Rover System Research Articles

Shape effects of wheel grousers on traction performance on sandy terrain

This paper presents the effects of different wheel grouser shapes on the traction performance of a grouser wheel traveling on sandy terrain. Grouser wheels are locomotion gears that allow small and lightweight exploration rovers to traverse on the loose sand on extraterrestrial surfaces. Although various grouser shapes have been analyzed by some research groups, a more synthetic and direct comparison of possible grousers is required for practical applications. In this study, we developed a single wheel testbed and experimentally investigated the effects of four grouser shapes (parallel, slanted, V-shaped, and offset V-shaped) on the traction performance of linear movement on flat sand. The wheel slip, sinkage, traction and side force acting on the wheel axle, the wheel driving torque, and the efficiency of each wheel were examined. Thereafter, the effects on the lateral slope traversability of a small and lightweight four-wheeled rover with different grouser shapes were also examined. The traversability experiment demonstrated the vehicle mobility performance in order to contribute to the design optimization of rover systems. These experimental results and their comparisons suggested that, of the shapes studies herein, the slanted shape was the optimal grouser design for use in wheeled rovers on lunar and planetary soil.

Minimal vision system for linear camera self-calibration and 3D reconstruction using translation platform

Camera calibration and 3D reconstruction are two crucial steps in computer vision. With the progress of robot and autonomous rover systems, zooming cameras are widely applied, where online calibration and 3D reconstruction are becoming more and more important. This paper proposed a minimal vision system that consists of a translation platform and an un-calibrated camera mounted on. With this minimal system, we can linearly calibrate the camera online and reconstruct 3D structures from three un-calibrated images by utilizing translation motions. The two images generated by translating the camera to allow the recovery of scene depths. Depths are then analyzed by error analysis models and are utilized to determine the infinite homography between the third image and any of the two translated images. The intrinsic parameters are then calibrated linearly from the computed infinite homography. Camera motion estimation and 3D reconstruction are then readily determined from the intrinsic calibration results. We also proposed a two-step optimization method to refine both the calibration and 3D reconstruction results by minimizing the overall back-projection errors across the three images within a tiny-scale bundle adjustment framework. The proposed method has been validated with both simulation and real image data. The results demonstrate that the proposed minimal linear system can solve the online camera self-calibration problem and the reconstruction of 3D structure. The paper suggests a framework of minimal linear system by using an un-calibrated camera and a low-cost translation platform to address the problems of linear self-calibration of camera, motion estimation, 3D reconstruction, and optimization, in a practical, easy, and accurate way.

Design of a Portable Soil Analysis Instrument for Remote Teleoperated Rover Platforms

The search for extant life has long been an interest since people have been able to successfully explore other worlds. However, on space missions, experiments must be performed autonomously, with limited resources, and a carefully selected suite of instruments. Instruments are additionally constrained by weight, reliability, and size which limits use of many modern advanced systems. The Queen’s Space Engineering Team (QSET) is proposing the design of a portable (12” x 12” x 12”) instrument to identify signs supporting extant life aboard a mobile rover platform during exploration missions. The instrument will receive soil samples collected by the rover, analyse the composition to identify key molecules, and transmit data back to a ground station. This system relies on colorimetric measurements using a UV-VIS spectrometer and features a solvent recycle system to minimize weight and waste. This project is part of a larger environment characterisation module to be mounted on a Mars rover system designed for competition at the University Rover Challenge (URC) at the Mars Desert Research Station (MDRS) in Utah. As of this date, each subsystem has successfully passed performance testing and the entire instrument is entering its system-level prototyping stage.

