Uneven Terrain Research Articles

Gait variability of outdoor vs treadmill walking with bilateral robotic ankle exoskeletons under proportional myoelectric control.

Lower limb robotic exoskeletons are often studied in the context of steady-state treadmill walking in laboratory environments. However, the end goal of these devices is often adoption into our everyday lives. To move outside of the laboratory, there is a need to study exoskeletons in real world, complex environments. One way to study the human-machine interaction is to look at how the exoskeleton affects the user's gait. In this study we assessed changes in gait spatiotemporal variability when using a robotic ankle exoskeleton under proportional myoelectric control both inside on a treadmill and outside overground. We hypothesized that walking with the exoskeletons would not lead to significant changes in variability inside on a treadmill or outside compared to not using the exoskeletons. In addition, we hypothesized that walking outside would lead to higher variability both with and without the exoskeletons compared to treadmill walking. In support of our hypothesis, we found significantly higher coefficients of variation of stride length, stance time, and swing time when walking outside both with and without the exoskeleton. We found a significantly higher variability when using the exoskeletons inside on the treadmill, but we did not see significantly higher variability when walking outside overground. The value of this study to the literature is that it emphasizes the importance of studying exoskeletons in the environment in which they are meant to be used. By looking at only indoor gait spatiotemporal measures, we may have assumed that the exoskeletons led to higher variability which may be unsafe for certain target populations. In the context of the literature, we show that variability due to robotic ankle exoskeletons under proportional myoelectric control does not elicit different changes in stride time variability than previously found in other daily living tasks (uneven terrain, load carriage, or cognitive tasks).

Design and modeling of hexapod robot using telescopic legs connected to pivot joints at the hips

Hexapod robots are widely used in applications such as search and rescue, exploration, and surveillance due to their improved mobility and stability on uneven terrain. However, conventional hexapod robots typically suffer from issues such as heavy weight and complex design, which limits their effectiveness in certain scenarios. In this paper, we propose a new hexapod robot that addresses the issues of weight and complexity often associated with conventional hexapod robots. Our proposed design uses telescopic legs connected to pivot joints at the hips, resulting in a two-DOFs-leg configuration. The robot’s six legs are aligned with a parallelepiped body, with each leg configured with a revolute joint and a prismatic joint. With a total of twelve degrees of freedom (DOFs), the proposed robot can move in a straight line or turn. Our solution for stabilizing the robot’s horizontally oriented body on uneven terrain, using analytical kinematics, inverse kinematics, and geometric analysis, is a valuable contribution. Additionally, we present simulation of path generation and gait design for various inclined planes and stairs using a virtual prototype modeled in MATLAB/Simulink Simscape Multibody. The results of our simulated and physical prototype experiments demonstrate that the proposed design and body control algorithm effectively maintain the orientation of the robot’s body usually stable while it moves on different types of surfaces. Overall, our proposed hexapod robot using telescopic legs offers a promising solution for achieving improved mobility and stability on uneven terrain, with reduced weight and complexity compared to conventional hexapod robots.

It is not just the work you do, but how you do it: the metabolic cost of walking uphill and downhill with varying grades.

The cost of walking and running on uneven terrain is not directly explained by external mechanical work. Although metabolic cost of transport increases linearly with gradient at uphill and downhill gradients exceeding 15%, at shallower gradients, the relationship is nonlinear, with the minimum cost occurring at ∼10% downhill grade. Given these nonlinear relationships between grade and metabolic cost, we projected a significant difference in the total metabolic cost of two walking conditions that required the same total external mechanical work be performed over the same total period of time; in one condition, time was spent walking to gradients that were fixed at +10.5% and -10.5% and in the other condition time was spent walking to gradients that varied from 0 to +21% and from -21 to 0%. We compared these two conditions experimentally, using an approach to quantify nonsteady-state oxidative energy expenditure. In line with our projection, the "variable" grade condition resulted in an 8.3 ± 2.2% higher total cumulative oxidative energy expenditure (J·kg-1) compared with the "fixed" grade condition (P < 0.001). Future work should aim to apply our approach across different gradients, speeds, and forms of locomotion; especially those that might provide insight into how humans optimize locomotion on variable grade routes.NEW & NOTEWORTHY We use a method for quantifying nonsteady-state energetics to show that regardless of whether the same total gain and loss in elevation (i.e., same total external mechanical work) is achieved over the same period of time, the total energy expenditure of different graded walking conditions can vary depending on the grades that are walked at and for how long they are walked at.

