Re: Opinions on Haptic Feedback Devices with NAMD/VMD

From: Axel Kohlmeyer (
Date: Fri Mar 25 2016 - 08:52:33 CDT

On Fri, Mar 25, 2016 at 9:37 AM, Ben Fritch <> wrote:

> Hi,
> I am looking into purchasing a haptic feedback device to use with NAMD
> simulations. These simulations will involve pulling on different proteins
> under various conditions and will be similar to the tutorial, "Stretching
> Deca-Alanine". I know the NAMD tutorial on interactive molecular dynamics
> suggests the Sensable PHANTOM device, but I am curious to hear the
> opinions and recommendations from those who have experience with a
> particular haptic feedback device using NAMD/VMD.

​hi ben,

i would worry less about specific hardware, but rather about software and
driver support. as far as hardware is concerned, the very nature of the
time and length scales involved make it that you are more limited by the
physics of the problem and way how you link length and time scales (e.g.
would you expect that the mass of your hand and the inertia caused by it,
has a major impact on what you can or cannot do well with a haptic device
during interactive MD?). by that token, even rather simple devices with 3
degrees of freedom suffice (which is all that IMD currently supports
anyway)​. some more discussion on such issues are in this paper:

the software side is more problematic. i don't think if john has yet
managed to update the VRPN client in VMD. if not, you would need to compile
your own VMD binary to have a VRPN client compatible with the current VRPN
server software. then you need to have suitable support for your device in
VRPN itself. it supports a wide variety of devices, but not all are fully
up-to-date with current library versions. and for some devices support is
lacking. for example, when i received a couple of Falcon devices from (now
defunct) Novint for IMD experiments, i had to write the interface myself,
and ran into a few quirks with the USB interface of the low-level library.
however, after that was solved, we used them with great effect in outreach


> Thanks,
> Ben

Dr. Axel Kohlmeyer
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.

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