basic robotics - xlr8 basics

7/29/2019 Basic robotics - XLR8 basics

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XLR8

BASICS

-ARPIT GUPTA

-HIMANI SINGHAL


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WHEELS

No of wheels

Size of the wheels

Traction??


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NUMBER OF WHEELS

Four wheel drive

Three wheel drive

Two wheel drive

One wheel drive ?????


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FOUR WHEEL DRIVE

More no. of motors more torque

Easy to climb inclined plane

If not aligned properly => 1 motor useless

Different RPM | Power loss


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THREE WHEEL DRIVE

Minimum no of points to form a plane

Wheels always in contact

Only 2 motors

Wheelie can occur at the start of motion


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REMOVE GRIP OF

FRONT WHEELS

Easily rotated than 4 wheel

driveMore torque than 3 wheel

drive


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TWO WHEEL DRIVE

Segway

One wheel

drive

Self balancing bot


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SIZE AND STRENGTH

Diameter Large : positioning less accurate

Task


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Given a motor of torque

High force requirement

small diameter

opposing torque produce by friction reduces

(friction)=R*F(friction)

High speed requirement

Large diameter

V=R*


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MOTORS

What motors to choose??

Choosing the motors is a very big task as a wide variety of

motors of different r.p.m , torque, size, power, weight,material are available in the market .


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There is always a tradeoff between the motors as torque andR.p.m are inversely proportional.

Some robots even have weight constrains (heavy metal motors orlight plastic motors)?


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MATERIAL FOR

CHASSIS

Acrylic

Aluminum

Wood


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MATERIAL FOR

CHASSIS

Acrylic

Aluminum

Wood


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ACRYLIC

Advantages

Light weight

Easy milling

Transparent acrylic sheets can be used in the robots in

which internal mechanisms need to be presented

Disadvantage

Very brittle and fragile

Is not reliable for long term usage of the machine


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ALUMINUM

Advantage

Light weight

Easy machining (compared to other metals)

Readymade sections, bars, boxes etc are easilyavailable in the market which can be directly

used

More strength to weight ratioDisadvantage

Sheet of same dimension is very heavy as compared to

rest of the two materials


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WOOD

Advantages

Lightest among the three

Relatively cheaper than acrylic

Disadvantages

Very weak

Not Waterproof

CENTER OF GRAVITY


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CENTER OF GRAVITY

Low

Stability

Impulsive force & at start of motion

F

A lot of care must be taken about issues like center of mass and center of gravity

As the robot must be very stable and should be avoided from toppling , and other

stability problems


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CONTINUED

D T Toppling

Close to the wheels having grip

Gripper motor

positioning

Brake wire (Cycle)

Use Pulley - Rope System


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7805

Three terminalpositive voltageregulator.

It is used toconvert 12Vcurrent suppliedby the battery to5V current.

Dont forget toattach heat sink .


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FOR A WIRELESS ROBOT THAT

RECEIVES A SIGNAL ONLY OF 5 VOLTSOR LESS THAN 5VOLTS.

SO HOW DO WE RUN MOTORS OF 12

VOLTS???

WE NEED A CIRCUIT THAT ACTS AS AN SWITCH

I.E WHEN IT GETS 5VOLT SIGNAL IT SWITCHES 12

VOLTS TO THE MOTORS.


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L293D

16 pins and their numbering


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L293D AND 7805

CIRCUIT


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BATTERIES

We generally use 3 types of

batteries

Lead acid battery Rechargable, generally used.

Nickel Metal Hydride (Ni-MH)

battery

Lithium Ion (Li-ion) battery


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WHICH BATTERY TO USE??

Lead acid batteries- Heavy,cheap,easyand safe to use.

Lithium ion battery-light

weight,costly,carefull chargingneeded.

Lithium polymer- light weight , very

costly , carefull charging and balancingneeded.

Nickel metal hydride-slightly heavy ,

safe to use.


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CONTACT DETAILS

Managers:-

Mohit - 9820721145

Ashima - 9167146655

Co-ordinators:-

Deepak - 8655600593

Shaimak - 9167647616

Rishi - 8879490822

Arpit - 9920134740

Krishnakant - 9820715401

Himani - 9405621818

Newton (PG Co-ordinator)-9930742189

basic robotics - xlr8 basics

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