Force Limited Velocity Constraints: what are they??
Posted: Wed Oct 17, 2007 12:09 am
hi,
I came across this term in the paper "Facilitating Controller Evolution in Morpho-functional-Machines -- A Bipedal Case Study" (by Torsten Reil/NaturalMotion). In the paper they claim that Force Limited Velocity Constraints can be used as a replacement for PID controllers, and that the former are more robust than the latter as well as being able to cope with different loads (while typically you need different sets of PID constants, or procedural adjustment of the constants, to get good behaviour across a range of loads).
Sadly the paper doesn't explain at all what FLVCs are, or how they're modeled, and doesn't provide any references! They were using MathEngine, and the only hits google was able to find are from KarmaUserGuide.pdf -- in the glossary entry for "Constraint", it says that an inequality condition could be used "to impose motion in a joint by applying a
force limited velocity constraint which is used to model a motor". This isn't helpful.
Basically I'm curious about this because we're currently using PD controllers to set motor velocities, and it's been difficult to get good behaviour (stable without oscillations) across a wide range of situations/loads. Does anyone have any ideas about what sort of practice/technique/idea they're referring to? It seems like the terminology FLVC is MathEngine-specific.
thanks,
raigan
I came across this term in the paper "Facilitating Controller Evolution in Morpho-functional-Machines -- A Bipedal Case Study" (by Torsten Reil/NaturalMotion). In the paper they claim that Force Limited Velocity Constraints can be used as a replacement for PID controllers, and that the former are more robust than the latter as well as being able to cope with different loads (while typically you need different sets of PID constants, or procedural adjustment of the constants, to get good behaviour across a range of loads).
Sadly the paper doesn't explain at all what FLVCs are, or how they're modeled, and doesn't provide any references! They were using MathEngine, and the only hits google was able to find are from KarmaUserGuide.pdf -- in the glossary entry for "Constraint", it says that an inequality condition could be used "to impose motion in a joint by applying a
force limited velocity constraint which is used to model a motor". This isn't helpful.
Basically I'm curious about this because we're currently using PD controllers to set motor velocities, and it's been difficult to get good behaviour (stable without oscillations) across a wide range of situations/loads. Does anyone have any ideas about what sort of practice/technique/idea they're referring to? It seems like the terminology FLVC is MathEngine-specific.
thanks,
raigan