How to calculate turns.

Circumference is the distance around a circle once.
Being able to calculate the circumference of a circle or
wheel is the starting point for programming a robot.

Calculate Circumference using on of these these formulas:
Circumference = 2 X Radius X 3.1416
or
Circumference = Diameter X 3.1316


Two Important Dimensions

Wheel diameter and the distance between the wheels must be
known to accurately program the movement of a robot.
The distance between the wheels is also called axle length.
WheelDiameterDistanceBetweenWheelsPic.png

Wheel Circumference
Circumference is the distance around a wheel.
The circumference of the wheels is important because
the distance a wheel travels in one rotation is the wheel's circumference.

In a formula this is:

Distance traveled = Wheel-Circumference X Wheel Rotations
or
Distance = Wheel-Cir X Rots

Use these formulas to calculate the rotations needed
by both wheels to go a specific distance.
Also use these formulas to determine the rotations needed
by one wheel to go a specific turn-distance.

Video and Presentation on How to Calculate Going a Distance

Swing Turn
The outside wheel travels on a circle during a swing turn.
(Video At this link: http://www.education.rec.ri.cmu.edu/content/electronics/boe/robot_motion/images/making%20swing%20turns.webm )
Swing Turn arrows.jpg


Turn Circle Circumference
For two wheels connected by an axle, if one wheel rotates and the other doesn't,
the turning wheel will go in a circle.
This is called the Turn-Circle or T-Circle and is the blue circle shown below.
The distance between the wheels or axle length is the radius of the Turn-Circle.
The circumference of the Turn-Circle can be calculated using the axle length as the radius.
SwingTurn_Robot_Circle.png

To calculate a turn, the distance the wheel must travel on the turn-circle must be determined.
This can be done by putting the turn-angle and turn-circle-circumference into the formula below.
Turn Angle
=
Turn-Distance






360

Turn-Circle







Video and presentation Explanation of Turning
Video and presentation Explanation of How to Calculate a Turn
This link has another short explanation.



Calculate Circumference using these formulas:
Circumference = 2 X Radius X 3.1416
or
Circumference = Diameter X 3.1316

Determine the circumference of the wheel.
Wheel Diameter is 5cm
Wheel Circumference =

Determine the Circumference of the Turn circle.
The axle of the robot is 12.5 cm.
T-Circle Circumference =

How many program degrees are required for a robot to turn 137 degrees?
Step 1 - Determine the Turn-Distance.
Step 2 - Use the Turn-Distance to determine the number of rotations needed for the wheel to go this distance.
Step 3 - Multiple the rotations by 360 if you want to program in degrees instead of rotations.

How many program degrees are required for a robot to turn 274 degree?
Turn 5.png



More problems and practice.