High Efficiency All Terrain Exploratory Rover

High Efficiency All Terrain Exploratory Rover

Vishnu Sasidharan, Vivek Dharmarajan Vivek H. Menon, Vysakh Sethumadhavan, Dhanesh M. S.

Department of ECE

Rajagiri School of Engineering and Technology

Abstract The paper describes the implementation of a research rover using the Arduino Mega microcontroller as its brain. The features of a mars rover such as autonomous solar tracking, terrain adaption, methane detection, autonomous rover traverse and precise arm placement are implemented here. The solar tracking is implemented using light sensors and a pan and tilt unit. An OWI robotic arm is used here which is controlled by the arduino board. The communication between the base station and the rover is done by RF communication implemented using Xbee. In the autonomous traverse process the base station points the robot to the target and the rover autonomously moves to the target. The rover proceeds to acquire science measurements with the instrument.

1. INTRODUCTION

   An autonomous robot is a robot that performs behaviors or tasks with a high degree of autonomy, which is particularly desirable in fields such as space exploration, cleaning floors, mowing lawns, waste water treatment and delivering goods and services.

   Some modern factory robots are "autonomous" within the strict confines of their direct environment. It may not be that every degree of freedom exists in their surrounding environment, but the factory robot's workplace is challenging and can often contain chaotic, unpredicted variables. The exact orientation and position of the next object of work and (in the more advanced factories) even the type of object and the required task must be determined. This can vary unpredictably (at least from the robot's point of view).

   One important area of robotics research is to enable the robot to cope with its environment whether this is on land, underwater, in the air, underground, or in space.

   A fully autonomous robot can:

   1. Gain information about the environment [5].

   2. Work for an extended period without human intervention [2].

   3. Move either all or part of itself throughout its operating environment without human assistance [3].

   4. Avoid situations that are harmful to people, property, or itself unless those are part of its design specifications.

   An autonomous robot may also learn or gain new knowledge like adjusting for new methods of accomplishing its tasks or adapting to changing surroundings [1][3]. There are many different types of exploratory robots in the world. Some examples are the Crabster cr200, Mars Rover and a robot that was sent down into the Titanic a few years ago. These Robots can help us with our past, present and even the future. They are amazing little "creatures" that help us out. Exploratory robots can be used anywhere. There are different designed robots for each project/ mission. Say NASA wants to know what different things are on Venus. They would create a robot with certain exterior and interior so it would not break while being shipped off to Venus.

2. PROJECT BLOCK DIAGRAM

   The rover is controlled by the arduino microcontroller. It communicates with the base station using Xbee radios. The rover is made highly efficient using the solar tracking unit which points the solar panel to the direction of maximum sunlight. An accelerometer has been incorporated into the system for control of speed of the motors [3]. A wireless

   camera on the rover gives a live video feed to the base station which enables autonomous navigation [2]. The robotic arm consisting of the sample testing sensors is controlled from the base station itself. As an additional feature the rover also has the ability to detect methane [5].

3. SOLAR TRACKING AND METHANE DETECTION

   There are four LDRs placed on the rover that helps in solar panel movement. They were each placed at left top, left bottom, right top and right bottom. The left top and bottom formed a pair so did right top and bottom. These pairs helped in the vertical movement of the rover. The left top and right top also formed a pair along with the left bottom and right bottom LDRs. These pairs support the horizontal movement. Once the light is detected these resistor pairs give out different values based on which the rover would move either left/right or top/bottom. Two motors are mounted one on top of the other which enhances the rover movement. The sunlight decreases the resistances of the respective LDRs which set the motors in motion. The motors used are of 600rpm and are programmed at a default value. Their initial position is at 90 degrees [1].

   MQ6 sensor is used for organic carbon detection here. Its programmed using Arduino. MQ6 sensor gives the analog value when an organic compound is detected. The software allows the value ranging from 0-1023 to be displayed on the monitor screen. Once the compound is detected the value on the monitor keeps increasing whereas if a compound is not detected the monitor would read a small value. MQ6 sensors are easily interfaceable with the arduino board. In our project, only if the sensor detects the presence of organic carbon, the rover transmits a message back to the base station [5].

4. TERRAIN ADAPTION UNIT

   The rover is embedded with an accelerometer which helps in terrain detection. This enables the rover to control its speed while traversing through different terrains. Since the rover is autonomous, we have adopted a system wherein the rover automatically adapts to the terrain and controls its speed. Our rover is designed to move on sandy, rocky or gravel terrains. The rover also features a capability to autonomously traverse rocky terrain for a distance of 10 15 m, tracks the target(s) of interest during the traverse, positions itself for approaching the target, and then precisely places an arm-mounted instrument within 2-3 cm from the originally designated target. The rover proceeds to acquire science measurements with the instrument [3].

5. OWI ROBOTIC ARM

   The OWI Robotic Edge Arm is a cheap and compact 5- degree-of-freedom robotic arm.

