Adaptive Locomotion of Soft Microrobots
Networked Control and Communication
Controller Learning using Bayesian Optimization
Event-based Wireless Control of Cyber-physical Systems
Model-based Reinforcement Learning for PID Control
Learning Probabilistic Dynamics Models
Gaussian Filtering as Variational Inference
Perceptual Integration of Contact Force Components During Fingertip Sliding
]. The change in the amplitude of the force vector predicted participants' responses better than the change of the coefficient of dynamic friction, suggesting that intensive tactile cues are meaningful in this task.
Humans need to accurately process the contact forces that arise as they perform everyday haptic interactions such as sliding the fingers along a surface to feel for bumps, sticky regions, or other features. Several different mechanisms are possible for how the forces on the skin could be represented and integrated in such interactions. Forces on the finger could also be of several types: frictional, kinesthetic, normal. Each force type will target specific afferents within the fingerpad, eliciting different neural codes. These applied forces can also result either from conscious decision (often the case for the normal force) or from the bilateral interaction with the touched object or surface (typically the case of friction that depends on both the material properties and touch characteristics).
To investigate the respective contibution of different force types to the human feeling of tactile pressure on a surface, we built an apparatus that could independently modulate each of these forces. This cutting-edge tool combined the force-controlled displacement capacities of an industrial robot with a mounted display capable of finger-surface friction modulation through ultrasonic lubrication.
This experimental setup enabled us to show that humans are up to three times less sensitive to brief variations of normal force compared to similar variations in friction or lateral force regardless of the stickiness of the touched surface []. After that, we also showed that despite the difference in sensitivity, human perception of tactile pressure relied equally on the normal and lateral components of the contact force. Support vector machine analysis of participants psychophysical responses suggested that the sense of touch most probably relied on the amplitude of the three-dimensional force vector applied on the fingerpad rather than on the coefficient of dynamic friction [].
This research project involves collaborations with Julien Lambert (Institute of Neuroscience of UCLouvain) and Jean-Louis Thonnard (Institute of Neuroscience of UCLouvain).
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