Sean N Brennan

• Ph.D.
• Professor (Associate) at Pennsylvania State University

The ability to update a path plan is a required capability for autonomous mobile robots navigating through uncertain environments. This paper proposes a re-planning strategy using a multilayer planning and control framework for cases where the robot's environment is partially known. A medial axis graph-based planner defines a global path plan based...

title>ABSTRACT Robot path-planning is a central task for navigation and most path-planners perform well in mapped environments with explicit obstacle boundaries. However, many obstacle fields are better defined by the probability of obstacles and obstacle geometries rather than by explicit locations. Few tools and data structures exist, other than...

title>ABSTRACT This work investigates the effects of obstacle uncertainty on the speed, distance, and feasibility of a planned traversal path. Simulation results for artificial and real-world environments are used to numerically quantify how geometric uncertainty within a map affects path traversal cost. A significant outcome of this research is t...

title>ABSTRACT In the field of ground robotics, the problems of global path planning and local obstacle avoidance are often treated separately but both are assessed in terms of a cost related to navigating through a given environment. Traversal cost is typically defined in terms of the required fuel [ 1 ], required travel time [ 2 ], and imparted...

div class="section abstract"> A critical first step for a robot navigating an obstacle field is to plan a collision-free path through the environment. Historically, solutions for path planning largely use grid-based search methods particularly when guarantees are required that do not permit randomization-based methods. In large operational domains,...

This paper presents algorithms to predict the energy used by a skid‐steer robot to complete a given path, including the refinement of that prediction during operation. The vast majority of commercially available ground mobile robots utilize skid‐steer technology due to the robustness and maneuverability of the design. However, the complex track/ter...

Spent nuclear fuel, after cooling within a pool storage system, is generally stored in stainless steel dry storage casks. Some dry storage casks have been in regular use for decades, causing increasing interest in technologies to inspect these units. This work presents a case study on the design and prototyping challenges of a robotic inspection sy...

In prototyping complex systems, concept iterations often reach a point where incremental modifications to one part in a complex system can produce unexpected, cascading changes in the rest of the system. This phenomenon can require time-consuming and expensive corrections, particularly when physical prototypes are involved — as was the situation in...

Extended dry storage of spent nuclear fuel makes it desirable to assess the structural integrity of the storage canisters. Stress corrosion cracking of the stainless steel canister is a potential degradation mode especially in marine environments. Sensing technologies are being developed with the aim of detecting the presence of chloride-bearing sa...

This paper presents ongoing results from a Tractor Driving Simulator study at Penn State University studying how tractor overturn events can be prevented. The simulator is used to expose subjects, in a controlled environment, to situations that would be unsafe to test in the field. Two sets of experiments are examined here. The first experiment con...

This article optimizes the allocation of external current demand among parallel strings of cells in a lithium-ion battery pack to improve Fisher identifiability for these strings. The article is motivated by the fact that better battery parameter identifiability can enable the more accurate detection of unhealthy outlier cells. This is critical for...

Developing devices for stability monitoring and rollover alerts is a promising possibility to prevent overturn events, which pose a severe risk to tractor operators. However, performing relevant tests with operators in the field is dangerous and impractical. As an alternative, this work identifies the challenges of simulating a tractor driving envi...

Currently, there is a lack of low-cost, real-time solutions for accurate autonomous vehicle localization. The fusion of a precise a priori map and a forward-facing camera can provide an alternative low-cost method for achieving centimeter-level localization. This paper analyzes the position and orientation bounds, or region of attraction, with whic...

There are over three million wheelchair users within the United States and that number is growing. This paper is concerned with improving the safety of wheelchair operation by the on-line estimation of tire slip. Wheelchair tire slip is a result of icy or low friction surfaces, often representative of dangerous conditions. In this research, wheel s...

This paper presents implementation details and performance metrics for software developed to connect the Robot Operating System (ROS) with Simulink Real-Time (SLRT). The communication takes place through the User Datagram Protocol (UDP) which allows for fast transmission of large amounts of data between the two systems. We use SLRT’s built-in UDP c...

