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1/9/15 -- Our second release -- NTRT V1.1 -- just went live! See below!

6/9/14 -- We have just released our first "Stable" beta release! See below!

NASA Tensegrity Robotics Toolkit (NTRT)

The NASA Tensegrity Robotics Toolkit (NTRT) is a collection of C++ and MATLAB software modules for the modeling, simulation, and control of Tensegrity Robots. Tensegrity Robots are a biologically inspired approach to building robots based on the tension networks of tensegrity structures, which have no rigid connections between elements. The NTRT was created to enable: the rapid co-exploration of structures and controls in a physics based simulation environment; the development of tensegrity robotics algorithms such as structural analysis, kinematics, and motion planning; and the validation of the algorithms and controls on hardware prototypes of the tensegrity robots.

NTRT is an evolving collection of loosely connected open-source modules designed by the NASA Ames Intelligent Robotics Group. Modules of the NTRT will be released one at a time as they reach maturity. The first module to be released is the NTRT Simulator Core, which is the core library for doing physics based simulations of Tensegrity Robots, and will be described in further detail below.

Stable releases of the software modules of NTRT will be provided below, and the source code for all NTRT modules is available on Github.


The NTRT Simulator is a tensegrity-specific simulator built to run ontop of the Bullet Physics Engine, version 2.82. The NTRTsim includes a set of builder tools for specifying rods and strings as a set of points in Cartesian coordinates. Structures built out of these rods and strings can be specified as a tree of substructures, and can be rotated and moved, which greatly simplifies the task of creating new tensegrity structures. The NTRTsim also includes libraries for controllers such as Central Pattern Generators and a machine learning framework, which allows users to specify their own learning algorithms. For strings, instead of the default Bullet softbodies, which are not physically accurate, we used a two point linear string model using Hooke's law forces with a linear damping term. Finally, terrains can be created, and the performance of the controller can be tested as the tensegrity robot moves through the simulated world.

Downloading and Installation

  • NTRTsim v1.1 and Doxygen Documentation for v1.1
  • NTRTsim v1.0.0-beta and Doxygen Documentation for v1.0.0-beta

  • To obtain the most recent source code, please visit the NTRTsim repository on github.

    We have recently submitted a journal paper on our tensegrity robotics research. Below we have included a link to an early archival version of the NTRTsim which contains the experiments reported on in that paper. This version should only be used by those wishing to recreate the results as published as this early version of the simulator is poorly documented and we cannot provide support for it.

  • NTRTsim v0.1 (pre-beta archival) and ReCTeR
  • Documentation

    The software has been written to support Doxygen documentation, and as discussed in the INSTALL instructions, you can build that documentation by running doxygen on the doxyfile in the src dir if you want to get the most recent documentation for your current source files.

    Otherwise, we are now building the documentation on every successful commit which passes through our continuous integration server. Thus, you can see Current Doxygen documentation and tutorials here, built straight from the head of the github repository

    Mailing List

    All bugs, feature requests, and general discussion regarding NTRT should be sent to the NTRT user mailing list:

    ntrtusers [at] lists [dot] nasa [dot] gov

    To subscribe to this list, send an empty email message with the subject 'subscribe' (without the quotes) to

    ntrtusers-request [at] lists [dot] nasa [dot] gov

    or visit the list subscription page.

    To contact the lead developers and project manager directly, send mail to:

    ntrtusers-owner [at] lists [dot] nasa [dot] gov

    Contributing to NTRT

    Please contact ntrtdev-owner [at] lists [dot] nasa [dot] gov if you wish to contribute to the NASA Tensegrity Robotics Toolkit and be added to the Github developers team. NTRT is Apache 2 licensed. Due to NASA policy, all contributors will also need to complete a Individual Contributor License Agreement (CLA) and send it to the address specified on the form. Organizations that would like to support this work can also get broad agreement for employees to contribute by completing the Corporate Contributor License Agreement. Please send any questions to ntrtdev-owner [at] lists [dot] nasa [dot] gov.


    We have published a number of research papers on Tensegrity Robots, many of which used earlier versions of this simulator. Especially the more recent papers will give interesting insight into how to use the simulator. Not all models and features of prior research have made it into the current release -- we are trying to release stable code, and will migrate more features into the repository as time allows.

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