Md. Mozasser Rahman

Control characteristics of two humans in cooperative task and its application to robot control

Control systems for cooperative robots should be designed to work imitating human characteristics. So it is important to know the human characteristics in cooperative task, i.e. carrying an object by two humans. In this study, we have tried to achieve these goals by means of controlling a simple one degree-of-freedom cooperative robot. Firstly, the control characteristics of two humans in cooperative task are investigated. Then, the cooperative task is modelled and the parameters of the model are evaluated. Finally, the proposed model is implemented to control a robot in order to perform a cooperative task with humans. It is observed that the proposed control methodology has given human like movements to the robot for cooperating with human.

Investigating the impedance characteristic of human arm for development of robots to co-operate with human operators

In the near future many aspect of life will be encompassed by tasks performed in co-operation with robots. As a result, robots need to be made human-friendly and to execute tasks in co-operation with humans. Control systems for such robots should be designed to work by imitating human characteristics. We aim to achieve these goals by controlling a simple one degree-of-freedom robot. First, the impedance characteristics of the human arm in a co-operative task are investigated. Then, these characteristics are implemented in a robot which performs a co-operative task with a human. The proposed control method produced good characteristics for robots co-operating with humans.

Robotic Exoskeleton for Rehabilitation and Motion Assist

For elderly and or physically disabled people who have lost their body functioning of motions due to geriatric disorders, and/or disease processes including trauma, sports injuries, spinal cord injuries, occupational injuries, and strokes, we have been developing a 3 DOF mobile robotic exoskeleton for rehabilitation and for assisting motion of elbow and shoulder, since human shoulder and elbow motions are involved in a lot of activities of everyday life. The robotic exoskeleton is mainly activated and is controlled by the skin surface electromyogram (EMG) signals, since EMG signals of muscles directly reflect how the user intends to move. This paper focused on the mechanism of mobile robotic exoskeleton and proposed passive and active assist mode of rehabilitation scheme in addition to assist daily upper-limb motion by the aid of robotic exoskeleton. The proportional derivative (PD) control has been applied to the controller for the passive mode of rehabilitation whereas neuro-fuzzy based biological controller is responsible for active assist mode of rehabilitation as well as to assist daily upper limb motion

Mathematical Modeling and Trajectory Planning of Hand Finger Movements

This paper presents a mathematical model of trajectory during movement of human hand finger. Mathematical models of fingers movement are necessary to control the finger of prosthetic hands, rehabilitation platform, and hand of cooperative robots. A simple platform is constructed with flexi force sensor and data acquisition circuit. Trajectories are calculated from the position data of the finger movement. Movement with various speed of the finger are maintained. Finally, Curve Fitting Toolbox of MATLAB is used to derive the mathematical model of finger trajectory. The obtained result could be beneficial to design the controller of the finger of prosthetic hands, rehabilitation platform, and hand of cooperative robots.

Candida isolates from pregnant women and their antifungal susceptibility in a Malaysian tertiary-care hospital.

Objective: Pregnant women are susceptible to vaginal colonization and infection by yeast. The purpose of the study was to determine the prevalence of Candida spp in high vaginal swabs of pregnant women and their antifungal susceptibility. Methods: High vaginal swab samples received from Serdang Hospital, Selangor, Malaysia during 2011 initially had microscopic examination, Gram-staining and fungal culture. These were finally confirmed by growth in chromogenic medium (CHROMagarCandida; Difco BBL, USA) and commercial biochemical identification kit (API 20C AUX; bioMérieux, Lyon, France). Antifungal susceptibility was performed by E-test method. Results: Out of 1163 specimens 200 (17.2%) candida spp were confirmed from high vaginal swabs of pregnant women. Candida albicans (83.5%) is the most common species detected followed by Candida glabrata (16%) and Candida famata (0.05%). All C. albicans and C.famata isolates were susceptible to fluconazole while C.glabrata isolates were dose dependent susceptibility. First and second trimester, and diabetes were considered significant factors in patients for the vaginal candidiasis (p < 0.001). Conclusions: In pregnant women, C. albicans was the frequently isolated yeast from high vaginal swabs. Routine screening and treatment are important of pregnant women regardless of symptoms.

Collision free control of variable length hyper redundant robot manipulator

Hyper-redundant robot (HRR) manipulators are useful at navigating convoluted paths, but conventionally complicated to control. The control of a hyper-redundant manipulator is complex due to its redundancy. In this paper, a simple but effective control algorithm for obstacle avoidance is proposed. The algorithm derives a collision free path around known obstacles so that the end-effector of a variable length hyper redundant robot (VHRR) is able to reach the target location following the path without hitting the obstacles. The algorithm can be grouped into two tasks to drive the end-effector along the collision free trajectories: first, solve the inverse kinematics without disregarding the existence of obstacles in the system; and second, fit the manipulator to the respective prescribe trajectories. This method has the capability to allow VHRR maneuver within its workspace without penetrating to the neighboring obstruction. Further, this method is very effective in the sense that it forms a nice coil profile avoiding zig-zag configuration, and thus eliminates sharp turn on the robot. The performance of a VHRR was tested through simulation to demonstrate the effectiveness of the proposed method. The approach succeeded in delivering the path that avoids obstacle.

A comparative study of the difference between MFCC and PLP in the recognition of sound

Sound is one of the most important tools for classification, recognition and identification of objects in the environment. The raw sound signal is complex and is not suitable to be feed as input to the sound identification system; hence the need for a good front-end arises. The identification rate using the RNN classifier and MFCC is 72.7%, 73.7%, 78.9% 57.1% and 58.3% for aircraft, car, rain, thunder and train respectively as compared to what was obtained by using MLP. 31.6%, 19.4%, 18.5%, 38.0% and 26.4% decline is achieved for aircraft, car, rain, thunder and train respectively when comparing between MLP and RNN for MFCC. As far as sound recognition using the input used in this experiment is concerned, MFCC outperforms PLP and MFCC and PLP using MLP as classifier.

A new geometrical approach to solve inverse kinematics of hyper redundant robots with variable link length

In this paper a new approach that generates a general algorithm for n-link hyper-redundant robot is presented. This method uses repetitively the basic inverse kinematics solution of a 2-link robot on some virtual links, where the virtual links are defined following some geometric proposition. Thus, it eliminates the mathematical complexity in computing inverse kinematics solution of n-link hyper redundant robot. Further, this approach can handle planar manipulator with variable links eliminating singularity. Numerical simulations for planar hyper redundant models are presented in order to illustrate the competency of the model.