Comparative Finite Element Analysis of a Novel Robot Chassis Using Structural Steel and Aluminium Alloy Materials

This work presents a comparative finite element analysis of a 3-wheeler novel robot chassis used for uneven terrain robot applications. The chassis was modeled using SolidWorks and further analyzed in Ansys for its total deformation, equivalent stress, equivalent elastic strain and thermal strain. Two materials were taken into consideration for comparative analysis: Aluminium alloy and Structural steel. A load (force) of 500 N was distributed on the chassis uniformly and an acceleration of 5 mm/sec2 was given. Thermal conditions were added by raising the temperature from 22°C to 50°C in 1 sec. The analysis performed was majorly divided into three parts: a) Only considering force, b) Considering force as well as acceleration, c) Considering force, acceleration and thermal conditions. Total deformation in Aluminium alloy was observed 1.51 to 2.79 times that of structural steel in all the cases. Both metals exhibited almost identical equivalent stress in absence of thermal effect and structural steel exhibit 1.5 times that of Aluminium alloy at elevated temperature. Aluminium alloy possess relatively more (1.86-2.63 times) equivalent elastic strain compared to structural steel. Although, distribution of thermal strain remained constant throughout the chassis for both the materials, its magnitude was 1.91 times high in Aluminium alloy. This type of analysis helps in evaluating the current design and decide whether it will sustain the required load and acceleration under given thermal conditions

Interactive Quadruped Felid Class Robot with a Neural Processing Unit

The authors consider the urgent task of developing bionic robots, in particular robots on four legs. Their advantages are the ability to move on uneven terrain, to perform reconnaissance, rescue and other dangerous work, where they could replace humans. A review of the existing best-known and most functional bionic four-legged robots is given, with descriptions of their strengths and weaknesses, as well as peculiarities of their movement and use. The main problems in the development of such devices and their control systems are highlighted. The article provides information on the research and development of an interactive bionic robot of the felid class, whose skeletal structure control implementation is deeply explored. The features of hardware and software implementation of the robot are considered, and schematic and real images of the construction are presented. The application of a microcomputer device with a neural processing unit to solve the problem of machine vision is highlighted. The results of testing machine vision using the Yolo3 neural network in streaming video mode are presented. The average accuracy of the open face recognition as a result of the tests was 95 %. For different degrees of occlusion, the average score was 80 %, and occlusion variants in which the neural network was unable to recognize faces were also identified. The article concludes with a discussion of the advantages and disadvantages of the proposed robot and the possibility of its application in human life, including the solution of various practical tasks.

The Effects of Structural Characteristics of the Rollator on the Elderly’s Gait Strategies in Various Walking Environments

A rollator, one of the most widely used among walking assistance devices, can assist the elderly with stable walking in their daily lives. In this study, we investigated how the structural characteristics of two types of rollators affect the upper and lower extremity muscle activity and plantar pressure of the elderly in various walking environments. We quantified muscle activity (upper and lower limbs) and plantar pressure (mean force, peak pressure, and contact area) of 11 older adults walking in various environments (flat, obstacle, uneven, and sloped terrain) using two types of rollators. Upper extremity muscle activity was highest in the obstacle terrain and the uneven terrain, and a significant difference was found due to the structural differences of the rollator. Additionally, it was observed that lower extremity muscle activity and plantar pressure patterns appeared in accordance with the gait strategy to maintain stability in an unstable or inclined walking environment. In other words, it was confirmed that the weight of the rollator, the size of the wheel, grip type, and the auxiliary tools had a great effect on the upper and lower extremity muscle activity and plantar pressure of the elderly during walking. From the results of this study, it can be suggested that it is absolutely necessary to consider the biomechanical characteristics of the elderly and the structure of the rollator, which appear differently depending on the walking environment, in the development of walking aids. In the future, more clinical data will be collected, and based on this a rollator that can safely assist the elderly in various walking environments will be developed.

