Learning Motion Predictors for Smart Wheelchair using Autoregressive Sparse Gaussian Process

Constructing a smart wheelchair on a commercially available powered wheelchair (PWC) platform avoids a host of seating, mechanical design and reliability issues but requires methods of predicting and controlling the motion of a device never intended for robotics. Analog joystick inputs are subject to black-box transformations which may produce intuitive and adaptable motion control for human operators, but complicate robotic control approaches; furthermore, installation of standard axle mounted odometers on a commercial PWC is difficult. In this work, we present an integrated hardware and software system for predicting the motion of a commercial PWC platform that does not require any physical or electronic modification of the chair beyond plugging into an industry standard auxiliary input port. This system uses an RGB-D camera and an Arduino interface board to capture motion data, including visual odometry and joystick signals, via ROS communication. Future motion is predicted using an autoregressive sparse Gaussian process model. We evaluate the proposed system on real-world short-term path prediction experiments. Experimental results demonstrate the system's efficacy when compared to a baseline neural network model.Comment: The paper has been accepted to the International Conference on Robotics and Automation (ICRA2018

OpenPTrack: Open Source Multi-Camera Calibration and People Tracking for RGB-D Camera Networks

OpenPTrack is an open source software for multi-camera calibration and people tracking in RGB-D camera networks. It allows to track people in big volumes at sensor frame rate and currently supports a heterogeneous set of 3D sensors. In this work, we describe its user-friendly calibration procedure, which consists of simple steps with real-time feedback that allow to obtain accurate results in estimating the camera poses that are then used for tracking people. On top of a calibration based on moving a checkerboard within the tracking space and on a global optimization of cameras and checkerboards poses, a novel procedure which aligns people detections coming from all sensors in a x-y-time space is used for refining camera poses. While people detection is executed locally, in the machines connected to each sensor, tracking is performed by a single node which takes into account detections from all over the network. Here we detail how a cascade of algorithms working on depth point clouds and color, infrared and disparity images is used to perform people detection from different types of sensors and in any indoor light condition. We present experiments showing that a considerable improvement can be obtained with the proposed calibration refinement procedure that exploits people detections and we compare Kinect v1, Kinect v2 and Mesa SR4500 performance for people tracking applications. OpenPTrack is based on the Robot Operating System and the Point Cloud Library and has already been adopted in networks composed of up to ten imagers for interactive arts, education, culture and human\u2013robot interaction applications

A Cost-Effective Person-Following System for Assistive Unmanned Vehicles with Deep Learning at the Edge

The vital statistics of the last century highlight a sharp increment of the average age of the world population with a consequent growth of the number of older people. Service robotics applications have the potentiality to provide systems and tools to support the autonomous and self-sufficient older adults in their houses in everyday life, thereby avoiding the task of monitoring them with third parties. In this context, we propose a cost-effective modular solution to detect and follow a person in an indoor, domestic environment. We exploited the latest advancements in deep learning optimization techniques, and we compared different neural network accelerators to provide a robust and flexible person-following system at the edge. Our proposed cost-effective and power-efficient solution is fully-integrable with pre-existing navigation stacks and creates the foundations for the development of fully-autonomous and self-contained service robotics applications

EPypes: a framework for building event-driven data processing pipelines

Many data processing systems are naturally modeled as pipelines, where data flows though a network of computational procedures. This representation is particularly suitable for computer vision algorithms, which in most cases possess complex logic and a big number of parameters to tune. In addition, online vision systems, such as those in the industrial automation context, have to communicate with other distributed nodes. When developing a vision system, one normally proceeds from ad hoc experimentation and prototyping to highly structured system integration. The early stages of this continuum are characterized with the challenges of developing a feasible algorithm, while the latter deal with composing the vision function with other components in a networked environment. In between, one strives to manage the complexity of the developed system, as well as to preserve existing knowledge. To tackle these challenges, this paper presents EPypes, an architecture and Python-based software framework for developing vision algorithms in a form of computational graphs and their integration with distributed systems based on publish-subscribe communication. EPypes facilitates flexibility of algorithm prototyping, as well as provides a structured approach to managing algorithm logic and exposing the developed pipelines as a part of online systems

Evaluation of Microsoft Kinect 360 and Microsoft Kinect One for robotics and computer vision applications

To understand which one beetween Kinect 360 and Kinect One is better in computer vision or robotic applications, an in-depth study of the two Kinects is necessary. In the first section of this thesis, the Kinects’ features will be compared by some tests; in the second section, instead, these sensors will be evaluated and compared for the purpose of robotics and computer vision application

