Shamsudin H. M. Amin

Techniques for vibration control of a flexible robot manipulator

This paper presents investigations into the applications and performance of positive and negative input shapers in command shaping techniques for the vibration control of a flexible robot manipulator. A constrained planar single-link flexible manipulator is considered and the dynamic model of the system is derived using the finite element method. An unshaped bang-bang torque input is used to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. The positive and specified amplitude negative input shapers are designed based on the properties of the system. Simulation results of the response of the manipulator to the shaped inputs are presented in the time and frequency domains. Performances of the shapers are examined in terms of level of vibration reduction, time response specifications and robustness to parameters uncertainty. The effects of derivative order of the input shaper on the performance of the system are investigated. Finally, a comparative assessment of the impact amplitude polarities of the input shapers on the system performance is presented and discussed.

Particle Swarm Fuzzy Controller for Behavior-based Mobile Robot

The attractive researches in the field of mobile robotics is behavior-based mobile robots. Behavior-based approach should have an ideal controller to generate perfect behavior action and able to handle conflicting ones that are seemingly irreconcilable. Schemas to overcome these problems based on fuzzy logic controller (FLC) are provided, known as fuzzy behavior-based robot. This paper presents a novel approach that the fuzzy membership functions and fuzzy rule bases are tuned automatically by particle swarm optimization (PSO), named as particle swarm fuzzy controller (PSFC). PSO is an optimization method that uses a principle of social behavior of a group of particles. The behaviors are controlled by PSFC to generate individual command action. Later, a context dependent blending (CDB) based on meta fuzzy rules coordinates the commands to produce final control action. The algorithm is validated using parameters of MagellanPro mobile robot and tested by simulation using MATLAB/SIMULINK. Simulation results show that the proposed model offers hopeful advantages and has improved performance

Trajectory tracking of steering system mobile robot

In this paper, the kinematic model of nonholonomic differential wheeled mobile robot steering system is established. Based on the model, a nonlinear feedback path tracking controller is proposed, which causes the closed loop system state equation for the robot to have equilibrium condition at the origin. Lyapunov candidate function is used to prove that the closed loop system is asymptotically stable at origin. Simulation results verify the usefulness of the tracking control approach.

Locomotion simulation of a quadruped robot on general level terrain

To design a quadruped mobile robot that has a capability to move on a general terrain, its motion on a specific terrain should be studied carefully. The level terrain is classified into three classes, horizontal, inclined and vertical terrain. Kinematics algorithms for modelling and simulating the robot locomotion on these three terrain classes are presented. The walking stable wave and the wall climbing gaits are simulated in 3-D graphics.

Simulation kinematics model of a multi-legged mobile robot

This paper addresses the kinematics modeling of a four legged mobile robot which has been developed to study the leg swinging and robot motion during locomotion. The robot motion is categorized into: The leg swinging motion as an open loop kinematics chain and the robot trunk motion relative to the feet during locomotion as a closed kinematics chain. Algorithms for solving the forward and inverse kinematics problems of these two categories have been developed. A closed kinematics chain algorithms of the whole robot structure is presented. This closed kinematics model is used in off-line animation of the robot motion in different cases and to simulate the stable wave gait in off-line programming. The robot motion by computer graphics is displayed.

Mechanical design of a quadruped robot for horizontal ground to vertical wall movement

In this paper, an emphasis is given towards the mechanical structure of a quadruped robot which is able to walk on ground, climb on vertical walls, and perform the ground-wall-movement automatically. An overview of the robot is shown and the configuration, number of DOFs, and actuation system of the leg are analyzed. The biologically inspired gaits of the robot are discussed. The movement of the leg from the ground to the wall is analyzed. The integrated leg movement-trunk regulation sequences are simulated. The trajectories of specific points on the trunk are traced, showing the limits for safe movement inside meandrous chimneys or zigzag tubing.

Stereo vision based robots: Fast and robust obstacle detection method

In this paper we present a new obstacle detection method, based on stereo vision, without combination with any other kind of sensors. The proposed method uses a differential image transform algorithm to gain robustness against illumination changes. This method increases the speed of program execution while keeping the performance of stereo vision algorithm in term of accuracy in the same level with the previous algorithms. Moreover, we implement this method into a stereo vision based robot while adding some new features to widen the depth detection range. With the help of the proposed method, the robot detects obstacles between 25cm to 400cm from robot cameras. The result shows the robot has the ability to work in a wide variety of lighting conditions, while the stereo vision part of the robot does the depth detection computation with the speed of 30FPS.

A biologically inspired hybrid three legged mobile robot

This paper describes the development of a biologically inspired mobile robot. The locomotion mechanism is a hybrid combination of legged locomotion supported by wheels for stability purposes. The mechanism design, the applied electronic circuit design and the behavior-based controller for navigation and reactive response to stimuli of the robots environment are described. The locomotion mechanism of the mobile robot consists of a set of wheels and legs with crab-like features. Static and dynamic stability is provided by the set of wheels, while locomotion is mainly dependent on the three legs. The mechatronic modules of the mobile robot consist of the integration of micro-controller, motors and sensors. Each leg is powered by independently controlled actuators. Sensors placed at each of the legs provide the posture information. At the sides, front and rear of the robots body, proximity sensors are arranged in an array to give information about the environment to the controller. The behavior of the hybrid three legged mobile robot is coordinated by the subsumption architecture implemented and it can be modified incrementally as the need arises. The navigation behavior of the mobile robot is emphasized with the behavior-based controller. It is expected that the robot will be able to traverse different terrain.

Fuzzy logic based behaviors blending for intelligent reactive navigation of walking robot

The reaction of an autonomous mobile robot to dynamic, uncertain, and changeable environments is one of most difficult issues in control of intelligent autonomous robot movement. Fuzzy control appears as a very useful tool for handling intelligent reactive navigation. The present work deals with building of fuzzy behavior based reactive navigation for obstacle avoidance, and proposes a method to blend and coordinate multi-behaviors at the same time. This method using a fuzzy technique and fixed priority value to reflect the importance of the behavior. We have built our simulation and animation programs that can reflect online the robot movement using a graphical user interface.

A fuzzy multi-behaviour reactive obstacle avoidance navigation for a climbing mobile robot

The navigational planning is a central issue in development of real-time autonomous mobile robots. Reactive methods solve the real-time reactive navigation problems, but still there are some challenging problems. Fuzzy behaviours present a successful method to solve the real-time reactive navigation problems in unknown environment. Fuzzy behaviours for free movement, obstacle avoidance, and wall following will be presented here. We shall describe fuzzy controller behaviours, the input/output parameters, and the membership functions. Some simulation results will be present to show the navigation of the robot.