Jinguo Liu

Analysis of stairs-climbing ability for a tracked reconfigurable modular robot

Stairs-climbing ability is the crucial performance of mobile robot for urban environment mission such as urban search and rescue or urban reconnaissance. The track type mobile mechanism has been widely applied for its advantages such as high stability, easy to control, low terrain pressure, and continuous drive. Stairs-climbing is a complicated process for a tracked mobile robot under kinematics and dynamics constraints. In this paper, the stairs-climbing process has been divided into riser climbing, riser crossing, and nose line climbing. During each climbing process, robots mobility has been analyzed for its kinematics and dynamics factor. The track velocity and accelerations influences on riser climbing have been analyzed. And the semiempirical design method of the track grouser and the module length has been provided in riser crossing and nose line climbing correspondingly. Finally, stairs-climbing experiments have been made on the two-module robot in line type, and three-module robot in line type and in triangle type respectively.

AMOEBA-I: a shape-shifting modular robot for urban search and rescue

This work intends to enhance the mobility and flexibility of a tracked mobile robot through changing its shape in unstructured environments. A shape-shifting mobile robot, AMOEBA-I, has been developed. With three tracked modules, AMOEBA-I has nine locomotion configurations and three of them are symmetrical configurations. The key advantage of this design over other mobile robots is its adaptability and flexibility because of its various configurations. It can change its configuration fluently and automatically to adapt to different environments or missions. A modularized structure of the control system is proposed and designed for AMOEBA-I to improve the fault tolerance and substitutability of the system. The strategies of cooperative control, including cooperative shape shifting, cooperative turning and cooperative obstacle negotiation, have been proposed to improve the capability of shape shifting, locomotion and obstacle negotiation for AMOEBA-I. A series of experiments have been carried out, and demonstrated that such a structure possesses excellent mobility and high flexibility under various urban environments including stairs, a narrow space, an obstacle, uneven debris and an underground garage. Being small, portable, and remotely controlled, AMOEBA-I has potential applications in areas such as urban search and rescue and environment reconnaissance.

CURRENT RESEARCH, KEY PERFORMANCES AND FUTURE DEVELOPMENT OF SEARCH AND RESCUE ROBOT

A survey of the research status for search and rescue robots in Japan,USA,China,and other countries is provided. According to current research,the experience,and the lessons learned from application,there are four key performances for search and rescue robot,which are,survivability,mobility, sensing,communicability,and operability.It is proved that, research of search and rescue robot is converted to practice from experiment gradually,Multi-technique fusion and multi-agent intelligent network are considered to be the future development requirement of the search and rescue robot.Dis- aster prevention,disaster reduction,and disaster rescue are important parts of the national public safety.And they are also crucial issues in the safety of citizens and their estates. Search and rescue robotic technique is an urgently needed, strategic,and core technique for national development.It will have important and strategic effect on the national economy and the national safety.

Center-configuration selection technique for the reconfigurable modular robot

The reconfigurable modular robot has an enormous amount of configurations to adapt to various environments and tasks. It greatly increases the complexity of configuration research in that the possible configuration number of the reconfigurable modular robot grows exponentially with the increase of module number. Being the initial configuration or the basic configuration of the reconfigurable robot, the center-configuration plays a crucial role in system’s actual applications. In this paper, a novel center-configuration selection technique has been proposed for reconfigurable modular robots. Based on the similarities between configurations’ transformation and graph theory, configuration network has been applied in the modeling and analyzing of these configurations. Configuration adjacency matrix, reconfirmation cost matrix, and center-configuration coefficient have been defined for the configuration network correspondingly. Being similar to the center-location problem, the center configuration has been selected according to the largest center-configuration coefficient. As an example of the reconfigurable robotic system, AMOEBA-I, a three-module reconfigurable robot with nine configurations which was developed in Shenyang Institute of Automation (SIA), Chinese Academy of Sciences (CAS), has been introduced briefly. According to the numerical simulation result, the center-configuration coefficients for these nine configurations have been calculated and compared to validate this technique. Lastly, a center-configuration selection example is provided with consideration of the adjacent configurations. The center-configuration selection technique proposed in this paper is also available to other reconfigurable modular robots.