Electric wheelchair users depend on a reliable power system in order to regain mobility in their daily lives. If a wheelchair’s battery power depletes without the user being aware, the individual may become stranded, further limiting their freedom of mobility and potentially placing the user in a harmful situation. This research seeks to develop a...

This paper describes the derivation and experimental validation of geometric equations that govern insertion and extraction of a robotic inspection system that operates in gaps around vertical dry storage casks. During insertion, a robotic system may become jammed due to unbalanced forces acting on the robot, or wedged due to over-sized robot geome...

Extended dry storage of spent nuclear fuel makes it desirable to assess the structural integrity of the storage canisters. Stress corrosion cracking of the stainless steel canister is a potential degradation mode especially in marine environments. Sensing technologies are being developed with the aim of detecting the presence of chloride-bearing sa...

The controllability of a dynamical system or network describes whether a given set of control inputs can completely exert influence in order to drive the system towards a desired state. Structural controllability develops the canonical coupling structures in a network that lead to un-controllability, but does not account for the effects of explicit...

This research investigates the viability of detecting vehicle road departure via the measurements of anomalies in vehicle dynamics, especially under conditions when left and right tires experience imbalance of forces (split-μ condition). This approach is based on established low-order vehicle models to facilitate real-time implementation. Vehicle s...

The severity of a road departure event strongly depends on the features around the roadway: trees and other “hard” fixed objects represent a severe collision hazard, steep slopes nearby may be representing rollover threats or frontal impact hazards, and sharp road-edge drop-offs may exist that prevent high-speed road recovery. But the near-road are...

Freedom of mobility is a crucial aspect of our daily lives. Consequently, engineering solutions for mobility, including smart wheelchairs, are becoming increasingly important for those with disabilities. However, the lack of a reliable solution for indoor localization has affected the pace of research in this direction. GPS signals cannot be measur...

This research investigates vehicle control techniques for rollover prevention in a collision avoidance scenario. The zero-moment point (ZMP) is used to evaluate the vehicle’s current and near-future rollover propensity with the purpose of predicting and correcting impending wheel lift. Specifically, a linear-quadratic (LQ) output regulator is utili...

A parallel hybrid electric vehicle (HEV) combines the power produced by electric machines and a combustion engine to enable improved fuel economy. Optimization of the power-split algorithm managing both torque sources can be readily achieved offline, but online implementation results often show great deviation from expected fuel economy due to traf...

The advent of intelligent vehicle technologies holds significant potential to alter the dynamics of traffic flow. Prior work on the effects of such technologies on the formation of self-organized traffic jams has led to analytical solutions and numerical simulations at the mesoscopic scale, which may not yield significant information about the dist...

Tractor instability is a major cause of serious injuries and fatalities in the agricultural industry. Thus, preventing tractor rollover can have a vital impact in reducing injury risk and saving lives of operators. This study presents preliminary experimental results on the perception of tilt angles. Using a novel tractor driving simulator develope...

This research estimates the minimum preview time needed to prevent untripped wheel lift events by analyzing simple maneuvers that are idealizations of a human driver's response in collision avoidance situations. To predict a vehicle's future rollover propensity, the zero-moment point (ZMP) metric is applied to projected vehicle trajectories. Compar...

Current research methods directed towards measuring the influence of specific agents on the dynamics of a large-scale multi-agent system (MAS) rely largely on the notion of controllability of the full-order system, or on the comparison of agent dynamics via a user-defined macroscopic system property. However, it is known that several large-scale mu...

This paper proposes a model-based method to estimate lateral planar vehicle states using a forward-looking monocular camera, a yaw rate gyroscope, and an a priori map of road superelevation and temporally previewed lane geometry. Theoretical estimator performance from a steady-state Kalman-filter implementation of the estimation framework is calcul...

Improvements in sensor technology and data processing rates are leading to the collection of vast databases of time series data. These data sets are spawning new applications that are transforming the way we live, work, and learn. In particular in the domain of vehicles, the rapid expansion of sensors to monitor both the state of the system and the...

This paper describes a dynamical model-based method for the localization of road vehicles using terrain data from the vehicle's onboard sensors. Road data are encoded using linear dynamical models and then, during travel, the location is identified through continuous comparison of a bank of linear models. The approach presented has several advantag...

