grid workshop

8/4/2019 GRID Workshop

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It is a competition in Tryst in which one has to design a robot which cantrace its path from the start position of the grid to the finish over a givenpath.

The path will be given in form of series of coordinates which you are

expected to trace.

You have to program your machine to traverse this path.

The winner would be decided on the basis of time.


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We can approach the problem in many ways..Following are the two suggested methods->

1.Using a DC-motor drive system and an array of black line sensors for feedback.2.Using a stepper motor drive system in which one may not need to have

feedback from the sensors .

Though the second method is a much professional way to solving the problem wewill in our talk consider the first method usind sensors and DC motors without

encoders.


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ARRAY OFSENSORS

ANALOGSIGNALS

COMPARITORLM 324

BINARY DATA

PIC18F4550

TO THE MOTORDRIVER

L293-D

MOTORS

Here is the overview of the robot that would be required for grid.It shows the independent modules of the robot and their interconnections


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SENSORPOSITION FORCOUNTING No.OF CROSSINGS

SENSOR

POSITION FORFOLLOWING

THE LINE

LINES INBLACK


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Sensor C on

Sensor D onMotor C is onMotor D is on

Sensor D off

Sensor C onMotor D is offMotor C is on

Sensor D onSensor C off

Motor D is onMotor C is off


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Cross Detection Sensors on thecrossing (On)

Cross Detection Sensorsaway from crossing (Off)


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COMPARITOR IS A DEVICEWHICH CAN COMPARE TWO

VOLTAGES AND WILL GIVE AN

OUTPUT ONLY WHEN+IN > -IN

BY USING LM 324 WE CAN

SIMULTANEOUSLY COMPARE 4VOLTAGE PAIRS


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The circuit shown is the basicprogrammable circuit ofMicrochips Programmable IC.

The shown hardware can bedirectly connected to the PC usinga USB cord and can be

programmed according to ourrequirements.

There are around 30 pins availablefor use that can be independentlycontrolled by the program code.

There are also some special pinsfor activities such as PWM and

ADC and serial communication,etc.


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Need for motor drivers->We cannot drive our motors using an output port of the PIC.We therefore require current amplification using motor drivers.Further motor drivers provide us a method to drive the motor forward andbackward according to the signals received from the MCU.(PIC)

For unidirectional drive->ULN2003AFor bidirectional drive->L293D


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L293D The current amplifier


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Motor interface and control circuit


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We use DC motors in thebot as they are easy todeal with.

Alongside is shown thefigure if the grid followerwith 2 DC motorsmounted on the PCB

which contains thecircuit and acts like achassis as well.


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Shown is the circuitry ofthe grid follower


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Bottom side of thegrid follower


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grid workshop

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