Network-based reconfiguration routes for a self-reconfigurable robot

This paper presents a network-based analysis approach for the reconfiguration problem of a self-reconfigurable robot. The self-reconfigurable modular robot named “AMOEBA-I” has nine kinds of non-isomorphic configurations that consist of a configuration network. Each configuration of the robot is defined to be a node in the weighted and directed configuration network. The transformation from one configuration to another is represented by a directed path with nonnegative weight. Graph theory is applied in the reconfiguration analysis, where reconfiguration route, reconfigurable matrix and route matrix are defined according to the topological information of these configurations. Algorithms in graph theory have been used in enumerating the available reconfiguration routes and deciding the best reconfiguration route. Numerical analysis and experimental simulation results prove the validity of the approach proposed in this paper. And it is potentially suitable for other self-reconfigurable robots’ configuration control and reconfiguration planning.

Development of a shape shifting robot for search and rescue

A novel link-type modular robot, which can change its shape, has been developed for potential application in urban search and rescue (USAR) operation. The advantages of the robot with link-type structure have been specified, and its shape shifting principle has been discussed. A three-module shape shifting robot has three kinds of symmetry configurations, that is, line type, triangle type and row type. Each configuration possesses its unique mobility. A tracked prototype has been built and tested under various unstructured environment Experiments have demonstrated its mobility and flexibility.

Experiments on fuzzy sliding mode variable structure control for vibration suppression of a rotating flexible beam

Space robots are a kind of coupling system with a rigid body and flexible structures, in which harmonic drive gears are usually used as speed reducers. Thus, the vibration problem is unavoidable due to maneuvering and external disturbances. This paper is concerned with the design and implementation of a fuzzy sliding mode control (FSMC) algorithm and a composite controller to dampen the vibration of a flexible manipulator with a flexible link and a harmonic drive gear (flexible joint). The designed controllers are used to dampen the end-point vibration of the flexible link and flexible joint manipulator, to compensate for unknown and time-varying nonlinear uncertain parameters, such as friction torque and flexible joint characteristics of a harmonic drive gear, etc. The experimental comparison research was conducted, including set-point active vibration control and vibration suppression under resonant excitation. The experimental results demonstrate that the FSMC and the composite algorithms can significantly enhance the performance of vibration suppression for flexible manipulator.

China's robotics successes abound.

The In Brief news story “Chinas lunar rover languishes” (6 June, p. [1066][1]) should be put in the context of Chinas ambitious robotics development, which began more than 40 years ago. Recent advances in robotics have allowed China to explore extreme environments such as space, natural

Path planning of a snake-like robot based on serpenoid curve and genetic algorithms

The path of the snake-like robot has no repetition because its motion is influenced by manifold indeterminate factors such as ground condition, mechanisms vibration and motor voltages variety. A novel path planning technique based on serpenoid curve and genetic algorithms (GAs) has been proposed to control the snake-like robot in Shenyang Institute of Automation (SIA, China). First, the ranges of the path and the curvature deviation have been calculated approximately and set as the bounds of genetic algorithms. Then using real time dual genetic algorithms, this path planning technique not only can decide the shortest path and the minimum curvature deviation, but also can limit the motion errors influence. Simulation results show that the results of the second layer of GAs are more available than that of the first layer of GAs and this novel technique is effective for the path planning of the SIA snake-like robot.

Fuzzy adaptive PD control for quadrotor helicopter

Quadrotor is a strong coupling, under actuated complex system with multi inputs and multi outputs. In this paper, the quadrotor UAV model was presented at first. In order to control the position and attitude respectively, a nested loops control strategy was employed. The full control was divided into two parts, i.e. position control and attitude control. Both a PD controller and a fuzzy adaptive PD control er were designed. Finally, in order to give the comparison results, a quadrotor simulation system was set up in Matlab Simulink.