Differential game theory for versatile physical human-robot interaction

The last decades have seen a surge of robots working in contact with humans. However, until now these contact robots have made little use of the opportunities offered by physical interaction and lack a systematic methodology to produce versatile behaviours. Here, we develop an interactive robot controller able to understand the control strategy of the human user and react optimally to their movements. We demonstrate that combining an observer with a differential game theory controller can induce a stable interaction between the two partners, precisely identify each other’s control law, and allow them to successfully perform the task with minimum effort. Simulations and experiments with human subjects demonstrate these properties and illustrate how this controller can induce different representative interaction strategies

Locomotor adaptation to a powered ankle-foot orthosis depends on control method

<p>Abstract</p> <p>Background</p> <p>We studied human locomotor adaptation to powered ankle-foot orthoses with the intent of identifying differences between two different orthosis control methods. The first orthosis control method used a footswitch to provide bang-bang control (a kinematic control) and the second orthosis control method used a proportional myoelectric signal from the soleus (a physiological control). Both controllers activated an artificial pneumatic muscle providing plantar flexion torque.</p> <p>Methods</p> <p>Subjects walked on a treadmill for two thirty-minute sessions spaced three days apart under either footswitch control (n = 6) or myoelectric control (n = 6). We recorded lower limb electromyography (EMG), joint kinematics, and orthosis kinetics. We compared stance phase EMG amplitudes, correlation of joint angle patterns, and mechanical work performed by the powered orthosis between the two controllers over time.</p> <p>Results</p> <p>During steady state at the end of the second session, subjects using proportional myoelectric control had much lower soleus and gastrocnemius activation than the subjects using footswitch control. The substantial decrease in triceps surae recruitment allowed the proportional myoelectric control subjects to walk with ankle kinematics close to normal and reduce negative work performed by the orthosis. The footswitch control subjects walked with substantially perturbed ankle kinematics and performed more negative work with the orthosis.</p> <p>Conclusion</p> <p>These results provide evidence that the choice of orthosis control method can greatly alter how humans adapt to powered orthosis assistance during walking. Specifically, proportional myoelectric control results in larger reductions in muscle activation and gait kinematics more similar to normal compared to footswitch control.</p

Passive Upper Limb Exoskeletons: An Experimental Campaign with Workers

Wearable exoskeletons are currently evaluated as technological aids for workers on the factory floor, as suggested by the philosophy of Industry 4.0. The paper presents the results of experimental tests carried out on a first prototype of a passive upper limbs exoskeleton developed by IUVO. Eighteen FCA workers participated to the study. Experimental tests were designed to evaluate the influence of the exoskeleton while accomplishing different tasks, both in static and dynamic conditions. Quantitative and qualitative parameters were analyzed to evaluate usability, potential benefits and acceptability of the device. Results show, on average, that wearing the exoskeleton has a positive effect in increasing: (i) endurance time while holding demanding postures with raised arms and/or having to lift and hold small work tools, (ii) endurance time and accuracy execution in precision tasks. The users also declared a lower perceived effort, while performing tasks with the exoskeleton

Dimension Reduction of Anthropometric Measurements with Support Vector Machine for Regression: Application to a French Military Personnel Database

International audienceCollecting anthropometric data is a heavy and time-consuming procedure. The aim of this study was to find a reduced set of anthropometric measurements able to estimate the full-body dimensions of a given individual. The method was developed and applied on a database of 122 measurements carried out on 459 females and 771 males of the French military personnel. Among the 122, 26 key measurements were chosen. A regression method based on support vector machine was used to predict these key measurements in relation to each other. The designed "minimal measurement set selecting algorithm" chose 6 main inputs to predict the remained 20 measurements with mean correlation of 0.94 and 0.92, respectively on the training and on the testing data. This result tends to prove that the regression method can be used to predict the French military personnel anthropometrics

Analysis of Exoskeleton Introduction in Industrial Reality: Main Issues and EAWS Risk Assessment

Exoskeletons are part of the technological and organizational innovation sought by the fourth industrial revolution to support and re-launch the manufacturing area. In the present study, we described the experimental protocol designed to test the usability and acceptance of an upper limbs passive exoskeleton. In total, 42 workers from FCA plants volunteered to participate in the research study. The testing campaign included static and dynamic tests aimed at evaluating the potential benefit of the exoskeleton (lessen muscle strain, higher comfort rating and dexterity) vs. possible restrictions to movements and workdevice interactions in tasks resembling work activities. Open questions remain on how to assess the biomechanical workload risk, especially in the design phase, for which holistic methods like EAWS are needed