Terrain Angles Research Articles

Height Measurement for Meter Wave MIMO Radar based on Matrix Pencil Under Complex Terrain

Height measurement with meter wave (MW) MIMO radar in the actual complex terrain environment is a difficult problem because of terrain fluctuation, ground inclination, and multiple reflection points. Therefore, a practical signal model is studied, and a height measurement method of matrix pencil based on this signal model is proposed. Firstly, a more practical signal model of MW MIMO radar with the complex terrain is derived, and then the modified generalized MUSIC and maximum likelihood estimation algorithms are proposed. However, the modified algorithms need to know a priori information of reflected terrain angle. Therefore, the height measurement methods based on matrix pencil are studied which includes forward matrix pencil method, forward and backward matrix pencil method and unitary matrix pencil method. These method can quickly estimate the elevation and height without a priori information. Finally, the advantages/disadvantages of proposed algorithms under this complex terrain are compared by computer simulations. The results of simulations show that the effectiveness of our proposed algorithms.

Agroecological land typification

The minimum required information and the sequence of agroecological land type allocation on the land management territory of the experimental station (ES) located in the forest-steppe of the Priob'ye region of Novosibirsk is described. Two agroecological land types are distinguished: the first type (upland lands) is represented by leached chernozem in combination with common, podzolized and dark-grey forest soils; the second type (slightly erosive lands) is represented by leached chernozem in combination with dark-grey forest soils. Soil cover of ES in both types of lands is represented by leached chernozem (Lch-2-2s), the share of which for the first type is 75.26%, for the second - 76.26% of the total area of the types. The first agroecological land type is characterized by a range of heights from 134 to 165 m. The working areas are located on the slopes between 0 and 3 degrees in relation to the terrain angle. Vertical dissection of the relief averages 1.3 m, horizontal dissection by erosion forms is 0.8 km/km2. The second type of land is characterized by an elevation of 113 to 137 meters above sea level and a slope of 1 to 4 degrees. Vertical dissection of the terrain averages 1.7 m, horizontal dissection by erosion forms 0.9 km/km2. Typification was carried out with the help of a generated Digital Land Use Model (DLM) of the ES based on the analysis of geographical information, remote sensing materials (ERS) and cadastral map. The DLM consists of the following geo-information layers: topography, land cover, digital elevation model (DEM), working areas. The DEM includes information on slope steepness and exposure, vertical and horizontal dissection.

Numerical Investigation of the Effect of Sloped Terrain on Wind-Driven Surface Fire and Its Impact on Idealized Structures

In this study, a time-dependent investigation has been conducted to numerically analyze the impact of wind-driven surface fire on an obstacle located on sloped terrain downstream of the fire source. Inclined field with different upslope terrain angles of 0, 10, 20, and 30° at various wind-velocities have been simulated by FireFoam, which is a large eddy simulation (LES) solver of the OpenFOAM platform. The numerical data have been validated using the aerodynamic measurements of a full-scale building model in the absence of fire effects. The results underlined the physical phenomena contributing to the impact of varying wind flow and terrain slope near the fire bed on a built area. The findings indicated that under a constant heat release rate and upstream wind velocity, increasing the upslope terrain angle leads to an increase in the higher temperature areas on the ground near the building. It is also found that raising the inclined terrain slope angle from 0 to 30°, results in an increase in the integrated temperature on the surface of the building. Furthermore, by raising the terrain slope from 0 to 30°, the integrated temperature on the ground for the mentioned cases increases by 16%, 10%, and 13%, respectively.

A Study on Obstacle-surmounting Performance of Sand Milling Vehicles

According to the changing characteristics of the geological environment of Gobi desert pollution abatement area, this paper introduces a kind of milling vehicle of 3point supporting type. The general equilibrium equations under the simultaneously surmounting obstacle by front wheels were derived using a simplified obstacle surmounting mechanical mode. As in a complex environment, the key terrain obstacle parameters are uncertain and the traction force to surmount the obstacle is also uncertain. This paper uses fuzzy sets method for terrain angle and the traction force needed by the vehicle to surmount the obstacle was calculated. By establishing a wheel-road model and using multi-dynamics software, the simulations showed that the theoretical results were reliable.

Force-balancing algorithm to remove the discontinuity in soil force during wheel loader excavation

An important issue in developing a virtual simulation environment for a wheel loader is capturing the interaction force between the bucket and soil during excavation. In this work, we review several important studies on fundamental earthmoving equations (FEE) and confirm that discontinuity of soil force occurs when soil is loaded with a large terrain angle using a soil model based on traditional FEE for a wheel loader. This discontinuity is removed by recalculating the external friction angle to satisfy the force equilibrium condition under the assumption that the combined net normal and frictional force is zero in a certain condition. Comparison of an actual test with an inverse dynamic simulation using measured data confirms that the soil model proposed in this study is sufficient for estimating the external force transferred to the structure during actual operation. This soil force model can be used for durability and performance assessments in the initial design of wheel loaders.

