How do I calculate required torque for two dc motors?

In summary, the conversation discusses the equations needed to calculate the torque for a handicapped golf vehicle powered by two motors. These equations include rolling resistance, grade resistance, and acceleration force, which are then used in the main torque equation. The question is whether these equations are correct or if more complicated ones, such as taking into account rotational inertia, should be used. The expert confirms that the equations provided are correct and explains how to incorporate rotational inertia if needed.
  • #1
Kaylin
2
0
Hi,
I am doing a design project but I'm kinda stuck with choosing motors because i am not sure of the required torque. My project is a handicapped golf vehicle powered by 2 motors, so it would need to be able of climbing steep gradients.
I currently have an equation but I am not entirely sure if it's right.
It consist of :
1. Rolling resistance = (Gross Vehicle Mass) X (Co-efficient of Rolling Resistance)
2. Grade resistance = (Gross Vehicle Mass) X ( Sin(angle of max gradient) )
3. Acceleration force = (Gross Vehicle Mass/Gravity) X Acceleration
Adding all 3 up to give you Total Tractive Effort.

That's then used in the equation
Torque = (Friction factor for bearings and axles, etc.) X (Total Tractive Effort) X (Radius of drive wheel)

My question is, are these equations right or do I need to use more complicated equations dealing with moment of inertia, etc.

Thank you!
 
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  • #2
These are the right equations to use.

To take into account the rotational inertia, you only need to add a mass factor to the third equation. More info on this page.
 
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  • #3
Kaylin said:
3. Acceleration force = (Gross Vehicle Mass/Gravity) X Acceleration

I think that should be..
Acceleration force = Gross Vehicle Mass X Acceleration
 
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  • #4
jack action said:
These are the right equations to use.

To take into account the rotational inertia, you only need to add a mass factor to the third equation. More info on this page.
Sorry for the late reply; but thank you.
 

1. What is torque and why is it important when calculating for two DC motors?

Torque is a measure of the force that causes an object to rotate around an axis. It is important when calculating for two DC motors because it determines the amount of rotational force that each motor needs to produce in order to achieve a desired movement.

2. How do I determine the required torque for a single DC motor?

The required torque for a single DC motor can be calculated by dividing the desired angular acceleration (in radians per second squared) by the inertia of the load being moved. This will give you the required torque in Newton-meters (Nm).

3. What factors should be considered when calculating for two DC motors?

When calculating for two DC motors, factors that should be considered include the desired speed and direction of movement, the weight and inertia of the load, the efficiency of the motors, and any external forces acting on the system.

4. Is there a specific formula for calculating required torque for two DC motors?

Yes, the formula for calculating required torque for two DC motors is: T = (J * α) / η, where T is the torque (in Nm), J is the inertia of the load (in kgm²), α is the desired angular acceleration (in rad/s²), and η is the efficiency of the motors (usually expressed as a decimal value).

5. Are there any online tools or calculators available for calculating required torque for two DC motors?

Yes, there are many online tools and calculators available for calculating required torque for two DC motors. Some popular options include the Motion Control Engineering's torque calculator, the Oriental Motor torque calculator, and the Kollmorgen torque calculator. However, it is always recommended to double check the results and calculations with a professional engineer.

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