Case Study: Ayurvedic Treatment of Vatakantaka through Raktamokshana

According to Acharya, it has been observed that when an individual traverses an irregular or uneven terrain, the vata dosha becomes localized and exacerbated in the ankle joint, resulting in pain in the heel region commonly referred to as Vatakantaka. It may be likened to Plantar Fasciitis, a painful condition affecting the heel that impedes daily activities. Plantar Fasciitis is caused by the repetitive stretching and straining of the plantar fascia, resulting in injury and inflammation that presents as heel pain. A 34-year-old female patient reports experiencing left heel pain during the first few steps in the morning, which is alleviated after walking. However, the pain returns after a prolonged period of rest. The present case study employs Raktmokshana to evaluate its effectiveness in alleviating pain. According to Acharya, pain arises solely from the vitiation of Vata Dosha or Rakta Dhatu. Given the patient's severe burning sensation and pain, Raktamokshana was done through Siravedh techniques at the ankle region over the course of four sessions, spaced seven days apart. This treatment resulted in complete pain relief for the patient.

In situ skid estimation for mobile robots in outdoor environments

AbstractSkidding is a surface hazard for mobile robots' navigation and traction control systems when operating in outdoor environments and uneven terrains due to the wheel–terrain interaction. It could lead to large trajectory tracking errors, losing the robot's controllability, and mission failure occurring. Despite research in this field, the development of a real‐world feasible in situ skid estimation system with the capability of operating in harsh and unforeseen environments using low‐cost/power and ease of integrating sensors is still an open problem in terramechanics. This paper presents a novel velocity‐based definition for skidding that enables a real‐world feasible estimation for the mobile robot's undesired skidding at the vehicle‐level in outdoor environments. The proposed technique estimates the undesired skidding using a combination of two proprioceptive sensors (e.g., inertial measurement unit and wheel encoder) and deep learning. The practicality of a velocity‐based definition and the performance of the proposed undesired skid estimation technique are evaluated experimentally in various outdoor terrains. The results show that the proposed technique performs with less than 11.79 mm/s mean absolute error and estimates the direction of undesired skidding with approximately 98% accuracy.

Assessing the risk of slope failure to highway infrastructure using automated time-lapse electrical resistivity tomography monitoring

Electrical resistivity tomography (ERT) monitoring provides time-lapse images of the subsurface. These images can be used to assess spatiotemporal variation in moisture content, which is a key driver of slope failure, making ERT monitoring an effective tool to evaluate precursory conditions of failure. This work presents the results of ERT monitoring on a slope above a major highway located on the border between England and Wales. During highway construction in the 1960s the slope was subject to several large landslide events which resulted in the re-design of the carriageway and installation of engineered mitigation measures. A section of the slope known as the ‘partially slipped area’ exhibited partial displacement during this time but did not progress to full slope failure, and therefore presents an ongoing risk to the highway, even though it does not experience ongoing displacement. An ERT monitoring system was installed across this area to monitor subsurface variations in moisture content. The results show a complex pattern of subsurface moisture dynamics within the partially slipped area when compared to the adjacent area of stable slope. This is most likely a result of the uneven and hummocky terrain in the partially slipped area and its effects on rainfall infiltration, storage and drainage, combined with the displacement-induced jointing present in the underlying sandstone units. The ERT results are used to assess the volume of unstable ground, placing the volume at the upper end of estimates from previous studies. Furthermore, analysis of the ERT dataset for surface displacements shows no movement at the site, which is confirmed by analysis of differential LiDAR plots and ground motion data derived from InSAR. This study demonstrates the application of ERT monitoring on a low activity, high risk slope, highlighting the need to understand subsurface processes at the slope-scale to inform long-term slope management.

Powered Knee and Ankle Prosthesis Control for Adaptive Ambulation at Variable Speeds, Inclines, and Uneven Terrains.

