ABSTRACT. The Hourglass mission has been conducted to investigate the gravitational dependence of basic parameters for reproduction of behavior of granular materials such as regolith and ground sand, and to obtain information that contributes to future spacecraft design. In the Hourglass mission, the behaviors of regolith and ground sand in an arbitrary gravity environment are observed with an artificial gravity generator included in the Cell Biology Experiment Facility (CBEF) in the Kibo module of the International Space Station (ISS). The purpose of this mission is to investigate the effect of low gravity on the properties of granular materials. An hourglass-type container and a measuring-cylinder-type container including particles such as simulated regolith of planets and ground sand are packed into a sealed metal box mounted on the artificial gravity generator. The behavior of particles is observed with an optical camera while the containers are periodically flipped under arbitrary low gravity. Eight kinds of specimens are employed for the target samples, and dynamic behavior and sedimentation state (bulk density, angle of repose, etc.) of these granular materials are evaluated. Hourglass mission would have the contribution of understanding of the celestial growth process, provision of basic data for the construction of terramechanics on celestial bodies, optimization of design for future landers, exploration rovers, automatic construction machines on the lunar surface and manned pressurized rover for lunar exploration, and the appeal of the value and ability of Kibo artificial gravity environment. This presentation outlines the Hourglass mission, from start-up to development, and provides application examples of the results obtained.

ABSTRACT. Gravity-dependent characteristics of regolith, fine-grained granular media covering extraterrestrial surfaces, are essential for reliable design and feasible operation of space probes. Parabolic flight or drop tower facilities for simulating reduced gravity experiments on Earth can only perform short test durations and a limited number of tests with less quality artificial gravity. A numerical simulation requires an accurate interaction model of space probe and regolith. Further, the model parameters must be carefully identified for verification and validation. Therefore, the experimental dataset of granular media under stable reduced gravity is essential for solving the abovementioned issues.

We performed a granular flow experiment under varied artificial gravity generated by a centrifuge on the International Space Station. An hourglass-shaped apparatus containing granular media was used to observe the granular flow in high-quality, long-term, and stable gravity conditions. We also performed a numerical simulation that calculates the granular flow in both artificial and natural gravity environments. The simulation verifies that the granular flow at the hourglass’s orifice in artificial gravity is equivalent to natural gravity. The mass flow rate of the granular media measured from the experiment follows a well-known physics-based law, while some deviations are found in low- and micro-gravity conditions. The deviation implies that the bulk density of the granular media decreases as the gravity decreases. This finding provides a useful insight that improved simulation of space probes in reduced gravity can be realized by reducing the bulk density of the granular media, resulting in reliable design and analysis of the space probes.

ABSTRACT. Analyzing the mobility of wheeled rovers on loose sand in low-gravity environments remains a significant challenge. Among several experimental techniques, such as parabolic flight and reduced-weight tests, granular scaling laws (GSL) have recently been proposed to predict wheel mobility under low-gravity conditions via earth-gravity tests. Although the GSL accurately predicts the wheel mobility on flat terrain in low-gravity environments, its capability to predict the wheel mobility on slopes in such environments still needs to be verified. In this study, we developed a GSL and investigated its accuracy for predicting wheel mobility on slopes in low-gravity environments. The discrete element method (DEM) was utilized to test wheel mobility at various slope angles under Earth’s gravity. Subsequently, by applying a multiple scaling function, the GSL converted the results from the Earth-gravity tests to predict the wheel mobility under lunar gravity. The GSL-based predictions were compared with DEM simulations conducted under lunar gravity conditions. The results indicated that the wheel mobility under lunar gravity predicted by the GSL closely corresponded to that calculated via the DEM. These findings indicate that the GSL can accurately predict wheeled-rover mobility on slopes in low-gravity environments.

