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Dear colleagues,
Dr Hwan-Tak Hee has recently inquired about the use of robots to study knee
kinematics.
I think that the question is worth a wider exchange of opinion on the most
suitable equipment for this purpose and I wuold like to listen other
scientists opinion on the subject.
Let's start with ROBOTS.
In my experience there are fine 6dof (or more) passive or active robots
suitable for studing passive knee or joint kinematics, having a sufficiently
large workspace and enough dof to allow natural motions or specific stress
tests in all directions.
Nevertheless their use is not always easy, because robot's joints provide 6
dof composed and related among them in a different way from the joint, so
that mechanical constraints may produce innatural forces even far from
singularities. For example using a FARO arm (6dof "antropomorphic" passive
robot) for recording manual passive range of motions in norml and
pathological knee specimen is more or less "natural" according to the
robot't type. Type 2-2-2 (2 dof in the wrist, 2 in the elbow, 2 in the
shoulder) produces heavy resistence in most range of motion, while type
3-2-1 is much easier to use, having 3 concurrent dof that probably match
knee main ones.
So probably a first guess on joint kinematics is useful to use/choose a
robot, but the result is very precise, reliable as mechanics can be
nowadays, tests are easily reproducible using active robots (eg Puma560) and
easily extended integrating other sensors. I don't know much about a
possible "in vivo" use, but KT200 is a special robot for laxities
investigations, so that no special problems should arise.
I hope others would add their comment,
Sandra Martelli.
----------------------------------------------------------------------------
ISTITUTI ORTOPEDICI RIZZOLI (II.OO.R)
Lab. Biomeccanica biomec@bo.nettuno.it
via di Barbiano 1/10 fax: (+39).51.583 789
I-40136 Bologna
----------------------------------------------------------------------------
Dr Hwan-Tak Hee has recently inquired about the use of robots to study knee
kinematics.
I think that the question is worth a wider exchange of opinion on the most
suitable equipment for this purpose and I wuold like to listen other
scientists opinion on the subject.
Let's start with ROBOTS.
In my experience there are fine 6dof (or more) passive or active robots
suitable for studing passive knee or joint kinematics, having a sufficiently
large workspace and enough dof to allow natural motions or specific stress
tests in all directions.
Nevertheless their use is not always easy, because robot's joints provide 6
dof composed and related among them in a different way from the joint, so
that mechanical constraints may produce innatural forces even far from
singularities. For example using a FARO arm (6dof "antropomorphic" passive
robot) for recording manual passive range of motions in norml and
pathological knee specimen is more or less "natural" according to the
robot't type. Type 2-2-2 (2 dof in the wrist, 2 in the elbow, 2 in the
shoulder) produces heavy resistence in most range of motion, while type
3-2-1 is much easier to use, having 3 concurrent dof that probably match
knee main ones.
So probably a first guess on joint kinematics is useful to use/choose a
robot, but the result is very precise, reliable as mechanics can be
nowadays, tests are easily reproducible using active robots (eg Puma560) and
easily extended integrating other sensors. I don't know much about a
possible "in vivo" use, but KT200 is a special robot for laxities
investigations, so that no special problems should arise.
I hope others would add their comment,
Sandra Martelli.
----------------------------------------------------------------------------
ISTITUTI ORTOPEDICI RIZZOLI (II.OO.R)
Lab. Biomeccanica biomec@bo.nettuno.it
via di Barbiano 1/10 fax: (+39).51.583 789
I-40136 Bologna
----------------------------------------------------------------------------