Sizing DC Motors for a Two-Wheeled Balancing Device

In summary, the conversation discusses the process of building a two-wheeled balancing device similar to a Segway. The main concern is determining the appropriate size motors, taking into consideration torque and rotational speed. The desired rotational speed can be calculated using a desired speed and wheel size. However, determining torque requirements is more complex. Two motors are being compared, with the more expensive one having a higher torque. Other differences between the two motors include size and maximum power output.
  • #1
uglyoldbob
5
0
I recently started doing research to build one of these (popular?) two-wheeled balancing things. (A segway clone)
I don't know how to calculate the proper size motors (a pair of motors) for this. I know you have to consider the torque and rotational speed required to size the motor.

Desired rotational speed is easy, I just take a desired speed and a wheel size and figure out how fast it needs to rotate to reach that speed.

I'm not sure how to calculate torque requirements.
 
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  • #2
Here are some motors I am comparing. The difference here is price (and obviously additional hardware on the more expensive one)

There is the CIM motor, according to the specs:
http://www2.usfirst.org/2005comp/Specs/CIM.pdf
Torque, speed, current, power, efficiency
0, 5310, 2.7, 0, 0 (free)
64, 4320, 27, 205, 63 (normal)
45, 4614, 19.8, 154, 65 (max efficiency)
171.7, 2655, 67.9, 337, 41 (max power)
343.4, 0, 133.0, 0, 0 (stall)

Here is a midwestMotion products motor: (it is the expensive one)
http://www.midwestmotion.com/products/brushed/12VOLT/12%20VOLT,%20250-324%20RPM%20GEARMOTORS/12%20VOLT,%2040-149%20IN-LBS/ENCODER%20-%20BRAKE%20COMPATIBLE/MMP%20S28-150E4-12V%20GP81-014%20TECH%20SPECS.pdf
Torque, speed, current, power, efficiency
0, 4140, 1.7, 0, 0 (no load)
110, 3640, 28.2, 296, N/A (rated continuous)

The more expensive motor has more torque from what I read on the datasheets. It is 3.2" diameter vs 2.5" on the CIM motor. What other big differences am I missing here (I put up links to the spec sheets of each motor)?
 
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Related to Sizing DC Motors for a Two-Wheeled Balancing Device

1. How do you determine the appropriate size of a DC motor for a two-wheeled balancing device?

The size of a DC motor for a two-wheeled balancing device is determined by several factors, including the weight of the device, the desired speed and torque, and the efficiency of the motor. A general rule of thumb is to select a motor with a torque rating at least three times the weight of the device, and a speed rating at least twice the desired speed.

2. What is the importance of balancing the weight of the two-wheeled balancing device and the DC motor?

Balancing the weight of the device and the motor is crucial for the stability and maneuverability of the two-wheeled balancing device. If one side is significantly heavier than the other, it can cause the device to tilt and lose balance, making it difficult to control.

3. How does the voltage and current of the DC motor affect its size for a two-wheeled balancing device?

The voltage and current of a DC motor are directly related to its power output. Higher voltage and current ratings can result in a more powerful motor, allowing for a larger and heavier two-wheeled balancing device. However, it is important to consider the limits of the motor and ensure it can handle the voltage and current without overheating or causing damage.

4. Is it better to use a brushed or brushless DC motor for a two-wheeled balancing device?

Both brushed and brushless DC motors have their advantages and disadvantages. Brushed motors are typically less expensive and easier to control, but they require more maintenance and have a shorter lifespan. Brushless motors are more efficient and have a longer lifespan, but they are more expensive and require more complex control systems. Ultimately, the choice will depend on the specific needs and requirements of the two-wheeled balancing device.

5. How important is it to have a feedback control system when using a DC motor for a two-wheeled balancing device?

A feedback control system is crucial for maintaining the balance of a two-wheeled device. It provides real-time data on the device's position and velocity, which can be used to adjust the motor's speed and direction to keep the device upright. Without a feedback control system, the device would be much more difficult to control and could easily tip over.

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