Construction of Spherical Spy robot

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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)

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ISSN (Print): 2319-3182, Volume -6, Issue-1-2, 2017 122

Construction of Spherical Spy robot

1Dhiraj P Velhal, ²Sushil B. Chopade, ³Rashi Gaikwad

Email: [email protected]¹, [email protected]², [email protected]³

Abstract— The spy-bot essentially is a special purpose robot characterized by its spherical shape which can travel in any direction. The combination of its compact dimensions and a wireless camera module enables the spy-bot to reach into small gaps and record, transmit video back to us. Also by making spherical shaped robot, we can move it in 360 degrees.

Index Terms— spy bot, 8052

I. INTRODUCTION

Mobile robots have very significant application in military and other defense purposes. The spy-bot under development here is unlike many other traditional mobile robots such as legged or wheeled robots. The spherical shape is ideal for inspection in environment where humans can’t possibly reach.

The spy-bot works on the principle of conservation of angular momentum. Because there are two motors working in unison, the relative motor speed allows the bot to make zero radius turns. This property of the robot makes it to turn nimbly and work in confined spaces like pipe and tunnels.

Fig 1A, shows the basic assembly of the bot. It consist of central chassis, which holds the microcontroller with its circuit board, batteries, two dc motors and a wireless camera mounted on it. Spherical body splits into two hemispheres are keyed to the motor shafts. Intel’s 8052 microcontroller is used to control the motors independently, which in turn operates the two hemispheres independently [1]

Fig 1 A: Basic Assembly of Spy Robot

Fig 1 B: Internal Construction

Robot Motion relative to motor rotation is one of important criterion in spherical robot following Table1 gives general idea of robot motion relative to motor direction

Motor 1 Motor 2 Output

Clockwise Clockwise Forward

Anticlockwise Anticlockwise Backward Clockwise Anticlockwise Left Anticlockwise Clockwise Right

Table 1: Robot Direction 1

II. LITERATURE REVIEW

Vrunda A. Joshi et al [1] proposed a spherical mobile robot, rolling on a plane with the help of two internal rotors and working on the principle of conservation of angular momentum. Hall Effect sensor is used to measure the speed and according to the sensor speed of the angular momentum generating motors will be controlled to follow the decide path. The main controller in the system is a blue tooth enabled PC, which generates control signals according to the algorithm programmed

Yao Cai et.al [2] proposed a paper about dynamic path following method presents a systematic framework for non holonomic mobile robot. The structure consists of two motors, a hollow shaft, a camera and a shell. The hollow shaft is connected with the spherical shell by bearings and serves as a frame to install other devices.

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The output axle of motor 1 is fixed to the spherical shell while the output axle of motor 2 is fixed to a mass by a link. The camera installed on the ending of the hollow shaft is used for environment exploring. Uses a kinematics expression by Euler angle in order to facilitate the path tracking control of spherical robot. The path tracking purposes, some state variables are reinterpreted:

(xc, yc) is the instant position of the robot, θ denotes the orientation, β is defined as the side-roll angle, ż refers to the forward speed. It must be noted that the kinematics part of system is similar to the kinematics of a car-like mobile robot, their steering motions are both achieved by the forward motion with a steering angle/side-roll angle Kang Houa,et.al [3] proposed a paper on autonomous positioning and navigation system for spherical robot.

This spherical mobile robot contained two parts: two hemispherical shells and the inner actuator. The two parts connected together with the flanges. Two hemispherical shells, as the moving parts, can drive the robot to make motions. When the two shells had the same speed of rotation, the robot walked a straight line. When the two shells had the different speeds, the robot turned a corner to the side of slow shell. The GPS system was used for the robot to position and navigate in a long distance, and the robot compare the robot’s GPS data and the target’s GPS data to get the relative position between both, which guides the direction of motion for the robot later. The visual processor was adopted in the close distance, and when the robot was away from the target in some distance, the visual processor was launched and searched the target.

Chang-Hsuan Chiu et al [4]. proposed a paper on four different types of helical composite springs were made of structures including unidirectional laminates (AU), rubber core unidirectional laminates (UR), unidirectional laminates with a braided outer layer (BU), and rubber core unidirectional laminates with a braided outer layer (BUR), respectively. The spring constant of a helical metal spring depends mainly on its shape, dimensions and material properties. The spring constant, the failure load and the maximum compression for each helical composite spring can then be evaluated. From the evaluation, the results are the helical composite spring with a rubber core can not only increase its failure load in compression by about 12%, but also reduce the amounts of prepress. And the helical composite spring with a braided outer layer can not only increase its failure load in compression by about 18%, but also improve the spring constant by approximately 6%. In addition, it can reduce the difference in the fabrication of springs and improve the structure stability of springs as well. Used, and thus lower the material costs. The helical composite spring with a BUR structure has the highest mechanical properties among the four types of helical composite springs, its failure load in compression approximately equals 336.2 kgf, and the spring constant is almost 16.27 kgf/mm.

Jeehong Kim et.al [5] proposed a paper on crawler wheel

system equipped with an asymmetric variable shape single-track. Development of this symmetric single-tracked wheel system required analysis of the design elements, especially the variable configuration elements based on the length and rotation of the frame and the kinematical tension elements. This consists of an arm frame on the front side of the body frame that can change the track shapes, bearing-coupled passive wheels on both sides of the arm frame, and moving wheels for mobility and propulsive forces on the rear side of the body frame.

