Critical Mass

Similar to Havok, Critical Mass Labs (http://www.cm-labs.com) produce a commercial tool called Vortex available for IRIX, Linux and Windows operating systems. Vortex also sports an impressive feature list of which the highlights are:

• Collision detection
• Fast, stable integrator for constrained or articulated rigid bodies
• Multiple joint types
• Multiple actuation models and constraints
• Motors and actuated joints
• Full control over springs, including rest length, deformation and restitution
• Wheel traction systems for stable and accurate vehicle dynamics
• Vehicle suspension models
• Mass properties such as friction, inertia, torque, rotation
• Multiple friction models