Performance measures for locomotion robots

We design two performance measures for a planar locomotion robot, modeled closely after the Platonic Beast. The first measure is proportional to the total motion of all joints during locomotion of the robot. This is a rough approximation to the energy consumption of the robot. The second measure determines the maximal speed of locomotion, for given limits on the joint speeds. We compute optimal modes of locomotion on different slopes for various designs. The results indicate that a variable link length can greatly improve the ability of the robot to walk on steep slopes. © 1997 John Wiley & Sons, Inc.     

Experiments with nontraditional hybrid control technique of biped locomotion robots

By using the previously established zero-moment point theory and the semi-inverse approach [1–4] for solving the artificial gait synthesis based on the prescribed dynamics to part of the active mechanism, in this new approach to dynamic control of legged locomotion robots, the conventional control synthesis, based on complete dynamic robot model, is abandoned. The paper describes the simulation experiments of biped control with a hybrid approach that combines the traditional model-based and fuzzy logic-based control techniques. The combined method is developed by extending a model-based decentralized control scheme by fuzzy logic-based tuners for modifying parameters of joint servo controllers. The simulation experiments performed on a simplified two-legged mechanism demonstrate the suitability of fuzzy logic-based methods for improving the performance of the robot control system.     

Hybrid control of biped robots to increase stability in locomotion

This article proposes a new hybrid control method, a combination of impedance control and computed‐torque control, to control biped robot locomotion. The former is used for the swinging (or unconstrained) leg and the latter for the supporting (or constrained) leg. This article also suggests that the impedance parameters be changed depending on the gait phase of the biped robot. To reduce the magnitude of the impact and to guarantee a stable footing during foot contact with the ground, the damping of the leg is increased drastically at the moment of contact. Computer simulations of a biped robot, with 3 DOF in each leg and the environment represented by a 3‐DOF environment model composed of linear and nonlinear compliant elements, were performed. Simulation results show that the performance of the proposed controller is superior to that of the computed‐torque controller, especially in reducing impact and stabilizing the footing. They also show that the proposed controller makes the biped robot more robust to the uncertainties in its own parameters as well as in its environment. © 2000 John Wiley & Sons, Inc.     

Design and control of mechanical hands for robots

This paper deals with connexions among researches on biomechanics and the design and realization of mechanical hands for robots. High complexity of systems may be reached by use of computer aided design techniques and by the optimized determination of parameters of models, which biomechanics may present to robot scientists and designers.     

Survey of locomotion control of legged robots inspired by biological concept

Compared with wheeled mobile robots, legged robots can easily step over obstacles and walk through rugged ground. They have more flexible bodies and therefore, can deal with complex environment. Nevertheless, some other issues make the locomotion control of legged robots a much complicated task, such as the redundant degree of freedoms and balance keeping. From literatures, locomotion control has been solved mainly based on programming mechanism. To use this method, walking trajectories for each leg and the...     

A simple approach to the control of locomotion in self-reconfigurable robots

In this paper we present role-based control which is a general bottom-up approach to the control of locomotion in self-reconfigurable robots. We use role-based control to implement a caterpillar, a sidewinder, and a rolling track gait in the CONRO self-reconfigurable robot consisting of eight modules. Based on our experiments and discussion we conclude that control systems based on role-based control are minimal, robust to communication errors, and robust to reconfiguration.     

A 'sidewinding' locomotion gait for hyper-redundant robots

This paper considers a novel form of hyper-redundant mobile robot locomotion which is analogous to the 'sidewinding' locomotion gait employed by several species of snake. It is shown that this gait can be generated by a repetitive traveling wave of mechanism deformation. This paper considers primarily the kinematics of the sidewinding gait. The kinematic analysis is based on a continuous 'backbone curve' model which captures the robot's important macroscopic features. Using this continuous model, we first develop algorithms which enable travel in a uniform direction. We subsequently extend this basic gait pattern to enable changes in the direction of travel.     