A Software Architecture for RGB-D People Tracking Based on ROS Framework for a Mobile Robot

This paper describes the software architecture of a distributed multi-people tracking algorithm for mobile platforms equipped with a RGB- D sensor. Our approach features an efficient point cloud depth-based clus- tering, an HOG-like classification to robustly initialize a person tracking and a person classifier with online learning to drive data association. We explain in details how ROS functionalities and tools play an important role in the possibility of the software to be real time, distributed and easy to configure and debug. Tests are presented on a challenging real-world indoor environment and track- ing results have been evaluated with the CLEAR MOT metrics. Our algo- rithm proved to correctly track 96% of people with very limited ID switches and few false positives, with an average frame rate above 20 fps. We also test and discuss its applicability to robot-people following tasks and we re- port experiments on a public RGB-D dataset proving that our software can be distributed in order to increase the framerate and decrease the data ex- change when multiple sensors are used

Robot Learning by observing human actions

Nowadays, robotics is entering in our life. One can see robot in industries, offices and even in homes. The more robots are in contact with people, the more requests of new capabilities and new features increase, in order to make robots able to act in case of need, help humans or be a companion. Therefore, it becomes essential to have a quick and easy way to teach new skills to robots. That is the aim of Robot Learning from Demonstration. This paradigm allows to directly program new tasks in a robot through demonstrations. This thesis proposes a novel approach to Robot Learning from Demonstration able to learn new skills from natural demonstrations carried out from naive users. To this aim, we introduce a novel Robot Learning from Demonstration framework by proposing novel approaches in all functional sub-units: from data acquisition to motion elaboration, from information modeling to robot control. A novel method is explained to extract 3D motion flow information from both RGB and depth data acquired by using recently introduced consumer RGB-D cameras. The motion data are computed over the time to recognize and classify human actions. In this thesis, we describe new techniques to remap human motion to robotic joints. Our methods allow people to natural interact with robots by re-targeting the whole body movements in an intuitive way. We develop algorithm for both humanoids and manipulators motion and test them in different situations. Finally, we improve modeling techniques by using a probabilistic method: the Donut Mixture Model. This model is able to manage several interpretations that different people can produce performing a task. The estimated model can also be updated directly by using new attempts carried out by the robot. This feature is very important to rapidly obtain correct robot trajectories by means of few human demonstrations. A further contribution of this thesis is the creation of a number of new virtual models for the different robots we used to test our algorithms. All the developed models are compliant with ROS, so they can be used to foster research in the field from all the community of this very diffuse robotics framework. Moreover, a new 3D dataset is collected to compare different action recognition algorithms. The dataset contains both RGB-D information coming directly from the sensor and skeleton data provided by a skeleton tracker

Robust perception of humans for mobile robots RGB-depth algorithms for people tracking, re-identification and action recognition

Human perception is one of the most important skills for a mobile robot sharing its workspace with humans. This is not only true for navigation, because people have to be avoided differently than other obstacles, but also because mobile robots must be able to truly interact with humans. In a near future, we can imagine that robots will be more and more present in every house and will perform services useful to the well-being of humans. For this purpose, robust people tracking algorithms must be exploited and person re-identification techniques play an important role for allowing robots to recognize a person after a full occlusion or after long periods of time. Moreover, they must be able to recognize what humans are doing, in order to react accordingly, helping them if needed or also learning from them. This thesis tackles these problems by proposing approaches which combine algorithms based on both RGB and depth information which can be obtained with recently introduced consumer RGB-D sensors. Our key contribution to people detection and tracking research is a depth-clustering method which allows to apply a robust image-based people detector only to a small subset of possible detection windows, thus decreasing the number of false detections while reaching high computational efficiency. We also advance person re-identification research by proposing two techniques exploiting depth-based skeletal tracking algorithms: one is targeted to short-term re-identification and creates a compact, yet discrimative signature of people based on computing features at skeleton keypoints, which are highly repeatable and semantically meaningful; the other extract long-term features, such as 3D shape, to compare people by matching the corresponding 3D point cloud acquired with a RGB-D sensor. In order to account for the fact that people are articulated and not rigid objects, it exploits 3D skeleton information for warping people point clouds to a standard pose, thus making them directly comparable by means of least square fitting. Finally, we describe an extension of flow-based action recognition methods to the RGB-D domain which computes motion over time of persons' 3D points by exploiting joint color and depth information and recognizes human actions by classifying gridded descriptors of 3D flow. A further contribution of this thesis is the creation of a number of new RGB-D datasets which allow to compare different algorithms on data acquired by consumer RGB-D sensors. All these datasets have been publically released in order to foster research in these fields