Radzi Ambar

A Stereo Vision System for Underwater Vehicle-Manipulator Systems – Proposal of a Novel Concept Using Pan-Tilt-Slide Cameras –

Underwater Vehicle-Manipulator Systems (UVMS) are expected to be used in various tasks in underwater environments. The manipulators of the UVMS are designed to execute tasks such as handling and catching objects. It is therefore necessary to equip UVMS with sensors that observe and measure the position of target objects. Stereo vision systems are one type of such sensors. We propose a stereo vision system for UVMS consisting of 2 mobile cameras that pan, tilt and slide individually using motors. This vision system is installed inside a waterproof cylindrical container that enables it to track a target object in underwater environments. Stereo vision system concept and mechanism are proposed, and the effectiveness of the proposed system is shown by experiments using a vision system prototype.

Development of a master controller for a 3-link dual-arm underwater robot

Master-slave system is a vital technique for controlling robot motions. An intuitive master controller enables precise and easy control of robot, especially for underwater robotics applications. Most of the commercially available master-slave systems are very complex and expensive, and operators need to receive extensive training before being able to correctly operate the robot. This paper addresses these problems by introducing a simple and intuitive master controller for an experimental semi-autonomous underwater vehicle equipped with 3-link dual-arm. The master controller includes a vehicle main master controller and two units of 3-link manipulator master controller. Moreover, each end-tip of the manipulator master controller is attached with a vehicle sub-master controller that consists of a joystick and tactile switches. These sub-master controllers are designed to control the position and attitude of the vehicle. The ability to simultaneously control two units of 3-link dual-arm and the position and attitude of the vehicle is the uniqueness of the proposed controller. In this work, the design of the developed master controller and the structure of a unilateral master-slave system are presented. The usefulness of the master controller is verified through experiment on controlling an actual dual-arm underwater robot to catch a target object in underwater environment.

Experiment on a dual-arm underwater robot using resolved acceleration control method

An underwater vehicle-manipulator system (UVMS) is an underwater robot equipped with one or more robotic arms. Various research studies have been focusing on the development of single-arm UVMS. To increase the efficiency and dexterity of underwater robotic manipulation, multiple-arm UVMS is a much better option than a single-arm UVMS. However, the installation of robotic arms can create challenging control issues due to the coupling effects of the robot body and robotic arms. Hence, in our previous work, we have proposed a resolved acceleration control (RAC) method to control a dual-arm UVMS. The proposed method enables coordinated control between both robotic arms and vehicle by considering the effects of hydrodynamic forces. In this paper, the mechanical design of a 2-link manipulator is described. Furthermore, experiment results demonstrating the effectiveness of the proposed RAC method on a 2-link dual-arm UVMS is presented. In the experiment, both end-tips were controlled to move to desired positions along straight paths in a horizontal plane. At the same time, the desired position and attitude of the robot vehicle were similar to the initial values. The results show that although there were substantial movements on the position and attitude of the vehicle, the proposed method was able to effectively control the movements of the end-tips to reach the desired positions by significantly reducing the influence of modelling errors of hydrodynamic forces using the position, attitude and velocity feedback of UVMS.

Preliminary Design of a Dual-Sensor Based Sign Language Translator Device

There are many different types of sign languages that are used around the world which are important as the medium of conversation among hearing impaired community. However, majority of hearing people do not know or understand sign languages. Thus, communication between a hearing-impaired person and a hearing person is a difficult issue. In order to solve this problem, this project proposes a development of a dual-sensor based sign language translator. The goal of the project is to translate sign language into speech and display on screen by using the device. The device was developed in a glove-based system which was able to read the movements of every finger and arm using two (2) types of sensors, an accelerometer and five (5) units of flex sensors. This paper describes the design of the glove-based sign language translator. Subsequently, the preliminary experimental results show the usefulness of the accelerometer and flex sensors.

Design of a low-cost instrumented glove for hand rehabilitation monitoring system

Hand paralysis is typical disabilities resulting from stroke. Rehabilitation assists stroke survivors to gaining back to their normal life and accomplishing the best level of independence. Repetitive practice is imperative to improve grasping strength and retrain the brain motor skills. Thus, this paper proposes an instrumented glove utilizing flex sensors and force resistive sensors for post-stroke hand rehabilitation system. The flex sensors are used to measure flexion/extension of each finger, while force sensitive resistor (FSR) sensors is attached on each finger tips to measure the forces applied at the fingertips when an object is grasped. Analogue signals from the sensors are conveyed to PIC16F877A microcontrollers for data processing then transferred to a personal computer for monitoring and analysis process. The results are then documented for the purpose of post-processing and progressive status tracking. Preliminary experimental results involving squeezing a rubber ball shows the usefulness of the developed glove by demonstrating the relation of fingers flexion/extension with forces applied on each fingertip.