Emergent synthesis of motion patterns for locomotion robots

Emergence of stable gaits in locomotion robots is studied in this paper. A classifier system, implementing an instance-based reinforcement-learning scheme, is used for the sensory-motor control of an eight-legged mobile robot and for the synthesis of the robot gaits. The robot does not have a priori knowledge of the environment and its own internal model. It is only assumed that the robot can acquire stable gaits by learning how to reach a goal area. During the learning process the control system is self-organized by reinforcement signals. Reaching the goal area defines a global reward. Forward motion gets a local reward, while stepping back and falling down get a local punishment. As learning progresses, the number of the action rules in the classifier systems is stabilized to a certain level, corresponding to the acquired gait patterns. Feasibility of the proposed self-organized system is tested under simulation and experiment. A minimal simulation model that does not require sophisticated computational schemes is constructed and used in simulations. The simulation data, evolved on the minimal model of the robot, is downloaded to the control system of the real robot. Overall, of 10 simulation data seven are successful in running the real robot.     

SnakeSIM: a ROS-based control and simulation framework for perception-driven obstacle-aided locomotion of snake robots

Biological snakes are capable of exploiting roughness in the terrain for locomotion. This feature allows them to adapt to different types of environments. Snake robots that can mimic this behaviour could be fitted with sensors and used for transporting tools to hazardous or confined areas that other robots and humans are unable to access. Snake robot locomotion in a cluttered environment where the snake robot utilises a sensory–perceptual system to perceive the surrounding operational environment for means of propulsion can be defined as perception-driven obstacle-aided locomotion (POAL). The initial testing of new control methods for POAL in a physical environment using a real snake robot imposes challenging requirements on both the robot and the test environment in terms of robustness and predictability. This paper introduces SnakeSIM, a virtual rapid-prototyping framework that allows researchers for the design and simulation of POAL more safely, rapidly and efficiently. SnakeSIM is based on the robot operating system (ROS) and it allows for simulating the snake robot model in a virtual environment cluttered with obstacles. The simulated robot can be equipped with different sensors. Tactile perception can be achieved using contact sensors to retrieve forces, torques, contact positions and contact normals. A depth camera can be attached to the snake robot head for visual perception purposes. Furthermore, SnakeSIM allows for exploiting the large variety of robotics sensors that are supported by ROS. The framework can be transparently integrated with a real robot. To demonstrate the potential of SnakeSIM, a possible control approach for POAL is considered as a case study.     

移动机器人Java Agent控制系统设计

针对移动机器人的任务和硬件组成,提出了基于Java 开发平台的Agent控制系统设计方法。以目前应用较广泛的JADE作为Agent开发平台,采用JNI方法实现了Agent与硬件系统的交互。在运动控制卡上设计了有实时性要求的轨迹生成、运动控制、位姿估计和安全控制等4个行为任务,将数据库和路径规划等管理性行为设计在车载PC104工业控制计算机上。人机交互界面可作为独立的Agent驻留在上位监控计算机上。这种方法结合了Java Agent开发平台的普遍性和工业控制的实时性,实验证明了该方法的可行性。     

