The Portfolio Choice in Emergent Markets a Rational or a Behavioral Decision: a Cognitive Answer

The purpose of this study is to explore the relationship between the rational and the behavioral portfolio theories, two theories that describes the decision making process on the domain of portfolio choice, under investors' perception. This will offer a more realistic answer that describes the investors' decision on term of portfolio choice. Our sample contains 30 Tunisian investors who trade at the Tunisian stock exchange (BVMT). We introduce an approach based on cognitive mapping with a series of interviews. We combine both concepts that belong to the mean-variance and the behavioral approach and we explore the interactions between them. We introduce some new notions such as the zone of communication between the two cited theories and the variables of connection. We demonstrate that investors use the mean-variance theory of portfolio choice but they are affected by their cognitive biases and emotions when making their portfolio choice decision. Keywords: Mean-variance portfolio Choice, Behavioral Portfolio Choice, cognitive maps, areas of communication, concepts of connection

TEAM: a parameter-free algorithm to teach collaborative robots motions from user demonstrations

Learning from demonstrations (LfD) enables humans to easily teach collaborative robots (cobots) new motions that can be generalized to new task configurations without retraining. However, state-of-the-art LfD methods require manually tuning intrinsic parameters and have rarely been used in industrial contexts without experts. We propose a parameter-free LfD method based on probabilistic movement primitives, where parameters are determined using Jensen-Shannon divergence and Bayesian optimization, and users do not have to perform manual parameter tuning. The cobot's precision in reproducing learned motions, and its ease of teaching and use by non-expert users are evaluated in two field tests. In the first field test, the cobot works on elevator door maintenance. In the second test, three factory workers teach the cobot tasks useful for their daily workflow. Errors between the cobot and target joint angles are insignificant -- at worst 0.28 deg -- and the motion is accurately reproduced -- GMCC score of 1. Questionnaires completed by the workers highlighted the method's ease of use and the accuracy of the reproduced motion. Public implementation of our method and datasets are made available online.Comment: 8 pages, 4 figures, accepted to ICINCO202

Parallel robotics, from research to industry

New trends and impact of parallel robotics and machinery in industry

A Novel Verticalized Reeducation Device for Spinal Cord Injuries: the WalkTrainer, from Design to Clinical Trials

Non

Are Functional Measures Sufficient to Capture Acceptance? A Qualitative Study on Lower Limb Exoskeleton Use for Older People

Lower limb exoskeletons (LLE) are robotic devices developed to assist walk. In the field of healthcare, this technology has been available for almost a decade, yet it still faces important acceptance issues. While LLE were first developed for patients with spinal cord injuries, we expect their use to expand to everyday settings to benefit other populations, namely that of older people with reduced mobility (RM). We propose a qualitative approach to unearth key psychosocial themes on the acceptance of LLE in daily living for older people. The study analyses perceptions of older people with RM, as well as their entourage, including informal and professional caregivers. Using a grounded theory approach we analysed 12 semi-structured interviews with older people with RM; 2 focus groups with informal caregivers, and 2 focus groups with professional caregivers. LLE were introduced to participants through photo-elicitation. Older people with RM believed that LLE would increase their autonomy. They also perceived that using LLE would make them feel less of a burden for their entourage. Beyond these expected benefits, results captured participants' ambivalence, dependent on their experiences of the ageing process and perceptions on the human-machine interaction. Informal caregivers highlighted that LLE could provide important relief related to the burden of care. Nonetheless, professional caregivers raised the fear of LLE leading to dehumanization of care. While each group had specific concerns on how LLE use would impact their lives, psychosocial considerations played a key role in LLE acceptance

ExoRecovery: Push Recovery with a Lower-Limb Exoskeleton based on Stepping Strategy

Balance loss is a significant challenge in lower-limb exoskeleton applications, as it can lead to potential falls, thereby impacting user safety and confidence. We introduce a control framework for omnidirectional recovery step planning by online optimization of step duration and position in response to external forces. We map the step duration and position to a human-like foot trajectory, which is then translated into joint trajectories using inverse kinematics. These trajectories are executed via an impedance controller, promoting cooperation between the exoskeleton and the user. Moreover, our framework is based on the concept of the divergent component of motion, also known as the Extrapolated Center of Mass, which has been established as a consistent dynamic for describing human movement. This real-time online optimization framework enhances the adaptability of exoskeleton users under unforeseen forces thereby improving the overall user stability and safety. To validate the effectiveness of our approach, simulations, and experiments were conducted. Our push recovery experiments employing the exoskeleton in zero-torque mode (without assistance) exhibit an alignment with the exoskeleton's recovery assistance mode, that shows the consistency of the control framework with human intention. To the best of our knowledge, this is the first cooperative push recovery framework for the lower-limb human exoskeleton that relies on the simultaneous adaptation of intra-stride parameters in both frontal and sagittal directions. The proposed control scheme has been validated with human subject experiments.Comment: Submitted for a conference. 8 pages including references, 8 figure

Profibus PC based motion control with application to a new 5 axes parallel kinematics

Generally the classical control architecture used to carry out a robot position control is based on a classical industrial motion planner that needs encoders cabling and analog cabling to insure the regulation loop. This work proposes a Profibus PC based control architecture that has a double-originality. The first originality concerns the hardware architecture and the second concerns the software flexibility that allows easiness in implementation, either modification, for controlling parallel robots. The hardware architecture is based upon so-called “intelligent” digital drives and the whole fieldbus hardware

Maximizing Performance with Minimal Resources for Real-Time Transition Detection

Assistive devices, such as exoskeletons and prostheses, have revolutionized the field of rehabilitation and mobility assistance. Efficiently detecting transitions between different activities, such as walking, stair ascending and descending, and sitting, is crucial for ensuring adaptive control and enhancing user experience. We here present an approach for real-time transition detection, aimed at optimizing the processing-time performance. By establishing activity-specific threshold values through trained machine learning models, we effectively distinguish motion patterns and we identify transition moments between locomotion modes. This threshold-based method improves real-time embedded processing time performance by up to 11 times compared to machine learning approaches. The efficacy of the developed finite-state machine is validated using data collected from three different measurement systems. Moreover, experiments with healthy participants were conducted on an active pelvis orthosis to validate the robustness and reliability of our approach. The proposed algorithm achieved high accuracy in detecting transitions between activities. These promising results show the robustness and reliability of the method, reinforcing its potential for integration into practical applications.Comment: Submitted for a conference. 7 pages including references, 8 figures, 3 table