Inchworm: Dynamics in Segmented Creatures
Rama Hoetzlein, Media Arts & Technology Program, UCSB


Inchy is a simulation of the muscles and dynamics of articulated, segmented creatures. This inchworm creature attempts to maintain dynamic "target" poses, accomplished by simulated muscle forces to change or maintain joint angles and keep the creature upright. Unlike kinematics, which determines joint angles using user-controlled or scripted motions, dynamics simulates the actual forces in the muscles of moving bodies. The poses in this simulation are dynamic poses which specify target joint angles over time. Time-based sinusoids represent the goal state of each pose. The creature attempts to maintain the pose by applying torque and torsional forces to joints, simulating muscles. The creature can inch forward in both directions, or attempt to maintain an arch pose. Increasing or decreasing gravity, friction or muscle strength causes the creature to move more or less easily.

Three torque forces are applied to each joint (red, green, blue), which collectively maintain the joint angle (phi). An additional torsion force (yellow) attempts to keep the creature up-right by attempting to rotate the joint into the body plane.