Robotic Colonizer Control System Computer Science Essay

Published Date: 02 Nov 2017

C.Venkatesh1, C.Chandra Sekhar2, Dr.S.Narayana Reddy3

123Department of ECE, 12JNTUA, 3SV University, A.P, India

1AITS, Rajampet, 2SVCET, Chittoor, 3 SV University, Tirupathi, A.P, India

[email protected], [email protected], [email protected]

Abstract— Now a days there is a huge interest on underwater communication systems for various applications in order to explore aqueous environments. Intelligent robots and cooperative multi- agent robotic systems can be very efficient tools to speed up search and research operations in remote areas. Robots are also useful to do jobs in areas and in situations that are hazardous for human. They can go anywhere that is not reachable my humans and can go into gaps and move trough small holes that are impossible for humans and even trained dogs. In this paper, a wireless underwater mobile robot system is designed in order to study the behavior of Artemia group. A new idea has been presented for underwater mobile robot system which is consists of two parts, first is the underwater mechanical robot and the second is ZigBee wireless based mobile robot which controls and moves the first part. By this system different patterns motion control (Linear, Circular, Zigzag, etc.) has been performed and proved the ability to control group of robot by controlling the group of Artemia and monitoring the underwater mobile robot control with the help of water proof RF wireless camera and also explore the details present around the mobile robot.

Keywords- aqueous; hazardous; Robotics; ZigBee; Artemia;

Introduction

The interest about underwater localization has been increased in various fields. Among the received signal strength indication (RSSI) type radio frequency (RF) sensor is an interesting possibility as an underwater sensor. This paper describes the sensor model relation between RSSI and distance. Also the three dimensional extended kalman filter (EKF) localization was simulated using RF sensor model.

The wireless communication technologies are rapidly spreading to many new areas, including the automation and the importance of the use of wireless technologies in the data acquisition, building control, monitoring systems and automation of manufacturing processes will grow. Understanding and modeling the relative mechanisms and operational principles of collective behavior of animals have been a source of inspiration for multi-agent control strategies based on decentralized algorithms. The study of flocking may therefore provide useful ideas for developing formation control, distributed cooperative control and coordination of multiple mobile autonomous agents/robots [1].

Salina is a crustacean smaller than insects in size and mass. The hatched Artemia is called nauplius, has a length typically less than 0.4 mm and shows an anatomical structure different than that of adult Artemia. The nauplius has only one eye, containing a photo receptor, and uses a pair of antennae as fins for swimming as shown in Fig. 1 [2].

aa.nauplius

A photo of a nauplius.

Collective behavior of Artemia is good model for the development of useful distributed control systems (DCS) for robot applications [3]. The direction of Artemia motion is highly sensitive to intensity of light especially the short waves of light [3].Wireless control based on spot of light which is moved by underwater mobile robot system will be achieve in order to populate Artemia. Artemia is widely affected by internal draughts which generated by swimming robot because Artemia is small in size and has weak motion torque. The challenge of internal draughts has been solved by using small size underwater robot which consists of mechanical parts only. Wireless micro swimming robot which is controlled by the magnetic field is more close to natural and free state, in which it is more convenient to study biomimetic swimming principle. In the meantime, being characterized with high reliability and safety, it could reach deep cavern by the medium of body fluid inside organism with flexibility, thus micro swimming robot, as a new important approach on therapy in term of interposition, has a widespread prospect in the field of biosystems engineering [4].

3 In this paper, a new idea for underwater mobile robot system which consists of two parts has been presented, first is the underwater mechanical robot and the second is ZigBee wireless based mobile robot which controls and moves the first part. By this work three types of wireless control has been achieved, first, the Artemia motion control by light [3], second wireless control using magnetic field for underwater mechanical robot, and the third is wireless sensor (ZigBee standard) based mobile robot as shown in Fig.2.

Underwater robot system.

Robot motion control

In two-wheeled mobile robot control, many motion control design methods [5-10] are proposed in order to move efficiently in a two-dimensional space. One motion control problem of two-wheeled mobile robot is how to communicate with mobile robot through personal computer (PC) in order to control the motion of mobile robot.

In this paper, a design of two-wheeled mobile robot controlled by PC through ZigBee standard based wireless sensor network is suggested. A two-wheeled mobile robot is

considered and its structure is described in Fig. 3 [11], where X-Y is the global coordinates and xm-ym is the local coordinates which is fixed to the robot with its center p as the origin.

The study of flocking may therefore provide useful ideas for developing formation control, distributed cooperative control and coordination of multiple mobile autonomous agents/robots. GPS module is interfaced to track the robot and sensors are used for obstacle detection.

Schematic diagram of 2-wheeled robot for motion control

The mobile robot body is of symmetric shape and the center of mass is at the geometric center p of the body. R is the radius of the wheel and L is the displacement from the center of robot to the center of wheel. The set (x0, y0) represents the position of the geometric center p in the world X-Y coordinates, and the angle Ï´ indicates the orientation of the robot.

The two fixed wheels are controlled independently by two motors. The direction of mobile robot depending on velocity of each motor since the formation of different patterns (linear, circular, zigzag, etc.) depend on the variation of the velocity of each robot wheel.

According to the schematic design of the two-wheeled mobile robot indicated in Fig. 3, its kinetic equation can be

described by

X cos Ï´ 0

Y = sin Ï´ 0 V

Ï´ 0 1 W

Where X, Y denote the velocity of robot in the direction of X-axis and Y-axis respectively denotes the linear velocity of the robot in the head direction of robot and Ï´ =W denotes the rotational angle velocity of the robot.