ABSTRACT. The exploration of the lunar surface requires a wide range of mobility, thus wheeled mobile robots, called rovers, which are capable of traveling on the loose soil, called lunar regolith. To investigate the traction performance of wheels on such loose soil, it is essential to consider the multi-pass effect. That is the influence to the wheel’s traction performance due to the alteration in the soil property caused by the previous wheel’s traveling (compaction and digging). The single-wheel testing is helpful to analyze the driving performance of a wheel. In this study, the soil with a cohesive property and heterogeneity in particle size and shape, which offers a nonlinear characteristics of lunar regolith, is prepared in the sandbox of the single-wheel testbed. To investigate the multi-pass effect, Toyoura sand, which is a non-cohesive and homogeneous sand, is compared with the lunar regolith simulant: FJS-1. This paper presents the experimental results of a repetitive running experiment conducted to measure the multi-pass effect. In this experiment, the wheel was run 5 times in a row over the same area from the same direction, and the traction coefficient, sinkage, and the shear strength of the soil were measured each time. This experiment was also conducted under several conditions by varying the vertical load applied to the wheel and the slip ratio. The wheel employed in the experiments is the same model of grouser wheels as installed on the Rashid Rover that was actually planned to be deployed on the lunar exploration mission. The results revealed that the soil compaction was observed only at a deep level of FJS-1 sand. This is because FJS-1 sand flows in shallow locations due to the action of the grouser, on the other hand, Toyoura sand has no adhesive force.

ABSTRACT. Simulation of vehicle motion in planetary environments is challenging. This is due to the modeling of complex terrain, optical conditions, and terrain-aware vehicle dynamics. One of the critical issues of typical simulators is that they assume terrain is a rigid body, which limits their ability to render wheel traces and compute the wheel-terrain interactions. This prevents, for example, the use of wheel traces as landmarks for localization, as well as the accurate simulation of motion. In the context of lunar regolith, the surface is not rigid but granular. As such, there are differences in the rover's motion, such as sinkage and slippage, and a clear wheel trace left behind the rover, compared to that on a rigid terrain. This study presents a novel approach to integrating a terramechanics-aware terrain deformation engine to simulate a realistic wheel trace in a digital lunar environment. By leveraging Discrete Element Method simulation results alongside experimental single-wheel test data, we construct a regression model to derive deformation height as a function of contact normal force. The region of interest in a height map is retrieved from the wheel poses. The elevation values of corresponding pixels are subsequently modified using contact normal forces and the regression model. Finally, we apply the determined elevation change to each mesh vertex to render wheel traces during runtime. The deformation engine is integrated into our ongoing development of a lunar simulator based on NVIDIA's Omniverse IsaacSim. We hypothesize that our work will be crucial to testing perception and downstream navigation systems under conditions similar to outdoor or terrestrial fields. A demonstration video is available here: https://www.youtube.com/watch?v=TpzD0h-5hv4

ABSTRACT. This study focuses on the locomotion characteristics of a high-speed lunar exploration rover. On the loose soil such as lunar regolith, wheeled mobility systems often encounter wheel sinkage and slippage, leading to trafficability challenges. While conventional exploration rovers are designed to improve mobility using grouser wheels, their exploration speed remains relatively slow (~10^-2 m/s). High-speed traversal is essential for expanding exploration areas in future missions. In this paper, we conduct single-wheel tests under high-speed conditions and provide detailed results from force measurements. Three types of wheels are prepared: no grouser, low grouser, and high grouser, and their traction performance are compared. The testbed allows speeds of 1 m/s, which is about a hundred times faster than conventional exploration speeds. We measured traction coefficients (the ratio of drawbar pull to vertical load) and traction efficiency (the ratio of input energy to output energy) for variable slip ratios to assess traction performance. Our results revealed a trend where traction performance decreases as driving velocity increases. This behavior of performance at various speeds differs from that at low speeds. Each performance exhibited substantial dependence on the slip ratio, with efficiency peaking around a slip ratio of approximately 5% to 10%. Additionally, experiments varying grouser height under identical driving conditions demonstrated improved traction performance with higher grouser wheels. Through this experimental evaluation, we confirmed the effectiveness of grouser wheels even at high speeds. These terramechanical findings contribute to the wheel design and locomotion control of next-generation exploration rovers.

