task a report

8/9/2019 Task a Report

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PICK AND PLACE ROBOTTASK A

Group Members:

Mohammad Johirul Islam

(245185)

Samuel Olaiya Afolaranmi

(245179)


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TASK A: PICK AND PLACE ROBOT

1

Table of Contents

Introduction.............................................................................................................................................................................. 2

Components Used.................................................................................................................................................................. 2

Building the Model................................................................................................................................................................. 3

Program Algorithm:............................................................................................................................................................... 5

Flow Chart................................................................................................................................................................................ 6

Full System PICs...................................................................................................................................................................... 6

System Running (Video)....................................................................................................................................................... 8

Challenges Faced.................................................................................................................................................................... 8

Remedy ..................................................................................................................................................................................... 8

Limitations of the Systemand Further Recommendations:........................................................................................ 8

FiguresFig 1: Robot ARM .3

Fig 2: Gear assembly .3

Fig 3: Input buffer .4

Fig 4: Output Buffer .4


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IntroductionPick and Place is a very common function in Robotics industries. In industries many robots are used

in different work cells to pick up the objects from the production line and place it to buffer zone or

deliver it to packaging area.

This Pick up and Placing has been done by Robot Arms. There are also different type of manipulator

to hold the objects. There is one motor require to pick up and placing and one required for

transportation. The sorting in the output buffer can be done depending on size, color. We have sorted

here depending on color (2 color)

Components UsedItem Name Type Port Used Quantity Description

1 Lego

NXT Motor

Servo

OUTPUT

A

&

C

2 This motor is specific to the NXT set.

Includes a rotation encoder, returning

to the NXT the position of the shaft

with 1 resolution.

2 Light Sensor INPUT 2 1 The Light Sensor reads the light

intensity of an object to distinguish

values of the light and dark, shades of

gray.

3 Lego

Touch Sensor

INPUT 1 1 The touch sensor detects when an

object touches the endpoint of the

sensor, or when the sensor is released

again.

4 Lego

Programming

Brick

CONTRO

LLER

N/A 1 Real brain of your robot, the NXT

brick centralizes information from the

sensors, calculates and issues

commands to actuators.

5 4X2 bricks Objects N/A 4 Two of blue color and two of Yellow

color.

6 Lego Blocks Building

Blocks

N/A Many These has been used to build the

model


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Building the Model

The first step of the project is to design the model and building it.

We had to build One Pick and Place Robot, One Input Buffer and Two Output buffers.

We followed the design of the sample PnP Robot model given as sample for this project.

We used Lego Digital Designer to analyze the design of the sample.

Fig 1: Robot ARM

We went to Building guide mode to follow building step by step as it was the first time for us

with these lego.

Here we assigned the lower servo as Motor A and the upper one as Motor B

Motor A is responsible for the rotational motion of the arm. We can also call it the translationmotion from one place to another.

Motor B is responsible for the vertical movement of the arm to pick au and placing the blocks.

Later we developed one input buffer and two output buffers.

One of the important consideration of building the robot is Motor A carries all the loads of

the arm and to have a steady motion a bigger gear is introduced as driven gear. This gives

lower speed of the arm but higher torque for the Motor A.

Fig 2: Gear assembly


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The light sensor has been placed with the input buffer in such a way that it can sense the light

reflection value on the way of ascendance of the arm.

Fig 3: Input buffer

Two output buffers are built in basic ways. But important consideration of these buffers is

their front legs. They are needed to design in such a way that it does not make any obstacle

for the Robot arm.

Fig 4: Output Buffer


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Program Algorithm:The programming part has been done in LEGO MINDSTORM NXT 2.0

Motor A moves 0.5 clockwise rotation and this lead the Robot Arm under the input Buffer.

Then Motor C makes a 54 degree of rotation which creates a vertical motion of the arm.

This 54 degree motion make the arm reach near the light sensor.

The sensor differentiate the color depending on reflection intensity.

If the intensity is less than 40% than the block will be consider as blue.

Else the block will be consider as yellow.

For the Blue Block the Motor A will give 1 full clockwise rotation to achieve the position of

the arm tip over the Blue output buffer.

Then Motor C will descend gradually 94 degree so that it can easily place the block over the

output buffer and arm reaches to its vertical initial position.

To get to its horizontal initial position, Motor A give 1.5 anticlockwise rotation.

For the Yellow Block the Motor A will give 2 full clockwise rotation to achieve the position

of the arm tip over the Yellow output buffer.

Then Motor C will descend gradually 94 degree so that it can easily place the block over the

output buffer and arm reaches to its vertical initial position.

To get to its horizontal initial position, Motor A give 2.5 anticlockwise rotation.

The whole process is in an infinite loop for continuous operation.

The touch sensor is used as emergency stop.


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Flow Chart


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Full System PICs

Fig: Robot in Initial Position

Fig: After Completion of a Full Cycle.


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System Running (Video)http://youtu.be/Ko5O8hePU4w

Challenges Faced

Firstly, we faced a challenge of getting familiarize with the commands and user interface of

the NXT 2.0

While building the model, we have found that there was many blocks missing, which actually

forced us to improvise alternative designs with available lego blocks.

Finally a great challenge we have faced on the demonstration day that the Robot and the input

buffer and the output buffers are not be able to fixed in its own position due to lack of base

lego brick.

We have to identify the input buffer and the output buffers each time we change the position

of the robot. And it was really very hard as there is no scaling system about the positions of

the buffers.

Remedy

We used the some NXT tutorials and help files to familiarize with the NXT interface and the

commands.

We tried to find the missing blocks that we need in the lab, if not found the design need to be

modified.

To restrict the slipping of the robot and the buffers we used some adhesive tapes so that they

can be fixed to their positions.

Limitations of the System and Further Recommendations:

The light sensor can detect depending on the reflection intensity. So it cannot detect more than

two color. Using color sensor can solve the problem.

In our system there was no sensor to detect the condition of the input buffer as if it is emptyor full. An ultrasonic sensor can be used to solve this issue.

The light sensor can be fixed with the Arm, then we would not have to wait for sensing.

A conveyor in the output buffer can make the system more live.
http://youtu.be/Ko5O8hePU4whttp://youtu.be/Ko5O8hePU4whttp://youtu.be/Ko5O8hePU4w

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