ROV Stability Analysis: Calculating Time for System to Settle

Click For Summary
SUMMARY

The discussion focuses on calculating the stability of a remotely operated vehicle (ROV) during its flight by analyzing the dynamics of a damped pendulum system. The key formula presented is I*Theta''(t) + m*g*L*Theta(t) + Gamma*L^2*Theta'(t) = 0, where I represents inertia, m is mass, g is gravitational acceleration, L is the length to the center of flotation, and Gamma is the damping coefficient. The user seeks to determine the time required for the system to settle at theta = 0, given initial conditions, and inquires about calculating the damping coefficient Gamma using drag force data from a SolidWorks model.

PREREQUISITES
  • Understanding of pendulum dynamics and stability analysis
  • Familiarity with damping ratios and their calculations
  • Proficiency in using SolidWorks for modeling and simulation
  • Knowledge of basic physics principles, including torque and angular motion
NEXT STEPS
  • Research methods for calculating damping coefficients in mechanical systems
  • Explore the use of SolidWorks for simulating fluid dynamics and drag forces
  • Learn about the mathematical modeling of damped oscillatory systems
  • Investigate techniques for determining settling time in dynamic systems
USEFUL FOR

Engineers and designers involved in ROV development, mechanical engineers focusing on dynamic stability, and researchers studying oscillatory motion in fluid environments.

andesam
Messages
9
Reaction score
0
Hi.

Im designing an ROV and need to know it will be stabile during "flight".

I am considering the (imaginary) line between the center of flotation, CF, and center of mass, CM, as a pendulum. Where the tourqe around CF = -mgl*sin(theta). Theta being the angle between the pendulum and the direction of g (the ground).

Alsow, the pendulum is dampend. Tourqe = (ohmega^2)*konstant. Ohmega = rad/s, konstant is calculatet using computer CAD software. (Edit: I am not shure if ohmega skould be squared or not here. By definition, the damping ratio is not squared (Ff=-c*v), but for drag force, velocity is squared (Fd=K*v^2).

Now, how can i calculate the time needed for the system to settle (thetha = 0), given a initial angel and angular velocity? Anyting else i should calculate to determine system stability?

- Thanks
 
Last edited:
Engineering news on Phys.org
OK. so i have found a formula which describes a damped pendulum:

I*Theta''(t)+m*g*L*Theta(t)+Gamma*L^2*Theta'(t)=0

Assuming small variations in theta (-10 - 10 degrees) and that damping force is propotional to gamma.
I being the inertia (m*L^2) and Gamma the damping coff.

Now, i am wondering if its possible to determine Gamma. From the solidworks model i can calculate a formula for drag force (with respect to the water velocity), perpendiculary on to the vessle. Is it possible to calculate Gamma from this information?

(Please notify me if you need more information)

- Thanks