The goal of a sophisticated robot programming system is the ability to accept natural language input, such as English, and be able to convert this to a series of robot commands that will achieve the desired robot movement. This paper first examines what is meant by the concept of natural language understanding. Then a bottom-up development of a model of a robot system identifies the levels of control in a robot system and the role of software at each of these. This is related to the various models of software hierarchy that have been proposed by different authors and an essential deviation from these at the object level (or sub-task level) is identified. Finally, a new route is proposed that should be taken in defining the levels of software if intelligent programming of robots is to be achieved.

The frog-inspired robots with amphibious locomotion ability have greatest application prospects and practical value in the fields of resource exploration and environmental reconnaissance. Although frog-inspired robots have been of interest over many years, research on frog-inspired amphibious robots is still in its infancy. Since the locomotion mechanism is the basis for the research of frog-inspired amphibious robots, the research methods of the single motion mechanism of frogs are firstly inductive analyzed, and a reference scheme is proposed to inspire the research on the amphibious motion mechanism. Then, we collect and introduce a systematic discussion of the research status of frog-inspired robots according to the locomotion mode. The characteristics of the robots are analyzed from the aspects of design concept, structural characteristics, driving method, and motion performance. Finally, the technical challenges faced by the research on the frog-inspired robots are analyzed, and the development trend is predicted. The authors hope that this study can provide an informative reference for future research in the direction of frog-inspired amphibious robot.

The concept of distance between two rigid-body poses is important in path planning, positioning precision, mechanism synthesis, and in many other applications. In the definition of such a distance, two approaches mainly prevail, which lead to a number of formulas devised to match the needs of motion tasks. Despite the different approaches and formulas, some important theoretical results, which drive toward distance-metrics definitions useful for design and application purposes, have been stated. This paper summarizes the two different approaches together with a critical review of the literature on the distance metrics they generated, and, then, it illustrates a technique, previously proposed by the author, for combining different metrics to obtain novel distance-metric definitions that are tailored to specific applications.

The dynamics of a mechanical manipulator have the inherent characteristics of being highly non-linear and strongly coupled due to the interaction of the inertial, centripetal, coriolis and gravitational forces.

These characteristics produce difficulties in predicting the dynamic behaviour of a given manipulator's structure. These interactive forces depend largely on the geometrical configuration and operational conditions of a manipulator. Therefore, it is essential to investigate the dynamics behaviour under different conditions in order to obtain an optimal design.

This paper presents a study of the dynamics behaviour of a robot's arm with particular reference to the mechanical manipulator being designed by the AEAC. A computer software package has been developed to facilitate the investigation of the potential dynamics behaviour of a robot's arm and provides the designer with useful information for the real time control of high performance robots. This package also enables the designer to closely monitor the implications of his design.

The software of this package is based on the Lagrangian model, taking advantage of the recursive formulation. A brief description of the types of velocity trajectories used in this study is also included in this paper.

The software for the modelling was written in FORTRAN 77 in single precision and run on a UNIVAC operating system.

This note describes a new class of devices, corrugated polyvinylidene fluoride bimorphs. It describes the fabrication, testing and analysis of one simple configuration and discusses the general potential of the devices. As actuators, they offer promise for applications involving relatively large amplitude displacements and small forces with ease of control. As tactile sensors, the devices offer considerable promise due to their potentially high resolution, selectable compliance, sensitivity and durability.

Although numerous sophisticated nonlinear control algorithms exist in literature, it is still state of the art to use simple linear joint controllers in industrial robotic systems. Most nonlinear concepts are based on a more or less accurate inverse model of the robot. In this paper a forward-model-based control system, the so-called Model Following Control (MFC), for robot manipulators is presented. Its theoretical basics and its concept are explained. The quality and the applicability of the MFC control concept has been analyzed in many experiments. The MFC system is compared with classical linear controllers and nonlinear feedforward controllers with respect to robustness. Qualitative as well as quantitative results are presented and discussed.

This paper presents a mathematical model of a robot with one degree of freedom and numerical investigation of its dynamics in a particular parameter scan which is close to the upper boundary of the estimates for the parameters of rigidity and friction, while the length parameter L is treated as a free control parameter. In this L-scan the quasiperiodic and frequency locked solutions, their pattern and order of appearance are studied in the interval from the parameter range of immediate engineering significance to the point of appearance of transient chaos. In particular, a fractaltype multiple splitting of Arnold tongues is found in the parameter region bordering the range of engineering significance.

