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Modeling and Control of One-legged Somersaulting Robot

Zabihi, Mehdi | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50152 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Alasty, Aria
  7. Abstract:
  8. Inspired by the agility of animal and human locomotion, the number of researchers studying and developing legged robots has been increasing at a rapid rate over the last few decades. In comparison to multi-legged robots, single-legged robots only have one type of locomotion gait, i.e., hopping, which represents a highly nonlinear dynamical behavior consisting of alternating flight and stance phases. Hopping motion should be dynamically stabilized and therefore, presents challenging control problems. A large fraction of studies on legged robots have focused on modeling and control of single-legged hopping machines. In this research, somersaulting is introduced as a kind of hopping motion for single-legged robots. In somersaulting motion, single-legged robots are able to jump with both their springy legs, located at both sides of the robots’ body in contrast with hopping robots which only have one springy leg to jump. Somersaulting motion helps robots have longer step length and lower energy consumption to pass obstacles in comparison with hopping motion. In this research, at first, a one-legged somersaulting robot is introduced that has two linear actuators and one rotary actuator. In the stance phase, the point foot is modeled as a revolute joint. Fuzzy controller is applied to achieve a double limit cycle in robot’s motion. The next robot is made by eliminating linear actuators of the first robot and applying linear controllers for its rotary actuator that cause the robot to achieve different limit cycles with different horizontal velocities. This provides velocity control for the robot. By considering slipping motion at the stance phase, the modeling of the robot is improved. Similar to the second robot, for achieving different limit cycles, linear controllers for the rotary actuator are applied. Poincare map is used to analyze the stability of limit cycles in these three robots. Since the work done on the reaction wheels is not zero, the rotary actuator becomes saturated after finite cycles. To avoid this problem, the one-legged somersaulting robot with two links is introduced. Each link acts as a rotary actuator for another link. This robot achieves a stable quasi periodic behavior by using a linear controller for the rotary actuator at the stance phase
  9. Keywords:
  10. Poincare Map ; Locomotion Control ; Hybrid System ; One-Legged Somersaulting Robot ; One-Legged Robot Modeling ; Limit Cycles Stability

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