Ankit Ravankar

• PhD (Robotics)
• Professor (Associate) at Tohoku University

Generating smooth and continuous paths for robots with collision avoidance, which avoid sharp turns, is an important problem in the context of autonomous robot navigation. This paper presents novel smooth hypocycloidal paths (SHP) for robot motion. It is integrated with collision-free and decoupled multi-robot path planning. An SHP diffuses (i.e.,...

Line detection is an important problem in computer vision, graphics and autonomous robot navigation. Lines detected using a laser range sensor (LRS) mounted on a robot can be used as features to build a map of the environment, and later to localize the robot in the map, in a process known as Simultaneous Localization and Mapping (SLAM). We propose...

Map generation by a robot in a cluttered and noisy environment is an important problem in autonomous robot navigation. This paper presents algorithms and a framework to generate 2D line maps from laser range sensor data using clustering in spatial (Euclidean) and Hough domains in noisy environments. The contributions of the paper are: (1) it shows...

In past years, there has been significant progress in the field of indoor robot localization. To precisely recover the position, the robots usually relies on multiple on-board sensors. Nevertheless, this affects the overall system cost and increases computation. In this research work, we considered a light detection and ranging (LiDAR) device as th...

Robot navigation is an indispensable component of any mobile service robot. Many path planning algorithms generate a path which has many sharp or angular turns. Such paths are not fit for mobile robot as it has to slow down at these sharp turns. These robots could be carrying delicate, dangerous, or precious items and executing these sharp turns ma...

In recent years, automation has significantly advanced the automobile manufacturing industry. However, many tasks still involve human intervention, so there is a demand for the development of robots to support workers. Additionally, as the human-centric approach, such as Industry 5.0, is gaining attention, it is expected that support robots like th...

Autonomous vehicles and self-driving cars are under development and several test phases have successfully been carried out. Robust road detection in different environments is an essential component of self-driving vehicles. Compared to traditional image processing techniques, recent developments in deep learning has enabled robust road detection. T...

Robot navigation is a critical component of mobile robots. In non-autonomous modes, robots are typically controlled using direct commands through keyboard, joystick, or mouse. However, in certain cases, such as robotic wheelchairs, a disabled patient might not be able to use these methods. This paper presents an indirect method of robot control use...

In nations like Japan, where demographic shifts strain healthcare systems, the potential of Robotics and AI to support the aging population is crucial. Yet, despite progress in assistive robotics, their application in real-world home care settings is limited. This paper proposes a novel approach to utilize a network of caregiving robots, which inte...

This paper introduces a navigation system that leverages both topological and metric information, enhanced by the integration of semantic features for service robots operating in indoor environments. The system is designed to improve the autonomy, efficiency, and adaptability of service robots in dynamic and partially known environments. The propos...

In recent years, with the increase in the elderly population, there is a need for training programs that meet individual needs. However, with conventional training programs, it is difficult to customize them in consideration of individual needs and interests, and issues remain in maintaining motivation and achieving effective training. Therefore, w...

The construction of road markings is accomplished by drawing draft lines and applying paint along those lines. Because road markings require visibility, accurate positioning, and straight lines, the drafting process is an important step. Conventionally, this drafting work is done manually by workers, who have to stand or squat repeatedly, which pla...

In recent years, labor shortages due to the aging of construction workers and the succession of construction techniques have become issues. Against this background, various types of ICT construction equipment are being introduced at construction sites, and automation of white line application work is also required. This paper proposes an automatic...

Previously path switching was done manually by remote control on Yorisoi Robot, the walking support robot. In this paper, we have automated it by estimating the user’s walking direction. This is expected to enable users with walking disabilities to concentrate on their own walking. We estimate the user’s walking direction by using machine learning...

Robot navigation is a critical component of mobile robots. In non-autonomous modes, robots are typically controlled using direct commands through keyboard, joystick, or mouse. However, in certain cases, such as robotic wheelchairs, a disabled patient might not be able to use these methods. In this paper, a speech recognition based robot navigation...

Grid-maps are often used by autonomous robots to navigate in environment. However, grid-maps have a limitation that they only contain information about free space and obstacles in the map. They do not contain semantic information about the obstacles and the place. Semantic SLAM has been proposed to solve this problem. However, sometimes, replacing...

Robot navigation is a critical component of mobile robots. Robots are typically controlled autonomously, or using direct commands through keyboard, joystick, or mouse. Traditional path planners like RRT (Rapidly Exploring Random Tree) algorithm find it difficult to generate a path though narrow passages in the map. In this paper, we improve the tra...

In recent years, the demand for service robots capable of executing high-level tasks has grown. In the future, service robots will be expected to perform complex tasks like ‘Set table for dinner’. Such high-level tasks require that the robot possess the ability to retrieve multiple objects from the environment. Thus this paper investigates the chal...