   With the robotic arm, a wrist motion of 120 degrees, an extensive elbow range of 300 degrees, base rotation of 270 degrees of 180 degrees, vertical reach of 15 inches, horizontal reach of 12.6 inches, and lifting capacity of 100g is possible. The communication technology used here is Zigbee. A base station exist which connects with the arm through the Xbee interfacing on its arduino board. The commands once received by the board sets the arm in action moving almost spontaneously. It requires 2 Xbee boards, a base station (PC) and an arduino board to control the arm movements. The arm will have basically two kinds of motion. The first motion will be to place the sensor on the target. The second motion will be to collect samples. These motions require the dc motors to move in a pre- determined sequence [4]. The commands for the movement of each motor are send from another arduino board with the

   communication between them occurring wirelessly. ZigBee protocol enabled Xbee modules, each interfaced with an arduino board, are used for this purpose.

6. AUTONOMOUS TRAVERSE ALGORITHM

   This feature of the rover is implemented in matlab. The rover is equipped with a wireless camera that is capable of transmitting a live video feed of what the robot sees. The algorithm used in traversing to the clicked target is localization and boundary mapping. Upon mouse click the snapshot of the scenario is taken along with the target coordinates in he image which is stored in the base station for later use. The scaling of the image is done before hand to allow a precise traverse towards the target. A binary mapping of the image is done by making the obstacles and the target as white and the surface as black. The rover then traverses along the only black path until it reaches the target coordinates [2].

7. HARDWARE

   MQ6 SENSOR

   The Gas Sensor (MQ6) is an ideal sensor for use to detect the presence of methane in any environment. This unit can provide us with visual indication of the presence of methane. The sensor has excellent sensitivity combined with a quick response time. It is composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and a heater. These are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. It heats the surrounding gases which are in the close vicinity of the sensor. Once the gases get heated up, it will react with the chemicals in the sensor. Sensitive material of MQ-6 gas sensor is SnO2, which has lower conductivity in clean air. When the target combustible gas exists, the sensors conductivity increases along with the gas concentration rise. Thus, the presence of methane can be detected on observing these changes in the property of chemicals in the sensor. The voltage for the internal heater is very important. Some sensors use 5V for the heater, others need 2V [5].

   MPU 6050

   The MPU-6050 sensor contains a MEMS accelerometer and a MEMS gyro in a single chip. It is very accurate, as it contains 16-bits analog to digital conversion hardware for each channel. Therefore it captures the x, y, and z channel at the same time. The sensor uses the I2C-bus to interface with the Arduino. IMU sensors are one of the most inevitable types of sensors used today in all kinds of electronic gadgets. They are seen in smartphones, wearables, game controllers, etc. IMU sensors help us in getting the attitude of an object, attached to the sensor in three dimensional spaces. These values usually in angles thus help us to determine its attitude. Thus, they are used in

   smartphones to detect its orientation. And also in wearable gadgets like the nike fuel band or fit bit, which use IMU sensors to track movement. The MPU 6050 is a 6 DOF (Degrees of Freedom) or a six axis IMU sensor, which means that it gives six values as output; three axes values from the accelerometer and three axes from the gyroscope. The MPU 6050 is a sensor based on MEMS (Micro Electro Mechanical Systems) technology. Both the accelerometer and the gyroscope are embedded inside a single chip. An accelerometer works on the principle of piezoelectric effect.

   OWI 235 ROBOTIC ARM EDGE

   The OWI Robotic Edge Arm is a cheap and compact 5- degree-of-freedom robotic arm. With the robotic arm, a wrist motion of 120 degrees, an extensive elbow range of 300 degrees, base rotation of 270 degrees of 180 degrees, vertical reach of 15 inches, horizontal reach of 12.6 inches, and lifting capacity of 100g is possible. The communication technology used here is Zigbee. A base station exists which connect with the arm through the Xbee interfacing on its Arduino board. The commands once received by the board sets the arm in action moving almost spontaneously. It requires 2 Xbee boards, a base station (PC) and an Arduino board to control the arm movements.

8. CONCLUSION

In this paper we have presented the details of a high- efficiency all-terrain exploratory rover. The first feature of this rover is the solar tracking mechanism which has been proven to work to absorb maximum sunlight source for high efficiency solar harvesting applications. The second feature is the terrain adaption capability which basically consists of a speed control mechanism based on the axes values received from an accelerometer. The communication between the rover and the base station

occur wirelessly using XBee modules on the rover side as well as the base station side. Finally the rover has the ability to traverse any terrain autonomously and place the robotic arm at the designated target. The baste station assigns a specific target, available via a wireless webcam, to the rover by clicking on the target. The rover will then autonomously traverse the surface till it reaches near the target and then deploys the arm which serves two purposes; collection of samples and placement of instruments like soil moisture sensor. These features enable the rover to retrieve samples or analyze a surface, from different remotely accessible areas to which they are deployed, in an efficient yet simple manner

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