A Novel Wearable Apparatus to Measure Fingertip Forces in Manipulation Tasks Based on MEMS Barometric Sensors

MEMS-Based Tactile Sensors: Materials, Processes and Applications in Robotics

Commonly encountered problems in the manipulation of objects with robotic hands are the contact force control and the setting of approaching motion. Microelectromechanical systems (MEMS) sensors on robots offer several solutions to these problems along with new capabilities. In this review, we analyze tactile, force and/or pressure sensors produced by MEMS technologies including off-the-shelf products such as MEMS barometric sensors. Alone or in conjunction with other sensors, MEMS platforms are considered very promising for robots to detect the contact forces, slippage and the distance to the objects for effective dexterous manipulation. We briefly reviewed several sensing mechanisms and principles, such as capacitive, resistive, piezoresistive and triboelectric, combined with new flexible materials technologies including polymers processing and MEMS-embedded textiles for flexible and snake robots. We demonstrated that without taking up extra space and at the same time remaining lightweight, several MEMS sensors can be integrated into robotic hands to simulate human fingers, gripping, hardness and stiffness sensations. MEMS have high potential of enabling new generation microactuators, microsensors, micro miniature motion-systems (e.g., microrobots) that will be indispensable for health, security, safety and environmental protection.

Multi-Physical Models of Bending Characteristics on the Double-Clamped Beam Switch for Flexible Electronic Devices Application

In this paper, multi-physical models of bending characteristics, including the static, dynamic and microwave models, are firstly proposed for the double-clamped beam switch based on flexible substrate. Both simulated and experimental verification have been carried out to prove that the changing regularity of the driving voltage and time of the switch is inversely proportional with the increase in the bending curvature of the flexible substrate. The microwave performance of the switch at the ON state is found to get worse with the increase in the bending curvature. The measured results indicate that when the bending curvature increases from 0 m⁻¹ to 28.6 m⁻¹, the measured driving voltage decreases from 90.0 V to 72.6 V with the error of 5.9% compared with the calculated results. The measured driving time decreases from 52.4 μs to 35.6 μs with the error of 16.7% compared with the calculated results. When the substrate bending curvature increases from 0 m⁻¹ to 28.6 m⁻¹, the measured reflection loss S₁₁ of the switch gradually deteriorates from −27.1 dB to −22.0 dB with the error of 1.3 dB corresponding to the calculated results at 10 GHz. All the simulated and experimental results are consistent with the theoretical calculated results.

Flexible Tactile Sensor Array for Slippage and Grooved Surface Recognition in Sliding Movement

Flexible tactile sensor with contact force sensing and surface texture recognition abilities is crucial for robotic dexterous grasping and manipulation in daily usage. Different from force sensing, surface texture discrimination is more challenging in the development of tactile sensors because of limited discriminative information. This paper presents a novel method using the finite element modeling (FEM) and phase delay algorithm to investigate the flexible tactile sensor array for slippage and grooved surfaces discrimination when sliding over an object. For FEM modeling, a 3 × 3 tactile sensor array with a multi-layer structure is utilized. For sensor array sliding over a plate surface, the initial slippage occurrence can be identified by sudden changes in normal forces based on wavelet transform analysis. For the sensor array sliding over pre-defined grooved surfaces, an algorithm based on phase delay between different sensing units is established and then utilized to discriminate between periodic roughness and the inclined angle of the grooved surfaces. Results show that the proposed tactile sensor array and surface texture recognition method is anticipated to be useful in applications involving human-robotic interactions.

Measurement of Dorsal First Ray Mobility: A Topical Historical Review and Commentary

Despite evidence that instability of the first ray (first metatarsal and medial cuneiform) alters the loading mechanics of the foot, surprisingly few studies have linked the condition with disorders of the foot. A factor limiting this research is the difficulty associated with measuring first ray mobility (FRM). To quantify dorsal FRM, clinicians and researchers have devised a variety of methods that impose a dorsally directed load, and record displacement. The methods include manual examination, radiographs, mechanical devices, and handheld rulers. Since different methods yield different results; each of these methods is worthy of scrutiny. This article reviews the methods used to quantify dorsal FRM and offers commentary on how the testing procedures could be standardized. The measurement of dorsal FRM informs surgical decisions, orthotic prescriptions, and research design strategies mostly as it pertains to the identification and treatment of first ray hypermobility. This review found sufficient support to recommend continued use of radiographs and mechanical devices for quantifying dorsal displacement, whereas measurements acquired with handheld rulers are prone to the same subjective error attributed to manual examination procedures. Since measures made with radiographs and existing mechanical devices have their own drawbacks, the commentary recommends ideas for standardizing the testing procedure and calls for the development of a next-generation device to measure dorsal FRM. This future device could be modeled after arthrometers that exist and are used to quantify stability at the knee and ankle. Level of Evidence: Level V, expert opinion.