Colab NAS: Obtaining lightweight task-specific convolutional neural networks following Occam's razor

The current trend of applying transfer learning from convolutional neural networks (CNNs) trained on large datasets can be an overkill when the target application is a custom and delimited problem, with enough data to train a network from scratch. On the other hand, the training of custom and lighter CNNs requires expertise, in the from-scratch case, and or high-end resources, as in the case of hardware-aware neural architecture search (HW NAS), limiting access to the technology by non-habitual NN developers. For this reason, we present ColabNAS, an affordable HW NAS technique for producing lightweight task-specific CNNs. Its novel derivative-free search strategy, inspired by Occam's razor, allows to obtain state-of-the-art results on the Visual Wake Word dataset, a standard TinyML benchmark, in just 3.1 GPU hours using free online GPU services such as Google Colaboratory and Kaggle Kernel

Introducing wearable haptics for rendering velocity feedback in VR serious games for neuro-rehabilitation of children

Rehabilitation in virtual reality offers advantages in terms of flexibility and parametrization of exercises, repeatability, and continuous data recording and analysis of the progress of the patient, also promoting high engagement and cognitive challenges. Still, most of the proposed virtual settings provide a high quality, immersive visual and audio feedback, without involving the sense of touch. In this paper, we show the design, implementation, and first evaluation of a gaming scenario for upper limb rehabilitation of children with cerebral palsy. In particular, we took care to introduce haptic feedback as a useful source of sensory information for the proposed task, considering—at the same time—the strict constraints for haptic wearable devices to comply with patient’s comfort, residual motor abilities, and with the embedded tracking features of the latest VR technologies. To show the potential of haptics in a rehabilitation setup, the proposed device and rendering method have been used to improve the velocity control of upper limb movements during the VR exercise, given its importance as a motor recovery metric. Eight healthy participants were enrolled, and results showed that haptic feedback can lead to lower speed tracking errors and higher movement smoothness, making the proposed setup suitable to be used in a rehabilitation context as a way to promote movement fluidity during exercises

a Soft Hand Exoskeleton With a Novel Tendon Layout to Improve Stable Wearing in Grasping Assistance

: We present a novel soft exoskeleton providing active support for hand closing and opening. The main novelty is a different tendon routing, folded laterally on both sides of the hand, and adding clenching forces when the exoskeleton is activated. It improves the stability of the glove, diminishing slippage and detachment of tendons from the hand palm toward the grasping workspace. The clenching effect is released when the hand is relaxed, thus enhancing the user's comfort. The alternative routing allowed embedding a single actuator on the hand dorsum, resulting more compact with no remote cable transmission. Enhanced adaptation to the hand is introduced by the modular design of the soft polymer open rings. FEM simulations were performed to understand the interaction between soft modules and fingers. Different experiments assessed the desired effect of the proposed routing in terms of stability and deformation of the glove, evaluated the inter-finger compliance for non-cylindrical grasping, and characterized the output grasping force. Experiments with subjects explored the grasping performance of the soft exoskeleton with different hand sizes. A preliminary evaluation with Spinal Cord Injury patients was useful to highlight the strengths and limitations of the device when applied to the target scenario

A Mechanical Hand-Tracking System with Tactile Feedback Designed for Telemanipulation

: In this paper, we present a mechanical hand-tracking system with tactile feedback designed for fine manipulation in teleoperation scenarios. Alternative tracking methods based on artificial vision and data gloves have become an asset for virtual reality interaction. Yet, occlusions, lack of precision, and the absence of effective haptic feedback beyond vibrotactile still appear as a limit for teleoperation applications. In this work, we propose a methodology to design a linkage mechanism for hand pose tracking purposes, preserving complete finger mobility. Presentation of the method is followed by design and implementation of a working prototype, and by evaluation of the tracking accuracy using optical markers. Moreover, a teleoperation experiment involving a dexterous robotic arm and hand was proposed to ten participants. It investigated the effectiveness and repeatability of the hand tracking with combined haptic feedback during a proposed pick and place manipulation tasks