Ambulation in everyday life requires walking at variable speeds, variable inclines, and variable terrains. Powered prostheses aim to provide this adaptability through control of the actuated joints. Some powered prosthesis controllers can adapt to discrete changes in speed and incline but require manual tuning to determine the control parameters, leading to poor clinical viability. Other data-driven controllers can continuously adapt to changes in speed and incline but do so by imposing the same non-amputee gait patterns for all amputee subjects, which does not consider subjective preferences and differing clinical needs of users. Here, we present a controller for powered knee and ankle prostheses that can continuously adapt to different walking speeds, inclines, and uneven terrains without enforcing a specific prosthesis position, impedance, or torque. A virtual biarticular muscle connection determines the knee flexion torque, which changes with both speed and slope. Adaptation to inclines and uneven terrains is based solely on the global shank orientation. Continuously variable damping allows for speed adaptation. Minimum-jerk programming defines the prosthesis swing trajectory at variable cadences. Experiments with one individual with an above-knee amputation suggest that the proposed controller can effectively adapt to different walking speeds, inclines, and rough terrains.

Analyzing the Role of Goat Rearing for Livelihood Improvement

The goat is an essential component of the dry land agricultural method and is also known as the “poor man’s cow” in India. On marginal or uneven terrain that is unsuited for other species like cows or buffalo, the goat is the best option. Small and marginal farmers can start goat farming, a lucrative industry, with very little investment. The objective of the current study was to ascertain whether the huge concentration of goat population was a factor in the decision to analyze the function of goat husbandry in improving livelihoods. Seven goat farmers were picked at random from each of the 16 villages in each of the district’s four blocks to make up the sample size of 50. Data were acquired utilizing a pre-tested interview schedule, and this study used an ex-post factor research technique. Regression, Pearson’s correlation coefficient, chi-square analysis, and descriptive statistics for frequency distribution were used to edit, tabulate, and analyze the gathered data.

Uneven terrain affects metabolic cost and gait in simulated complex lunar surfaces

Objective. Upcoming missions of the National Aeronautics and Space Administration (NASA) to the Moon will include extensive human exploration of the lunar surface. Walking will be essential for many exploration tasks, and metabolic cost during ambulation on simulated complex lunar surfaces requires further characterization. In this study, ten healthy subjects (6 male and 4 female) participated in three simulated lunar terrain walking conditions at the NASA Johnson Space Center’s planetary ‘Rock Yard’: (1) flat terrain, (2) flat terrain with obstacles, and (3) mixed terrain. Approach. Energy expenditure and gait were quantified with a wearable metabolic energy expenditure monitoring system and body-worn inertial measurement units (IMUs), respectively. Main results. It was found that participants walking on the mixed terrain, representing the highest workload condition, required significantly higher metabolic costs than in other terrain conditions (p < 0.001). Additionally, our novel IMU-based gait variables discriminated different terrains and identified changes in gait in simulated lunar terrain environments. Significance. Our results showed that the various surface irregularities and inconsistencies could cause additional physical effort while walking on the complex terrain. These findings provide insight into the effects of terrain on metabolic energy expenditure during simulated lunar extravehicular activities.

ღარული არხების დეფორმაციები

. Deformations of ditch channels are the main obstacle to their use. The work is devoted to the use of reinforced concrete channels for irrigation systems. The advantages of the arrangement of ditch channels for the uneven terrain conditions of Georgia are discussed. It is explained that their deformations – falling from the supports – can be caused either by violation of the technological scheme of the grooved channel arrangement during construction (repair) and by using cement solution instead of sealing with elastic linings of the edges, or by constructional reasons - the uneven effect of temperature deformation (extension-and-shortening) on different ends of the groove in the conditions of swaying of the channels. The different effects of this reason on non-uniform (double-sided smooth-bottomed) and uniform (parabolic, tubular) grooves are explained. A natural study of the issue – the influence of the type and construction of the supports on the stability of the channel is given. The article provides ways to prevent this from happening.