ABSTRACT. Soil cutting and throwing behavior during rotary tillage is useful to evaluate the mechanical design of the tillage blade. For this reason, several evaluation methods have been proposed in the past. In this study, a device to measure the angular velocity and acceleration of soil clods was fabricated in a laboratory test. The measured soil cutting and throwing behavior was compared with the behavior computed by the three-dimensional discrete element method (DEM), and the validity was also evaluated. As a result, it was found that the soil cutting and throwing behavior obtained by the inertial measurement device almost agreed with that obtained by the image analyses. Furthermore, the soil cutting motion by the rotary tillage blade differed between the measured results and the 3D DEM analysis results.

ABSTRACT. In these days, construction sites are facing workforce shortages caused by declining labor and lack of young workers. Therefore, “Improve Productivity” is very important. Automation and autonomy of construction machinery is one of the solutions. As above, ICT hydraulic excavators and bulldozers are widely used in many sites, but the scope of the application is limited. In particularly, automated digging in hydraulic excavators still has many difficulties in actual use. The root cause is needed to the complicated operation during digging affected by the soil conditions. Since the soil conditions change anytime, if the operation is not adjusted to match to them, the efficiency will be decreased significantly. In other words, to achieve automated digging, the machine must recognize variation of soil conditions first. While digging, the operator has been sensing the machine's response affected by the soil conditions to consider it and adjusting machine operation simultaneously. In other words, human senses were used to recognized soil conditions to perform efficient operations. In that case, we thought that if we could replace human senses with internal sensors of the machine, the machine could recognize the soil conditions by itself. In this study, based on this hypothesis, we conducted measuring sensor data during digging in various soil conditions (e.g. hardness, materials…). The test results indicated that the soil hardness measured by simplified N-value meter, has a high correlation with the work efficiency and bucket tooth speed calculated from internal sensor data. This implicated that the sensor data from the excavator can be used to be determine soil conditions. In addition, there is a possibility that machine could recognize soil conditions by itself.

ABSTRACT. In the road-subbase reclamation method, a stabilizer's rotor bits (teeth) are rotated to crush deteriorated asphalt pavement in-situ while mixing it with additives such as cement and asphalt emulsion, which are then compacted with rollers to create a new, stable subbase. The uniformity and the quality of crushing and mixing is affected by the shape and arrangement of the rotor bits, rotational speed, and working speed. Therefore, it is important to understand the behavior of the crushed materials. However, since those actual behaviors inside the rotor hood cannot be observed, an attempt was made to analyze and visualize particle behaviors using the three-dimensional discrete element method (3D-DEM). In this study, an actual stabilizer was used to crush and mix the deteriorated pavement layer in a test section to compare with the analysis results. The surface of the test section was painted with spray paint in six different colors, square grid lines were drawn with white chalk, and a total of 780 numbered stickers were pasted within each grid. After the mixing test, all particles with the numbered stickers were recovered (these particles are called as “marking particles” hereafter), and the moving distance in the front-back direction were measured and a number of particles distributed in the left-right direction was counted. Test results show that about 80% of the crushed marking particles are blown away once and deposited behind the rotor, never to be mixed again. The number of marking particles counted in the left-right direction was similar and uniform. Since the test results were generally similar to the 3D-DEM results, it was concluded that this analytical method is capable of simulating the behavior of crushed material in the rotor hood.

ABSTRACT. Diesel engines are commonly found in off-road, agricultural and forestry equipment because of giving the best option in terms of weight, range and fuel storage. Given the current potential of electric powertrains, in this area, electrification does not seem to be competitive in the near future. Regulations tighthening for on road (EURO7) and non-road vehicles (Tier 4, Stage V) in many parts of the world and tends increasingly focusing on to ensure that as many as possible of the vehicles with low or no emission standard can be retrofitted to reach decreasing emissions. The overwhelming majority of vehicles fall into this category, around the world. Retrofitting should be as simple and cost-effective as possible. One such option could be the retrofitting with water injection systems. The exhaust gas recirculation (EGR) achieves the lower temperature required for reduced nitrogen-oxide (NOx) emissions by reducing the oxygen content and thus impairing combustion, water injection achieves this essentially by enriching the charge air and thus increasing its heat capacity and by the heat dissipation effect of the liquid-vapour phase change. Contrary to common belief, the two techniques are not only able to reduce NOx separately, but also together they cause further emission reductions on NOx and on other emission components. This has been shown through the use of practical applications, as the operation of EGR and water injection is linked to different engine operating conditions. This is also an important achievement, as it means that when the water injection system is installed in an existing vehicle, after that only software intervention is needed to make the system work properly and reach the emission reductions.

