Ball-shaped robots to Inspect nuclear power plants

2 CONTENTS Introduction about the history and inspection of spherical robots in nuclear plants. Ball shaped robots Main parts of the system. Propulsion system Conclusions.

NEED OF ROBOTIC SYSTEMS To perform automated and repetitive work. Safety of workers and regulation. Profitibility

ROBOTS USED FOR MONITORING SIMON-developed in 1990. MACS-developed in 1996. UBIB –developed 1996. ARIES-developed in 1999

INSPECTION AND MAINTANENCE Inspection of reactor vessel. Underwater inspection. Pipe inspection.

BALL SHAPED ROBOTS Developed by Massachuttus Institute of Technology. Harry Asada,Fond Professor of MIT. Designed to efficiently enter the underground pipes. About the size of an egg.

Inspection is done without digging up the buried pipes. Signs of corrosion and leakage are detected. Onboard camera takes images along the pipe’s interior. Wireless underwater communications across distances of upto 100m.

Design and construction Works on the principle of change in center of gravity. Energy source-NiCd battery. Same as hamster ball. Moving eye ball mechanism.

Controlling speed of drive controls the speed of robot. Mobility was provided by generating torque directly to the lever. Revolutions are counted by an inductive sensor. Large instrument board carries an onboard computer and interactivity tools. Pulse encoders for motor rotation measurement.

Sensors for temperature,pan,tilt and heading of inner mechanics. Local server transmits control using commands that are kinematics-invariant. Has an automatic localization command. User interface contains virtual model for communication between remote user and a local system.

Main parts of the system Sensors: Gyroscope: It will be used to calculate the angular velocity of the roll angle of the ball. Accelerometer: It will be used to measure the motor acceleration Encoder: Used to measure the rotational speed of the motor. Wireless camera.

Wireless camera node A computer module. Wireless LAN adaptor. Wired LAN adaptor utilized for connecting image card. CMOS camera with fisheye lens. GPS locator.

System configuration of camera node

Prototype of wireless camera Passive self-righting structure keeps the camera vertical.

Examples of captured view developed by wireless camera.

Main parts of the system Processor & Software: Teensy++, based in Arduino Software.. Electronics Board: It integrates H-Bridge. Teensy, sensors and motor will be connected in it. Power supply: Cells or batteries. Motor: DC Motor with nominal voltage between 12V-15V.

MATHEMATICAL MODEL Model was established by using No rolling slip constraints. Conservation of angular momentum. Algorithm motion planning Spherical structure offer extra - ordinary motion properties.

PROPULSION SYSTEM No external propellers or rudders. Smarter propulsion method. A multi-axis thrust mechanism with a network of Y-shaped valves within the skin. Creating a jet stream that propels robot in opposite direction.

Devised of special valve for switching direction of flow with a tiny change in pressure.

Advantages Shorten the maintenance time and number of workers. Allow inspection without digging out the buried pipes. Easy to handle, less power consumption. Overcome large obstacles since it is small in size.

Conclusion Asada’s ball shaped robot’s system has a simplicity, which is very attractive. For inspecting tight,confined spaces. Able to withstand a reactor’s environment and can transmit images in real time for within.

references A.Halme,T.Schonberg,Y.Wang,Motion control of a spherical mobile robot in 4th IEEE International Workshop on Advanced Motion control. Ferriere,L, Raucent. B”Automation RollMOBS,A New universal Wheel concepts”.1998 IEEE conference on Robotics and A R.E Sharp and D.R Garlick ,”Radiation Effects on Electronic Equipment “for the nuclear power industry.1994. “Industial Remote Inspection System”by E.B.Silveman,Proceedings of the Robotics and remote handling in Hostile Environments,National topical meeting ,American Nuclear Society 1984 Cavale .J(2009) Ball shaped robot online accessed . http://trendsupdates.com/spherical-robot-looks- futuristic-but-is-amazingly-mundane/

accelerometer Used to measure the motor acceleration. Consists of 3D-MEMS sensing element. Temperature sensor, internal oscillator and non- volatile memory. BACK

encoder Used to measure the rotational speed of the motor. AEDA-3300 . BACK

H-bridge Inputs- - supply voltage. -PWM(30Hz). - EN -DI Output- -voltage to drive the motor. BACK

Power distribution Lead acid batteries provide power. Generates electricity by electrochemistry reaction. BACK

motor Used to control the attitude of pendulum for rolling and steering. Gear boxes installed to increase torque output. BACK