# Calculate turning angle - 2 wheels car

• alona1
In summary, the conversation is about finding a function for calculating the turning angle of a model car with two engines and two wheels without steering. The suggestion is to measure the radius of the curve using the width of the car and the relative speeds of the two wheels. The conversation also discusses how to measure or control the wheel position or rates using shaft encoders or stepper motors.
alona1
i am looking for a function for calculating the turning angle, using the difference between two wheels speed.

i have a model car , with 2 engines and 2 wheels, without steering.

thanks.

Welcome to PF.
What do you mean by turning angle? Maybe the radius r, of the curve measured from the midpoint of the car to the centre of the arc would be a better measure. If the car has a width w, with half width being h=w/2, then the radii of the two wheel tracks about the centre of the turn will be r–h and r+h. The relative speeds of the two wheels, u and v, will be proportional to the ratio of the radii.
u/v = (r-h) / (r+h) which I think will give you something like r = h * (u+v) / (u-v)
The sign of r should give you the direction of the turn.

Thanks.
I can't measure the radius r while the car is driving. I know the width W between both wheels and can control the velocities of the wheels.
Is there opportunity to know the angle of the curve by these? For example, for turning 30 degrees what velocities will be needed in each wheel?

You do not need to measure the radius. You specify the radius you require, then compute the ratio of the wheel speeds needed to achieve that radius.

If you know the radius you can work out the distance you must travel to change direction by say 30°. Circumference = 2 Pi r,
therefore the distance needed to turn 30° is d = 2 π r * 30 / 360.

Are you programming a boe-bot?

How do you measure or control the wheel position or rates. Shaft encoders, stepper motors?

## 1. How do I calculate the turning angle for a 2 wheels car?

To calculate the turning angle for a 2 wheels car, you need to know the wheelbase of the car (the distance between the front and back wheels) and the radius of the turn. Then, you can use the formula turning angle = arctan(wheelbase/radius) to calculate the turning angle in radians. You can convert the result to degrees by multiplying it by 180/π.

## 2. Can I use the same formula for all 2 wheels cars?

Yes, the formula for calculating turning angle is the same for all 2 wheels cars. However, the wheelbase and radius values may vary depending on the specific car model and the turn being made.

## 3. How can I measure the wheelbase and radius for a 2 wheels car?

The wheelbase can be measured by taking the distance between the front and back wheels of the car. The radius can be measured by finding the distance from the center of the car to the center of the turn.

## 4. Does the weight of the car affect the turning angle?

Yes, the weight of the car can affect the turning angle. A heavier car may have a wider turning angle compared to a lighter car, as it requires more force to turn.

## 5. Can I use this formula for a car with more than 2 wheels?

No, this formula is specifically for 2 wheels cars. Cars with more than 2 wheels have different steering mechanisms and require different calculations for turning angles.

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