We propose a new walking support robot concept, “Nimbus Guardian,” designed to enhance the mobility of both healthy and frail elderly individuals who can walk independently. The proposed robot differs from traditional walker-type or cane-type aids by offering adaptive, minimal touch support based on the user's walking dynamics. Our goal is to reali...

Robots were placed under fixed safeguards in the early stages of robotics development. Safety and real-time risk assessment are not easy, especially when robots are in places that co-exist with humans. However, robot and human interaction have essential applications in human physical assistance, human-robot task coordination and cooperation. This p...

Skilled technicians primarily use manual tools to maintain the geometry and surface conditions of railcar wheels. To ensure efficient wheel maintenance, the development of an automated inspection system is required. Herein, an inspection method for railcar wheels is proposed based on the assessment of wheel tread dimensions and surface conditions a...

Participating in sports is of great significance to people's physical and mental well-being. While physical activity is commonplace for healthy individuals, it presents challenges for those with visual impairments, as they can not rely on visual cues to perceive essential information related to sports participation, such as their surroundings. Many...

Field robots equipped with visual sensors have been used to automate several services. In many scenarios, these robots are tele-operated by a remote operator who controls the robot motion based on a live video feed from the robot’s cameras. In other cases, like surveillance and monitoring applications, the video recorded by the robot is later analy...

In recent years, many countries including Japan are facing the problems of increasing old-age population and shortage of labor. This has increased the demands of automating several tasks using robots and artificial intelligence in agriculture, production, and healthcare sectors. With increasing old-age population, an increasing number of people are...

Overground gait training under body weight support (BWS) for patients who suffer from neurological injuries has been proven practical in recovering from walking ability. Conventionally, skilled therapists or additional robots are required to assist the patient’s body weight and pelvis movement, making the rehabilitation process physically and econo...

This paper introduces an overview of the “Adaptable AI-enabled Robots to Create a Vibrant Society” project, which is part of the “Moonshot R &D Program” led by the Cabinet Office of Japan. We also introduce CARE, Cooperation of Ai-Robot Enablers, which are being researched and developed to improve productivity in the nursing care field. The importa...

Demographic changes in our society are putting a heavy burden on care facilities and health-care infrastructure. While the elderly population is steadily increasing, there is an acute shortage of caregiving experts and professionals. This problem is becoming more severe in superaging societies, namely, Japan. Hence, this urges new and practical sol...

In recent years, social robots have been used everywhere, and the office is no exception. The office environment has become more flexible, and there are concerns about the lack of communication and its negative effects on physical and mental health. As a first step to solve this problem, this study develops a system for office robots that can notic...

Semantic SLAM is defined as the extraction and integration of semantic awareness with geometric information to produce dense, multi-layered maps. Semantic maps are crucial for service robots to perform higher-level tasks while fostering human-robot interactions. Searching for objects is one such higher-level task that will become increasingly neces...

In this research, we propose a novel lightweight and compact walking-assist robot to prevent users from falling accidents. We propose the concept for a new walking assist robot. A two-legged wheeled balancing robot is developed to follow the user’s walking motion based on the concept. Each leg consists of a two-link structure, including one driving...

We propose a novel system for teaching nursing care movements using mixed reality technology and human pose estimation technology. This paper proposes a teaching system that guides a patient from a lying posture to a sitting posture. This nursing care operation is not easy to learn because it requires several steps to guide the patient to an approp...

Path planning is a fundamental problem in mobile robots that optimize the path to determine how the robot reaches its goal. In particular sampling-based methods are popular in robotics. However, the sampling-based method is unsuitable for dynamic and narrow environments, unlike the adaptive method due to its prior planning before moving. Moreover,...

In this research, we propose a novel autonomous mobile robot for transporting passive welfare objects in medical facilities. To actuate the robot, together with a welfare object, a differential wheeled robot is developed. Additionally, to combine the robot with various types of welfare objects safely, the robot can adjust its geometrical shape in t...

Robots used at vineyards are either autonomous or tele-operated by a remote operator who controls the robot motion based on a live video feed from the robot’s cameras. Unlike structured environments like buildings which have smooth ground surface, the surface of vineyards are uneven. There could be jitters in the video due to a bumpy ground, or loo...

Precision agriculture practices play a pivotal role in improving the crop yield and optimizing maximum output for quality products and profit. In recent years, mobile robots have been actively employed to take several jobs in the agriculture field, such as monitoring farmland and tracking crop growth over time. Recent advances in sensor technology,...

This paper proposes a multi-robot path planner for intelligently accessing a limited number of charging points distributed on the map. Unlike traditional path planners, which mainly consider the shortest path criterion to generate paths, the proposed planner also considers the remaining battery power of the robots, task priority, and robot’s locati...