The track shape was transformed by the rotatable arm frame, which had two passive wheels on both endpoints, and the distances from the rotation point to the two end-points are appropriately chosen to reduce the gap between the track lengths. The rotation center of the arm was connected to actuators that can pivot. The conditions for calculating the maximum length were surveyed with numerical tools and we were able to study the relations between the length of the body and arm frames. Based on these studies, we introduced a compensation method and showed an efficient design procedure to make an asymmetric single-tracked wheel system.

Jarosław Majchrzak, et.al [6] proposed a paper on the results of tests conducted with an ultrasonic proximity measurement system which is used in sensory subsystems in many mobile robots. The tested sensor, a Polaroid 600–series model, is composed of two galvanic ally isolated main parts: a steel case and a circular membrane made of gold foil. In the transmitter mode the silent circular membrane generates an ultrasonic beam the emission is a result of a vehement increase of charge in the capacitor (the phenomenon of electrostriction) formed by the sensor’s casing and the circular membrane. In the receiver mode, the circular membrane acts as a mechanical detector of the reflected wave any displacement of the membrane changes the capacity of the capacitor. From the evaluation its came to know that, the modal value of the measuring results distribution could be chosen as an alternative of the real distance value. The usage of as a distance estimator leads to greater measuring errors, but such a choice could be a necessity in the presence of strong disturbance.

III. MOTIVATION AND PROBLEM DEFINITION

Military rescue operations at the time of natural catastrophe is where a small, compact robot like the ball bot have significant application. Saving life becomes first priority. A versatile yet compact robotic system can be developed and revised to investigate under ruins and provide much required data for further military operations.

On the basis of some ground rule in literature review and applying same principles to spherical robot our aim is to

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develop a protean robotic system, simple and cost effective at the same time.

IV. CONSTRUCTION AND WORKING OF SPHERICAL SPY ROBOT

The working is as shown in the block diagram. The micro-controller takes power from the battery, and according to the control program, generates signals to actuate each motor independently. The camera used is a wireless module which sends video to wireless receiver connected to the laptop computer.

Micro-controller used is a 4 port 40 pin 8052 based unit. It is interfaced with radio transmitter which is in turn connected from the camera module.

The camera module is a compact, low weight unit meant for rugged use. Since the whole camera module is capable of recording and transmitting the video over radio frequency channel, just a radio receiver is required at the laptop to decode the signals and the video transmitted is displayed on computer screen via a TV tuner card. There are two actuators in the form of two gear reduction type DC motors. These motors are fitted with speed reduction gear train with the effective gear ratio to operate at around 80 - 100 rpm.

The battery unit have two dry cell 9 V batteries and one high performance alkaline battery to run the camera module.

Fig 2: Spherical Robot Working

V. SYSTEM ARCHITECTURE

Microcontroller specifications:

The microcontroller unit running the spy bot is as shown.

Some of the unique specifications against the 8051 are 8

kb ROM, 256 bytes RAM, 32 pins, 1 serial port and 8 interrupts. Since it is also clocked at highest speed, the robot feels nimble and agile.

Fig 3: Pin Diagram of 8052 Motor specifications:

Here in our system, we are using two gear reduction DC motors, which are run by microcontroller. The motors are identical 1.5 V. DC units running at 1200 rpm. Since the high speed generates jerky motion, we use gear reduction system to it operate smoothly.

Fig 4: Gear Reduction DC Motor

VI. ACTUAL SYSTEM

The System is shown in Fig 5 and Fig 6, the robot can be used in spy work because camera module installed in system which can be operated from Laptop by using WIFI. Because of spherical shape balancing is not needed in this system.

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Fig 5: System Circuit Diagram

Fig 6: Spherical Spy Robot 1

VII. CONCLUSION AND FUTURE SCOPE

This paper here concluding that, the ballbot has designed and assembled with electronics and motors and camera.

The ballbot has moved on the ground by transmitting the video according to the control commands from the

controller. This ballbot robotic system can be used in attack and rescue operations to get information about human unreachable areas while doing the military operations.

In future if some dampers are used and if it is placed in canon and fired it can give live streaming of all enemy positions on war field. Also Implementation of internet instead of WIFI will increase range of spy sphere bot.

REFERENCES

[1] R. N. B. a. R. H. Vrunda A. Joshi a, "Design and analysis of a spherical mobile robot," in

Mechanism and Machine Theory, 2012, p. 58–73.

[2] Q. Z. Yao Cai, "Path tracking control of a spherical mobile robot," in Mechanism and Machine Theory, 2012, p. 58–73.

[3] H. S. Kang Houa, "An Autonomous Positioning and Navigation System for Spherical Mobile Robot," Procedia Engineering 29, p. 2556 – 2561, 2012.

[4] C.-L. H. b. H.-S. T. Chang-Hsuan Chiu a, "An experimental investigation into the mechanical behaviors of helical composite springs," Science direct Composite Structures, p. 331–340, 2007.

[5] C. L. Jeehong Kim a, "Study of machine design for a transformable shape single-tracked

vehiclesystem," in Mechanism and Machine theory, 2010, p. 1082–1095.

[6] M. M. Jarosław Majchrzak, "Distance Estimation With a Long-Range Ultrasonic Sensor System,"

IEEE sensors journal, 2009.

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