Trajectory generation and step planning of a 12 DoF biped robot on uneven surface

SUMMARYOne of the primary goals of biped locomotion is to generate and execute joint trajectories on a corresponding step plan that takes the robot from a start point to a goal while avoiding obstacles and consuming as little energy as possible. Past researchers have studied trajectory generation and step planning independently, mainly because optimal generation of robot gait using dynamic formulation cannot be done in real time. Also, most step-planning studies are for flat terrain guided by search heuristics. In the proposed method, a framework for generating trajectories as well as an overall step plan for navigation of a 12 degrees of freedom biped on an uneven terrain with obstacles is presented. In order to accomplish this, a dynamic model of the robot is developed and a trajectory generation program is integrated with it using gait variables. The variables are determined using a genetic algorithm based optimization program with the objective of minimizing energy consumption subject to balance and kinematic constraints of the biped. A database of these variables for various terrain angles and walking motions is used to train two neural networks, one for real-time trajectory generation and another for energy estimation. To develop a global navigation strategy, a weighted A* search is used to generate the footstep plan with energy considerations in sight. The efficacy of the approach is exhibited through simulation-based results on a variety of terrains.

Influence of micro-topography and crown characteristics on tree height estimations in tropical forests based on LiDAR canopy height models

Tree or canopy height is an important attribute for carbon stock estimation, forest management and habitat quality assessment. Airborne Laser Scanning (ALS) based on Light Detection and Ranging (LiDAR) has advantages over other remote sensing techniques for describing the structure of forests. However, sloped terrain can be challenging for accurate estimation of tree locations and heights based on a Canopy Height Model (CHM) generated from ALS data; a CHM is a height-normalised Digital Surface Model (DSM) obtained by subtracting a Digital Terrain Model (DTM) from a DSM. On sloped terrain, points at the same elevation on a tree crown appear to increase in height in the downhill direction, based on the ground elevations at these points. A point will be incorrectly identified as the treetop by individual tree crown (ITC) recognition algorithms if its height is greater than that of the actual treetop in the CHM, which will be recorded as the tree height. In this study, the influence of terrain slope and crown characteristics on the detection of treetops and estimation of tree heights is assessed using ALS data in a tropical forest with complex terrain (i.e. micro-topography) and tree crown characteristics.Locations and heights of 11,442 trees based on a DSM are compared with those based on a CHM. The horizontal (DH) and vertical displacements (DV) increase with terrain slope (r = 0.47 and r = 0.54 respectively, p<0.001). The overestimations in tree height are up to 16.6m on slopes greater than 50° in our study area in Sumatra. The errors in locations (DH) and tree heights (DV) are modelled for trees with conical and spherical tree crowns. For a spherical tree crown, DH can be modelled as R sin θ, and DV as R (sec θ – 1). In this study, a model is developed for an idealised conical tree crown, DV=R (tan θ – tan ψ), where R is the crown radius, and θ and ψ are terrain and crown angles respectively. It is shown that errors occur only when terrain angle exceeds the crown angle, with the horizontal displacement equal to the crown radius. Errors in location are seen to be greater for spherical than conical trees on slopes where crown angles of conical trees are less than the terrain angle. The results are especially relevant for biomass and carbon stock estimations in tropical forests where there are trees with large crown radii on slopes.

Balance and recovery on coronally-uneven and unpredictable terrain

Stepping on coronally-uneven and unpredictable terrain is a common gait disturbance that can lead to injurious falls. This study identified the biomechanical response to a step on coronally-uneven and unpredictable terrain through observation of participants traversing a walkway with a middle step that could be blinded to participants, and positioned either 15° inverted, 15° everted, or flush. The isolated disturbance was intended to simulate stepping on a rock, object, or other transient coronal disturbance and allow for observation of the subsequent balance recovery. Gait balance was affected by the disturbance, and was measured by the range of coronal whole-body angular momentum, which compared to unblinded flush, increased during blinded eversion, and decreased during blinded inversion. Analysis of external coronal moments applied to the body about the center-of-mass by the disturbed and recovery legs suggested the disturbed leg contributed more to differences in the range of coronal angular momentum, and thus more to balance recovery. The stepping strategy for the disturbed and recovery steps was measured by mediolateral foot position, and appeared to have been mostly affected by anticipatory actions taken by participants before stepping on the blinded terrain, and not by the terrain angle. In contrast, on the disturbed step, distinct differences between blinded inversion and eversion in the coronal moments of the hip and ankle suggested the hip and ankle joint moment strategies were important for adapting to the terrain angle. A clinical implication of this result was interventions that augment these moments may improve gait balance control on coronally-uneven and unpredictable terrain.

