Some 5,000 years ago, the Chinese “Yellow Emperor” used mobile navigation devices to help his soldiers to march in the heavy smog generated by his enemy in the battle against Chi You, according to the record in the legendary “The Classic of Mountains and Seas (also known as Shan Hai Jing, formerly romanized as the Shan-hai Ching). Since then, making robots cross various rough terrains is always a challenge people trying to tackle. Compared to the wheeled or tracked mobile robots, legged platforms demonstrate better flexibility and terrain adaptability at the cost of low speed and increased control complexity.
This special issue on “Multi-legged Robots” reports research work on robots with more than three legs. It collects a set of 6 manuscripts after a rigorous two rounds of reviews. The robotic platforms under investigation range from weights of less than one gram to tens of kilograms; and the research areas cover mechanism design, locomotion control, and navigation. Together, these papers provide a broad coverage of the different aspects of people’s efforts to invent biologically inspired mobile platforms, learning from legged animals including mammals, reptiles, and insects.
The survey paper by Chai et al. gives an overview of the quadruped robotic platforms, with a brief historical account and future prospect. Then the biomimetic structure and the motion control method of the quadruped robots are summarized, with the advantages and disadvantages analyzed in relation to gait switching, terrain adaption, and disturbance resistance. Subsequently, aiming at the mobile manipulation of the quadruped robots, the representative leg-arm collaborative robots, and the multi-task-oriented whole-body control methods are introduced. Finally, the paper ends with a summary and future work of the quadruped robots.
The paper by Tang et al. focuses on the locomotion control of an insect-like robot that is composed of several identical body segments, each of which with two legs. The authors propose a novel gait planning method for a multi-legged robot that has only 1 degree-of-freedom in each leg and has a passive body joint between two body segments. The legged locomotion is achieved by under-actuation and verified by simulation and experimental studies.
Sun et al. develops a soft multi-legged miniature robot with excellent motion performance and strong adaptability to various harsh environments. Based on the magnetic field model of the permanent magnet, this paper analyzes the robot gaits under different magnet motion modes and qualitatively analyzes the motion mechanism of the robot. Finally, the experiments show that the robot can move forward and backward, steering, and cross obstacles under the control of the magnetic field, and can combine these abilities to navigate across a maze.
An adaptive gait planning framework for a quadruped robot is presented in Chen et al. In this paper, a simple measuring method is proposed for obtaining the total force applied on the center of inertia of the quadruped robot with force sensing information in the static gait. Based on the zero moment point stable criterion, an extended criterion on the virtual supporting plane is presented to guarantee the stable walking of the quadruped robot. Moreover, an adaptive omnidirectional gait planning is developed for the quadruped robot, applying the extended zero moment point on the center of inertia to obtain the stable criterion over rough terrain. The proposed gait planning algorithm enables the sprawling-type quadruped robot to walk steadily over the flat and uneven terrains, as well as rough slope without visual perception.
Zhang et al. aims to investigate the fast-running mechanism of cheetahs. First, referring to the body property of a real cheetah, a reasonable and simplified model of the cheetah was established. Then, the biological data of the cheetah's running gait is analyzed, followed by the kinematic and dynamic modeling of the cheetah leg mechanism. After that, system parameters such as the joint angles, length of the virtual leg, leg-to-ground contact angle, leg energy, joint torque, and the manipulability of the leg mechanism are compared and analyzed in the time domain. Finally, the high-speed motion law with engineering guiding significance is summarized.
A comprehensive evaluation of autonomous quadruped robot navigation in confined environments is presented by Koval et al. They integrate the software system and multiple sensors to empower a quadruped robot the ability to navigate autonomously. The robot is utilized to build the offline map of the environment. Then the online environmental information from the autonomy package sensors and the offline map is provided to the onboard computer to localize the robot on the known map. Finally, the occupancy information is provided to the online grid-based path planner that generates risk-aware paths. Extensive experimental evaluations of the proposed system are performed in corridors and SubT environments.
We hope that you enjoy this special issue and submit your own contributions to this journal for publication.
本文作者：
孟庆虎（Max Q.-H.Meng）教授，BIRob主编，南方科技大学电子与电气工程系讲席教授、系主任，IEEE Fellow，加拿大工程院院士。
宋锐（Rui Song）教授，BIRob“多足机器人”专题责任主编，山东大学控制科学与工程学院教授，博士生导师，长江学者。
扫描二维码
查看原文