Rendering tiny tactile signals through a miniaturized, self contained hydraulic haptic thimble

<p>Poster presentation at IRIM3D conference, dealing with a miniature hydraulic actuator based on a linear electromagnetic motor with an embedded ferrofluidic sealing (remarkably it shows no static friction and the output force can be scaled by hydraulic reduction principles) applied for haptic rendering in virtual reality and telemanipulation.</p&gt

CORA hand: a 3D printed robotic hand designed for robustness and compliance

This work presents design and experimental evaluation of CORA (COmpliant Robotic hAnd), a robotic hand designed for easy manufacturing and maintenance, and for robustness and compliance in real operational environments. It takes advantage of recent soft-polymer printable filaments to obtain intrinsic compliance during grasping and accidental contacts. All parts are designed and optimized for manufacturing with conventional fused deposition modeling 3D printers, in order to allow simple fabrication and replacement of parts. In this paper design of the CORA hand is presented, focusing on specific design solutions adopted for improving robustness of the final 3D printed parts and for obtaining compliance in interaction with the environment. A prototype of the CORA hand was built and experimentally tested in terms of grasping capabilities, measuring contact forces and the distributed grasping pressure. Compliance introduced by soft polymer links was evaluated with finite element method simulation and experimental bending tests. A collision test evidenced robustness of the finger mechanism and transmission to pronounced passive deformations, induced by lateral contacts possibly occurring in common manipulation tasks

A survey on innovative refreshable braille display technologies

This works presents a survey on recent technologies applied for Refreshable Braille Displays (RBD): these devices allow the dynamic rendering of refreshable Braille characters, analogously to a computer monitor rendering text and other visual information. Although commercially available RBD share a similar technology based on piezo actuators, and feature a single line of characters at a relatively high cost, alternative solutions have been proposed in recent years. They include adaptation of existing actuators and technologies to the rendering of Braille, and innovative materials used for developing actuators appositely designed for RBDs. In this survey, we compare performance of the above methods analyzing potential benefits and limitations of the different technologies

A passive and scalable magnetic mechanism for braille cursor, an innovative refreshable braille display

In this work, we present the design and experimental analysis of a novel mechanism for a refreshable braille display (RBD). It implements a single actuated slider for refreshing braille cells composed of simple and passive ferromagnetic pins. The approach potentially decouples the cost of the final device from the number of braille cells and pins. In this work, we present the rationale of the actuating method and a design solution implemented in a working prototype of the mechanism. Experimental characterization supported by FEM analysis provided a clearer view of the interacting forces and dynamics of the tactile pins refreshing cycle, and allowed to improve calibration and performance with respect to previous preliminary results. Such knowledge can be transferred to full-size refreshable braille display prototypes. A final cost and scalability analysis, and comparison with conventional RBDs devices highlights limits and potentials of the proposed method, in particular for implementation of large RBDs and tactile matrices

A Miniature Direct-Drive Hydraulic Actuator for Wearable Haptic Devices based on Ferrofluid Magnetohydrodynamic Levitation

<p>Hydraulic and pneumatic actuators in haptics offer the advantage of soft and compliant interfaces, with the drawback of cumbersome driving devices and limited modulation capabilities. We propose a miniature hydraulic actuator based on a linear electromagnetic motor with an embedded ferrofluid sealing. The solution has two main advantages: it shows no static friction due to the magnetohydrodynamic levitation effect of the ferrofluid, and the output force can be scaled (by varying the radius of the actuator) without introducing noise and friction of mechanical reduction mechanisms. Moreover, soft and compliant interfaces in the form of actuated pouches can be obtained on wearable devices with embedded actuators. As a concept prototype, we present here a compact and soft haptic thimble integrating the proposed actuator: experimental characterization at the bench, and perception experiments with the final prototype, evaluate the low-noise rendering capability of the method.</p&gt