Documentation: No road grade angles in model equations

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Hello,
I was going through the documentation of blocks Vehicle body 6DOF, Vehicle body 3DOF and Vehicle body 3DOF Longitudional and all three seem to miss the road grade angles in their equations. Moreover, the blocks Vehicle body 6DOF and Vehicle body 3DOF do not have any input for road grade angle or road incline even though the Vehicle body 6DOF block has defined road grade angle in variables.
Did someone encounter this? Do you know where I can find the equations?
Is it possible to get the road incline inside the Vehicle body 6DOF and Vehicle body 3DOF blocks?
Any help is appreciated. Thank you.
  1 Comment
Jiri Minarik
Jiri Minarik on 6 Apr 2020
I will add here what I used for those who would have similiar problem.
As @Ryan Chladny suggested, you can took whole subsystem of vehicle body + suspension + wheels and then specify road grade angle as ground difference between wheels in Combined Slip Wheel blocks inputs.
You can do that by taking "sin(road grade angle)*distance_of_rear_wheels_from_front_wheels" as distance input for front wheels and for rear wheels take simply 0.
Regards and thanks to @Ryan Chladny and @Chris Erkkinen,
Jiří Minarik

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Accepted Answer

Chris Erkkinen
Chris Erkkinen on 26 Feb 2020
Edited: Chris Erkkinen on 26 Feb 2020
Hi Jiri - Thank you for your careful review of the documentation! I'm the technical writer for the Powertrain Blockset and Vehicle Dynamics Blockset documentation.
Looks like you're using the Vehicle Dynamics Blockset.
Hope this response helps:
Vehicle body 3DOF - Block models longitudinal, lateral, and yaw motion. As of now, the block does not include considerations for road incline and/or bank angles. We could incorporate the incline and bank angles in the future, but we need to work with users to decide how to specify them. For example, should the block model instantaneous loads or a global road profile? The distinction is important as we'd need to account for the reaction loads while the vehicle is traversing up the side of a hill at a lateral angle and could potentially roll over.
Vehicle body 6DOF - Block models translational (3DOF) and rotational (3DOF) motion. The block implicity accounts for road incline via the gravity vector. I will take the 'road grade angle' entry out of the variable list in the documentation; I can see why that might be confusing.
Vehicle body 3DOF Longitudinal - Block does account for road incline. I will consider enhancing the documentation to include the specific road incline equations.
Thank you!
Chris Erkkinen
  4 Comments
Jiri Minarik
Jiri Minarik on 6 Apr 2020
Hey,
even though, it's very late response. I will add what I used for those who would have similiar problem.
As @Ryan Chladny suggested, you can took whole subsystem of vehicle body + suspension + wheels and then specify road grade angle as ground difference between wheels in Combined Slip Wheel blocks inputs.
You can do that by taking "sin(road grade angle)*distance_of_rear_wheels_from_front_wheels" as distance input for front wheels and for rear wheels take simply 0.
Regards and thanks to @Ryan Chladny and @Chris Erkkinen,
Jiří Minarik

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