I have prepared a simulator of the mentioned robot in MATLAB software, and during the simulation, I realized that if the mass of the robot is less than 16 kg, the robot becomes unstable. The question is, is the mass of the robot really 11.5 kg, or is there a mistake in providing technical details?

Hi @9914574 , welcome to the forum :slight_smile: [image] mohammad: is the mass of the robot really 11.5 kg, or is there a mistake in providing technical details? Our standard BlueROV2 specifies a weight in air of 11-12 kg with default ballast and our battery. The BlueROV2 Heavy should be a l…

thanks for your reply. In the simulation, the mass of the robot is assumed to be 11.5 kg according to the technical information given on the site. I assumed the body device on the center of the robot’s buoyancy and the center of mass is 2 cm lower than the center of buoyancy. I assumed the moments…

[image] mohammad: I assumed the moments of inertia, added mass coefficients and drag coefficients according to the attached article. That PhD thesis was written in 2018, since which the base BlueROV2 kit has undergone some changes (see the Revision History in the Technical Details), including…

I checked the suggested items and there was no problem. Only one thing caught my attention. I set the added mass parameter for moving along the transverse axis equal to the added mass parameter along the longitudinal axis, the simulation is much better and more logical. Is it possible that the val…

[image] Eliot: I expect this is the most likely cause - have you tried simulating a much simpler system and seeing if it also fails with seemingly reasonable factors? Unfortunately no. Because hydrodynamic coefficients were not available for a simpler submarine system. For this reason, I pre…

[image] mohammad: Is it possible that the values given in the thesis have errors? It’s always possible for things to have errors. In the case of that thesis, I’ve come across it before but am not super familiar with it. I’m not aware of anyone who has validated the coefficients it provides…

Did you find out what was causing the instability in your model? I have set up a Matlab/Simulink simulation using the model from the same thesis. When actuating only the horizontal thrusters to go forward in the x-direction and keeping all the vertical thrusters at zero input, ROV pitches a little b…

The reason for vertical movement is what you mentioned. Because of body coordinate system is placed on center of buoyancy and center of mass is placed below it and also all functions are evaluated in body coordinate system, this movement is predictable and true. In my thesis, I prepared 3D simulat…

If you found a optimized parameter to control correctly, please tell me how to get the parameter. Did you run the BlueROV model in matlab/simulink and conduct parameter tuning?

My thesis was about identification of ROV hydrodynamic coefficients. so no control law is needed and just for movment of robot, thruster coefficient is extracted from figures which is presented in Blue Robotics website.

BlueRov Heavy 2 technical details

Blue Robotics Vehicles BlueROV2 Heavy

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A post was split to a new topic: Deepvision BR-ROV Sonar availability

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