In this paper, a novel cable-constrained parallel mechanism is presented as a lightweight, low-cost leg mechanism design for walking machines to be used on flat surfaces. The proposed leg mechanism has three translational degrees of freedom. It is based on two specific hybrid kinematic topologies being herewith proposed. The paper reports the kinematic analysis formulation and a position performance evaluation to confirm the main characteristics of the proposed solutions. A 3D CAD model and simulations are carried out to demonstrate the feasibility of the proposed design for performing a human-like gait trajectory. A prototype has been built, and preliminarily tests have been conducted to confirm the motion capabilities of the proposed mechanism design. Then a second, enhanced prototype has been designed and built. An experimental validation is carried out for tracking a planar walking trajectory with the built prototypes by using a real-time PCI controller. Results are presented to validate the operation characteristics of the proposed mechanism and to prove its feasibility for legged walking machines.

This paper presents closed-form analytic solutions for collision detection among multiagents traveling along specified paths. Previous solutions for centralized multiagent systems have mainly used iterative computational approaches for collision detection, which impose a heavy computational burden on the systems. In this paper, we formalize a new mathematical approach to overcoming the difficulty on the basis of simple continuous curvature (SCC) path modeling and a collision representation tool, extended collision map (ECM) method. The formulation permits all the potential collisions to be detected, represented, and parameterized with physical and geometric variables. The proposed parameterized collision region (PCR) method is a simple but precise, computationally efficient tool for describing complicated potential collisions with time traveled. Several simulations are presented to validate the proposed approach for use in centralized collision detectors and to compare the results with those of the iterative computational method and the proximity query package (PQP) method that are available.

This paper describes a hybrid approach to a fast and accurate localization method for legged robots based on Fuzzy-Markov (FM) and Extended Kalman Filters (EKF). Both FM and EKF techniques have been used in robot localization and exhibit different characteristics in terms of processing time, convergence, and accuracy. We propose a Fuzzy-Markov–Kalman (FM–EKF) localization method as a combined solution for a poor predictable platform such as Sony Aibo walking robots. The experimental results show the performance of EKF, FM, and FM-EKF in a localization task with simple movements, combined behaviors, and kidnapped situations. An overhead tracking system was adopted to provide a ground truth to verify the performance of the proposed method.

This paper addresses the orientation-singularity analysis and the orientationability evaluation of a special class of the Stewart–Gough parallel manipulators in which the moving and base platforms are two similar semi-symmetrical hexagons. Based on the half-angle transformation, an analytical polynomial of degree 13 that represents the orientation-singularity locus of this special class of parallel manipulators at a given position is derived. Graphical representations of the orientation-singularity locus of this class of manipulators are illustrated with examples to demonstrate the results. Based on the description of the orientation-singularity and nonsingular orientation region of this class of parallel manipulators, a performance index, referred to as orientationability, which describes the orientation capability of this class of manipulators at a given position, is introduced. A discretization algorithm is proposed for computing the orientationability of the special class of parallel manipulators at a given position in the workspace. Moreover, the effects of the design parameters and position parameters on the orientationability are also investigated in detail. Based on the orientationability performance index, another performance index, referred to as practical orientationability, representing the practical orientation capability of the manipulators at a given position, is introduced. In this performance index, singularities, the limitations of active and passive joints and link interferences are all taken into consideration. Furthermore, the practical orientationability of the special class of parallel manipulators studied here is also analyzed over several plane sections of the position-workspace in detail.

In this paper, Clifford Algebra is used to model and facilitate solving the inverse kinematic problem for robots with only two consecutive parallel axes. It is shown that when a solution exists, it is usually the case that one of the angles of rotation can be arbitrarily chosen from a union of intervals. The remaining angles are then uniquely determined. Of course, there are cases when no solution exists, such as when the object is out of reach. But typically, when solutions exist, there are infinitely many sets of solutions.

Constrained motion is essential for varying robotics tasks, especially in surgical robotics, for instance, the case of minimally invasive interventions. This article proposes generic formulations of the classical bilateral constrained motion (i.e., when the incision hole has almost the same diameter as that of the tool) as well as unilaterally constrained motion (i.e., when the hole incision has a larger diameter compared to the tool diameter). One of the latter constraints is combined with another surgical task such as incision/ablation or suturing a wound (modeled here by 3D geometric paths). The developed control methods based on the hierarchical task approach are able to manage simultaneously the constrained motion (depending on the configuration case, i.e., bilateral or unilateral constraint) and a 3D path following. In addition, the proposed methods can operate with both straight or curved surgical tools. The proposed methods were successfully validated in various scenarios. Foremost, a simulation framework was proposed to access the performances of each proposed controller. Thereafter, several experimental validations were carried out. Both the simulation and experimental results have demonstrated the relevance of the proposed approach, as well as promising performances in terms of behavior as well as accuracy.