Multimode locomotion via SuperBot reconfigurable robots

One of the most challenging issues for a self-sustaining robotic system is how to use its limited resources to accomplish a large variety of tasks. The scope of such tasks could include transportation, exploration, construction, inspection, maintenance,in-situ resource utilization, and support for astronauts. This paper proposes a modular and reconfigurable solution for this challenge by allowing a robot to support multiple modes of locomotion and select the appropriate mode for the task at hand. This solution relies on robots that are made of reconfigurable modules. Each locomotion mode consists of a set of characteristics for the environment type, speed, turning-ability, energy-efficiency, and recoverability from failures. This paper demonstrates a solution using the SuperBot robot that combines advantages from M-TRAN, CONRO, ATRON, and other chain-based and lattice-based robots. At the present, a single real SuperBot module can move, turn, sidewind, maneuver, and travel on batteries up to 500 m on carpet in an office environment. In physics-based simulation, SuperBot modules can perform multimodal locomotions such as snake, caterpillar, insect, spider, rolling track, H-walker, etc. It can move at speeds of up to 1.0 m/s on flat terrain using less than 6 W per module, and climb slopes of no less 40 degrees. Harris Chi Ho Chiu is a PhD Student in Computer Science at the University of Southern California and a research assistant in Polymorphic Robotics Laboratory of Information Science Institute. He received his Master in Computer Science from the University of Southern California and his Bachelor of Engineering from the University of Hong Kong. His research interests include intelligent automated systems, modular self-reconfigurable systems, artificial intelligence, and machine learning. Michael Rubenstein is currently a PhD student at the Polymorphic Robotics Laboratory, working on the CONRO and Superbot self-reconfigurable robotic systems. He has received his bachelors in Electrical Engineering from Purdue University, and his masters in Electrical Engineering from the University of Southern California, and is currently working towards his PhD in Computer Science from the University of Southern California. His interests include modular self-reconfigurable systems, autonomous robots, self-healing systems, and self-replicating systems. Jagadesh B Venkatesh is a member of the Polymorphic Robotics Laboratory at the Information Sciences Institute. He is currently a Master’s candidate in the Product Development Engineering program at the University of Southern California. He received his MS in Computer Science with specialization in Intelligent Robotics, also at the University of Southern California in 2005. His current interest is the commercialization of robotic technologies, specifically in the consumer robotics sector.     

工业机器人浇铸控制系统的设计与应用

根据浇铸机器人的功能需求和特点,设计了具有良好通用性和开放性的工业机器人浇铸控制系统的软硬件结构.以三轴浇铸机器人为应用实例,分析了其运动学正逆解算法,并根据实际生产需求,通过PLC程序中定义的M指令实现整个浇铸系统的I/O信号交互控制.实际应用结果表明,该浇铸控制系统有效地提高了浇铸生产效率,并且运行稳定可靠.     

Integration of prioritized impedance controller in improved hierarchical operational-space torque control frameworks for legged locomotion robots

Multibody System Dynamics - This paper proposes to integrate our prioritized impedance controller (PIC) into four kinds of improved hierarchical operational-space torque-control frameworks: one...     

A distributed and morphology-independent strategy for adaptive locomotion in self-reconfigurable modular robots

In this paper, we present a distributed reinforcement learning strategy for morphology-independent life-long gait learning for modular robots. All modules run identical controllers that locally and independently optimize their action selection based on the robot’s velocity as a global, shared reward signal. We evaluate the strategy experimentally mainly on simulated, but also on physical, modular robots. We find that the strategy: (i) for six of seven configurations (3–12 modules) converge in 96% of the trials to the best known action-based gaits within 15 min, on average, (ii) can be transferred to physical robots with a comparable performance, (iii) can be applied to learn simple gait control tables for both M-TRAN and ATRON robots, (iv) enables an 8-module robot to adapt to faults and changes in its morphology, and (v) can learn gaits for up to 60 module robots but a divergence effect becomes substantial from 20–30 modules. These experiments demonstrate the advantages of a distributed learning strategy for modular robots, such as simplicity in implementation, low resource requirements, morphology independence, reconfigurability, and fault tolerance.     

Modelling and control of class NSP tensegrity structures

The method of constrained particle dynamics is used to develop a dynamic model of order 12 N for a general class of tensegrity structures consisting of N compression members (i.e. bars) and tensile members (i.e. cables). This model is then used as the basis for the design of a feedback control system which adjusts the lengths of the bars to regulate the shape of the structure with respect to a given equilibrium shape. A detailed design is provided for a 3-bar structure.     

