader are some of the achievable results, which we apply to nonholonomic planar vehicles.
In this paper, we develop a planar Lagrangian swarm model using the Direct Method of Lyapunov to ... more In this paper, we develop a planar Lagrangian swarm model using the Direct Method of Lyapunov to construct the instantaneous velocity of each individual in the swarm. The velocity controllers ensure the cohesion and therefore the stability of the swarm. We introduce novel Lyapunov functions which allow the swarm to navigate in obstacle-free and obstacle-cluttered environments. We apply the methodology to a swarm of planar nonholonomic vehicles. Via computer simulations, we illustrate several self-organizations such as parallel formation, emergent leader, split/rejoin maneuver, and tunnelling for obstacle avoidance.
Here, we explore the fundamentals of an emerging technique applicable, at least, in principle, to... more Here, we explore the fundamentals of an emerging technique applicable, at least, in principle, to robot navigation, or motion planning. The second method of Lyapunov is currently a powerful mathematical technique used to study the qualitative behaviour of natural or man-made systems that could be modeled, in an approximate way, by differential equations. We review the Lyapunov method and then, in a simple and direct way, we use it to propose a theoretical technique to control the motion of a planar arm in a constrained environment. The controllers are mathematical entities which are nonlinear in nature. Computer simulations are used to illustrate the effectiveness of the proposed controllers.
This paper gives the asymptotic theory of a class of Cramér-von Mises statistics {T ^ N,j , j=1,⋯... more This paper gives the asymptotic theory of a class of Cramér-von Mises statistics {T ^ N,j , j=1,⋯,m} for the m-sample problem pertaining to the empirical processes based on the square residuals from a class of ARCH models. An important aspect is that, unlike the residuals of ARMA models, the asymptotic distribution depends on those of ARCH volatility estimators. Based on the asymptotics of {T ^ N,j , j=1,⋯,m} we numerically assess the relative asymptotic efficiency and ARCH volatility effect for some ARCH residual distributions. Then this aspect of {T ^ N,j , j=1,⋯,m} based on such residual distributions is illustrated numerically. In contrast with the independent, identically distributed or ARMA settings, these studies illuminate some interesting features of ARCH residuals.
Based on an emerging artificial potential field technique that models constraints in a robotic sy... more Based on an emerging artificial potential field technique that models constraints in a robotic system via the second method of Lyapunov, this paper proposes nonlinear controllers to guide the end-effector of a single three-link planar robot arm to the desired target in a structured or constrained environment. Numerical examples show how the controllers provide collision detection and avoidance.
International Journal of Applied Mathematics and Computer Science
Tractor-trailer mobile robots are nonholonomic multibody vehicles that are capable of performing ... more Tractor-trailer mobile robots are nonholonomic multibody vehicles that are capable of performing wide-ranging tasks in either fully known or partially known environments. The paper deals with standard and general 1-trailer robots, controlled via artificial potential field method produced from a Lyapunov-based control scheme. The authors present a set of new artificial potential field functions that improves upon the motion planning and posture control, with theoretically guaranteed point and posture stabilities, convergence and collision avoidance properties. Concept of ghost walls and the distance optimization technique are utilized to strengthen point and posture stabilities of the dynamical model. Simulations demonstrate the effectiveness of the proposed control laws.
Hot swaging experiments were carried out on as-sintered Al composite preforms in order to evaluat... more Hot swaging experiments were carried out on as-sintered Al composite preforms in order to evaluate its pore closure characteristics. The effect of tungsten carbide and iron carbide in plain aluminium has been investigated under triaxial stress state condition. Cylindrical preforms with 0.5 aspect ratio and 88% fractional theoretical density have been produced for pure Al, Al-2WC and Al-2WC-4Fe3C through classical powder metallurgy route. Then, the as-sintered preforms are hot swaged to various height strains to further enclose the residual porosities; thereby to enhance density and mechanical properties. It is observed that induced strain substantially helped to close the porosities; however this largely depends on the reinforcing carbide particles in the Al-matrix.
The Lyapunov-based control scheme is applied to construct new continuous control laws for multi a... more The Lyapunov-based control scheme is applied to construct new continuous control laws for multi agents to perform a number of subtasks integral to the motion planning and control problem, in a priori known environment. The subtasks include navigation in the dynamic environment; respecting kinodynamic constraints; parking; and being aligned to a given final orientation. In this paper, we will incorporate a new subtask classified as the blindman’s problem that will require avoidance of a special category of dynamic obstacles. This category involves dynamic obstacles that are contained within a framework of unique constraints. A requirement of this interesting problem is that the avoidance maneuvers be executed by the mobile robots only and not by the dynamic obstacles. To the authors’ knowledge, this is the first ever attempt to design a one-way avoidance scheme to solve the blindman’s problem. In this work, the Minimum Distance Technique (MDT) coupled with tuning parameters will be i...
Asia-Pacific World Congress on Computer Science and Engineering, 2014
In this paper, we propose a relatively simple approach to solve the motion control problem of a t... more In this paper, we propose a relatively simple approach to solve the motion control problem of a three dimensional articulated manipulator arm. The manipulator arm has two links connected by a revolute joint and is anchored on a rotatable base. The kinematic model is developed and a velocity based algorithm is used to move the end-effector from an initial position to a goal position taking into account the mechanical singularities of the system. For obstacle avoidance, we require every point on the two links to avoid any obstacle that it may encounter. Computer simulations are presented to illustrate the effectiveness of the proposed control laws.
The intention of this report is to critically analyze and assess the Dyson’s current goals, objec... more The intention of this report is to critically analyze and assess the Dyson’s current goals, objectives, and mission and vision statements, by understanding what particularly can bring into survive the future growth and competition.
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