[Paper Review] Kirin: A Quadruped Robot with High Payload Carrying Capability

Yueheng Zhou, Ming Liu+2 more|arXiv (Cornell University)|Feb 17, 2022

Robotic Locomotion and Control4 citations

TL;DR

This paper presents Kirin, a 50 kg electrically-actuated quadruped robot with a prismatic quasi-direct-drive (QDD) leg mechanism designed for high payload carrying. By optimizing mechanical design, actuator parameters, and locomotion control, Kirin achieves 125 kg static lifting and 50 kg dynamic carrying in trotting, demonstrating enhanced payload capability over conventional articulated-knee designs.

ABSTRACT

The quadruped robot is a versatile mobile platform with potential ability for high payload carrying. However, most of the existing quadruped robots aim at high maneuverability, highly dynamic and agile locomotion. In spite of this, payload carrying is still an indispensable ability for the quadruped robots. Design of a quadruped robot with high payload capacity is yet deeply explored. In this study, a 50 kg electrically-actuated quadruped robot, Kirin, is presented to leverage the payload carrying capability. Kirin is an characterized with prismatic quasi-direct-drive (QDD) leg. This mechanism greatly augments the payload carrying capability. This study presents several design principles for the payload-carrying-oriented quadruped robots, including the mechanical design, actuator parameters selection, and locomotion control method. The theoretical analysis implies that the lifting task tends to be a bottleneck for the existing robots with the articulated knee joints. By using prismatic QDD leg, the payload carrying capability of Kirin is enhanced greatly. To demonstrate Kirin's payload carrying capability, in preliminary experiment, up to 125 kg payload lifting in static stance and 50 kg payload carrying in dynamic trotting are tested. Whole body compliance with payload carrying is also demonstrated.

Motivation & Objective

• To address the lack of research on high payload carrying in quadruped robots despite their potential for such tasks.
• To overcome the mechanical bottleneck in existing robots with articulated knee joints that limit payload capacity.
• To develop a quadruped robot design optimized specifically for high payload performance through innovative mechanical and control strategies.
• To validate the payload-carrying capability through experimental testing under static and dynamic conditions.

Proposed method

• Design of a prismatic quasi-direct-drive (QDD) leg mechanism to enhance force transmission and payload capacity.
• Selection of actuator parameters based on theoretical analysis of lifting performance and mechanical advantage.
• Implementation of whole-body compliance control to maintain stability during payload carrying.
• Use of static and dynamic gait experiments to evaluate payload performance.
• Theoretical modeling to identify articulated knee joints as a performance bottleneck in payload lifting.
• Integration of mechanical design and control strategies to maximize load-bearing efficiency.

Experimental results

Research questions

• RQ1 How does the prismatic QDD leg mechanism improve payload carrying capacity compared to conventional articulated knee joints?
• RQ2 What mechanical and actuator design principles maximize payload performance in quadruped robots?
• RQ3 What is the upper limit of static and dynamic payload capacity achievable with the proposed design?
• RQ4 How does whole-body compliance contribute to stability during payload carrying?
• RQ5 To what extent does theoretical analysis predict performance bottlenecks in existing quadruped robots?

Key findings

• Kirin achieved a static payload lifting capacity of up to 125 kg, demonstrating the effectiveness of the prismatic QDD leg mechanism.
• The robot successfully carried a 50 kg payload during dynamic trotting gait, confirming robustness under motion.
• Theoretical analysis identified articulated knee joints as a key bottleneck in payload lifting due to reduced mechanical advantage.
• The prismatic QDD leg design significantly enhanced force transmission, enabling higher payload capacity than conventional designs.
• Whole-body compliance was successfully maintained during payload carrying, ensuring stability and adaptability.
• The study establishes design principles for payload-carrying-oriented quadruped robots, including mechanical architecture and actuator selection.