Documentation: No road grade angles in model equations

2 views (last 30 days)
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

Sign in to comment.

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
Ryan Chladny
Ryan Chladny on 2 Mar 2020
Edited: Ryan Chladny on 2 Mar 2020
Hi Jiri,
Presently the block does not support the direct application of a grade (which could be interpreted as a form of pitch constraint).
Keep in mind, unlike the other vehicle block equations of motion, the 6DOF block pitch or roll are not constrained and it does not have any notion of where the road surface(s) are located. Rather, the user will typically use the 6DOF block in conjunction with wheel and suspension elements which are in contact with a road while being subjected to a gravitational load.
Hope this helps,
Ryan
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

Sign in to comment.

More Answers (0)

Categories

Find more on Aerospace Applications in Help Center and File Exchange

Products


Release

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!