Optimal Traction Forces for Four-Wheel Rovers on Rough Terrain

This paper addresses the minimization of the risk of wheel slippage for a popular class of rovers. In the absence of any constraints on the system (e.g., force/torque balance and maximum motor torques), the optimal traction solution is known to be that with equal “friction requirements” (ratios of tractive to normal force) for all wheels. Nevertheless, the current state of the art is to routinely perform computationally expensive constrained optimization because of the presumed importance of the constraints in a real system. The contribution of this paper is a thorough investigation of the configuration space for four-wheel rovers, driving straight over rough terrain, in search of configurations where the unconstrained optimal answer does or does not satisfy the constraints, and, thus, is or is not valid. Equal “friction requirements” are added to the four-wheel rover's system of quasi-static equations and a valid solution is sought to this augmented system of equations. It is found that the equal “friction requirements” solution is almost always valid, except for the case where two of the wheels are wedged against opposing vertical faces, a highly unusual and unlikely scenario. Therefore, we can conclude that computationally expensive constrained optimization is not required to achieve traction control for four-wheel rovers.

Free-space Polygon Creation based on Occupancy Grid Maps for Trajectory Optimization Methods

Abstract In this paper, we present a strategy for incorporating occupancy grid maps into local trajectory optimization methods to allow for safe autonomous navigation. We construct polygons as surface representations of the locally visible area and merge them with the aid of third-party software to form connected free-spaces. The method can be applied to any two-dimensional environments and different representations of vehicle dimensions. It allows direct optimization methods to be used consistently for different problem levels from control to planning. The strategies developed are applied to a rover system that moves in the plane. We evaluate our algorithms on the basis of simulation results and real-world experiments.

Early Mass Diagnosis of Fusarium Wilt in Banana Cultivations using an E-Nose Integrated Autonomous Rover System

Nucleic acid based diagnostics are the standard means for diagnosis of infected plant material. However, these methods are expensive and time-consuming, but they are accurate. On the contrary, disease prediction methods based on Volatile organic compound (VOC) emission from plants are less accurate but, allow for screening of large volumes of samples. This work reports the methodology for development of an inexpensive electronic nose for implementation as early warning systems intended to prevent plant disease outbreaks using VOC pattern analysis. It is proven that plants emit VOCs in response to pathogenic attacks. In this project, efforts were made to register the pattern of VOCs released by the diseased plants. The disease taken for this purpose was Fusarium wilt disease of banana. The E-Nose was successfully fabricated using five MOS sensors connected to a microcontroller, which along with a microSD card module was able to store the acquired VOC data. The VOC data analysis was done in MS-Excel, using NeuroXL Predictor, a neural networking add-in. A small scale banana field containing 35 plants, divided into disease, test and control groups, was established. The disease and test sets were subjected to similar disease induction protocols and VOC data was collected over a period of 40 days. NeuroXL Predictor was trained to recognize odours corresponding to diseases by feeding the neural network with the disease set VOC data. Finally, the training model was validated by providing the test set VOC data to the neural network and the results were found to be accurate. Efforts were made to automate the VOC data acquisition from the plants, as it will be impractical to carry around, a device, through several hectares of plantation. Therefore, a simple autonomous rover was fabricated using DC motors connected to a microcontroller. A DC motor placed on top was used to move the E-nose towards the plants in left and right of the rover. The microcontroller was programmed to stop, move forward and turn the E-nose towards left or right as per the measurements of the field.Int. J. Appl. Sci. Biotechnol. Vol 5(2): 261-266

AUTONOMY AND PATH PLANNING IN A PLANETARY ROVER

In this paper we present the autonomous and path planning functionalities of a Planetary Rover system. In order to make the Rover system completely independent of human intervention, a high level of navigational autonomy is desirable. Sun sensing and topographical properties are the two factors that are considered here as the Rover navigational aid. Autonomous hazard avoidance can be achieved using a stereo camera which evaluates terrain safety and to avoid obstacles.

Mineralogy and astrobiology detection using laser remote sensing instrument.

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100 m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20 km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters.

Hierarchical approach to fingerprint of places based real-time topological mapping for autonomous rovers

Autonomous navigation in partially known or unknown environment requires the ability of in motion mapping and localisation. Exploratory rovers employ a hybrid mapping approach comprising of locally metric and globally topological maps to meet resource constraints imposed by the payload. In this paper, we discuss a hierarchical fingerprint of places based approach to generating topological maps using a single camera mounted on the rover. We propose a novel feature extraction process for generation of the finger prints in a monocular vision framework. Each place is characterised by a multi-level hierarchical fingerprint which provides better localisation and loop closure detection. We use a two-pronged strategy for evaluating the performance of this approach: firstly, using standard datasets provided by different universities and secondly, in-situ validation on our experimental rover in indoor and outdoor environments. The proposed algorithm is amenable to real-time implementation in resource constrained rover systems. The comparison of the proposed method with those in literature brings out the computational attractiveness for real-time implementation.

