In the realm of quadrupedal locomotion, there's a growing interest in understanding the concept of passive leg stiffness. This stiffness, when tuned correctly, can significantly influence a robot's locomotion dynamics and performance. However, integrating passive stiffness into quadruped robots has been challenging due to complexities in design, tuning, and control.
Traditionally, many quadruped robots have relied solely on active control mechanisms, overlooking the potential benefits of passive compliance. While active control offers precision, it also adds to the system's complexity and cost. In contrast, passive compliance, especially through mechanisms like physical springs, can enhance stability, efficiency, and resilience while reducing power consumption and complexity.
Researchers at Arizona State University have developed a quadruped robot with tunable, passive leg stiffness aimed at changing the study and application of quadrupedal locomotion. The robot features compliant laminate legs designed with origami-inspired approaches, allowing for easy tuning of both series and parallel compliance. Each leg could comprise a four-bar linkage mechanism for extension and retraction, laminate springs for providing compliance, and actuation modules powered by servo motors.
By strategically designing the robot's legs and leveraging origami-inspired fabrication techniques, the researchers have simplified the integration of passive compliance into the robot's structure. This approach not only reduces fabrication time and material costs but also enhances accessibility for researchers both within and outside the robotics field.
Researchers have developed a prototype robot that is 400g (i.e., a footprint similar to an adult hand) and driven by tunable compliant laminate legs, whose series and parallel stiffness can be easily adjusted. The fabrication took 2.5 hours for all four legs. The robot can trot at 0.52m/s or 4.4 body lengths per second with a 3.2 cost of transport.
Related publications:
Direct Encoding of Tunable Stiffness Into an Origami-Inspired Jumping Robot Leg
Development of A Dynamic Quadruped with Tunable, Compliant Legs
Related video: Direct Encoding of Tunable Stiffness into an Origami-inspired Jumping Robot Leg
Potential Applications:
- Agricultural Robotics
- Search and Rescue Operations
- Military Operations
- Inspection and Maintenance
- Educational Robotics
Benefits and Advantages:
- Enhanced Locomotion Performance
- Simplified Design and Fabrication (low cost)
- Increased Accessibility