ABSTRACT. Even though regulations in the European Union talk about banning the registration of combustion cars after 2035, yet no such regulations have been introduced in other parts of the globe. The rapidly changing economic and political situation creates many complications for business including the automotive sector. Tests were carried out on a CI engine with a common rail injection system and an additional hydrogen system. Hydrogen was injected sequentially into the intake manifold with an injector opening time of 3 ms at a pressure of 0.115 MPa. The energy and ecological parameters of the engine installed in the Fiat Qubo were recorded in a mapped WLTC test on a MAHA chassis dynamometer. The effect of adding hydrogen on the above-mentioned parameters was analyses in relation to the use of diesel fuel alone. The use of hydrogen for co-firing with diesel can contribute to extending the life of current compression-ignition engines.

ABSTRACT. A review of the literature shows that the use of hydrogen improves the energy performance of an internal combustion engine. These properties are of interest in the context of improving the combustion processes of vegetable oils. Tests were carried out on a 1.3 Multijet compression-ignition engine built in a Fiat Qubo, which was fuelled with four different mixtures: diesel with hydrogen, diesel with LPG, rapeseed oil with 10% n-hexane solution, rapeseed oil with 10% n-hexane solution and hydrogen. The diesel engine, with a common-rail injection system, was adapted to run on various liquid fuels and an additional gaseous fuel supply system. While running on the MAHA chassis dynamometer, power and torque measurements were taken. The injection control parameters were also recorded each time. The results of the tests were synthesised in the context of the influence of the alternative fuel used on the injection control and the energy parameters achieved.

ABSTRACT. Bridgestone Corporation is taking on the challenge of developing tires for lunar vehicles. In this development, evaluating the tire traveling performance on the soft soil of the lunar surface is important because it is nearly impossible to conduct pre-testing using actual tires under actual conditions. Therefore, we are developing both experimental and simulation technologies for performance evaluation. In this presentation, we will explain two testing devices developed by Bridgestone Corporation for evaluating the performance, including examples of measurement results. The first device is an indoor installation type that uses scaled-down model tires. The device incorporates special features to simulate various traveling conditions such as constant slip ration mode, cornering, and climbing. The second device is an outdoor testing type that allows for testing with tires equivalent in size to those used on lunar vehicles. This device is portable and can be taken to various testing sites. Additionally, while conducting outdoor tests, it can reproduce steady-state traveling conditions which are important for accurate evaluations of tire traveling performance. Furthermore, in this presentation, we will briefly introduce the evaluation technology that combines experiments and simulation using the extended terramechanics model proposed by the Ozaki Laboratory at Division of System Research, Faculty of Engineering, Yokohama National University, with whom we are conducting joint research.

ABSTRACT. An image analysis procedure was proposed and adapted in this study to obtain rover wheel performance by analyzing wheel tread images remained on the surface of lunar simulant soil. Wheel-soil interaction is usually simulated by using Bevameter test results and adapting sinkage model such as Bekker’s and Wong and Reece methods. However, the pressure-sinkage models obtained from the Bevameter test do not clearly provide in-detail information about sinkage and slip of the wheel when a rover runs on loose and fine dry soil. The wheel tread images captured by a camera mounted on the single wheel tracking device were analyzed successfully by using a specific pattern recognition procedure that is composed of Gabor wavelet filter, Principal Component Analysis (PCA), and Support Vector Machine (SVM). Next, We do successfully develop a required scheme of machined learning that was used to obtain an improved calculated torque of the wheel that is required for the next movement of the rover running on lunar terrain.

