Velocities when generating an Archimedean spiral trajectory

In summary, the conversation discussed the use of velocity commands to generate a spiral trajectory and the velocities (angular and linear) required for this. The article shared by one of the participants provided insights on the Frenet equations and the Archimedes Spiral, which helped explain the relationship between angular and linear velocities. It was concluded that as the spiral gets larger, the linear velocity asymptotically approaches the angular velocity.
  • #1
Benyoucef Rayane
hey, I just want to know, if I am to send a velocity commands to generate a spiral trajectory, What would be these velocities (angular and linear)??
Thanks in advance
 
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  • #4
Since the usual definition of the Archimedes Spiral takes the angle as the input, it means you choose the angular velocity ω. Regarding linear velocity, I don't have an exact formula at hand, but since it gets closer to a circle with increasing angle, the linear velocity will asymptomatically approach ωr.
 
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  • #5
rumborak said:
Since the usual definition of the Archimedes Spiral takes the angle as the input, it means you choose the angular velocity ω. Regarding linear velocity, I don't have an exact formula at hand, but since it gets closer to a circle with increasing angle, the linear velocity will asymptomatically approach ωr.
For the OP @Benyoucef Rayane A google shows the Archimedes spiral has ## r=\theta^a ## with ## a=1 ##. This means ## r=\theta ## for this spiral. We can write the velocity ## \vec{v}=(\frac{dr}{dt}) \hat{a}_r+(r \dot{\theta}) \hat{a}_{\theta} ##. We have for ## r=\theta ##, that ## \frac{dr}{dt}=\dot{\theta}=\omega ##. This gives ## \vec{v}=\omega \hat{a}_r+(r \omega) \hat{a}_{\theta} ##. As ## r ## gets large, ## \vec{v} \approx (r \omega ) \hat{a}_{\theta} ## as @rumborak pointed out.
 
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  • #6
Charles Link said:
For the OP @Benyoucef Rayane A google shows the Archimedes spiral has ## r=\theta^a ## with ## a=1 ##. This means ## r=\theta ## for this spiral. We can write the velocity ## \vec{v}=(\frac{dr}{dt}) \hat{a}_r+(r \dot{\theta}) \hat{a}_{\theta} ##. We have for ## r=\theta ##, that ## \frac{dr}{dt}=\dot{\theta}=\omega ##. This gives ## \vec{v}=\omega \hat{a}_r+(r \omega) \hat{a}_{\theta} ##. As ## r ## gets large, ## \vec{v} \approx (r \omega ) \hat{a}_{\theta} ## as @rumborak pointed out.
Thanks guys, I got it now.
 
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FAQ: Velocities when generating an Archimedean spiral trajectory

1. What is an Archimedean spiral trajectory?

An Archimedean spiral trajectory is a type of spiral motion that follows a mathematical formula created by Greek mathematician Archimedes. It is a curve that starts at a fixed point and constantly increases its distance from that point at a constant rate.

2. How is the velocity calculated when generating an Archimedean spiral trajectory?

The velocity of an Archimedean spiral trajectory is calculated by taking the derivative of the position equation with respect to time. This results in a formula that takes into account the rate of change of both the distance from the fixed point and the angle of rotation.

3. What factors affect the velocity of an Archimedean spiral trajectory?

The velocity of an Archimedean spiral trajectory is affected by the rate of change of both the distance from the fixed point and the angle of rotation. This means that the velocity can be altered by changing the constants in the mathematical formula, such as the distance from the fixed point and the rotation rate.

4. How is the direction of motion determined in an Archimedean spiral trajectory?

The direction of motion in an Archimedean spiral trajectory is determined by the direction of rotation. The curve of the spiral will always move in the direction of rotation, which is typically counter-clockwise. However, this direction can be reversed by changing the sign of the rotation rate in the mathematical formula.

5. Can Archimedean spiral trajectories be used in real-world applications?

Yes, Archimedean spiral trajectories have been used in various real-world applications, such as designing spiral-shaped roads, creating spiral staircases, and even in the motion of galaxies. They can also be used in engineering and robotics to create smooth and efficient movements.

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