Kinematics and Robot Design IV, KaRD2021

This volume collects the papers published on the special issue “Kinematics and Robot Design IV, KaRD2021” (https://www.mdpi.com/journal/robotics/special_issues/KaRD2021), which is the forth edition of the KaRD special-issue series, hosted by the open-access journal “MDPI Robotics”. KaRD series is an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”. KaRD2021, after the peer-review process, accepted 12 papers. The accepted papers cover some theoretical and many design/applicative aspects

A Novel Transformer-Based IMU Self-Calibration Approach through On-Board RGB Camera for UAV Flight Stabilization

During flight, unmanned aerial vehicles (UAVs) need several sensors to follow a predefined path and reach a specific destination. To this aim, they generally exploit an inertial measurement unit (IMU) for pose estimation. Usually, in the UAV context, an IMU entails a three-axis accelerometer and a three-axis gyroscope. However, as happens for many physical devices, they can present some misalignment between the real value and the registered one. These systematic or occasional errors can derive from different sources and could be related to the sensor itself or to external noise due to the place where it is located. Hardware calibration requires special equipment, which is not always available. In any case, even if possible, it can be used to solve the physical problem and sometimes requires removing the sensor from its location, which is not always feasible. At the same time, solving the problem of external noise usually requires software procedures. Moreover, as reported in the literature, even two IMUs from the same brand and the same production chain could produce different measurements under identical conditions. This paper proposes a soft calibration procedure to reduce the misalignment created by systematic errors and noise based on the grayscale or RGB camera built-in on the drone. Based on the transformer neural network architecture trained in a supervised learning fashion on pairs of short videos shot by the UAV’s camera and the correspondent UAV measurements, the strategy does not require any special equipment. It is easily reproducible and could be used to increase the trajectory accuracy of the UAV during the flight

A Wide Area Multiview Static Crowd Estimation System Using UAV and 3D Training Simulator

Crowd size estimation is a challenging problem, especially when the crowd is spread over a significant geographical area. It has applications in monitoring of rallies and demonstrations and in calculating the assistance requirements in humanitarian disasters. Therefore, accomplishing a crowd surveillance system for large crowds constitutes a significant issue. UAV-based techniques are an appealing choice for crowd estimation over a large region, but they present a variety of interesting challenges, such as integrating per-frame estimates through a video without counting individuals twice. Large quantities of annotated training data are required to design, train, and test such a system. In this paper, we have first reviewed several crowd estimation techniques, existing crowd simulators and data sets available for crowd analysis. Later, we have described a simulation system to provide such data, avoiding the need for tedious and error-prone manual annotation. Then, we have evaluated synthetic video from the simulator using various existing single-frame crowd estimation techniques. Our findings show that the simulated data can be used to train and test crowd estimation, thereby providing a suitable platform to develop such techniques. We also propose an automated UAV-based 3D crowd estimation system that can be used for approximately static or slow-moving crowds, such as public events, political rallies, and natural or man-made disasters. We evaluate the results by applying our new framework to a variety of scenarios with varying crowd sizes. The proposed system gives promising results using widely accepted metrics including MAE, RMSE, Precision, Recall, and F1 score to validate the results

Epigenetic transcriptional regulation in Friedreich’s Ataxia

The Frataxin gene is pathologically partially silenced causing the neurodegenerative disorder, Friedreich’s Ataxia (FRDA). The occurrence of the GAA trinucleotide expansion within intron 1 has been shown to invoke several epigenetic mechanisms associated with gene silencing. In this thesis I have investigated the effect on the pathological silencing of frataxin through alteration of potential key regulators of gene expression. The occurrence of stochastic silencing of eye colour within the Drosophila eye following translocation of the white gene, which encodes eye colour, near a region of silent chromatin (heterochromatin) led to the description of position effect variegation (PEV). The ability to induce PEV of transgene expression in a mammalian system through the addition of GAA repeats to the 3’ end of the transgene was the first insight that PEV may be implicated in frataxin gene silencing. Furthermore, several regulators of PEV were identified in Drosophila screens. With the potential dynamic silencing mechanisms implicated in FRDA and the occurrence of PEV modifiers, I have assessed the effect in mammalian systems of altering the dosage of these modifiers using mouse transgenic models and human cell lines. These experiments have underlined the multifactorial and combinatorial nature of frataxin gene silencing, suggesting that the ability to concomitantly address several layers of silencing may be required to result in significant de-repression. Knockdown or knockout of the archetypal modifiers of PEV, SUV39H1, SUV39H2 (histone methyltransferases) as well as the polycomb silencing factor BMI1 did not significantly alter frataxin expression in vitro or in vivo. The histone deacetylase, nicotinamide has been shown to upregulate frataxin expression in FRDA. As yet the specific target of nicotinamide is not known. IRF I forgive you, but I won’t forget. Knockdown of one potential target of nicotinamide, the histone deacetylase SIRT1, did not alter frataxin expression. Recent discovery of a group of proteins that modify human PEV (the HUSH complex and histone methyltransferase, SETDB1) provided further potential targets for assessment as FRDA modifiers. Knockdown of the relatively recently identified histone lysine methyltransferase, SETDB1, did show a trend towards frataxin upregulation in both stable and transient knockdowns. Given the genome-wide effects of the knockout and knockdown methodologies, CRISPR based genome engineering technology was utilised to attempt to directly edit the frataxin epigenome with locus-specific targeting of transcriptional activators (dCas9-VPR), the histone acetyltransferase (dCas9-p300) and dominant-negative histone tail peptides (dCas9-H3KM). Downstream of the GAA repeat dCas9-VPR resulted in a trend towards upregulation. dCas9-p300 targeting the upstream region of the GAA resulted in a trend towards upregulation in both disease and control lines. Transient overexpression of H3.3 and H3K27M upregulated frataxin expression. I will carry this work forward to further establish the effect of several targeted epigenome modifiers at the frataxin locus during my postdoctoral fellowship.Open Acces

Aerial Vehicles

This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space