ABSTRACT. Lunar infrastructure construction involves leveling of the lunar surface and collecting lunar regolith as a building material. RASSOR 2.0 developed by NASA is one of the typical robotic vehicles as a lunar excavator. It features cylindrical rotating bucket drums for collecting regolith, positioning it as a pivotal tool for future lunar in-situ resource utilization and infrastructure development. However, the optimization of the bucket drum’s shape and its motion remain as open issue. Therefore, this study aims to find an optimal design of the bucket drum through numerical simulation using the discrete element method (DEM). We introduce five key design parameters of the bucket drum: two of them are related to the bucket shape (scoop throat length, scoop inlet number) and the rest of them are to motion (bucket vertical force, horizontal velocity, and angular velocity). These five parameters were examined in accordance with two performance indices: the sand fill ratio in the drum and the power consumption of the excavation. Solving the multi-objective problem of increasing the fill ratio and reducing power consumption, we found an optimal bucket drum shape and motion. Subsequently, a bucket drum reflecting the optimal shape was fabricated, and the optimal motion was tested. The test results qualitatively matched with the results derived from the DEM analysis. This outcome highlights the validity of the relationship between the design parameters and two performance indices.

ABSTRACT. We describe modeling and simulation approaches used to investigate the operation of NASA’s Regolith Advanced Surface Systems Operations Robot (RASSOR) excavator while operating in lunar gravitational environments. With a total mass of 66 kg, RASSOR is equipped with four wheels and two arms, each of the latter connected with a rotating bucket drum for soil excavation. The design compensates for the low mass and low gravitational pull by digging using two counter-rotating bucket drums. The rover can raise its drums when transporting the soil, and it unloads the material by reversing the drum's rotation at destination. We simulate digging operations at two levels of fidelity using Project Chrono, an open-source multi-physics simulation platform that provides terramechanics modeling, robot modeling, sensor models, and a ROS2 autonomy stack for synthesizing RASSOR’s autonomy in simulation.

We discuss two terrain modeling techniques – the Continuum Representation Method (CRM) and the Discrete Element Method (DEM). CRM employs the μ(I)-rheology model for describing the elasto-plastic behavior of the granular material, with the partial differential equations for the mass, momentum, and Cauchy rate of change spatially-discretized via the Smoothed Particle Hydrodynamics (SPH) method. The interaction between the implement and terrain is captured using Boundary Conditions Enforcement (BCE) markers. Unlike CRM, DEM represents the terrain discretely, by describing frictional contact forces at particle level. In this study, we compare the CRM and DEM results in terms of accuracy and time to solution.

ABSTRACT. Surveying is necessary before anything can be built on the Moon. Exploration Architecture Corp. (XArc) proposed that geotechnical surveying on the Moon could be performed with a SurveyorBot; a robot equipped with cone penetrometers and seismic instruments. This research consists of development and testing of a mini dynamic cone penetrometer (Mini-DCP) with variable impact energy. The Mini-DCP acts both as a penetrometer and a seismic source, that is used in tandem with seismic instruments – geophones. Experiments are performed at the Extraterrestrial Environmental Simulation (EXTERRES) laboratory at the Andy Thomas Centre for Space Resources at the University of Adelaide. The experiments are performed to test the hammering energies that are required for the Mini-DCP to both penetrate the soil at a certain speed and for the seismic signal to be detectable at certain distances. Hammering energies that are too large penetrate through the soil too fast, not providing enough data about the layering. But hammering energies that are too low produce seismic waves that are too weak to be detected. Exact values depend on many parameters of the soil (e.g. relative density, cohesion), environment (e.g. atmosphere, gravity), and instruments (e.g. cone shape and size, instrument mass). Several of these parameters are being explored in this research. Mini-DCP testing as a penetrometer and a seismic source are performed using Lunar Highlands simulant (LHS-1E) in the regolith pit at the EXTERRES lab. AKNOWLEDGEMENTS This work supported by NASA under contract award Number 80NSSC23PB427. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NASA.

