Hi guys ,
here is the second chapter regarding the drive of your robo car.
i made a mistake last post..not a mistake actually i could not put it clearly that all DC motors are not geared motors . the one which involves reduction in speed due to gears is a geared motor. whereas the one which u see in black colour is a normal dc motor that does not involve gears.
Now beginning with second chapter
- You can use any material for the body of your robo. It can be either wood, M.S plate. Aluminium, etc. depending upon the weight requirements
- Generally the cars on our roads are rear wheel drive. But for the competitions this won’t serve the purpose.Let us see the disadvantages
In the fig the one with dark rear wheel is rear wheel drive while the other is four wheel drive.{ ie. All the four wheels powered by motors } - How do the robo car overcome an obstacle ?
When a car is moving the wheel rotates in clockwise direction while moving forward. and hence the friction force acts in anticlockwise direction. This makes the car move forward.
Similarly it overcomes an obstacle.
Now if the car is climbing an inclined plane. Then in case of rear wheel drive there will be no friction force on the front wheels because they r not powered and hence unable to generate a reaction.
Due to this the car will topple upside down.
Same is the case while clearing an obstacle in rear wheel drive and it won’t be able to clear it.
But in four wheel drive each wheel generates a reaction . and there acts a friction force. Hence it is able to clear all the obstacles as well as climb the inclination with higher degree than that of rear wheel drive car.
- The very fact that Centre of gravity plays an important role .
The C.G ON A FOR WHEEL DRIVE ACTS ON THE CENTRE OF THE BODY.
ON REAR WHEEL DRIVE IT ACTS BETWEEN THE TWO MOTORS.
by adding some dead weight on the front side and shifting the C.G somewhere in between can serve the purpose in rear wheel drive.
- The very common example can be a normal four wheeler and a HUMMER.
Hummer is a four wheel drive vehicle hence can even climb uneven terrains.. - we can also use a belt as used in tanks on wheels as it can be seen in the pic. above. but again this har advantage on the sand. what is observed during robotics competitions is that the belt comes off while overcoming an obstacle or by excessive jerks. hence it is advisable to avoid such method.
- For normal competitions in robotics we need to clear a track in minimum possible time or win a knockout race. So we need speed as well as enough torque to overcome all obstacles. As I wrote on my last post a 300 r.p.m motor would serve both purpose and also it should be a four wheel drive.
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