Seeker—Autonomous Long‐range Rover Navigation for Remote Exploration

Under the umbrella of the European Space Agency (ESA) StarTiger program, a rapid prototyping study called Seeker was initiated. A range of partners from space and nonspace sectors were brought together to develop a prototype Mars rover system capable of autonomously exploring several kilometers of highly representative Mars terrain over a three‐day period. This paper reports on our approach and the final field trials that took place in the Atacama Desert, Chile. Long‐range navigation and the associated remote rover field trials are a new departure for ESA, and this activity therefore represents a novel initiative in this area. The primary focus was to determine if current computer vision and artificial intelligence based software could enable such a capability on Mars, given the current limit of around 200 m per Martian day. The paper does not seek to introduce new theoretical techniques or compare various approaches, but it offers a unique perspective on their behavior in a highly representative environment. The final system autonomously navigated 5.05 km in highly representative terrain during one day. This work is part of a wider effort to achieve a step change in autonomous capability for future Mars/lunar exploration rover platforms.

An Event Bridge Framework for Modeling and Simulating Networked Hybrid Dynamic Behaviors

Typical CPS system composes of large scale of smart physical nodes communicated by kinds of network, while each node shows certain hybrid dynamic behavior. Their dynamic behavior features with networked mix of discrete time-driven cyber behavior and continuous time-driven physical behavior, complicating the modeling and simulating of the entire CPS behavior during the design and analysis. In this paper, an event bridge framework is proposed, extending the composition semantics of the hybrid automata, to capture the communication relationship among CPS nodes as well as the transmission delay properties. First, the event bridge model is given and a rail control system is taken as an example to explain its conciseness; second, a modeling and simulating framework is designed and implemented according to the event bridge model, where the dynamic behavior of each node is required to be modeled as an event-driven state chart; finally, the framework is applied in the rail control system and the lunar rover system, and the results show that it is effective both in networked hybrid physical behaviors and in networked cyber physical behaviors.

Accuracy Estimation of TOPCON GRS-1 GNSS Receiver Parameters in Static and Dynamic Mode

This article describes some of the testing results for TOPCON Geodetic Rover System’s (GRS-1) Global Navigation Satellite System (GNSS) receiver in static and dynamic modes. First of all, our attention was focused on estimation of accuracy for GRS-1 receiver in static mode. Then we tried to evaluate these characteristics of the receiver in dynamic mode. Also, the article includes the results of inertial system possibilities to improve vehicle position estimates and movement parameters when the satellite signal is unavailable. DOI: http://dx.doi.org/10.5755/j01.eee.20.2.6385