ABSTRACT. The lunar surface is covered by a thick layer of soil known as regolith, which remains largely unexplored from a soil mechanics perspective. Additionally, significant uncertainties exist in geology and topography, posing risks to the safety and efficiency of lunar surface operations. Effective geotechnical risk assessment and management are essential for the safe planning and execution of lunar activities. To address these challenges, we are developing an unmanned exploration robot, named the Robotic Geotechnical Investigation System (RGIS), aimed at gathering critical data on the lunar surface. The RGIS is equipped with four key components: (1) a positioning and surveying system for detailed micro-topography measurements, (2) an active seismic survey system to investigate subsurface stratigraphy and bulk density distribution, (3) a radio isotope density meter for precise soil density measurement, and (4) a plate loading and shear testing system to evaluate the deformation and strength characteristics of lunar regolith. Data collected by the RGIS will enable the construction of a three-dimensional geological and geotechnical map of the lunar surface. This map will aid in predicting the behavior of exploration vehicles, construction robots, and designing earthworks such as excavation, filling, leveling, and module/structure installation. This presentation offers a comprehensive overview and outlines the current development status of RGIS.

ABSTRACT. The US Army recently updated its fleet of light tactical vehicles with an upgraded version of the Polaris MRZR, named the MRZR Alpha. The Polaris MRZR Alpha has substantially different characteristics in overall dimensions, drivetrain, suspension, electronics, and so on over the older model. Therefore, the Polaris Alpha has significantly different driving dynamics from the older model. The Army Corps of Engineers Cold Regions Research & Engineering Lab (USACE-CRREL) has previously identified and tested this new vehicle for its potential mobility in artic conditions. For artic conditions, the vehicle can be equipped with tracks and an artic cab enclosure kit. CRREL owns two older MRZR D4 and two newer MRZR Alphas and has substantial test data for both vehicles. This research includes field test data from USACE CRREL engineers on various types of snow surfaces and transition season soils and provides engineering feedback on the positives and negatives of the changed systems, and qualitative feedback from US Soldiers. The goal of this project is to characterize the vehicle on wheels and tracks on cold weather surfaces, as well as provide early insight into systems on the vehicle requiring improvement, as well as illuminate key successes and failures in comparison to the older MRZR D4.

ABSTRACT. Power hop refers to the coupled oscillation of vertical, longitudinal, and pitch motions observed when four-wheel-drive tractors tow moderate to high draft loads on dry soils or operate on slippery roads or slopes. The severe vibrations resulting from power hop reduce operational precision, ride comfort, and tractor stability, while also increasing soil compaction and damage to operators and tractor body. Unlike forced oscillations, power hop is a self-excited oscillation caused by the nonlinear dynamics of agricultural tractors, including stick-slip and impact dynamics. Our previous paper investigated how these nonlinear elements contribute to the power hop phenomenon in farm operations. In this study, we explore the efficacy of front axle suspension in mitigating the occurrence of power hop and its associated vibrations. Although front axle suspension is generally employed to improve ride comfort during tractor operation at higher speeds, its efficacy on power hop have not been investigated thus far. We newly developed a power hop model for an agricultural tractor equipped with front axle suspension and conducted numerical simulations varying model parameters of the developed model. Our results demonstrate that front axle suspension can effectively suppress power hop even under load and soil conditions that would induce power hop in a tractor without such suspension. However, we also observed occurrences of power hop in front axle suspension tractors under more severe conditions including higher draft loads and drier soils.

ABSTRACT. Continuously Variable Transmissions (CVTs) are typically implemented in agricultural tractors by means of a power-split configuration between the diesel engine and infinitely-variable hydrostatic unit (IVHU). The present work is based on an optimized output-coupled/compound architecture developed by the authors for a 200-kW reference tractor, originally equipped with a standard input-coupled CVT. A two-stage planetary gearset – serving as the power-split device – is complemented by a four-gear mechanical gearbox, to efficiently cover the full velocity range, up to 40 km/h, with power-shift capability, to supply an uninterrupted traction torque even during gear change. At any given constant engine speed and for each gear, an ideal reference condition is considered – in which the hydraulic units have ideal efficiencies – to analytically define a theoretical open-loop function, providing the requested IVHU transmission ratio as a function of vehicle velocity, and the theoretical shaft synchronization point, to shift to the previous/next gear. Real-world efficiencies affect the synchronization dynamics and, consequently, the traction force while shifting gears. An enhanced control has then been devised, keeping the simple open-loop foundation, with an additional smoothing contribution, triggered by the shaft speed feedback when speed matching is detected. The problem is studied via a lumped-parameter simulation model, focusing on the effect of the control on the longitudinal dynamics of the vehicle-wheel-terrain system. An exploratory investigation is carried out to tune the function, based on vehicle speed, drawbar pull and gear, for a smooth operation in a suitable range of operating conditions.