This paper describes a new vision-based playback method of a wheeled mobile robot. The path of the robot is divided into straight line parts and curved line parts. The curved line parts were approximated by a Bézier curve to decrease the volume of data. In order to track the curved line parts with good accuracy, tracking errors were detected by referring to two pre-recorded images on one part of the curve. Then, the errors were corrected by adjusting the control points of the Bézier curve. Outdoor experiments demonstrated good repeatability by using the proposed method.

An algorithm for the tele-operation of mobile-manipulator systems with a focus on ease of use for the operator is presented. The algorithm allows for unified, intuitive, and coordinated control of mobile manipulators. It consists of three states. In the first state, a single 6-degrees-of-freedom (DOF) joystick is used to control the manipulator's position and orientation. The second state occurs when the manipulator approaches a singular configuration, resulting in the mobile base moving in a manner so as to keep the end-effector travelling in its last direction of motion. This is done through the use of a constrained optimization routine. The third state is entered when the operator returns the joystick to the home position. Both the mobile base and manipulator move with respect to one another keeping the end-effector stationary and placing the manipulator into an ideal configuration. The algorithm has been implemented on an 8-DOF mobile manipulator and the test results show that it is effective at moving the system in an intuitive manner.

As a fatigable part of industrial products, cable is a valuable research topic to predict the product lifetime. Since the cable fatigue is related to the bending radius in motion, this paper presents a cable motion capture and bending radius calculation method based on optical tracking system. In particular, a marker sorting algorithm is developed for further spline interpolation in cable motion tracking. The cable bending radius calculation precision is analysed as well. The Results show that the proposed method can successfully track cable motion with an acceptable error for cable lifetime prediction.

A computational derivation of valid kinematic limbs for spatial 3-DOF parallel mechanisms (PMs) without redundant constraint is studied based on contracted graphs, topological graphs, and basic joints. First, some contracted graphs without any binary links are constructed, some curves with only binary links are distributed over contracted graphs and many valid topological graphs are derived. Second, a software is developed in Visual Basic for deriving the kinematic limb, and some basic chain structures are constructed by connecting various basic joints in series. Third, all valid kinematic limbs of the 3-DOF PMs without redundant constraint are derived computationally from the basic chain structures and some novel 3-DOF PMs are synthesized using this approach. Finally, the number of the different 3-DOF PMs without redundant constraint are determined based on the topological graphs and valid chain structures of the limb.

As a solution to soft material manipulation, dual-arm robots that are capable of multi-point grasping have become the latest trend due to their higher capability and efficiency. To explore further development in soft material manipulation and go beyond the hardware limit of dual arms, in this paper the robot platform “Quad-SCARA” that consists of four Selective Compliance Assembly Robot Arm (SCARA) is developed and introduced. With the base of hardware platform, a novel collision avoidance system designed for the motion planning of Quad-SCARA in multi-point grasping state is proposed. This system is inspired by the idea of “Buffered Voronoi Cell (BVC),” an algorithm originally proposed for multi-agent collision avoidance. After appropriate adaptation and new proposition in implementation of BVC, the experiments of folding and spreading a handkerchief are performed, and the results in simulation and robot experiments are presented and discussed for the validation and evaluation of entire system.

Each of several speed-limited planar robots is driven by the acceleration, limited in magnitude. There is an unpredictable dynamic complex object, for example, a group of moving targets or an extended moving and deforming body. The robots should reach and then repeatedly trace a certain object-dependent moving and deforming curve that encircles the object and also achieve an effective self-deployment over it. This may be, for example, the locus of points at a desired mean distance or distance from a group of targets or a single extended object, respectively. Every robot has access to the nearest point of the curve and its own velocity and “sees” the objects within a finite sensing range. The robots have no communication facilities, cannot differentiate the peers, and are to be driven by a common law. Necessary conditions for the solvability of the mission are established. Under their slight and partly unavoidable enhancement, a new decentralized control strategy is proposed and shown to solve the mission, while excluding inter-robot collisions, and for the case of a steady curve, to evenly distribute the robots over the curve and to ensure a prespecified speed of their motion over it. These are justified via rigorous global convergence results and confirmed via computer simulations.