Beyond keyframe animations: a controller character-based stepping approach

We present a controllable stepping method for procedurally generating upright biped animations in real-time for three dimensional changing environments without key-frame data. In complex virtual worlds, a character's stepping location can be limited or constrained (e.g., on stepping stones). While it is common in pendulum-based stepping techniques to calculate the foot-placement location to counteract disturbances and maintain a controlled speed while walking (e.g, the capture-point), we specify a foot location based on the terrain constraints and change the leg-length to accomplish the same goal. This allows us to precisely navigate a complex terrain while remaining responsive and robust (e.g., the ability to move the foot to a specific location at a controlled speed and trajectory and handle disruptions). We demonstrate our models ability through various simulation situations, such as, push disturbances, walking on uneven terrain, walking on stepping stones, and walking up and down stairs. The questions we aim to address are: Why do we use the inverted pendulum model? What advantages does it provide? What are its limitations? What are the different types of inverted pendulum model? How do we control the inverted pendulum? and How do we make the inverted pendulum a viable solution for generating 'controlled' character stepping animations?