Mechanism simulation with Working Model

Kinematics is a study of motion and force of linkages, gear trains and cams. To many students, visualizing the motion of a mechanism is very challenging. Physical models can be built to illustrate the motion, and modular models using Tinkertoy or Lego are also effective. However, the link lengths of these models are fixed to some extent, and the physical models can not represent many problems closely. Many software packages are available for linkage animation and analysis. Nevertheless few can easily promote an active learning environment analysis and motion simulation software on PC. A user can sketch a problem using a variety of simple geometric primitives. The user can then sketch additional constraints (joints, springs, and dampers) and actuators (cylinders and motors). With a click of the mouse, WM uses its simulation engine to put the model in motion. WM applies Newton's law along with physical constraints and external forces to calculate the internal forces and acceleration of each rigid body. Using numerical integration, the velocity and position of each body can be calculated. Since no closed form formula is used in WM for the animation, students can use WM to verify answers obtained from using loop closure equations. For a complex control problem, WM can establish real-time links with Excel, MATLAB, or other programs that support Windows DDE to carry out calculations.