Terrestrial movement energetics: current knowledge and its application to the optimising animal.

The energetic cost of locomotion can be a substantial proportion of an animal's daily energy budget and thus key to its ecology. Studies on myriad species have added to our knowledge about the general cost of animal movement, including the effects of variations in the environment such as terrain angle. However, further such studies might provide diminishing returns on the development of a deeper understanding of how animals trade-off the cost of movement with other energy costs, and other ecological currencies such as time. Here, I propose the 'individual energy landscape' as an approach to conceptualising the choices facing the optimising animal. In this Commentary, first I outline previous broad findings about animal walking and running locomotion, focusing in particular on the use of net cost of transport as a metric of comparison between species, and then considering the effects of environmental perturbations and other extrinsic factors on movement costs. I then introduce and explore the idea that these factors combine with the behaviour of the animal in seeking short-term optimality to create that animal's individual energy landscape - the result of the geographical landscape and environmental factors combined with the animal's selected trade-offs. Considering an animal's locomotion energy expenditure within this context enables hard-won empirical data on transport costs to be applied to questions about how an animal can and does move through its environment to maximise its fitness, and the relative importance, or otherwise, of locomotion energy economy.

Incorporating internal mechanical power into performance models in cycling

Background: A number of models have been developed to establish the energy cost of cycling. These models have become better refined to account for the various energy demands, including air and rolling resistances. Among the established models, however, there does not appear to be sufficient consideration for changes to internal mechanical power (IP), the rate of energy to move the limbs against gravitational and inertial forces. Values up to 100 W have been reported for IP in cycling for cadences between 80 and 115 , and so the inclusion of IP in performance prediction models is arguably warranted. Quantifying IP has previously been done using either 1) a physiological approach (IP met ), in which the metabolic counterpart of the external mechanical power (power applied to the cranks) was subtracted from A– (energy expenditure) to equal the metabolic equivalent of IP met , which was then multiplied by delta efficiency (DE) to yield the IP met ; or 2) a biomechanical approach (IP mech ), which used an inverse dynamics analysis of the kinematics and kinetics of cycling. Both approaches have notable advantages and limitations, which is why quantifying a range for IP, delimited by IP met and IP mech, has been proposed by this research group.  Purpose: The aim of this study was to assess whether incorporating a range of values for IP into an established performance model would provide a better prediction of A– than when IP was not included.  Methods: Steady-state A– was measured (K4 b 2 , Cosmed, Rome, Italy) for 10 elite male cyclists who cycled for 5-6 min at 200 W at 80 and 110 on the flat duckboard of an outdoor velodrome in calm conditions. Steady-state A– was compared to A– predicted by the established model (Equation 1, see in PDF document) (di Prampero et al. 1979: Journal of Applied Physiology, 47(1), 201-106; Olds et al. Journal of Applied Physiology, 75(2), 730-737): and A– predicted by the model that includes IP (IP met and IP mech ) (Equation 2, see in PDF document): where the first term of both equations represents the cost due to air resistance and includes a coefficient of drag (C drag ), the projected frontal surface area (A frontal ), the air density (r), the velocity of the wind (v w ) and the steady-state velocity of the cyclist (v ss ). The second term represents the cost due to rolling resistance, where C rr is the coefficient of rolling resistance, S is the angle of terrain, m body and m bicycle are the masses of the participant’s body and bicycle, respectively. IP met and IP mech were determined in the laboratory for each cyclist in an identical cycling position to that adopted in the outdoor trials. Results: Mean (± s) measured at 80 was 866 W (± 78 W) and at 110 was 937 W (± 75 W). The mean difference (± 95% limits of agreement) between measured and predicted by Equation 1 was -98 W (± 214 W) at 80 and -185 W (± 191 W) at 110 . When IP met was included in the prediction (Equation 2), mean differences (± 95% limits of agreement) were 125 W (± 192 W) and 182 W (± 153 W) at 80 and 110 , respectively. The mean differences (± 95% limits of agreement) between measured and predicted by Equation 2 incorporating IP mech were -48 W (± 201 W) at 80 and -148 W (± 274 W) at 110 . Discussion: Energy expenditure () predicted using an already-established model was shown, in this study, to fall short of the measured from respiratory gas during outdoor cycling for most participants at 80 and for all at 110 . Inclusion of IP mech into the performance prediction model resulted in values closer to the measured , however they were not sufficiently large enough to account for the entire deficit from the original prediction model (Equation 1) at either cadence. When the upper limit of the IP range, IP met , was incorporated it more than compensated, in almost all cases, for the deficit from Equation 1. That is to say, the measured during outdoor cycling fell within the range of values that was predicted for when estimates of IP were considered in the model. Conclusion: Based on these results, it is recommended that future predictions of cycling performance include a cost for IP.

