E-YANTRA:
It is a national level robotics competition where engineering people from all over India participate.The competition is organized at IIT Bombay and is sponsored by MHRDA.The competition is held every year and has various theme each year.the competition has a online qualification round and then the qualified TEAMS receive a FIREBIRD ROBOT for free and are given tasks, that have to be completed within a specified time frame the tasks are such as
the final competition is held at IIT BOMBAY
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This was the report we prepared for our e yantra competition hope you find it useful
e-Yantra
It is a national level robotics competition where engineering people from all over India participate.The competition is organized at IIT Bombay and is sponsored by MHRDA.The competition is held every year and has various theme each year.the competition has a online qualification round and then the qualified TEAMS receive a FIREBIRD ROBOT for free and are given tasks, that have to be completed within a specified time frame the tasks are such as
- printing the flex of the arena for bot navigation for practice
- building of the arena
- Preparing a Theme analysis and Implementation analysis
the final competition is held at IIT BOMBAY
The Seed-sowing Robot designed by us in the E-yantra 2014 competition,we were the among Top five finalist of the competition.
This was the report we prepared for our e yantra competition hope you find it useful
e-Yantra
Robotics Competition
State the scope of the theme assigned to you.
A seed sowing robot is an autonomous seed sowing machine as its name
implies .due to the increasing population the land available for agriculture is
rapidly diminishing, thus reducing the agricultural productivity. Today it has
become necessary to increase the agricultural productivity of India , to meet the
increasing demand of the ever increasing population
In the recent years the green house concept has emerged as a faithful
alternative for Indian farmers, where plants are grown in a controlled
environment suitable for them thus increasing the productivity.
The drawbacks of manual seed sowing in a green house are
• Increased time consumption
• Decline in the rate of production
• Wastage of precious seeds
Thus the basic remedy for this is the automation of the seed sowing process, and
thus building an autonomous seed sowing robot is the primary and most
important step in automation of this process.
Building Modules:
Identify the major building blocks in the robotic system that needs to be
designed for your theme.
• Sensors: sharp IR range sensors, black line sensors
• Actuators: DC motors, servo motors.
• Power supply
• Signal conditioning unit(ADC etc)
• processing unit
Actuators:
List all the actuators currently present on FIREBIRD V robot and also the
essential actuators required for designing the robotic system in your theme.
A seed sowing robot requires the following list of actuators for its specified
task
Available on firebird
• Servo motor (0-180’ rotation): required in the mechanism for
controlling the position of the sensors.
• DC motors: required for primary motion of the robot along the arena
External Actuators:
• Servo motors(0-360’ rotation) : required in the mechanism for rotation
by a specific angle for dropping a single seed at a time
Explain the mechanism for controlling the actuators on your robot.
• Servo motor(0-180’ rotation): this servo would be used to exactly orient
the nozzle above the hole detected in order to prevent dropping it
outside the hole
• DC motors: there motion would be controlled depending on the line
sensor reading
• Servo motors (0-360’ rotation): they would be rotated by a specific
angle to drop the required number of seeds in the hole. like for dropping
1 seed a rotation of 45 degree is rotated.
Environment sensing
Explain the functioning of environment sensing technique used by FIREBIRD V
robot in your theme.
• Line sensors: help the robot move across the arena along the line.
The three line sensors give different reading on black and white surface as
white reflects all of the light incident on it while black absorbs the light
incident .a program can be written depending on this values of the sensors
such that the robot moves along the line and self orients itself when it
deviates from the line.
• Sharp IR range sensors: Depending on the values of the IR range sensors
the operation of the different actuators can be controlled. IR range
sensors give the distance of a surface depending on the angle of
reception of the light and thus are more accurate than ordinary range
sensors which give distance depending on the intensity of the received
light.
• IR proximity Sensors: The proximity sensors provided with the robot are
used to maintain a safe distance from the thermocol sheet to prevent
any damage to the arena.
• Servo motors: Depending on the processors output and the program
these actuators would be switched on or off.
Power Management
Explain the power management system required for a robot in general and for
FIREBIRD V robot in particular.
• Servo motors: the servo motor require 5-10 volts supply and 500-1amp
of current depending on its application
• Dc motors: They are powered by internal “v mot” supply, a l293D IC is a
motor driver IC which is used to provide a maximum of 600 mA of
continuous and 1A of starting current to the two motors.
• Sensors: on board sensors are supplied by the battery connected
5 v supply is used to power the IR range sensors which a supply a
additional of 400 mA of current for external load
While a 3.3 v supply is used to power the white line sensors with an
additional supply capacity of 100mA.
Navigation Scheme
Explain in brief the basic navigation technique for path traversal in the arena.
Explain the concept and list the components required for basic navigation.