Observability and controllability are essential concepts to the design of predictive observer models and feedback controllers of networked systems. For example, noncontrollable mathematical models of real systems have subspaces that influence model behavior, but cannot be controlled by an input. Such subspaces can be difficult to determine in compl...

The objective of this study was to develop superelevation criteria for sharp horizontal curves on steep grades. Field studies were undertaken and vehicle dynamics simulations (point mass, bicycle, and multibody) were performed to investigate combinations of horizontal curve and vertical grade design criteria. The vehicle dynamics simulations used A...

This paper shapes the periodic cycling of a lithium-ion battery to maximize the battery's parameter identifiability. The paper is motivated by the need for faster and more accurate lithium-ion battery diagnostics, especially for transportation. Poor battery parameter identifiability makes diagnostics challenging. The existing literature addresses t...

This paper presents a new method for estimating the capacity of a lithium ion battery cell in the presence of a reference cell - the parameters of which are well characterized - in series with it. The method assumes that both cells are cycled using the same current trajectory starting from the same state of charge (e.g. fully charged). Voltage meas...

While decades of work and hundreds of research papers exist on unicycle robot control, the control of skid-steer robots is not yet as standardized due to the complexity of wheel slipping behavior. This work presents a method of utilizing the track or wheel Instantaneous Centers of Rotation (ICRs) on a skid-steer vehicle to map skid-steer dynamics t...

This work introduces the novel concept of an influential subspace, with focus on its application to highway traffic containing connected vehicles. In this context, an influential subspace of a connected vehicle is defined as the region of a highway where the connected vehicle has the ability to positively influence the macrostate, i.e. the traffic...

This paper examines the health-conscious optimal control of lithium-ion batteries. The paper focuses specifically on the optimizing battery control policies to minimize solid electrolyte interphase (SEI) layer growth. However, its approach is applicable to other degradation mechanisms. The paper exploits the fact, established by the mathematical co...

Increasingly, roadway designers use simulations to analyze how roadway design choices affect vehicle dynamics and ultimately safety. When using commercial multi-body simulations for analysis of vehicle dynamics, engineers are usually able to trust that the vehicle states predicted by simulations are reasonably accurate. This is because simulation s...

Intelligent vehicles equipped with adaptive cruise control (ACC) technology have the potential to significantly impact the traffic flow dynamics on highways. Prior work in this area has sought to understand the impact of intelligent vehicle technologies on traffic flow by making use of mesoscopic modeling that yields closed-form solutions. However,...

Introduction This paper presents the results of a comprehensive project whose goal is to identify roadway design practices that maximize the margin of safety between the friction supply and friction demand. This study is motivated by the concern for increased accident rates on curves with steep downgrades, geometries that contain features that inte...

This paper presents a method of estimating skid-steer robot power usage using on-line estimation of terrain and kinematic parameters. For vehicles operating at low speeds on hard, flat surfaces, kinematic models utilizing the instantaneous centers of rotation (ICRs) of the tracks or wheels of a skid-steer vehicle have been shown to provide accurate...

This paper presents a chance constrained approach to extracting linear models from reference data to be used in subsequence identification or pattern matching. Due to the ordered nature of time series data, the extracted models are sequential, with feasible domains separated by transition points. In a sequence of models, a transition point is defin...

This paper presents new methods for improving state of charge (SOC) estimation accuracy for Lithium Ion battery cells connected in series. The methods benefit from the fact that the cells share a common current trajectory. These methods extend previously studied techniques for SOC estimation, like the Extended Kalman Filter. While the existing lite...

Computer-based guidance of passenger vehicles is a common reality today, but cost, computation, and robustness challenges remain to obtain accurate vehicle state estimates. This study builds on previous work by the authors towards the development of a vehicle state estimation framework that uses optimal preview control theory to fuse map, GPS, iner...

This research estimates the minimum intervention distance needed for a vehicle to safely avoid an obstacle, while also preventing wheel lift and tire skid. The intervention strategy considered is an open-loop lane change avoidance trajectory. As the vehicle approaches the obstacle, it continually determines the available lane change maneuver, relyi...

