hey,
I have a fairly complex PKM that I need to control in forward kinematics (FK). Funnily, FK appears to be way more complex than inverse kinematics (IK) in that situation. Hw can I handle this in CoppeliaSim? From what I read, it is mainly IK that is supoported.
Additionally, I might want to control that machine in FK and IK (not at the same time, but sequentially) later in time. Is that possible? (I can see that by building 2 separate models one could archieve that)
thanks
Forward kinematics for parallel kinematic machine
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kinematicdude
- Posts: 1
- Joined: 19 Jul 2022, 07:30
Re: Forward kinematics for parallel kinematic machine
Hello,
yes, indeed, people usually think that forward kinematics is straightforward, which is not the case for parallel robots for instance. In that case, you can easily use inverse kinematics for each of the robot branche. In order to be able to use forward and inverse kinematics for such a robot, make sure to design your hierarchy tree as an actual tree-structure, where each loop is closed by an IK element. Take a stewart platform: the mobile platform has 6 legs, and when building the model, one of the leg will be the tree base, and the remaining branches, closing back to the floor, will be tree branches using each an IK element and loop closure.
I suggest you have a look at how the model Models/robots/non-mobile/stewart platform.ttm operates: notice that one of the legs is red, the remaining of the 5 legs are blue. The 5 blue legs are loop closure IK elements, and there is actually an additional IK element which is used when in inverse kinematics mode.
Cheers
yes, indeed, people usually think that forward kinematics is straightforward, which is not the case for parallel robots for instance. In that case, you can easily use inverse kinematics for each of the robot branche. In order to be able to use forward and inverse kinematics for such a robot, make sure to design your hierarchy tree as an actual tree-structure, where each loop is closed by an IK element. Take a stewart platform: the mobile platform has 6 legs, and when building the model, one of the leg will be the tree base, and the remaining branches, closing back to the floor, will be tree branches using each an IK element and loop closure.
I suggest you have a look at how the model Models/robots/non-mobile/stewart platform.ttm operates: notice that one of the legs is red, the remaining of the 5 legs are blue. The 5 blue legs are loop closure IK elements, and there is actually an additional IK element which is used when in inverse kinematics mode.
Cheers