VARIANCE ROVER SYSTEM: WEB ANALYTICS TOOL USING DATA MINING

Learning Analytics by nature relies on computationa l information processing activities intended to ext ract from raw some interesting aspects that can be used to obtain insi ghts into the behaviors of learners, the design of learning experiences, etc. There is a large variety of computational techniques that can be employed, all with interesting properties, but ithe interpretation of their results that really forms the core of the analytics process. As a rising subject, mining and busi ness intelligence are playing an increasingly important role in the decision support activity of every walk of life. The Variance Rover System (VRS) mainly focused on the large sets obtained from online web visiti ng and categorizing this into clusters according so me similarity and the process of predicting customer behavior and selecting actions to influence that behavior to benefit the company, so as to take optimized and beneficial decisions of business expansion. With the tremendous competition in the domestic and international business, Data Analytics has become o ne of matters of concern to the enterprise. This importan t concept has been given a new lease of life because of the g rowth of the Internet and E-business. Data analysis takes Data a t the center. It gives a new life to the enterprise organization system and optimizes the business process. Data Mining Can be Used in Various business application for different purposes such as decision support system, customer retention strategies ,selective marketing, business management user profile analysis to name a few. Data mining is the process of discovering the knowledge. In today's electronic information era it becomes highly challenged to dig ital firms to manage customer to retrieve useful informat ion as per their requirement from that data, so market segment ation can be used. Market segmentation also include customer retention strategies, allocation of resources for advertising , to check profit margins so outcome of segmentation plays bi g role in deciding price of the products, attracting new cust omers and identifying potential customers. Clustering analysi s is able to find out distribution and proper inter relatio nship between items clustering is defined as grouping of si milar data .Clustering splits records in the database or objects in the dataset into series of meaningful subclasses or gro up. Data mining is basically a useful process in which forma tion which is incomplete and random that has been generated fr om various business tasks such as production, marketin g, customer services of the enterprise. 1.1 Necessity The focus area of this system is market research an d analysis. It is a web-based application and aims at determini ng target markets and consumer density and identifying potential customers. We have used the concept of Cluster anal ysis for the same. This application will help determine the user's browsing details and monitor customer population. Web User analysis is a simple template that provides a graph ical, time- phased overview of process in terms of conceptual d esign, mission, analysis, and definition phases.

Curiosity's Fault Tolerant Wakeup and Shutdown Design

Curiosity spends roughly 70% of the day “sleeping”, in order to recharge the batteries from the nuclear power source. The system is designed to ensure the Rover goes to sleep and wakes back up to continue science and engineering activities. Additionally, the design is robust to off-nominal situations that may need additional actions performed by both hardware and software to ensure the Rover can communicate with the Earth. This paper describes nominal and off-nominal behavioral patterns, fault tolerance features designed into the Rover system (hardware and software), several off-nominal scenarios that are accommodated by the design, and some lessons learned from this development effort.

A Simulation Kernel for Lunar and Planetary Rover System

A Simulation Kernel for Lunar and Planetary Rover System

Applied design methodology for lunar rover elastic wheel

In recent years an increasing interest in the Moon surface operations has been experienced. In the future robotic and manned missions of Moon surface exploration will be fundamental in order to lay the groundwork for more ambitious space exploration programs. Surface mobility systems will be the key elements to ensure an efficient and safe Moon exploration. Future lunar rovers are likely to be heavier and able to travel longer distances than the previously developed Moon rover systems. The Lunar Roving Vehicle (LRV) is the only manned rover, which has so far been launched and used on the Moon surface. Its mobility system included flexible wheels that cannot be scaled to the heavier and longer range vehicles. Thus the previously developed wheels are likely not to be suitable for the new larger vehicles.Taking all these considerations into account, on the basis of the system requirements and assumptions, several wheel concepts have been discussed and evaluated through a trade-off analysis. Semi-empirical equations have been utilized to predict the wheel geometrical characteristics, as well as to estimate the motion resistances and the ability of the system to generate thrust. A numerical model has also been implemented, in order to define more into the details the whole wheel design, in terms of wheel geometry and physical properties. As a result of the trade-off analysis, the ellipse wheel concept has shown the best behavior in terms of stiffness, mass budget and dynamic performance.The results presented in the paper have been obtained in cooperation with Thales Alenia Space-Italy and Sicme motori, in the framework of a regional program called STEPS11STEPS–Sistemi e Tecnologie per l'EsPlorazione Spaziale is a research project co-financed by Piedmont Region and firms and universities of the Piedmont Aerospace District in the ambit of the P.O.R-F.E.S.R. 2007–2013 program. .

Integration of multiple acoustic and language models for improved Hindi speech recognition system

Despite the significant progress of automatic speech recognition (ASR) in the past three decades, it could not gain the level of human performance, particularly in the adverse conditions. To improve the performance of ASR, various approaches have been studied, which differ in feature extraction method, classification method, and training algorithms. Different approaches often utilize complementary information; therefore, to use their combination can be a better option. In this paper, we have proposed a novel approach to use the best characteristics of conventional, hybrid and segmental HMM by integrating them with the help of ROVER system combination technique. In the proposed framework, three different recognizers are created and combined, each having its own feature set and classification technique. For design and development of the complete system, three separate acoustic models are used with three different feature sets and two language models. Experimental result shows that word error rate (WER) can be reduced about 4% using the proposed technique as compared to conventional methods. Various modules are implemented and tested for Hindi Language ASR, in typical field conditions as well as in noisy environment.

