A novel track-drive mobile robotic framework for conducting projects on robotics and control systems

This paper presents a novel robotic framework to help students to practically grasp the concepts of Robotics and Control Systems in a laboratory environment. The framework is centered on a robotic rover having two tank-like tracks which permit locomotion on uneven terrains. The sensory system consists of encoders for position feedback while the actuation system comprises of six precise DC motors. To enhance the learning outcomes of students and to permit readily realizaion of applications, developed software library supports three different command levels. The efficacy of the framework has been demonstrated by presenting a list of projects conducted on the framework. In particular, as a case-study, a project titled tether tracking and control of robotic rover has been detailed in the paper with presentation of experimental results. The pilot study indicated that incorporating the framework in robotics laboratory resulted in an efficient methodology of imparting interdisciplinary knowledge to engineering students. Additionally, the framework finds its potential in research of advanced robotic and control algorithms

State estimation technique for a planetary robotic rover

Given the long traverse times and severe environmental constraints on a planet like Mars, the only option feasible now is to observe and explore the planet through more sophisticated planetary rovers. To achieve increasingly ambitious mission objectives under such extreme conditions, the rovers must have autonomy. Increased autonomy, obviously, relies on the quality of estimates of rover's state i.e. its position and orientation relative to some starting frame of reference. This research presents a state estimation approach based on Extended Kalman Filter (EKF) to fuse distance from odometry and attitude from an Inertial Measurement Unit (IMU), thus mitigating the errors generated by the use of either system alone. To simulate a Sun-sensor based approach for absolute corrections, a magnetic compass was used to give absolute heading updates. The technique was implemented on MotherBot, a custom-designed skid steered rover. Experimental results validate the application of the presented estimation strategy. It showed an error range within 3% of the distance travelled as compared to about 8% error obtained from direct fusion

Effective localization and tracking utilizing stereo vision for planetary micro-rover ROSA

Pianetary exploration mainly depends on orbiters, rovers and landers. Especially the rovers provide a large covering area and close-up investigations about the planets. ROSA is a prototype tracked rover for the Mars exploration developed in the project sponsored by European Space Agency (ESA). The localization of ROSA is relied on stereo vision from the stereo cameras standing on top of the lander. However, due to the fixed position of the lander and the stereo cameras as well as the small field of view (FOV) of the cameras, the area where ROSA can be localized is very limited. Moreover, the stereo cameras are located too far to observe the geographical features in detail and to find out the interesting samples. In order to enlarge the localization area, a new system is designed and implemented; meanwhile it provides close-up observation of geographical features and takes images of the interesting samples. A pan-tilt unit (PTU) is installed to hold the bar of the stereo cameras. It can rotate around the pan and tilt axes to enable the cameras to cover larger areas. To ensure that the rover stays in the images of both cameras when the localization of rover is required and also that the cameras can autonomously follow the rover, a tracking method is implemented. It is related with the active marker, utilizing the background subtraction and blob connection to obtain the accurate LED position in the images, which helps to infer the rover position in the images. This tracking procedure is thoroughly consistent with the localization method. On the basis of the rover position in the images, the PTU is controlled to move the cameras to a proper orientation to ensure that the rover always appears in both images. A model for localization is built, which provides accurate localization information with less computation. Another camera is installed in the front panel of ROSA to take images and send them back to the ground. To control the mobility of ROSA in a correct and easy way, a new program with graphic user interface is developed for the ground station. Furthermore, a tracking program with video feedback has been developed

Flexible joint robotic manipulator: Modeling and design of robust control law

This paper presents modeling and sophisticated control of a single Degree Of Freedom (DOF) flexible robotic arm. The derived model is based on Euler-Lagrange approach while the first and second order (super twisting) Sliding Mode Control (SMC) is proposed as a non-linear control strategy. The control laws are subjected to various test inputs including step and sinusoids to demonstrate their tracking efficiency by observing transient and steady state behaviours. Both orders of SMC are then compared to characterize the control performance in terms of robustness, handling external disturbances and chattering. Results dictate that the super twisting SMC is more accurate and robust against the external noise and chattering phenomena compared to the first order SMC

Tangle-Free Exploration with a Tethered Mobile Robot

Exploration and remote sensing with mobile robots is a well known field of research, but current solutions cannot be directly applied for tethered robots. In some applications, tethers may be very important to provide power or allow communication with the robot. This paper presents an exploration algorithm that guarantees complete exploration of arbitrary environments within the length constraint of the tether, while keeping the tether tangle-free at all times. While we also propose a generalized algorithm that can be used with several exploration strategies, our implementation uses a modified frontier-based exploration approach, where the robot chooses its next goal in the frontier between explored and unexplored regions of the environment. The basic idea of the algorithm is to keep an estimate of the tether configuration, including length and homotopy, and decide the next robot path based on the difference between the current tether length and the shortest tether length at the next goal position. Our algorithm is provable correct and was tested and evaluated using both simulations and real-world experiments