Components required for navigation:
• Sharp IR range sensors
• Line sensors
NAVIGATION SCHEME:
The line following sensors available at the bottom of the fire bird five would
the primary component required for its navigation across the arena along the
line .Besides this the Sharp IR range sensors would help the robot detect Hole and
execute the programmed code on detection of the hole .the sharp IR range
sensors will control the Operation of the mechanism.
Thus the combination of these two sensors would help the robot transverse
across the arena and help complete the specified task.
Challenges
What are the major challenges that you can anticipate in addressing this theme?
• SEED DROPING MECHANISM:
One of the major challenges would be to design an accurate and efficient
mechanism right from scratch, to drop specified number of seeds in every
hole.
• SERVO MOTION MANAGEMENT:
Based on the analysis done by us on the desired mechanism, we would
require utmost 3 servos of which one is included in the kit. The major
challenge would be to manage the order of operation of these servos as
operating more than one servo at a time may draw a large amount of surge
current damaging the microcontroller.
• POWER MANAGEMENT:
Since we would be using servos and sharp IR range sensors we need to
take into consideration there current and voltage ratings, and control
there switching so that they are off when not in use thus preventing
drainage of excess power
Preparing the Arena
How it works
Figure 5
FIGURE 7
After all of this the seeds are dropped in the hole and the robot moves ahead
Figure 9Q-4 Choose the actuator you will use to design the dispenser mechanism. (5)
Conclusion:
Algorithm Analysis
Design Analysis
Q-1 How will you detect the holes using the sensors available to you in the kit?
We will be using the following sensors for detection of holes :
We will be using the following sensors for detection of holes :
· SHARP IR RANGE SENSORS(GP2D120) INTRODUCTION:
We are using the sharp IR range sensors GP2D120. The Sharp GP2D12 infrared ranger is able to continuously measure the distance to an object. The usable range is 10 cm to 80 cm. The device generates an analog voltage that is a function of range, and the output voltage can be measured by an analog-to-digital (ADC) input line on fire bird 5.
How it works
The device emits a pulsed infrared beam at a wavelength of 850 nm ± 70 nm. If an object is within range and in line with the IR beam, reflected light forms an image on a linear CCD array in the receiver.
Triangulation is then used to determine range. Readings are updated at a rate of approximately 24 Hz. The detector is relatively insensitive to ambient lighting, as well as reflectivity of the object being detected. It is possible to detect relatively dark objects in full sunlight.
Triangulation Method:
The output voltage is a nonlinear function of the distance from the object to the receiver. In figure 1, the curve of voltage vs. distance was taken from Sharp documentation.
**Note that objects less than 10 cm away can look like objects at longer distances. This ambiguity needs to be taken into account if objects are allowed to be closer than the 10 cm threshold.
Triangulation Method:
In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angle to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly. The point can then be fixed as the third point of a triangle with one known side and two known angles.
The figure 2 shows the principle of triangulation method used in sharp sensors to calculate distance from the object
Q-2 Draw a labeled diagram to explain how you have planned to place the sensors on/around the robot? (15)
We are using only the two sharp IR range sensors provided in the kit for detection of hole. The figures 3 and 4 accurately determine the position of the two sharp sensors with respect to the arena and the position of the robot
JUSTIFICATION:
We have decided to place the sensors in the position shown above ,because it will help us detect the hole with great accuracy and prevent us from missing any hole .The sharp sensors have been adjusted in our arrangement at a height, such that it gives a great variation of output analog voltage when it moves from the thermocol surface towards a hole
.This output analog voltage is then feed to the respective ADC converters which gives the approximate distance of the surface from the sharp sensor.(*in our arrangement ,a value less than 85 represents the presence of the thermocol surface underneath and is indicated by a digital value 0, will a value returned by sharp sensor above 120 represents a hole and is indicated by a digital value 1.Thus whenever the value of the sensor goes from 0 to 1 it represents the presence of the hole underneath.)
DIFFICULTIES:
We had to place the sensor in such a way that the surface is always at a distance more than 10 cm ,as we have discussed earlier that objects at a distance closer than 10 cm can cause problem .
Q-3 Teams have to prepare the dispenser mechanism for dropping seeds into the holes.
a) Choose an option you would like to use to position the dispenser mechanism on the robot. (5)
1. Front 2. Back 3. Right/Left 4. On both sides
Answer: On both sides
**We have placed our mechanism at the center of the robot and have drawn to pipes, such that they are exactly over the left and right whole .thus we have selected the 4 option.
