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artofnothingness / mppic

MIT License
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Motion model have no implementation? #108

Closed vincentcheng62 closed 1 year ago

vincentcheng62 commented 1 year ago

I am current using a 4-wheel differential drive AMR and trying to config the parameters for motion model like wheel_base However when I look into the source code it seems there is no way to input such kinds of parameters and the implementation in motion_models.hpp seems empty for class DiffDriveMotionModel

Any help on this? Many thanks!

SteveMacenski commented 1 year ago

This is a trajectory planner, not a low-level controller where we need that kind of information

vincentcheng62 commented 1 year ago

But MPC need to know the kinematic model (like 4-wheel differential, tricycle...) in order to predict the trajectory, that is why MPC is Model Predictive controller. Am I correct?

SteveMacenski commented 1 year ago

The kinematic model is handled other ways through velocity limits and constraints. We don't need to know lower-level characteristics of the platform, we merely need to know what available actions the base can take in the base reference frame about its point of rotation. This is how we handle ackermann, omni, and differential dynamics and is pretty standard for trajectory planners. I'd recommend looking more into this topic.