Virtual pheromone trailing has successfully been demonstrated for navigation of multiple robots to achieve a collective goal using a leader follower scheme. Many previous works use a pheromone deposition scheme which assumes perfect localization of the robot, however there is always some uncertainty due to sensor errors. If the leader robot gets lo...

This research presents a dynamic motion planning method for mobile robots operating in crowded scenarios. We prioritize safe path planning between moving obstacles such as humans for applications in service robots, particularly for human-centered environments where the robot needs to handle the uncertainty of the moving obstacles. The moving obstac...

This paper presents a robot exploration algorithm which uses the repelling behaviour of anti-aphrodisiac pheromone mechanism. The algorithm can be used in a multi-robot system in which different robots can efficiently explore different areas of a scene while cooperating with each other through proper pheromone deposition. This eliminates the need o...

This paper proposes a cooperative navigation system for multi-robot systems. The proposed system uses a hitchhiking based approach with a driver and follower (hitchhiking) robot. Our method allows the hitchhiker robot to skip redundant computations in navigation like path planning, localization, obstacle avoidance, and map update by completely rely...

Automated driving technology has gained a lot of momentum in the last few years. For the exploration field, navigation is the important key for autonomous operation. In difficult scenarios such as snowy environment, the road is covered with snow and road detection is impossible in this situation using only basic techniques. This paper introduces de...

Quantifying the safety of the human body orientation is an important issue in human-robot interaction. Knowing the changing physical constraints on human motion can improve inspection of safe human motions and bring essential information about stability and normality of human body orientations with real-time risk assessment. Also, this information...

Certain wheeled mobile robots e.g., electric wheelchairs, can operate through indirect joystick controls from users. Correct steering angle becomes essential when the user should determine the vehicle direction and velocity, in particular for differential wheeled vehicles since the vehicle velocity and direction are controlled with only two actuati...

Scan matching is one of the most popular methods to localize. However, in snowy environments, there are differences between the map and the scan, which can adversely affect the localization. In this study, we used semantic segmentation to recognize the snow and project onto point clouds to eliminate the differences. We also verified this method for...

In the above article [1] , we had mentioned the SSMA in many result tables, but unfortunately, we had made a mistake in the citation, which would have made the readers unable to link to the original material of the method. The faults in the above article have been corrected in this article. The self-supervised model adaptation (SSMA) [2] is a f...

In recent years, autonomous robots have extensively been used to automate several vineyard tasks. Autonomous navigation is an indispensable component of such field robots. Autonomous and safe navigation has been well studied in indoor environments and many algorithms have been proposed. However, unlike structured indoor environments, vineyards pose...

In recent years, autonomous vehicle driving technology and advanced driver assistance systems have played a key role in improving road safety. However, weather conditions such as snow pose severe challenges for autonomous driving and are an active research area. Thanks to their superior reliability, the resilience of detection, and improved accurac...

Inclement weather conditions such as snowy en- vironments poses a lot of challenge for autonomous driving. Because of the dynamic changes in the environment, there will be difference between the prior map obtained from a LiDAR system and current sensor data. To overcome this problem, in this study, we present a semantic segmentation based method to...

In this paper, we present an improved motion planning algorithm for mobile robots operating in indoor environments. Collision free robot motion planning in obstacle rich environment is crucial for the safety of the robot and for other agents or people in the vicinity. There are a plenty of motion planning algorithms that have been proposed in the p...

Vineyards which are situated in remote mountainous areas receive weak GPS signals. Mobile robots working in such vineyards needs special algorithms to navigate without using GPS information. In this paper, we propose an algorithm of autonomous mobile robot navigation which uses only the local features of the vineyard. The algorithm only uses data f...

Recently service robots are increasingly been deployed for different applications such as for homes, hospitals, and other service industries. For efficient navigation of mobile robots in complex indoor and outdoor environments, it is essential for the robot to perform collision-free and optimized planning in dynamic scenarios. Recently, reinforceme...

Path planning and navigation is a very important problem in robotics, especially for mobile robots operating in complex environments. Sampling based planners such as the probabilistic roadmaps (PRM) have been widely used for different robot applications. However, due to the random sampling of nodes in PRM, it suffers from narrow passage problem tha...

In this paper, we present a hybrid feature based mapping for robots operating in indoor environments. We combine environment features such as line segments and corners to construct 2D map for the purpose of robot navigation. Our method uses an extended Kalman filter algorithm for fusing the hybrid features into a single feature map. The proposed me...

Service robots are being used for tasks like cleaning and surveillance. These robots are expected to work continuously, and require frequent recharging. Automatic charging points are available but they are expensive and occupy space. We propose an algorithm to manage limited charging points with multiple robots. The proposed planner is designed to...