We would be placing the dispenser mechanism on the robot as shown in the figure 5
a) Draw a diagram to show the dispenser mechanism and how it is mounted on the robot. (15)
The following figure determines the position of our designed mechanism for dispensing seeds one by one. We decided to mount our mechanism in the position shown after taking into consideration the following factors:
JUSTIFICATION:
We decided to place the mechanism on both sides of the robot such that the robot does not needs to deviate from the line. Thus the robot can remain in its position and can sow the seeds in the intended hole, preventing any error or confusion due to deviation from the line.
Other factors considered to decide the position of the mechanism:
· Weight balancing :
Initially we had decided to place two storage and dispensing mechanism on both sides of the robot i.e. left and right, but taking into consideration the weight balancing of the robot we decided to use a single storage and dispensing mechanism such that the overall weight of the robot is balanced and took out two outlets from the it one for sowing seed in the left and the other for sowing in the right hole as shown in the figure 5.Besides this it also provides one more advantage that ,the overall load on the motor is reduced thereby reducing the current drawn by the motor.
· Ease of mobility:
As discussed earlier we changed our plan of using 2 storage and dispensing mechanism, because it also brought a large amount of constraint on the motion of the robot. Thus reducing the ease with which the robot can move around the arena.
· Stability of the structure:
Figure 5
WORKING:
Our mechanism consists of three major sections:
· Seed Storage unit: The storage unit is basically used to store the seeds required for sowing .The unit is designed to store a maximum of 88 seeds .it consists of 8 tubular cylinders separated by 45 degrees , each tube having a capacity to store 11 seeds each as shown in the figure .it is always stationary.
· Temporary Single seed separation unit:
It basically consist of two parts .one part consists of two disk 1 and 2 as shown in the figure which are coupled together and are connected to the stepper motor .in between this two disk is another storage unit as above but has the capacity to hold only one seed at a time .the disk 1 and 2 each have a single hole in them along the rim of the disks
,separated by 45 degrees .the upper disk has a hole 45 degree ahead of the hole in the lower disk. the hole in the disk 1 allows a seed to come in the single seed storage unit , when it is rotated by 45 degrees the hole in the disk 2 comes directly below the seed and thus the seed finally comes out of the storage unit and is then feed into the dispensing unit
.this process is continued to drop one seed at a time.
Thus the above mechanism does not allow more then one seed to fall at the same time, preventing any unwanted loss of seed.
Figure 6
Figure 6
· Dispensing unit: After the seed comes in this unit, it is directed by the servo to the respective hole either left or right. The position of the servo motor is shown in the figure 7.We have used the servo motor to rotate the flap connected to its shaft a shown in the figure 8.The flap is rotated to decide in which hole does the seed actually go into, which is decided by the program .The figure 9 shown how the seed is diverted towards the left hole by the flap. Similarly the seed can be made to go in the right hole as well.
FIGURE 7
After all of this the seeds are dropped in the hole and the robot moves ahead
Figure 9Q-4 Choose the actuator you will use to design the dispenser mechanism. (5)
1. DC-Motor 2. Servo Motor 3. Stepper Motor 4. Others Answer: Stepper motor and servo motor both.
Justify your answer by stating the advantage of the chosen actuator over others. Also give reasons for not using other actuators.
JUSTIFICATION:
We are using both a stepper motor and a servo motor in our overall dispensing mechanism ,but the stepper motor forms an much more integral part of our mechanism .The Stepper motor is used to rotate the disc in our mechanism by a specific angle depending on the number of seeds to be dropped in the hole .We decided to use a stepper motor ,because we required the differentiating disc shown in the figure 6 to be rotated by a complete 360 degree and the servo provided in the kit can rotate only a angle of 180 degrees .
Stepper Advantages:
Stepper motors offer several advantages over servo motors:
· larger number of poles
· Easier drive control.
· The design of the stepper motor provides a constant holding torque without the need for the motor to be powered.
· The torque of a stepper motor at low speeds is greater than a servo motor of the same size.
· One of the biggest advantages of stepper motors is their relatively low cost and availability.
Conclusion:
For selecting the best motor for our application, we took into consideration the key design criteria for our system including cost, positional accuracy requirements, torque requirements, drive power availability, and acceleration requirements. Overall, servo motors are best for high speed, low torque applications while stepper motors are better suited for lower acceleration, high holding torque applications.
Thus we decided to use a stepper motor for rotating our disc as it required a high holding torque and their was no need of speed in this application.
Algorithm Analysis
Q-1 Draw a flowchart illustrating the algorithm used to complete the entire task. (40) We have divided the overall programs into three sub sections as follows:
· MAIN
· LINEFOLLOWER:
In the line follower algorithm below the sensors are represented by the terms left ,right and center respectively .while black and white terms are used to indicate the colour of the surface.
MAIN PROGRAM
LINE FOLLOWER FUNCTION
SEED SOWING FUNCTION
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