1A2-L11 次世代小天体探査ローバにおける移動メカニズム(【宇宙工学部門】宇宙工学とロボティクス・メカトロニクス(1))

The authors are involved in the development of a tiny rover system onboard "Hayabusa-2" spacecraft which is scheduled to launch in 2014 for the Near Earth asteroid "1999JU3." The development of Hayabusa-2 started very urgently after its predecessor spacecraft "Hayabusa" made a self-sacrificing reentry into the Earth in 2010. The authors have a heritage how to develop a surface exploration rover through the experience on "MINERVA" rover in Hayabusa mission. But the rover system for Hayabusa-2 is a brand-new one since it is designed to fit the new target asteroid, of which surface environment and conditions are different from those of the previous one. The mobile system of the primary rover has the same strategy on its hopping movement as MINERVA, but is slightly different on the configuration of the actuators. This paper describes the mobile system of the primary rover onboard Hayabusa-2.

Kinematic Discussion and Development of a Multi-Legged Planetary Exploration Rover with an Isotropic Leg Arrangement

This study deals with a multi-legged planetary rover with a spherically isotropic leg arrangement. The legged rover is a reliable rover system for exploration on rough terrains, because it can continue walking even after overturning. Moreover, the legged rover can also show a rotational motion by utilizing its isotropic shape. This paper discusses the walking performance of two types of rover shapes: one has a six-leg arrangement based on a regular octahedron and the other has an eight-leg arrangement based on a regular hexahedron. The design procedure of the proposed rover is explained, and a test-bed system, which is developed to demonstrate the fundamental motions, is also presented.

Applicability of an X-ray and gamma-ray portable spectrometer for activity measurement of environmental soil samples

This paper presents a study on the applicability of a commercial X-ray and gamma-ray portable spectrometer (Rover) for in situ gamma-ray spectrometry. This portable spectrometer consists of a 3 × 3 × 1 mm (CdTe) Cadmium Telluride detector and a 30 × 30 mm [NaI (Tl)] Sodium Iodide detector. The radioactive sources used were 241Am, 133Ba, 152Eu and 137Cs tablet type, sealed with aluminum and polyethylene, as well as soil samples contaminated with 137Cs. With the aid of these radioactive sources, this study determined the efficiency curve for both detectors. In addition, measurements were carried out to identify the minimum detectable activity (MDA) for both detectors, using time acquisition change ranging from 900 s to 138 h, depending on which detector was utilized and the sample distance. The results for the tablet-type sources were as follows: The MDA for the CdTe detector, while positioned 4.15 cm from the 137Cs source, was 15 kBq and 6 kBq for energy lines 32 keV and 661.65 keV, respectively. However, when the distance between the source and detector was 100 cm, the 661.65 keV line presented a MDA of 68 kBq. Results for the soil samples were as follows: Using the CdTe detector, positioned 4.15 cm from the source, the MDA was 73 Bq for the 137Cs 32 keV line. In relation to the 7Be soil samples, the MDA was 301 Bq when the detector was 4.15 cm from the source. Using the NaI (Tl) detector to analyze the 137Cs 661.65 keV line, the MDA was 8 kBq when the detector was 100 cm from the tablet-type source. For the soil sample containing 137Cs, the MDA was 7.4 Bq when the source was 2.8 cm from the NaI (Tl) detector. For those samples containing 7Be, and measured at the same distance (2.8 cm), the MDA was of 9.6 Bq. Based on the minimum detected activities obtained for both detectors, it is concluded that the in situ gamma-ray spectrometric system used to quantify soil sample activities with 137Cs and 7Be is only appropriate when those activities are around one or more orders of magnitude larger than the usual radioactivity levels found in the environment. Even though it is a commercialized machine, the Rover system’s manufacturer does not provide the information cited in this abstract.