Development of a dual-shaft propeller thruster equipped with rotational speed sensor for UVMS control

Majority of underwater robots utilize single propeller thrusters for navigation. A disadvantage of using a single-shaft propeller thruster is that the thrust force generated from a single propeller for reverse and forward thrust is asymmetric due to the disturbed flow caused by the thruster’s body which may reduce thruster efficiency. Moreover, measurement procedures to precisely calculate propeller’s rotation speed were also not available. To address these problems, this paper proposes a dual-shaft magnetic coupling-driven propeller thruster for underwater robot, equipped with sensors for measuring propeller’s rotational speed. Numerical studies and experimental results on the position and orientation control of the proposed thruster are presented. Detail comparison of the rotational speed, thrust force and duty ratio between numerical calculation and actual experimental measurement results show the effectiveness of the proposed thruster. This paper also demonstrated that by using the proposed thruster, the control performance of an underwater robot can be improved significantly compared to commercially available thruster. The ability to determine propeller rotation directions is also a major advantage of this work.

Wireless Wearable for Sign Language Translator Device using Intel UP Squared (UP2) Board

Sign language translator devices translate hand gestures into text or voice that allow interactive communication between deaf and hearing people without the reliance on human interpreters. The main focus of this work is the development of a wireless wearable device for a sign language translator using an Intel UP Squared (UP2) board. The developed device is consists of a wearable glove-based wearable and a display device using an Intel UP2 board. When hand gestures have been created by a user, the accelerometer and flex sensors in the wearable are able to measure the gestures and conveyed the data to an Arduino Nano microcontroller. The microcontroller translates the gestures into text, and then transmits it wirelessly to the UP2 board, subsequently displays the text on an LCD. In this article, the developed hardware, circuit diagrams as well as the preliminary experimental results are presented, showing the performance of the device, while demonstrating how the Intel UP2 board can be connected to a low-cost Arduino microcontroller wirelessly via Bluetooth communication.

Preliminary Design of a Robotic Exoskeleton for Arm Rehabilitation

This research paper presents the design of a low-cost and easy-to-use 2 degree of freedom (DOF) robotic exoskeleton for arm rehabilitation. The developed exoskeleton consists of a 2 DOF robotic arm attached on a chair. Force sensitive resistors are also utilized in the design of the device to measure muscles activities during rehabilitation process. Kinovea software is used to analyse the performance of the patient during exercise via video capture. The measured data hopefully can assist physicians and caregivers in designing suitable rehabilitation process for stroke patient. The proposed design provides a novel tool towards upper limb stroke rehabilitation process. Although there are many exoskeleton robotics arms which are commercially available, however, due to the disadvantages such as weight, high-cost and complex mechanisms, this paper proposed new ideas on solving these problems by designing an exoskeleton which is functional, low-cost and users friendly

Development of a Wearable Device for Sign Language Recognition

This project describes the development of a sign language translator that converts sign language into speech and text by using wearable device. The glove-based device is able to read the movements of a single arm and five (5) fingers. The device consists of five (5) flex sensors to detect finger bending, and an accelerometer to detect arm motions. Based on the combination of these sensors, the device is able to identify any particular gestures that correspond to words and phrases in American Sign Language (ASL), and translate it into speech via a speaker and text which is displayed on an LCD screen. This article explains mainly on the hardware design of the device. Based on preliminary experimental results on nine (9) simple sign languages, the device demonstrated an average value of 0.74 s to convert a sign language into speech and text, which demonstrate the usefulness of the proposed device.

NFC-based Data Retrieval Device

This paper describes the design and development of data retrieval system using near field communication (NFC) protocol to read and transfer data from the device storage panel located at the recycle bin. In existing systems, data are manually collected from the storage device using the SD card and sent for upload to regional workstation of the data center, which is located at the central server. The device automatically establishes the NFC connection with the recycle bin panel and once the connection is established, data will automatically be transferred to the device and the current data storage in the recycle bin will be erased. Next, the collected data will be uploaded to the server through regional workstation.