Improve interface for forward kinematics

[jslee02]

• Rename functions pertain to generalized coordinate
• Add setters for configurations, generalized velocities, and generalized accelerations to Skeleton and Joint

Here are some examples with improved API:

// We are able to set configurations, generalized velocity, and generalized acceleration to skeleton as
skeleton->setConfigs(q, false, false, false);  // Just store q to skeleton
skeleton->setConfigs(q, true, false, false);  // and also update transformations of body nodes
skeleton->setConfigs(q, true, true, false);  // and also update spacial velocities of body nodes
skeleton->setConfigs(q, true, true, true);  // and also update spacial accelerations of body nodes
skeleton->setGenVels(dq, true, false);  // Store generalized velocity and update spacial velocities of body nodes
skeleton->setGenAccs(dq, true);  // Store generalized acceleration, and update spacial accelerations and accelerations

// We are also able to set the values directly to the joints as
skeleton->getJoint("left_hip")->setConfigs(q, true, false, false);
skeleton->getJoint("left_hip")->setGenVels(dq, true, false);
skeleton->getJoint("left_hip")->setGenAccs(ddq, true);

// If you want to update the spacial values at once then
skeleton->setConfigs(q, false, false, false);
skeleton->setGenVels(dq, false, false);
skeleton->setGenAccs(ddq, false);
skeleton->computeForwardKinematics(true, true, true);

// If you want more simple way not considering performance, then you can just ignore all the Boolean flags as
skeleton->setConfigs(q);  // All the spacial values are updated as default
skeleton->getJoint("left_knee")->setConfigs(q);  // All the spacial values are updated as default

[karenliu]

How do you update spatial velocity if I give you a new position for a the joint? Do you compute the finite difference between the new and old joint positions?

[jslee02]

Joints contain position, velocity, and other generalized values inside them. If new joint position is set then spatial velocity is updated using the new position and the inside velocity.

On Mar 21, 2014, at 8:27 AM, Karen Liu notifications@github.com wrote:

How do you update spatial velocity if I give you a new position for a the joint? Do you compute the finite difference between the new and old joint positions?

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