In this paper, we present a pose graph map merging SLAM for multiple mobile robot system. The local maps from individual robots are merged in a global framework with little to no latency and the updated maps are sent to all the robots in the network to update the changes in the map. By merging the local maps from the robots, a global representation...

An intelligent cleaning robot for indoor environments is proposed. Traditional cleaning robots do not have access to real-time information about the room’s status. Hence, efficient dirt detection is not possible. We solve this problem through dirt detection using an external camera that can communicate with the robot. The external camera detects th...

In this paper, we present a path planning approach for mobile robots using semantic maps. Semantic mapping is qualitative description of the robot’s surroundings, that aims to augment the navigation capabilities and task planning for robots operating in human-robot scenarios. It presents a knowledge layer over an existing map representation such th...

In this paper, we propose a robust algorithm to detect landmarks in a vineyard field. The algorithm only uses image data from inexpensive web-camera sensor to accurately detect pillars supporting the grape plants in the presence of noise. Robust detection of these landmarks is important for the autonomous task execution by a robot in vineyards. The...

Heterogeneous robot teams offer significant advantages for exploration and navigation missions in unknown environments. Notably, the air-ground robot teams have superior efficiency due to their mixed abilities and shared sensor resources useful when completing missions. However, the high energy consumption and reduced payload capability of the vert...

In this paper, we propose a robust ridge detection method for autonomous navigation of a mobile robot in agricultural fields using an inexpensive RGB-D camera system. In this system, the ridge centerline is estimated using the depth images from RGB-D sensor by using our proposed methods. We propose an autonomous driving system utilizing digital opt...

This paper mainly focuses on environment perception in snowy situations which forms the backbone of the autonomous driving technology. For the purpose, semantic segmentation is employed to classify the objects while the vehicle is driven autonomously. We train the Fully Convolutional Networks (FCN) on our own dataset and present the experimental re...

Service robots are expected to work in real world scenarios which are dynamic in nature. The traversable and non-traversable passages of the environment might change at different times. For example, it is common for some of the passages or areas in the map to be inaccessible due to cleaning, repair works, or other reasons. On the other hand, some p...

Autonomous mobile robots are being used to automate many tasks such as cleaning, delivering items, and surveillance. Such tasks often require uninterrupted and continuous service. However, robots have limited battery power and must be recharged frequently. Since manually charging each robot is not always feasible, automatic charging (docking) stati...

Robot mapping and exploration tasks are crucial for many robotic applications and allow mobile robots to autonomously navigate in unknown environments. An accurate model of the environment is, therefore, essential for the robots to localize and perform navigation. In this paper, we present a line segment based mapping of indoor environments using r...

Many tasks involved in viticulture are labor intensive. Farmers frequently monitor the vineyard to check grape conditions, damage due to infections from pests and insects, grape growth, and to estimate optimal harvest time. Such monitoring is often done manually by the farmers. Manual monitoring of large vineyards is time and labor consuming proces...

The soiling of solar panels from dry deposition affects the overall efficiency of power output from solar power plants. This study focuses on the detection and monitoring of sand deposition (wind-blown dust) on photovoltaic (PV) solar panels in arid regions using multitemporal remote sensing data. The study area is located in Bhadla solar park of R...

Ride comfort is an indicative of the dynamic performance and ride quality of a railway vehicle. The most prominent motion related factor that affects the ride comfort of a railway vehicle is the vertical vibration of the railway car-body. This study aims to suppress the vertical flexural vibrations on a railway car-body floor by using a semi-active...

Low Frequency Vibrations have increased significantly in railway car-bodies designed for high-speed railway operations due to the dominant effect of flexural vibration of the car-body caused by weight reduction of railway vehicles to satisfy speed requirements and energy efficiency. To reduce such low frequency vibration a twin pronged approach is...

Lighter Railway car-bodies are preferred for High Speed Rail Transport due to its fuel efficiency. Vertical bending vibrations in low frequency range of 0-10 Hz become prominent in light car-bodies. This study aims to suppress low frequency bending vibrations of a 1/12 th scale car-body model by connecting a tuned multi-mode shunt circuit across th...

Safe robot navigation in human-centered environments is important to avoid collisions. A major limitation of the traditional path planning algorithms is that the global path is planned only with the knowledge of static obstacles in the map. This paper presents a novel ‘HMRP (heat map-based robot path planner)’ which uses fixed external cameras to g...

In this paper, we propose a robust algorithm to detect landmarks in a vineyard field. The algorithm only uses data from laser range sensor to accurately detect pillars supporting the grape plants in the presence of noise. Robust detection of these landmarks is important for the autonomous task execution by a robot in vineyards. The detected pillars...