Assessment of Seismically Induced Landslide Hazard for the State of Karnataka Using GIS Technique

Landslide hazards are a major natural disaster that affects most of the hilly regions around the world. In India, significant damages due to earthquake induced landslides have been reported in the Himalayan region and also in the Western Ghat region. Thus there is a requirement of a quantitative macro-level landslide hazard assessment within the Indian subcontinent in order to identify the regions with high hazard. In the present study, the seismic landslide hazard for the entire state of Karnataka, India was assessed using topographic slope map, derived from the Digital Elevation Model (DEM) data. The available ASTER DEM data, resampled to 50 m resolution, was used for deriving the slope map of the entire state. Considering linear source model, deterministic seismic hazard analysis was carried out to estimate peak horizontal acceleration (PHA) at bedrock, for each of the grid points having terrain angle 10A degrees and above. The surface level PHA was estimated using nonlinear site amplification technique, considering B-type NEHRP site class. Based on the surface level PHA and slope angle, the seismic landslide hazard for each grid point was estimated in terms of the static factor of safety required to resist landslide, using Newmark's analysis. The analysis was carried out at the district level and the landslide hazard map for all the districts in the Karnataka state was developed first. These were then merged together to obtain a quantitative seismic landslide hazard map of the entire state of Karnataka. Spatial variations in the landslide hazard for all districts as well as for the entire state Karnataka is presented in this paper. The present study shows that the Western Ghat region of the Karnataka state is found to have high landslide hazard where the static factor of safety required to resist landslide is very high.

Topographic correction of ETM images based on smoothed terrain

A new empirical topographic correction method is proposed in this paper. The main idea of the new method is smoothing the slope angle of terrain in the first place and then performing the cosine correction based on the smoothed terrain. A comparison is conducted among the new method and several other common methods using Landsat-7 ETM+ data. Visual analysis and statistical analysis are adopted to assess the performance of these methods from two aspects: overcorrection, homogeneity within a land cover class. Comparison results indicate that the new method is superior to the cosine correction, Gamma correction, Sun-Canopy-Sensor correction, and Minnaert correction. Compared with common methods, the proposed one can eliminate overcorrection better and is an effective topographic correction method.

Active bogies and chassis levelling for a vehicle operating in rough terrain

Four axle vehicles with bogies can adapt the position of the wheels to follow irregularities in the terrain, having an obstacle surpassing ability far greater than conventional 2-axle vehicles. Still, the ability to overcome discrete obstacles on a steep slope is very different depending on the wheel that is facing the obstacle. A possible solution to diminish this variation can be found if the vehicle is able to actively redistribute the load on each wheel. One strategy is to design the suspension mechanism so it can regulate its height, being able to level the chassis. Also, an active torque on the pin join between the bogie and the chassis can be applied with the same goal, adopting a system of active bogies. Both solutions have been parametrically studied in a bi-dimensional multibody model of a 4-axle vehicle with double bogies. The results show an improvement independent of obstacle position and terrain angle when using active bogies. With height regulation, this improvement is limited to the rear bogie wheels, but the obstacle surmounting capacity of the vehicle as a whole can be considerably increased if the optimal regulation point is found. Possible applications for such enhanced vehicles with bogies are performing different tasks in forest areas with obstacles on steep slopes or unstructured terrain exploration.

Automation and optimal design method of a wheeled vehicle operating over sloped weak sandy terrain

In this paper, a mathematical model of wheeled vehicle tractive or braking performance was developed and verified by experimental data. Then, various center of gravity and height of application force movement effects were analysed by simulation analysis. For a given set of vehicle dimensions and terrain wheel system constants, the simulation calculated effective tractive or braking effort and rear wheel sinkage, slip ratio or skid of a special designed wheeled robotic vehicle running over sloped weak sandy terrain for straight forward motion. For a 5.88 kN weight vehicle, the optimal eccentricity of center of gravity, the optimal application height and the maximum slope angle of terrain could be determined for rear-wheel drive (RWD), front-wheel drive (FWD), four-wheel drive (4WD) or rear-wheel brake (RWB), front-wheel brake (FWB), and four-wheel brake (4WB) travel systems.