This paper presents a kinematic extended Kalman filter (EKF) designed to estimate the location of track instantaneous centers of rotation (ICRs) and aid in model-based motion prediction of skid-steer robots. Utilizing an ICR-based kinematic model has resulted in impressive odometry estimates for skid-steer movement in previous works, but estimation...

Using terrain data and dynamical models is a promising approach to map-based passenger vehicle localization. In this approach, dynamical models are extracted from terrain data collected by a vehicle with a known location. The dynamical models are stored as a “map” of the data onto other vehicles. These vehicles can then discern their own location b...

This research focuses on determining the minimum preview time needed to predict and prevent vehicle rollover. Statistics show that although rollover only occurs in 2.2% of total highway crashes, it accounts for 10.7% of total fatalities. There are several dynamic rollover metrics in use that measure a vehicle’s rollover propensity under specified c...

Observability and controllability are vitally important in networks, but almost all of the present theory was developed for linear networks without symmetries. To advance beyond the study of such generic networks, we quantify observability and controllability in small (3 node) nonlinear neuronal networks as a function of 1) the connection topology...

The extraction of robust features for comparing and analyzing time series is a fundamentally important problem. Research efforts in this area encompass dimensionality reduction using popular signal analysis tools such as the discrete Fourier and wavelet transforms, various distance metrics, and the extraction of interest points from time series. Re...

This paper describes the development of a Hardware-in-the-Loop (HIL) driving simulator designed with ROS and Gazebo. An analysis of current driving simulator software is conducted focusing on the requirements for HIL simulators versus traditional simulator implementations. Finally, the process for implementing an open-source HIL-centric driving sim...

This paper proposes a method for using a forward-looking monocular camera along with previewed road geometry from a high-fidelity, low-dimensional map to estimate lateral planar vehicle states by measuring the vehicle's temporally anticipated reference trajectory. Theoretical estimator performance from a steady-state Kalman Filter implementation of...

To investigate the standardization of ground robot endurance as defined by the National Institute of Standard and Technology (NIST), this paper presents the development and applications of a novel robot tracking system that uses three overhead cameras to record the number of laps and the distance traveled by a robot over the duration of a test. The...

Self-organizing traffic jams are known to occur in medium-to-high density traffic flows, and it is suspected that adaptive cruise control (ACC) may affect their onset in mixed human-ACC traffic. Unfortunately, closed-form solutions that predict the occurrence of these jams in mixed human-ACC traffic do not exist. In this paper, both human and ACC d...

This paper describes a novel method for the location of road vehicles using vehicle pitch data obtained from on-board sensors. The method encodes the road map data using linear dynamical models, and then, during travel, identifies the vehicle location through continuous validation of the previously obtained linear models. The approach presented has...

This paper presents a novel approach to find patterns in vehicle x-y-z acceleration data for use in prognostics and diagnostics. In this problem, vehicles are assumed to travel on the same routes and often times as a part of convoys but their GPS and other position information has been removed for privacy reasons. The goal of the pattern matching s...

Vehicle electrification is an increasingly popular design strategy for improving efficiency and reducing operating costs. This study uses an experimental and model-based approach to quickly and easily predict and optimize the efficiency of an electric bicycle system based on selection of critical parameters, including motor efficiency curves, rider...

This paper proposes a method for using previewed road geometry from a high-fidelity map to improve estimates of planar vehicle states in the presence of unmodeled sensor bias errors. Using well-established, linear models for representing human driver behavior and for planar vehicle states, a causal link between previewed road geometry and vehicle s...

This paper considers the scaling principles associated with the power and energy density of batteries and generators as applied to mobile robots and similarly-sized vehicles. We seek to identify, based on present technology, the size range at which a generator inclusive of a direct current electric motor, gearbox, and internal combustion engine can...

Explosive ordinance disposal (EOD) robots are limited in endurance and range by the amount of energy available in the batteries used to power them. Continuously variable transmission (CVT) technology has developed quickly in recent years in the automotive field and is now being applied to smaller vehicles such as bicycles and electric scooters. Thi...

Feature vectors encoded by using extrema are known to be immune to different types of distortions of the original time series [1]. This property enables them to be effective in a wide range of pattern matching applications for time series data [2] [3]. The process of extracting extrema is usually preceded by a filtering step to reduce noise and to...