A versatile locomotion mechanism for amphibious robots: eccentric paddle mechanism

Most of recently developed rescue robots can only be deployed to limited attacked regions after tsunami and the floods, due to their limited mobility on complex amphibious terrains. To access such amphibious environments with improved mobility, we propose a novel eccentric paddle mechanism (ePaddle) which has a set of paddles eccentrically placed in a wheel to perform multiple terrestrial, aquatic, and amphibious gaits. One of the advantages of our proposed ePaddle mechanism is its unique locomotion versatility introduced by the eccentric distance between the paddle shaft and the wheel center. We demonstrate this versatility by proposing five typical gaits for traveling on different terrains. For instance, wheeled rolling gait is used to achieve high-speed locomotion on even terrain. Legged gait is applied to travel on the rough terrains. To access the soft terrains where wheels slip and legs sink, a wheel-leg-integrated gait is performed by digging the paddle into the ground. To swim in the water, rotational paddling and oscillating paddling gaits are proposed. For each of these gaits, standard gait sequence is defined and joint parameters are calculated based on kinematics. An ePaddle prototype is then built and tested with the proposed gait sequences. Experimental results verify the design of the ePaddle mechanism as well as its versatile gaits.     

Abstraction and control for Groups of robots

This paper addresses the general problem of controlling a large number of robots required to move as a group. We propose an abstraction based on the definition of a map from the configuration space Q of the robots to a lower dimensional manifold A, whose dimension is independent of the number of robots. In this paper, we focus on planar fully actuated robots. We require that the manifold A has a product structure A=G/spl times/S, where G is a Lie group, which captures the position and orientation of the ensemble in the chosen world coordinate frame, and S is a shape manifold, which is an intrinsic characterization of the team describing the "shape" as the area spanned by the robots. We design decoupled controllers for the group and shape variables. We derive controllers for individual robots that guarantee the desired behavior on A. These controllers can be realized by feedback that depends only on the current state of the robot and the state of the manifold A. This has the practical advantage of reducing the communication and sensing that is required and limiting the complexity of individual robot controllers, even for large numbers of robots.     

Image-based control for cable-based robots

Some human robot interactive applications involved in tele-robotics, remote supervisory and unmanned systems require specific capabilities. This demand has promoted various interactive modes and high-level control techniques such as tele-manipulation, speech, vision, gesture, etc. Among these interactive modes, the image based control which is often named point and click control has proven to be the most appropriate one that offers multiple advantages. This mode consists of only and simply pointing in an appearing object of an image received from a remote site, to convert this click into a robot command towards the corresponding location in the real world space. This mode is suitable for remote applications, frees the human operator from being involved into the loop enabling him/her to use commands in the sense of click and forget. This paper presents, firstly, the design and the realization of an experimental planar cable-based robot constituted of four cables. Secondly, it presents the design and the implementation of a high-level image-based control. Some typical experiments which have been performed prove the simplicity and the effectiveness of the image-based control. Moreover, it opens perspectives for new applications with cable-based robots, particularity for rehabilitation applications.     

Evolution of side-winding locomotion of simulated limbless, wheelless robots

Inspired by the efficient method of locomotion of the rattlesnake Crotalus cerastes, the objective of this work was the automatic design through genetic programming of the fastest possible, side-winding locomotion of simulated limbless, wheelless artifacts. The realism of the simulation is ensured by employing open dynamics engine (ODE), which allows accounting for all the physical forces resulting from the actuators (muscles), friction, gravity, collisions, and joint constraints. The empirically obtained results demonstrate that the complex side-winding locomotion emerges from relatively simple motion patterns of morphological segments (vertebrae). The robustness of automatically evolved locomotion is verified by (i) the reasonable performance degradation when partial damage to the artifact is inflicted, and (ii) the ability to tackle obstacles. Contributing to the better understanding of the unique, side-winding locomotion, this work could be considered as a step toward building real limbless, wheelless robots, featuring unique engineering characteristics, which are able to perform robustly in difficult environments.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004