Legged Robots for Object Manipulation: A Review

Legged robots can have a unique role in manipulating objects in dynamic, human-centric, or otherwise inaccessible environments. Although most legged robotics research to date typically focuses on traversing these challenging environments, many legged platform demonstrations have also included "moving an object" as a way of doing tangible work. Legged robots can be designed to manipulate a particular type of object (e.g., a cardboard box, a soccer ball, or a larger piece of furniture), by themselves or collaboratively. The objective of this review is to collect and learn from these examples, to both organize the work done so far in the community and highlight interesting open avenues for future work. This review categorizes existing works into four main manipulation methods: object interactions without grasping, manipulation with walking legs, dedicated non-locomotive arms, and legged teams. Each method has different design and autonomy features, which are illustrated by available examples in the literature. Based on a few simplifying assumptions, we further provide quantitative comparisons for the range of possible relative sizes of the manipulated object with respect to the robot. Taken together, these examples suggest new directions for research in legged robot manipulation, such as multifunctional limbs, terrain modeling, or learning-based control, to support a number of new deployments in challenging indoor/outdoor scenarios in warehouses/construction sites, preserved natural areas, and especially for home robotics.Comment: Preprint of the paper submitted to Frontiers in Mechanical Engineerin

TeNWs/Ti₃C₂T<i>_x</i> Nanohybrid-Based Flexible Pressure Sensors for Personal Safety Applications Using Morse Code

This report demonstrates the fabrication and development of a tellurium nanowire (TeNW) and MXene (Ti3C2Tx) nanohybrid-based pressure sensor. The fabricated sensor was later encapsulated in poly(dimethylsiloxane) (PDMS) and used as buttons for the communication system to demonstrate a personal safety application using Morse code. The fabricated pressure sensor demonstrated an excellent sensitivity of 9.29241 kPa–1 and stability withstanding over ∼3000 cycles of applied pressure (∼1.729 kPa). Real-time ultraviolet photoelectron spectroscopy (UPS) is utilized for realizing the band diagram of the TeNWs/Ti3C2Tx nanohybrid to understand the transport of charge carriers upon external pressure. The transduction mechanism of the fabricated pressure sensor is explained using the improved intrinsic piezoresistive properties of the MXene and TeNWs in TeNWs/Ti3C2Tx, which helps in increasing the tunneling current by a decrease in the effective interlayer resistance/interwire tunneling distance of the nanohybrid. Further, an Android application was created to wirelessly receive data via Bluetooth from the sensors connected to a microcontroller. The application displayed the pattern pressed on the sensors as a Morse dash or dot. This can further be used in a similar fashion to that of a telegraph to send complex messages such as “HELP”. Developing a TeNWS/Ti3C2Tx nanohybrid-based flexible sensor opens many possible wireless monitoring and communication applications

Dissecting the binding mechanism of the linker histone in live cells: an integrated FRAP analysis

The linker histone H1 has a fundamental role in DNA compaction. Although models for H1 binding generally involve the H1 C-terminal tail and sites S1 and S2 within the H1 globular domain, there is debate about the importance of these binding regions and almost nothing is known about how they work together. Using a novel fluorescence recovery after photobleaching (FRAP) procedure, we have measured the affinities of these regions individually, in pairs, and in the full molecule to demonstrate for the first time that binding among several combinations is cooperative in live cells. Our analysis reveals two preferred H1 binding pathways and we find evidence for a novel conformational change required by both. These results paint a complex, highly dynamic picture of H1–chromatin binding, with a significant fraction of H1 molecules only partially bound in metastable states that can be readily competed against. We anticipate the methods we have developed here will be broadly applicable, particularly for deciphering the binding kinetics of other nuclear proteins that, similar to H1, interact with and modify chromatin

Price discrimination in service industries

This article outlines recent methods and applications directed at understanding the profit and consumer welfare implications of increasingly prevalent price discrimination strategies in the service sector. These industries are typically characterized by heterogeneity in consumers’ valuation and usage of the service, resale constraints, and a focus on price as the service’s key attribute. The article focuses on how firms use nonlinear pricing or bundling strategies to benefit from the heterogeneity in consumer demand. We describe the basic economic model commonly used in the literature to analyze such strategic choices and present recent methodological improvements to this benchmark. A discussion of existing applications and future research opportunities concludes the article