Design of a landing gear system for UAV in complex ground environments

The current UAV technology is developing rapidly and there are various UAV concepts such as hybrid vertical take-off and landing (VTOL) UAV in addition to traditional UAV. The main solution direction of these UAV concepts lies in the compatibility of vertical take-off and landing and long endurance and high load. However, in some complex environments, such as post-earthquake debris, or uneven mountainous terrain, UAV take-off and landing still has great difficulties. Therefore, this paper designs a landing gear that can adapt to complex ground conditions and its corresponding landing algorithm based on DJI's publicly available UAV model. First, a movable landing gear controlled by a linear actuator is used to adapt to a variety of complex terrains. Then, we designed a UAV foot similar to a 3D carved needle with oil-hydraulic cushioning to make it fit more to the complex ground and stand stably on the ground. Then, we obtained the mathematical relationship between the linear actuator and the landing gear moving end based on the simplified mathematical model of the UAV model, and applied it in the subsequent landing algorithm. And then, in detecting the landing point, we use the column coordinate system for coordinate simulation while the algorithm written in C language to get the most suitable UAV landing point. Finally, we have simulated the UAV landing using MATLAB and the results show the high engineering value.

Mobility and postural limitations perceived by transtibial amputees undertaking agricultural activities: a qualitative study

Purpose In Colombia, 98% of landmines occur in rural areas, where the main victims of amputation are farmers. The challenges these amputees face in their agricultural work remain unknown. The aim of this study is to determine the mobility and postural limitations these farmers face in carrying out their daily activities. Method Forty-nine participants meeting the following criteria were interviewed: transtibial amputee, 18 years and over, performs agricultural labour and wears the prosthesis daily. Subsequently, the interview transcripts were subjected to a content conventional analysis and responses were organized according to the abstraction process to identify categories and subcategories of the problems. Results Main problems reported were walking on sloping, uneven and wet terrain, problems associated with the stump skin, squatting, kneeling, using vehicles or animals for transportation and carrying objects over 30 kg. Postures such as sitting, running, jumping, and standing on tiptoes were mentioned less frequently. Conclusions In conclusion, the prostheses worn by transtibial amputee farmers are not suitable for working on sloping and uneven terrain, nor for performing postures such as kneeling or squatting. These postures are very common in agricultural and livestock tasks in countries with mountainous areas such as Latin American countries. The recognition of problems reported by farmers transtibial amputees, may help to improve the design of prostheses so that they meet the needs of this population and decrease secondary injuries associated with prosthetic use. This information is useful to identify compensatory postures that facilitate prosthetic adaptation and rehabilitation for amputees.

Irrigation Cooling Effect on Local Temperatures in the North China Plain Based on an Improved Detection Method

Irrigation has excellent potential for altering surface characteristics and the local climate. Although studies using site observations or remote sensing data have demonstrated an irrigation cooling effect (ICE) on the air temperature (Tem) and land surface temperature (LST), it is difficult to eliminate other stress factors due to different backgrounds. We characterized the irrigation effect as the differences (Δ) of LST and DCT (DCT = LST − Tem) between irrigated and adjacent non-irrigated areas. An improved method was proposed to detect it over the North China Plain (NCP) based on satellite observations. We also investigated the effects of irrigation on Tem, precipitation, NDVI, and ET, and explored the relationships between them. The results show that irrigation induced a decrease in the daytime/nighttime LST and DCT (−0.13/−0.09 and −0.14/−0.07 °C yr−1), Tem (−0.023 °C in spring), and precipitation (−1.461 mm yr−1), and an increase in NDVI (0.03 in spring) and ET (0.289 mm yr−1) across the NCP. The effect on nighttime LST and NDVI increased by 0.04 °C 10 yr−1 and 0.003 10 yr−1, and that on ET weakened by 0.23 mm 10 yr−1 during 2000–2015. The ICE on the LST had evident spatiotemporal heterogeneity, which was greater in the daytime, in the spring, and in the northern area of the NCP (dry–hot conditions). The daytime ICE in the NCP and northern NCP was 0.37 and 0.50 °C during spring, respectively, with the strongest ICE of 0.60 °C in Henan; however, the ICE was less evident (&lt;0.1 °C) in the southern NCP throughout the year. The ΔNDVI, ΔET, and ΔTem were the main factors driving ICE, explaining approximatively 22%, 45%, and 25% of the daytime ICE, respectively. For every unit of these measures that was increased, the daytime ICE increased by about 7.3, 4.6, and 1.5 °C, respectively. This study highlights the broad irrigation effect on LST, ET, NDVI, and the climate, and provides important information for predicting climate change in the future. The improved method is more suitable for regions with uneven terrain and a varying climate.

