Goal-directed, dynamic animation of bipedal locomotion

摘要

Since the advent of three dimensional computer animation, motion control for articulated bodies such as humans has been a central problem.Two recent trends are most promising.One goes toward high-level, goal-directed control, reducing the amount of detail necessary to define a motion; the second trend is to apply dynamic analysis to the motion control process, leading to more realism in movements.In this thesis, a hybrid approach between goal-directed and dynamic control to animate bipedal locomotion is presented.Internal knowledge about the locomotion cycle determines the forces and torques that drive the dynamic model of the legs to produce a natural animation.The KLAW Keyframe-Less Animation of Walking) system can generate a variety of human walks with very little effort, depending on a few specifications, such as desired velocity or step length.JSLAW should be a useful tool for computer animators.Also, since the motion of the legs is based on dynamic simulation, results from KLAW could be helpful in the design and control of walking robots, or in the analysis of human movements in biomechanics and sports.iii To an amazing person "But the creative principle resides in mathematics.In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed." Albert EinsteinDue to the nature of the problem, this research required a considerable amount of experimentation.Progress was characterized by much trial and error; innumerable times I went through the simulationevaluationmodifhioncycle before reasonable results were obtained.I am grateful to all my friends, who were willing to endure me during this period.In particular, I would like to thank my supervisor, Dr. Thomas W. Calvert, for his guidance, support and patience throughout the work on this thesis.I am also indebted to Scott Selbie, who spent many hours introducing me to the theory of analytical dynamics and was helpful in resolving dynamic obstacles thereafter.I sincerely thank Sanjeev Mahajan for his many quick suggestions to geometrical and numerical problems.Finally, I am grateful to Severin Gaudet, whose invaluable advice particularly during the inplementation phase of KLAW is very much appreciated. 113).next page -Top: at heel-strike (frame 120).the body is centered between the legs.Bottom: at mid-stance for the left leg (frame 130), the body is shifted over the left leg. Figure F-7: Illustration of pelvic list in the coronal plane.Top: natural pelvic list at toe-off (frame 106) for the walk shown in figure F-2.Bottom: accentuated pelvic list at toe-off (frame 126) for the walk shown in figure F-3.trying to measure, analyze and represent it.In computer animation, this is often referred to as the DOF problem [Zeltzer 851, which indicates the non-trivial task of coordinating and controlling the limbs of an articulated body to achieve a desired motion out of the vast range of possibilities.In practice, a motion control system should offer some easy, natural means of specifying a motion and then should generate a realistic animation.Most current animation systems show some kind of a 'Throughout this paper, superscripts of capitalized letters are indices to the corresponding Appendix. Proposed WorkThis thesis introduces a control method for locomotion of legged figures, with particular emphasis on humans.The title Goal-Directed, Dynamic Animation of Bipedal Locomotion really indicates the interdisciplinary character of the problem: the application is computer animation, thus the main goal is to calculate a body reference position, orientation and all the joint angles over time.The term goal-directed is borrowed from Artificial Intelligence or Robotics.In this context, it stands for a high-level control, where the system, rather than the user is an expert on each of the various gaitsA of locomotion.The system is told what to do and not how to do it.Goal-directed, as used here, does not address issues like changing directions, path plann