Two wheels are fixed in mobile robot and each wheel is controlled independently by each motor, so the forward velocity of the robot and the wheel angular velocity are described by

V = 1/2 1/2 VL

W -1/2L 1/2L VR

where L is the displacement from the center of robot to the center of wheel. VL =RWL and VR = RWR are the linear velocities of the left wheel and right wheel, respectively. R is the radius of the wheel and WL and WR are angle velocities of the left wheel and right wheel, respectively. Based on equations (1) and (2), we can obtain the following equation:

VL cos Ï´ sin Ï´ L X

VR = -cos Ï´ -sin Ï´ L Y

Ï´

The velocity and direction of rotation of wheel motor is controlled by pulse width modulation (PWM) which is generated by the main board of mobile robot.

robot main board

Robot main board is the brain of mobile robot which receives the motion pattern parameters from PC through ZigBee wireless connection and processes these parameters to perform pattern motion control. The main part in the robot main board is AVR ATmega162 microcontroller which generates two PWM signals for each wheel motor.

The two active wheels of the robot are actuated by two independent servo motors modified for continuous rotation. In particular, we used ZS-F135 sub-micro servo motors with the following specifications: speed 0.16 s/60° at 4.8 V; torque 1.2 kg cm at 4.8 V; weight 8 g, size 22.8 mm× 11.6 mm× 22.6 mm. The robot is powered by three 1.5 V batteries. Mobile robot receives PWM parameters from PC through ZigBee wireless network as indicated in Fig. 4.

Hardware components of mobile robot system.

zigbee wireless sensor network

The ZigBee standard is developed by the ZigBee Alliance [12], which has hundreds of member companies, from the semiconductor industry and software developers to original equipment manufacturers (OEMs) and installers. The ZigBee standard has adopted IEEE 802.15.4 as its Physical Layer (PHY) and Medium Access Control (MAC) protocols [13].

ZigBee is a standard that defines a set of communication protocols for low-data-rate short-range wireless networking [14]. ZigBee-based wireless devices operate in 868 MHz, 915 MHz, and 2.4 GHz frequency bands. The maximum data rate is 250 K bits per second. ZigBee is targeted mainly for battery- powered applications where low data rate, low cost, and long battery life are main requirements. ZigBee wireless networking protocol layers are shown in Fig. 5.

ZigBee wireless networking protocol layers.

XBee ZigBee/Mesh RF module has been used for support ZigBee wireless network. XBee ZigBee/mesh modules provide developers with ZigBee mesh [16]. XBee ZigBee/mesh RF modules make mesh networking simple and easy to deploy. The XBee module is very easy to use, and the interface is based on a simple dialogue with a serial port, which can be easily handled by a microcontroller or a PC as shown in Fig. 6.

XBee ZigBee/Mesh RF module .

aqueous mechanical robot

Motion control of Artemia inside water needs wireless swim robot to form several types of fixed pattern (linear, zigzag, circular, etc.). This swim robot will be large compared with Artemia body size and the motion of this robot inside water make waves affected on the Artemia motion. To overcome the above difficulties, we need a very small size swimming robot or a micro robot (3 cm3 or less) controlled by wireless sensor network. This is very complicated, so to solve this problem, a simple mobile robot has been designed. The suggested robot consists of three iron ball wheels which are moved by applying a magnetic field source from outside water as shown in Fig. 7.

Aqueous mechanical robot

Experimental Results

The wireless underwater robot system has been used in order to control the motion of Artemia population to form three types of motion patterns (liner, circular and zigzag). By these experiments, we proved Artemia group can be controlled to move in any direction based on sensing to movable light spot. Also information extracted from these experiments are a good source for deriving complete wireless control system for multi mobile robot system based on external guide. Several videos have been recorded for Artemia group motion. Some frames of experiments videos referring to a straight line or linear pattern are shown in Fig. 8, circular pattern is shown in Fig. 9, and zigzag trajectory are in Fig. 10.

Linear Pattern

Circular Pattern

Zigzag Pattern

To process Artemia videos, a moving objects detection algorithm has been used in order to extract data like position, and number of individuals in Artemia group. The video split into a sequence of images and each image has been converted into gray scale image and then converted to binary image. All experiment done inside laboratory then experiments can be repeated several times to get good videos and suitable for image processing, the semitransparent orange color of Artemia body problem solved by using black environment, the well-defined spacing of the group, and the high contrast provided by individuals against the black background, permit mostly automatic detection of individuals in images, and the videos are acquired indoor without disturbing nature behavior like wind, waves, etc. Path trajectory of Artemia group motion with respect to no. of frames for linear motion pattern is shown in Fig. 11, circular motion pattern is shown in Fig. 12, and zigzag motion pattern are in Fig. 13.

Linear Pattern center Vs No.of frames

Circular Pattern center Vs No.of frames

Zigzag Pattern center Vs No.of frames

Conclusion

In this paper, we introduce new idea for wireless robot control system which is used as a tool to perform a wireless control on a group of Artemia to achieve several patterns to extract behavior of these organisms. The wireless robot control system contain three types of wireless control, first is used light to control the motion of Artemia group, second is used magnetic field to control the motion of underwater mechanical robot while the last one is used ZigBee standard to control the mobile robot by PC. This system is easy to construct, low cost and can control small organisms in small area with perform several patterns.