Prior experiments have confirmed that specific GPS-free terrain-based localization algorithms can perform vehicle tracking in real-time on a single road segment at a time. However, the ability of these algorithms to perform vehicle tracking on large road networks, i.e. across intersections and multiple road segments, has not been verified. In this...

Delays can be a critical property of control systems, since they introduce a frequency-proportional phase difference. In some applications, it is desirable to speed up the dynamic behavior of such systems. In this paper, a control will be provided that couples a delayed system that has a nonlinear state space function and linear input/output functi...

We quantify observability in small (3 node) neuronal networks as a function of 1) the connection topology and symmetry, 2) the measured nodes, and 3) the nodal dynamics (linear and nonlinear). We find that typical observability metrics for 3 neuron motifs range over several orders of magnitude, depending upon topology, and for motifs containing sym...

We quantify observability in small (3 node) neuronal networks as a function of 1) the connection topology and symmetry, 2) the measured nodes, and 3) the nodal dynamics (linear and nonlinear). We find that typical observability metrics for 3 neuron motifs range over several orders of magnitude, depending upon topology, and for motifs containing sym...

This paper proposes a method to evaluate vehicle rollover propensity based on a frequency-domain representation of the zero-moment point (ZMP). Unlike other rollover metrics such as the static stability factor, which is based on the steady-state behaviour, and the load transfer ratio, which requires the calculation of tyre forces, the ZMP is based...

Non-GPS localization of vehicles on roadways has received considerable attention in recent years and a number of solutions have been proposed, with most solutions addressing local tracking. This paper presents an algorithm that achieves global localization within very large road networks using pitch information. A key contribution is the developmen...

This work develops a particle filter algorithm to localise a vehicle in the direction of travel without the use of GPS. The inputs to the algorithm include a terrain map of road grade, pitch measurements from an in-vehicle pitch sensor, and wheel odometry. Simulations and experiments at The Thomas D. Larson Transportation Institute test track are u...

Many companies design families of products based on product platforms that enable economies of scale and scope while satisfying a variety of market applications. Product family design is a difficult and challenging task, and a variety of methods and tools have been created to support this platform-based product development. Unfortunately, many of t...

Prior experiments have confirmed that specific terrain- based localization algorithms, designed to work in GPS-free or degraded-GPS environments, achieve vehicle tracking with tactical-grade inertial sensors. However, the vehicle tracking performance of these algorithms using low-cost inertial sensors with inferior specifications has not been verif...

The localization of vehicles on roadways without the use of a GPS has been of great interest in recent years and a number of solutions have been proposed for the same. The localization of vehicles has traditionally been divided by their solution approaches into two different categories: global localization which uses feature-vector matching, and lo...

When engineered items fail, there are often indicators of decay long before the system collapses. This research explores this con- cept applied to complex vehicles operated in public transportation, and the results can be extrapolated to any vehicle system. Transit bus reli- ability data gathered from eight transit agencies distributed across the U...

Although vehicle dynamics simulations have long been used in vehicle design and crash reconstruction, their use for highway design is rare. This paper investigates the safety of highway medians through iterative simulations of off-road median encroachments. The commercially available software CarSim was used to simulate over one hundred thousand en...

Self-organizing traffic jams are known to occur in medium-to-high density traffic flows and it is suspected that ACC algorithms may affect their onset in mixed human-ACC traffic flows. Unfortunately, closed-form solutions that predict the statistical occurrence of these jams in mixed traffic do not exist. In this paper, a closed form solution that...

Rollover accidents are one of the leading causes of death in highway accidents due to their very high fatality rate. A key challenge in preventing rollover via chassis control is that the prediction of the onset of rollover can be quite difficult, especially in the presence of terrain features typical of roadway environments. These road features in...

This work develops an algorithm to initialize an Unscented Kalman Filter using a Particle Filter for applications with initial non-Gaussian probability density functions. The method is applied to estimating the position of a road vehicle along a one-mile test track and 7 kilometer span of a highway using terrain-based localization where the pitch r...

This work develops an algorithm to initialize an Unscented Kalman Filter using a Particle Filter for applications with initial non-Gaussian probability density functions. The method is applied to estimating the position of a road vehicle along a one-mile test track using terrain-based localization where the pitch response of the vehicle is compared...

