Roboticsin Schools

Making a Remote Controlled Robot

Before jumping into action, lets first learn the anatomy of a manual robot. It has the following parts :

  • Power Source
  • Chassis (Base)
  • Remote (Control System)
  • Motors (Actuators)
  • Wheels (Locomotion System)

    Brief description of the various parts of a robot:


    Motors :

    Actuators are electromechanical devices that converts electrical energy into mechanical energy. Here your motors are your actuators. The motor selection is a very important calculation to be made before making a robot. Hence when you go for buying a motor for your robot, you need to look into and search for the below mentioned information:


    a) Stall Torque: It tells us what is the maximum rotational force that can be applied when a motor is rotating to make it stop. The more the stall torque the more powerful is your motor. In your local market you will see motors are sold with the torque rating present in Kgcm units.


    b) Stall Current: It is the maximum current that a motor will draw when it is stalled. When you need to buy a power source always make sure thath the maximum ampere (A) rating is more than the sumof stall current of all the motors of your robot.


    c) RPM: It is the rotational velocity of a motor. A 100 rpm motor tells us that the shaft of the motor will rotate 100 times in one minute. If you wish to know the linear velocity i.e. the speed in cm/s then the formula to convert RPM to cm/s will be :

    Speed in cm/s = (RPM x radius of the wheel in cms)/60


    Power Source :

    There are many options for powering up your robot. You can power it up using an AC-DC adapters, Solar Cells or Batteries. Batteries are good solutions to power up your bot, the only disadvantage being that they get used up and have to be charged again (if its a rechargable one). On the contrary, using batteries increase the bot's freedom of movement. In case of a AC-DC adapter, the maximum current and the voltage rating is mentioned along with it. Hence make sure to buy a power adapter whose voltage rating is either same or less to the motor voltage rating. Avoid running motors on voltage more than the motors rated voltage.


    Now how to know the output current capacity (output load) of a battery? Because its not mentioned in Amperes but in Ampere Hour.

    Ampere hour of a battery is basically the

    Current output x Time for which it can provide


    Now, a 5 Amp-Hr battery, can give out 5 ampere current for an hour (ideally). Also, it can give out 10 Amperes of current for 30 minutes; Or 20 Amperes of current for 15 minutes. The idea is, the charge capacity is constant, i.e. the Current x Time (in hours) product is a constant and that is the Amp-Hr rating.


    Another thing to keep in mind is the Peak Discharge of the battery (if its mentioned). A 30C, 6 Amp-Hr battery means it can discharge a maximum of 30x6=180amperes of current at its peak at one go.

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