Design and Analysis of a Variable Inertia Spatial Robotic Tail for Dynamic Stabilization

Area of Science:

• Robotics
• Control Systems
• Mechanical Engineering

Background:

• Bipedal robots require dynamic stabilization for locomotion.
• Robotic tails can augment balance control.
• Existing tail designs may lack adaptability for complex maneuvers.

Purpose of the Study:

• To design and validate a four degree-of-freedom (DoF) spatial robotic tail.
• To demonstrate the tail's effectiveness in dynamic stabilization of a bipedal robot.
• To investigate the impact of a prismatic joint on tail-generated reactive moments.

Main Methods:

• Design of a 4-DoF tail with three revolute and one prismatic joint.
• Hardware-in-loop simulation for dynamic stabilization testing.
• Real-time experimental validation of the tail's mathematical model and dynamics using a 6-axis load cell.
• Development of a Zero Moment Point (ZMP) placement-based trajectory planner and model-based controller.

Main Results:

• Experimental results validated the derived mathematical model for tail dynamics.
• The 4-DoF tail prototype successfully stabilized a simulated unstable biped robot.
• Prismatic motion in the tail improved reactive moments for stabilization during complex trajectories.
• The ZMP-based planner and controller reduced system kinetic energy by maintaining ZMP within the support polygon.

Conclusions:

• The proposed 4-DoF robotic tail, particularly with its prismatic joint, offers enhanced dynamic stabilization capabilities for bipedal robots.
• The integrated motion planner and controller effectively manage instability by controlling the Zero Moment Point.
• The study validates the design and control strategy through both simulation and experimental data.