Hardware-in-the-loop (HIL) simulation enables experimental study of prototype hardware systems or control algorithms via real time interaction between physical hardware and virtual simulations. As a result, this method is a particularly valuable tool for hybrid vehicle powertrain analysis. In the case where novel or prototype hardware is being exam...

This work develops an algorithm for estimating the lateral lane index of road vehicles on multi-lane roadways by correlating vehicle attitude measurements to terrain maps of the individual lanes of travel. To localize a vehicle, a Bayesian belief algorithm and a particle filter algorithm are described and applied off-line using data collected from...

Across many consumer product industries, the prevailing practice is to design families of product variants that exploit commonality to provide the ability to easily customize a base platform for particular uses and to take advantage of commonality for streamlining design, manufacturing, maintenance and logistic; examples include Black & Decker, Sea...

This work develops a real-time algorithm to localize a vehicle in the direction of travel without the use of GPS. The inputs to the algorithm include a terrain map of road grade and pitch measurements from an in-vehicle pitch sensor. Localization is achieved in real-time using a particle filter described in detail in this work. Simulations and expe...

A method is presented that can often reduce the number of sched-uling parameters for gain-scheduled controller implementation by transformation of the system representation using parameter-dependent dimensional transformations. In some cases, the reduc-tion in parameter dependence is so significant that a linear parameter-varying system can be tran...

There are many situations where physical testing of a vehicle or vehicle controller is necessary, yet use of a full-size vehicle is not practical. Some situations include implementation testing of novel actuation strategies, analyzing the behavior of chassis feedback control under system faults, or near-unstable situations such as limit handling un...

In this study, we examine, for a six-link snake robot, how an optimal gait might change as a function of the snake- surface interaction model and how the overall locomotion performance changes under nonoptimal conditions such as joint failure. Simulations are evaluated for three different types of friction models, and it is shown that the gait para...

A novel method for estimating vehicle roll, pitch, and yaw using machine vision and inertial sensors is presented that is based on matching images captured from an on-vehicle camera to a rendered representation of the surrounding terrain obtained from a three-dimensional (3D) terrain map. U.S. Geographical Survey Digital Elevation Maps were used to...

This work evaluates a real-time algorithm to localize a vehi-cle on a highway in the direction of travel without the use of GPS. The algorithm uses a particle filter to estimate vehicle position along a map of road grade using real-time pitch measurements from an in-vehicle pitch sensor as the input. Experiments over 60 kilometers along Interstate...

This work presents results of low-order modelling of the planar dynamics of a tracked robot focusing on the coupled lateral, rotational, and longitudinal dynamics. This model is validated experimentally using a novel rolling roadway simulator that allows for uniform surface interaction as well as accurate sensing of vehicle position and orientation...

Hardware in the loop (HIL) simulation enables experimental study of prototype hardware systems or control algorithms via real-time interaction between physical hardware and virtual simulations. As a result, this method is a particularly valuable tool for hybrid vehicle powertrain analysis. In the case where novel or prototype hardware is being exam...

A novel method for estimating vehicle roll, pitch and yaw using machine vision and inertial sensors is presented that is based on matching images captured from an on-vehicle camera to a rendered representation of the surrounding terrain obtained from an on-board map database. United States Geographical Survey Digital Elevation Maps (DEMs) were used...

The 18 papers in this special issue focus on control applications in automotive engineering. The papers cover issues ranging from controlling engines and alternative powerplants (such as fuel cells), to issues in transmission, driveline, and integrated powertrain control (including hybrid electric vehicle control), and finally, to vehicular chassis...

A challenge with the development of any new laboratory is the cost-effective use of hardware resources. This work discusses the development of a reconfigurable data-acquisition architecture across three different application areas in university mechatronics and control systems instruction setting: undergraduate education, graduate education, and gr...

This work presents “lessons learned” from an ongoing experimental and simulation investigation of vehicle chassis dynamics. The overall goal of this work is to find low-order physics-based models that are easily fitted from experimental data, yet accurately describe vehicle chassis motion in yaw, sideslip, and roll angle. In previous work related t...