Figure 1: Photograph captured during one of our missions at the Mars Desert Research Station, depicting an environment characterized by extreme constraints, isolation, and confinement, with harsh conditions that can affect physical and psychological well-being.Note the deserted landscape, the strong sunlight, and the bulky equipment.In this setting, closely mimicking a Mars analog environment, we conducted two user experience studies exploring various pragmatic and hedonic dimensions of interaction with computer systems, with a baseline represented by user experience measured in a conventional environment.

Humans consider the parameters linked to movement goal during reaching to adjust their control strategy online. Indeed, rapid changes in target structure or disturbances interfering with their initial plan elicit rapid changes in behavior. Here, we hypothesize that these changes could result from the continuous use of a decision variable combining motor and cognitive components. We combine an optimal feedback controller with a real-time evaluation of the expected cost-to-go, which considers target- and movement-related costs, in a common theoretical framework. This model reproduces human behaviors in presence of changes in the target structure occurring during movement and of online decisions to flexibly change target following external perturbations. It also predicts that the time taken to decide to select a novel goal after a perturbation depends on the amplitude of the disturbance and on the rewards of the different options, which is a direct result of the continuous monitoring of the cost-to-go. We show that this result was present in our previously collected dataset. Together our developments point towards a continuous evaluation of the cost-to-go during reaching to update control online and make efficient decisions about movement goal.

Judging by the breadth of our motor repertoire during daily activities, it is clear that learning different tasks is a hallmark of the human motor system. However, for reaching adaptation to different force fields, the conditions under which this is possible in laboratory settings have remained a challenging question. Previous work has shown that independent movement representations or goals enabled dual adaptation. Considering the importance of force feedback during limb control, here we hypothesised that independent cues delivered by means of background loads could support simultaneous adaptation to various velocity-dependent force fields, for identical kinematic plan and movement goal. We demonstrate in a series of experiments that indeed healthy adults can adapt to opposite force fields, independently of the direction of the background force cue. However, when the cue and force field were in the same direction but differed by heir magnitude, the formation of different motor representations was still observed but the associated mechanism was subject to increased interference. Finally, we highlight that this paradigm allows dissociating trial-by-trial adaptation from online feedback adaptation, as these two mechanisms are associated with different time scales that can be identified reliably and reproduced in a computational model.

Current research on discrete and rhythmic movements differs in both experimental procedures and theory, despite the ubiquitous overlap between discrete and rhythmic components in everyday behaviors. Models of rhythmic movements usually use oscillatory systems mimicking central pattern generators (CPGs). In contrast, models of discrete movements often employ optimization principles, thereby reflecting the higher-level cortical resources involved in the generation of such movements. This letter proposes a unified model for the generation of both rhythmic and discrete movements. We show that a physiologically motivated model of a CPG can not only generate simple rhythmic movements with only a small set of parameters, but can also produce discrete movements if the CPG is fed with an exponentially decaying phasic input. We further show that a particular coupling between two of these units can reproduce main findings on in-phase and antiphase stability. Finally, we propose an integrated model of combined rhythmic and discrete movements for the two hands. These movement classes are sequentially addressed in this letter with increasing model complexity. The model variations are discussed in relation to the degree of recruitment of the higher-level cortical resources, necessary for such movements.

The paper considers the feedback stabilization of periodic orbits in a planar juggler. The juggler is “blind,” i.e, he has no other sensing capabilities than the detection of impact times. The robustness analysis of the proposed control suggests that the arms acceleration at impact is a crucial design parameter even though it plays no role in the stability analysis. Analytical results and convergence proofs are provided for a simplified model of the juggler. The control law is then adapted to a more accurate model and validated in an experimental setup.

The paper studies the properties of a sinusoidally vibrating wedge billiard as a model for 2-D bounce juggling. It is shown that some periodic orbits that are unstable in the elastic fixed wedge become exponentially stable in the nonelastic vibrating wedge. These orbits are linked with certain classical juggling patterns, providing an interesting benchmark for the study of the frequency-locking properties in human rhythmic tasks. Experimental results on sensorless stabilization of juggling patterns are described.

This paper describes a coding format in SGML for the output of a document recognition prototype. Our proposal is a DTD named "ODIL"-Office Document Image description Language-that describes precisely the layout structure of a document after all recognition phases, including OCR. All layout objects of a document are defined in the form of SGML elements, and their characteristics are defined by SGML attributes. The basic objects are blocks, containing homogeneous information. Five types of information are supported by the ODIL language: texts, photos, line graphics, tables, mathematic formulas. The ODIL representation of the recognition results is well adapted to a further logical structure recognition. Starting from the ODIL DTD and using the RAINBOW transit DTD will permit to use SGML tools for the logical structure recognition which is viewed as an SGML up-conversion problem.

The authors study internal-model representations in the framework of control theory and of visual system modelling. It is shown that the control of rapid orienting movements of the visual axis in space (saccadic system) can be modelled as a control system based on internal models. Moreover, a fuzzy approach is found to be very well adapted for the modelling of some parts of the saccadic system (related to highly nonlinear sensors and/or internal representations). Classical properties of this control structure such as robustness and disturbance rejection are met.>