Multibody Dynamics Simulation




Concurrent Dynamics creates high fidelity Multibody Dynamics Simulation programs to assess dynamics and control performances of mechanisms and robotics. They expedite:

  • Concept Feasibility Evaluation

  • Control System Design and Testing

  • Hardware-in-the-Loop Simulation

  • System Failure Analysis, etc..

NASA-JPL-Robosimian-robot (courtesy: NASA)

We now have ready-to-use simulation packages for a variety of mechanisms. Three packages are shown below and more on the space vehicle page and in the works. Models in these packages are jus as accurate as those generated by symbolic manipulator programs based on physics principles. They run significantly faster than programs built by leading commercial codes. Moreover, they can be modified easily to fit user's immediate needs.

Our simulations run on PC's with Window XP and Window 7/8 OS equipped with Matlab/Simulink. Their core engines connect easily with user defined control systems. In short, they:

  • Generate minimal state multibody dynamics equations for each vehicle or mechanism being simulated 

  • Solve the dynamics equations efficiently (by order(N) method) so you can concentrate on the design and testing of control systems

  • Permit easy model/ control system parameter modifications to achieve simulation goals quickly

The manual in each package has two parts. The first part explains how to define a model_file using the tool, buildx.exe. This definition encompass mechanism connectivity, mass property of bodies and wheels, force objects, gravity model selection and dynamics input/output/plot data list. The second part shows how to build a nominal control system for the mechanism represented by the model_file. It then uses that control system to perform a control task or a number of tasks. The result is a simulation program in the form of an mdl file that runs in Simulink. Examples are presented for illustration.

Our packages are excellent tools for engineers engaged in control system design and testing. They are geared for scientific and realtime simulations. Their model fidelity and ease-of-use eliminate, for practical purposes, the cost of formulating, programming, GUI design, testing and validating simulation programs. They are most valuable to projects that encounter frequent model/control system changes or need major model rebuild. These tools are also ideal for university courses that  teach multibody dynamics and control systems, robotics or mechatronics. Students use them to test and verify the dynamics and control algorithms generated to solve problems at hand. 

We invite you to get a free Project license for a package below by sending your request to Click 'manual' below to see how the model is created using the model editor, buildx.exe, and how the mdl file is designed for that application and more. We welcome suggestions on the mechanism/robotics simulations that you would like to have.

Arm6x : This simulation is about a ground fixed 6 joint robotic arm with a nominal position control system. It shows an algorithm to move the arm from one configuration to another. manual 

OneCylinderEngine: Combustion force profile and crank/piston friction forces determine engine performance. The simulations run under two-stroke and four-stroke modes. manual 

Inv_Pendulum : The simulation is about a cart carrying an inverted pendulm. The package shows how the pendulum is held upright while moving the cart to a commanded position. manual 


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Interesting Websites:

  1. Multibody System Dynamics- Research Activities ( )
  2. Space flight news ( )
  3. Review of multibody dynamics software ( )
  4. Aerospace news (
  5. Robotics news (
  6. Robots news 1 (
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Last modified: April 23, 2014