ABSTRACT. In planetary exploration mission, an exploration robot has to travel on unknown and uneven, soft ground. Thus, a locomotion mechanism is an important, and the locomotion systems are discussed three types such as wheel, crawler and legs. The leg type has advantages of adaptability and an effective locomotion for terrains. Because a walking robot is able to avoid rocks and depressed areas. However, the biped robot is structurally complex and fall down easily. In this research, we developed the biped robot that is made of a soft balloon body fulfilled by helium. Since the body of the robot is always floating by helium balloon, the robot cannot fall down while walking. The leg structure for walking is made of an artificial muscle actuator. When the control command applies to the actuators, the legs swing up lightly. When the control command stops applying, the legs swing down slowly. The robot is able to move forward when the legs swing up and down repeat alternately. We have achieved the walking movement by a manual ON-OFF control of actuators on firm grounds.　 The purpose of this research is to clarify the interaction between the leg mechanism and soft soil.

In this paper, we performed walking experiments on soft soil to estimate states of walking movements on flat soft soil using original flat shape of foots. It was confirmed that the foots did not sink and slip and the robot moved forward. Furthermore, we propose a new type of foot parts that is able to travel on uneven, soft or slope grounds, and perform experiments for verifying effectiveness.

ABSTRACT. Mobility indexes (MI) have been used to understand and compare the performance for ground vehicles, which must complete tasks or follows paths for several types of environments. The MI research has been studied by several authors (Wong 2008, Larin 2007, Chudakov, Vantsevich 2022). There are multiple methods that supports the evaluation of mobility, from experimental, numerical, and simulated (VCI, MMP, NTVPM). To estimate the MI is a key feature in an initial stage of concept and design of new types of ground vehicles. At the agriculture industry, the challenges for a MI estimation could be like the ones at military industry, but with different points of interest (soil conservation, reduce load transfer to soil, crop protection). For the sugar cane industry at the Valle del Cauca region (Colombia-South America), these considerations have become important since the sugar cane in that region, is a whole year crop growing, that means harvesting activities are developed no matter if there is dry or wet season. The conservation concerns for the industry at wet seasons appears, because the sugar cane supply equipment (harvester, cranes, trailers) with wheels and even with tracks, reduce the reliability, with the sinkage and compaction phenomena with heavy vehicles. This work proposes the application of mobility index concept for a new type of vehicle to transport the sugar cane on the field. For the sugar cane sector, the adoption for these methodologies would help reducing the risk to deploy unreliable technologies and to compare design alternatives at conceptual phases

ABSTRACT. The rockie-bogie suspension arm is a topic fully studied for experimental rovers (Nildeep Patel, 2010), (Weihua Li, 2013). These types of suspensions allow vehicles to increase the stability and move across with multiple obstacles on the ground. It has been tested this suspension system for some academic studies for the agricultural research topics, but it doesn’t have yet an industrial deployed application for agriculture sector. The agricultural sector is looking for solutions to increase the productivity without harming the environment and improve the health of soils. This global challenge must be faced with improved technological developments. For instance, the sugar cane industry at Colombia, South America has challenges to adopt new technological system to complain about. At the Cauca River Valley (24MTon/year sugar cane production), 75% of the fields to harvester and transport the sugar cane stalks is used with commercial harvesters and a system of trailers to move the sugar cane from the field to the mill factories. The main surface it has low slopes, otherwise. for the remain 25%, the industry faces with high slopes terrains, additionally with the lower capacity of the soil at the rainy and wet seasons. This condition increases the risk with commercial agricultural machinery (harvester, trailers and tractors). This work is inspired with the rockie-arm suspension, to propose a concept to transport sugar cane from the fields. A CAD Model has been developed to understand the kinematical and kinetics for the suspension and compared with other types of suspensions considered for this industry. This work aims to explore new possibilities to adopt technologies developed from other industries to solve the agriculture challenges.