Powerful, soft combustion actuators for insect-scale robots.

Insects perform feats of strength and endurance that belie their small stature. Insect-scale robots-although subject to the same scaling laws-demonstrate reduced performance because existing microactuator technologies are driven by low-energy density power sources and produce small forces and/or displacements. The use of high-energy density chemical fuels to power small, soft actuators represents a possible solution. We demonstrate a 325-milligram soft combustion microactuator that can achieve displacements of 140%, operate at frequencies >100 hertz, and generate forces >9.5 newtons. With these actuators, we powered an insect-scale quadrupedal robot, which demonstrated a variety of gait patterns, directional control, and a payload capacity 22 times its body weight. These features enabled locomotion through uneven terrain and over obstacles.

A Heuristics-Based Reinforcement Learning Method to Control Bipedal Robots

A new method is proposed to control bipedal robots to achieve flexible omni-directional motion and robust locomotion under complex disturbances, called the heuristics-based reinforcement learning (HBRL) framework. HBRL shows great training efficiency in simulation. Heuristic reference trajectories play a crucial role in HBRL, which guide the training process. Exploration rewards, leg-foot reset condition, and command curriculum are three significant components to optimize the training process. An estimator network is utilized to supply linear velocities and foot contact information. We train controllers on flat ground in simulation. To demonstrate robustness and versatility, the trained controllers were tested on BRAVER, a point-foot bipedal robot with three joints on each leg. The controllers enabled BRAVER to perform omni-directional locomotion with the maximum forward speed reaching 2[Formula: see text]m/s. The robot could also maintain balance under external pushing and over uneven terrains.

Neuromorphic sequence learning with an event camera on routes through vegetation.

For many robotics applications, it is desirable to have relatively low-power and efficient onboard solutions. We took inspiration from insects, such as ants, that are capable of learning and following routes in complex natural environments using relatively constrained sensory and neural systems. Such capabilities are particularly relevant to applications such as agricultural robotics, where visual navigation through dense vegetation remains a challenging task. In this scenario, a route is likely to have high self-similarity and be subject to changing lighting conditions and motion over uneven terrain, and the effects of wind on leaves increase the variability of the input. We used a bioinspired event camera on a terrestrial robot to collect visual sequences along routes in natural outdoor environments and applied a neural algorithm for spatiotemporal memory that is closely based on a known neural circuit in the insect brain. We show that this method is plausible to support route recognition for visual navigation and more robust than SeqSLAM when evaluated on repeated runs on the same route or routes with small lateral offsets. By encoding memory in a spiking neural network running on a neuromorphic computer, our model can evaluate visual familiarity in real time from event camera footage.

Gait planning and optimization of an 18 DOF quadruped robot with compliant shanks

Legged robots made of rigid links have disadvantages like poor energy efficiency and large impact forces during foot/terrain contact while walking on 3D uneven terrain. This paper proposes a unique design of an 18 DOF quadruped robot with compliant shanks. Compliance has been added to the quadruped by introducing a “c-section“ in the shank of each leg. The robot dynamics has been modeled using the projected Newton-Euler method, while the “Craig-Bampton Method” has been utilized to model the compliant shanks. Optimal body trajectory and foot placements while maintaining dynamic stability is obtained using an NLP based optimization strategy. A torque-based inverse dynamics control technique ensures that the quadruped follows the desired trajectory. The robot was simulated using Simscape Multibody, which utilizes the robot model’s “.stl,”“.step,” and “.xml” files to follow the optimized joint trajectories. The total energy consumed and joint torques are compared between the complaint and rigid link quadruped robots for walk on different types of terrain with different gaits and C-sections of 3, 4, 6, and 8 mm thickness. The simulation results show a significant reduction in joint torque spikes (more than 70% for all cases) due to the addition of compliance in each leg. This also leads to a reduction in total energy consumption during the walk especially over an uneven terrain. Hence, the results verify that the proposed design of quadruped is functionally more efficient than its rigid counterpart for walking on uneven terrain.