Magical Torque......

In the post At the Right Angle, I talked about the definition of force and its application in Robotic Arm and Base. In today's post, I will talk about how Torque can create magic!!

We need to apply a bit of mathematics here to understand the magic.

Torque is calculated by the formula:
T = F*d

T is the torque
F is the force applied perpendicular (at 90 deg.) to the axis
d is the distance

By using the above formula, we can calculate torque for Geared systems. Lets, take the example of the gear system below:

Here, we have attached a gear system with a pulley. Let us assume the load on the pulley is 1 kg and the diameter of the pulley is 1 inch. Then the torque would be:

T= F* d = 1 kg * 1 inch = 1 kg-inch

Now, what would be the torque on the Big Gear? The torque transferred on the Big Gear would also be 1kg-inch. This is because the torque remains constant on the shaft, and is transferred to the big gear.

The next step is to calculate the force on contact point B. We know the Torque is 1 kg-inch and the diameter of the Big Gear 1 inch. So,

F = T/d = 1 kg-inch * 1 inch = 1 kg

So now lets calculate the torque on the motor. The force on the Small Gear is 1 kg and its diameter is 1/4 inch. The resultant torque on the motor shaft is:

T= F * d = 1 kg * 1/4 inch = 1/4 kg-inch

Did you see the magic happen?
Torque at motor = 1/4 kg - inch
Torque at Pulley = 1 kg- inch!!

Torque increases magically, but only if we put the gear systems right!

At the Right Angle

What is Torque?

Torque is a force that tends to rotate objects. Any rotating body has three parts:

1. Origin of axis: The point around which the body rotates.

2. Distance of arm : The origin and the point at which force is applied

3. Angle of force: The angle between the arm and force applied.

The angle of force is very crucial. Any force directed parallel to the particle’s position vector does not produce torque.

Torque is applied in various parts of the robot:

1. The robot base:

If you require the robot base to move, we need to turn the robot. The torque at the base depends on the force applied by the motor. Force is a function of mass and acceleration. Hence both speed of the motor and weight of the robot matter in the robot base.

2. The robot arm:

The concept of torque is important in a robot arm. Here torque is generally applied on the shaft of the motor. We can increase the torque in the arm using Gear Systems. The application of gear systems is given in another document.

So next time you design a robot, remember to keep the angle right!!