Exploration of Unknown Environments Using a Tethered Mobile Robot

Exploration with mobile robots is a well known field of research, but current solutions cannot be directly applied for tethered robots. In some applications, tethers may be very important to provide power or allow communication with the robot. This thesis presents an exploration algorithm that guarantees complete exploration of arbitrary environments within the length constraint of the tether, while keeping the tether tangle-free at all times. While a generalized algorithm that can be used with several exploration strategies is also proposed, the presented implementation uses a modified frontier-based exploration approach, where the robot chooses its next goal in the frontier between explored and unexplored regions of the environment. The main modification from standard frontier-based method is the use of a cost function to sort multiple goals in one iteration and pick the cheapest one to go to, minimizing global path length in the process. The cost is calculated in terms of path length with tether constraints accounted for. The basic idea of the algorithm is to keep an estimate of the tether configuration, including length and homotopy, and decide the next robot path based on the length difference between the current tether length and the shortest tether length at the next goal position. The length difference is then used to determine whether it is safe for the robot to take the shortest path to the goal, or whether the robot has to take a different path to the goal in the way that would put the tether back into the most optimal configuration. The maximum length difference that would still guarantee global tangle-free paths has been shown to be the circumference of the smallest expected obstacle in the environment. The presented algorithm is provable correct and was tested and evaluated using both simulations and real-world experiments. Navigation of a planar robot is done with the aid of a Simultaneous Localization and Mapping (SLAM) system, with the data being provided by the on-board LiDAR scanner. The results from conducted experiments have demonstrated that the proposed algorithm results in the total path length increase of anywhere from 30% up to to 80% compared to untethered frontier-based approach, with the exact percentage increase dependent on the complexity of the environment. It is also approximately 6 times shorter than the total path length in a conservative approach of backtracking to the base to avoid tangling

TransFormers for Extreme Environments: Projecting Favorable Micro-Environments Around Robots and Areas of Interest

Surviving Extreme Space Environments (EE) is one of NASAs Space Technology Grand Challenges; we propose a paradigm shift in addressing this challenge. TransFormers (TFs) transform a region of an extreme environment into a favorable micro-environment, projecting energy at the precise location where robots or humans operate. TFs often use shape transformation to control the energy projection

NASA Tech Briefs, November 2012

The topics include: Visual System for Browsing, Analysis, and Retrieval of Data (ViSBARD); Time-Domain Terahertz Computed Axial Tomography NDE System; Adaptive Sampling of Time Series During Remote Exploration; A Tracking Sun Photometer Without Moving Parts; Surface Temperature Data Analysis; Modular, Autonomous Command and Data Handling Software with Built-In Simulation and Test; In-Situ Wire Damage Detection System; Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions; Wideband Agile Digital Microwave Radiometer; Buckyball Nucleation of HiPco Tubes; FACT, Mega-ROSA, SOLAROSA; An Integrated, Layered-Spinel Composite Cathode for Energy Storage Applications; Engineered Multifunctional Surfaces for Fluid Handling; Polyolefin-Based Aerogels; Adjusting Permittivity by Blending Varying Ratios of SWNTs; Gravity-Assist Mechanical Simulator for Outreach; Concept for Hydrogen-Impregnated Nanofiber/Photovoltaic Cargo Stowage System; DROP: Durable Reconnaissance and Observation Platform; Developing Physiologic Models for Emergency Medical Procedures Under Microgravity; Spectroscopic Chemical Analysis Methods and Apparatus; Low Average Sidelobe Slot Array Antennas for Radiometer Applications; Motion-Corrected 3D Sonic Anemometer for Tethersondes and Other Moving Platforms; Water Treatment Systems for Long Spaceflights; Microchip Non-Aqueous Capillary Electrophoresis (MicronNACE) Method to Analyze Long-Chain Primary Amines; Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles; Mars Science Laboratory Engineering Cameras; Seismic Imager Space Telescope; Estimating Sea Surface Salinity and Wind Using Combined Passive and Active L-Band Microwave Observations; A Posteriori Study of a DNS Database Describing Super critical Binary-Species Mixing; Scalable SCPPM Decoder; QuakeSim 2.0; HURON (HUman and Robotic Optimization Network) Multi-Agent Temporal Activity Planner/Scheduler; MPST Software: MoonKomman

Towards autonomy in agriculture: Design and prototyping of a robotic vehicle with seed selector

Traditional method of seeding by farmers demands laborious work and is now becoming story of the past. Technological revolution in mechatronics and allied areas is reshaping the agricultural processes, making the robots an integral part of this automation. This paper presents design details of an autonomous robot developed keeping in view the constraints imposed by an agricultural field. The novelty of the proposed low-cost indigenously developed modular vehicle lies in design of its seed selector. The simple but efficient mechanism of the single seed selector with extremely low miss rate distinguishes the vehicle from other designs. Hardware details including sensing, actuation, processing and communication modules and software architecture are detailed in the paper. Results of trajectory tracking obtained by implementing the proposed scheme on a mini-robot and functionality of seed selector demonstrate potential of the presented robotic vehicle

A multi-robot educational and research framework

Robots have greatly transformed human’s life. Multi-disciplinary research in robotics essentially demands having sophisticated frameworks with diverse range of capabilities ranging from simple tasks like testing of control algorithms to handling complex scenarios like multiple robot coordination. The present research addresses this demand by proposing a reliable, versatile and cheap platform enriched with enormous features. The framework has been conceptualized with three robots having different drive mechanisms, sensing and communication capabilities. The proposed ‘Wanderbot’ family consists of ForkerBot, MasterBot and HexaBot. The ForkerBot is a four-wheeled robot equipped with ultra sonic range finder, wheel encoder, bump sensor, temperature sensor, GSM, GPS and RF communication modules. The robot, having a payload capacity of 8 pounds, supports both Differential and Ackerman drive mechanisms and can be used to validate advanced obstacle avoidance algorithms. The MasterBot is also a wheeled robot with an on-board camera and is skid-steered. The robot finds potential in research on image processing and computer vision and in analysis and validation of algorithms requiring high-level computations like complex path traversal. The third member in the Wander family, HexaBot, is a six-legged robot, which is able to exhibit the movement of tripod gait and can be used for investigating walking and climbing algorithms. The three members of Wander family can communicate with one another, thus making it a good candidate for research on coordinated multi-robots. Additionally, such a prototyped platform with vast attractive features finds potential in an academic and vocational environment