Heading as a function of wheel rotations

In summary, the speaker has three robots with two motorized wheels and a skid wheel and is trying to calculate the change in heading based on the previous state. They have derived a formula but are unsure if it takes into account the axis of rotation changing depending on the angular velocity of each wheel. However, they have been reassured that this effect cancels out and the derived formula is still accurate. They are asking for further guidance on the matter.
  • #1
fishingspree2
139
0
Hello, I have a three robots which consists of two motorized wheels and a skid wheel. The two motorized wheels are on the front of the robot. I am trying to find the change in heading of the robot based on the previous state.

I have found out that ΔHeading = [(ΔDL-ΔDR)*radius of wheels]/wheelbase. where ΔD is the difference in wheel rotations between ti and ti-1. I have a feeling that this is not correct, since the axis of rotation changes depending on the angular velocity of each wheel. For example, if one of the wheels is at rest while the other rotates, then the axis of rotation of the robot is the wheel at rest. If the two wheels are rotating in opposite direction, then the axis of rotation of the robot is halfway between the two wheels. The formula I have derived does not take this into account.

Can anyone point me in the right direction?
Thank you
 
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  • #2
fishingspree2 said:
Can anyone point me in the right direction?
The effect you are concerned about is not a problem because it actually cancels.

When the radius of the turn is in the midway between the wheels, one wheel moves forward half the distance, while the other moves backwards half the distance. The difference is still the true heading.
 

Related to Heading as a function of wheel rotations

1. What is heading as a function of wheel rotations?

Heading as a function of wheel rotations is a concept used in navigation and robotics to determine the direction of movement based on the number of rotations of a wheel or set of wheels. It is often used in conjunction with other sensors, such as a compass or GPS, to accurately track the movement of a vehicle or robot.

2. How is heading calculated from wheel rotations?

Heading is typically calculated using the number of wheel rotations and the diameter of the wheel. By measuring the distance traveled using the number of rotations and knowing the circumference of the wheel, the change in direction can be calculated.

3. What factors can affect the accuracy of heading as a function of wheel rotations?

Several factors can affect the accuracy of heading as a function of wheel rotations, including wheel slippage, uneven terrain, and wheel calibration errors. Additionally, external factors such as magnetic interference or GPS signal loss can also impact the accuracy of the heading calculation.

4. How is heading as a function of wheel rotations used in robotics?

In robotics, heading as a function of wheel rotations is commonly used to track the movement and position of a robot. By continuously measuring the number of rotations of the wheels, the robot can determine its current heading and make adjustments to its movement to reach a desired destination.

5. Are there any limitations to using heading as a function of wheel rotations?

While heading as a function of wheel rotations is a useful tool for navigation and robotics, it does have some limitations. As mentioned before, external factors such as terrain and sensor errors can affect the accuracy. Additionally, this method is most accurate when used on flat and even surfaces, so it may not be suitable for more complex environments.

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