In this paper the mechanical design for a new 7-dofs leg is investigated as a walking module for a humanoid robot. In particular, a dynamic simulation is deduced by means of a Newton-Euler formulation and implemented numerically in order to compute the needed input actuator torques. A simulation is carried out for a similar built leg prototype that is used as a walking module for WABIAN-RIV (WAseda BIped humANoid robot-Revised IV). Experimental tests are carried out on this existing leg in order to validate the proposed formulation for a similar application. Thus, the validated formulation has been used in order to design the actuators for a new leg prototype.

A novel affect-sensitive human-robot cooperative framework is presented in this paper. Peripheral physiological indices are measured through wearable biofeedback sensors to detect the affective state of the human. Affect recognition is performed through both quantitative and qualitative analyses. A subsumption control architecture sensitive to the affective state of the human is proposed for a mobile robot. Human-robot cooperation experiments are performed where the robot senses the affective state of the human and responds appropriately. The results presented here validate the proposed framework and demonstrate a new way of achieving implicit communication between a human and a robot.

In this paper, we demonstrate a multi-phase genetic programming (MPGP) approach to an autonomous robot learning task, where a sumo wrestling robot is required to execute specialized pushing maneuvers in response to different opponents' postures. The sumo robot used has a very simple, minimalist hardware configuration. This example differs from the earlier studies in evolutionary robotics in that the former is carried out on-line during the performance of a robot, whereas the latter is concerned with the evolution of a controller in a simulated environment based on extended genetic algorithms. As illustrated in several sumo maneuver learning experiments, strategic maneuvers with respect to some possible changes in the shape and size of an opponent can readily emerge from the on-line MPGP learning sessions.

A new unified motion planning algorithm for autonomous Underwater Vehicle-Manipulator Systems (UVMS) has been presented in this paper. Commonly, a UVMS consists of two sub-systems, a vehicle and a manipulator, having vastly different dynamic responses. The proposed algorithm considers the variability in dynamic bandwidth of the complex UVMS system and generates not only kinematically admissible but also dynamically feasible reference trajectories. Additionally, this motion planning algorithm exploits the inherent kinematic redundancy of the whole system and provides reference trajectories that accommodates other important criteria such as thruster/actuator faults and saturations, and also minimizes hydrodynamic drag. Effectiveness of the proposed unified motion planning algorithm has been verified by extensive computer simulation. The results are quite promising.

To fully utilize the information from the sensors, this paper proposes a new sensor-fusion technique where the data sets for the previous moments are properly transformed and fused into the current data sets to enable an accurate measurement. Exploration of an unknown environment is an important task for the new generation of mobile service robots. The mobile robots may navigate by means of a number of monitoring systems such as the sonar-sensing system or the visual-sensing system. Note that in the conventional fusion schemes, the measurement is dependent on the current data sets only. Therefore, more of sensors are required to measure a certain physical parameter or to improve the accuracy of the measurement. However, in this approach, instead of adding more sensors to the system, the temporal sequence of the data sets are stored and utilized for the accurate measurement. The theoretical basis is illustrated by examples and the effectiveness is proved through the simulations and experiments. The newly proposed, STSF (Space and Time Sensor Fusion) scheme is applied to the navigation of a mobile robot in an unstructured environment, as well as in structured environment, and the experimental results show the performance of the system.

This paper describes current progress in a project to develop robotic systems for locating underground chemical sources. There are a number of economic and humanitarian applications for this technology. Finding unexploded ordinance, land mines, and sources of leaks from pipes and tanks are some examples. Initial experiments were conducted using an ethanol chemical source buried in coarse sand. To gain an understanding of the sensory environment that would be experienced by a robot burrowing through the ground, the factors affecting transport of chemical vapour through soil were investigated. A robot search algorithrn was then developed for gathering chemical gradient inforrnation and using this to guide a robot towards the source. Experiments were performed using a chemical sensing probe positioned by a UMI RTX robot manipulator arm. The resulting system was successful in locating a source of ethanol vapour buried in sand. This paper includes details of experiments to characterise the sand used in this project, the robot search algorithm, sensor probe and results of source location trials.

This paper presents a control law for the tracking of a cyclic reference path by an under-actuated biped robot. The robot studied is a five-link planar biped. The degree of under-actuation is one during the single support phase. The control law is defined in such a way that only the geometric evolution of the biped configuration is controlled, but not the temporal evolution. To achieve this objective, we consider a parametrized control. When a joint path is given, a five degree of freedom biped in single support becomes similar to a one degree of freedom inverted pendulum. The temporal evolution during the geometric tracking is completely defined and can be analyzed through the study of a model with one degree of freedom. Simple analytical conditions, which guarantee the existence of a cyclic motion and the convergence towards this motion, are deduced. These conditions are defined on the reference trajectory path. The analytical considerations are illustrated with some simulation results.

We present a description of asymptotic behaviour of languages of bi-infinitewords obtained by iterating morphisms defined on free monoids.

We exhibit a new class of grammars with the help of weightfunctions. They are characterized by decreasing the weight during the derivation process. A decision algorithm for the emptiness problem is developed. This class contains non-contextfree grammars. The corresponding language class is identical to the class of ultralinear languages.

We provide alternative proofs and algorithms for resultsproved by Sénizergues on rational and recognizable freegroup languages. We consider two different approaches to the basicproblem of deciding recognizability for rational free group languagesfollowing two fully independent paths: the symmetrificationmethod (using techniques inspired by the study ofinverse automata and inverse monoids) andthe right stabilizer method (a general approach generalizable to otherclasses of groups). Several different algorithmic characterizations ofrecognizability are obtained, as well as other decidability results.

This paper establishes computational equivalence of two seemingly unrelated concepts:linear conjunctive grammars and trellis automata.Trellis automata, also studied under the name of one-way real-time cellular automata,have been known since early 1980s as a purely abstract model of parallel computers, whilelinear conjunctive grammars, introduced a few years ago, are linear context-free grammars extendedwith an explicit intersection operation.Their equivalence implies the equivalence of several other formal systems,including a certain restricted class of Turing machines and a certain type of language equations, thusgiving further evidence for the importance of the language family they all generate.

In 1978, Courcelle asked for a completeset of axioms and rules for the equational theory of (discrete regular) words equipped with the operations of product, omega power and omega-op power. In this paper we find a simple set of equationsand prove they are complete.Moreover, we show that the equational theory is decidable in polynomial time.

This paper presents a simple and powerful diagrammatic framework for dealing with specifications in computer science. Following a classical line, we define diagrammatic specifications as a kind of generalised sketch. In addition, the specifications themselves are defined as the realisations of projective sketches. This meta level provides adjunction properties: this is due to a well-known result of Ehresmann. Moreover, we prove in this paper that this meta level also provides an efficient definition of deduction. This work results from a collaboration with Christian Lair.

We address the question of injectivity of coherent semantics of linear logic proof-nets. Starting from Girard's definition of experiment, we introduce the key-notion of ‘injective obsessional experiment’, which allows us to give a positive answer to our question for certain fragments of linear logic, and to build counter-examples to the injectivity of coherent semantics in the general case.