Human-robot teams in dynamic environments have the potential to leverage robot sensing and intelligence to augment human performance through motion suggestions. More specifically, we examine how humans can use external sensors (fixed or robotic) and a motion planning algorithm to help them navigate environments with dynamic obstacles. The novel human-centric velocity-obstacle (HCVO) algorithm suggests a feasible goal-oriented action while avoiding obstacles. Participants were placed in a custom virtual reality (VR) environment and tasked to follow a dynamic goal while avoiding collisions. We demonstrate, over N = 10 participants, that the HCVO algorithm’s guidance significantly improves safety compared to a base VO algorithm. We then examine the performance of N = 15 participants in three conditions: (1) no assistance/control, (2) a top-down drone-view of the entire environment, and 3) motion planner-informed suggestions. The core contributions of this research include (1) introducing and tuning of a human-centric velocity-obstacle (HCVO) algorithm, (2) demonstrating the benefits of the HCVO algorithm compared to a base VO algorithm, (3) demonstrating the benefits of the HCVO algorithm compared with a standard overhead drone view. Long term, the deployment of effective human-centric motion planners can make people safer from workplace to warzone. Code: https://github.com/ROAMR-GT/HCVO-Game . Video: https://www.youtube.com/watch?v=9ITD1GBBz24 .

Lumbar spine injuries caused by repetitive lifting rank as the most prevalent workplace injury in the United States. While these injuries are caused by both symmetric and asymmetric lifting, asymmetric is often more damaging. Many back devices do not address asymmetry, so we present a new system called the Asymmetric Back Exosuit (ABX). The ABX addresses this important gap through unique design geometry and active cable-driven actuation. The suit allows the user to move in a wide range of lumbar trajectories while the “X” pattern cable routing allows variable assistance application for these trajectories. We also conducted a biomechanical analysis in OpenSim to map assistive cable force to effective lumbar torque assistance for a given trajectory, allowing for intuitive controller design in the lumbar joint space over the complex kinematic chain for varying lifting techniques. Human subject experiments illustrated that the ABX reduced lumbar erector spinae muscle activation during symmetric and asymmetric lifting by an average of 37.8% and 16.0%, respectively, compared to lifting without the exosuit. This result indicates the potential for our device to reduce lumbar injury risk.

Visual engagement is common in many situations where human operators must perform tasks in challenging environments. This visual engagement has the potential to impact the safety of these operators when dealing with dynamic threats. Perceptual cues have been shown to elicit physical evasion maneuvers, thereby improving safety. In this article, we investigate the effects of cues and visual engagement on rapid whole-body responses. The visual task, inspired by the Trail Making Test (TMT), served as a proxy for visual engagement in the real world. Our continuous TMT minigame and threat simulation are implemented in a virtual reality environment. Participants attempt to maximize their performance score by quickly solving TMTs and dodging dynamic threats from various in-plane directions. They are provided with no cues (control), visual cues, and vibrotactile cues indicating impending threat directions. Participant’s ability to dodge threats is quantified by failure rate and reaction time within field of view and for all approach directions. An index of difficulty highlighted perceptual cue response sensitivity to varying threat speeds and sizes. This article provides two core key contributions and other interesting findings: 1) the results illustrate that tactile cues enable statistically significantly better dodging rates than visual cues or with human vision alone (control condition); and 2) that visual engagement degrades human evasion performance in a statistically significant way. Finally, tactile cue responses appear to be less sensitive than visual cues to visually engaging tasks within the higher portion of difficulty index range that is investigated.

In order to accomplish various missions, autonomous ground vehicles must operate on a wide range of terrain. While many systems such as wheels and whegs can navigate some types of terrain, none are optimal across all. This creates a need for physical adaptation. This paper presents a broad new approach to physical adaptation that relies on manipulation. Specifically, we explore how multipurpose manipulators can enable ground vehicles to dramatically modify their propulsion system in order to optimize performance across various terrain. While this approach is general and widely applicable, this work focuses on physically switching between wheels and legs. We outline the design of "swappable propulsors" that combine the powerful adhesion forces of permanent magnets with geometric features for easy detachment. We provide analysis on how the swappable propulsors can be manipulated, and use these results to create a functional prototype robot. This robot can use its manipulator to change between wheeled and legged locomotion. Our experimental results illustrate how this approach can enhance energy efficiency and versatility.

Legged humanoid robots promise revolutionary mobility and effectiveness in environments built for humans. However, inefficient use of energy significantly limits their practical adoption. The humanoid biped walking anthropomorphic novelly-driven efficient robot for emergency response (WANDERER) achieves versatile, efficient mobility, and high endurance via novel drive-trains and passive joint mechanisms. Results of a test in which WANDERER walked for more than 4 h and covered 2.8 km on a treadmill, are presented. Results of laboratory experiments showing even more efficient walking are also presented and analyzed in this article. WANDERER's energetic performance and endurance are believed to exceed the prior literature in human-scale humanoid robots. This article describes WANDERER, the analytical methods and innovations that enable its design, and system-level energy efficiency results.

Robotic grasping can enable mobile vehicles to physically interact with the environment for delivery, repositioning, or landing. However, the requirements for grippers on mobile vehicles differ substantially from those used for conventional manipulation. Specifically, grippers for dynamic mobile robots should be capable of rapid activation, high force density, low power consumption, and minimal computation. In this work, we present a biologically-inspired robotic gripper designed specifically for mobile platforms. This design exploits a bistable shell to achieve “reflexive” activation based on contact with the environment. The mechanism can close its grasp within 0. 12s without any sensing or control. Electrical input power is not required for grasping or holding load. The reflexive gripper utilizes a novel pneumatic design to open its grasp with low power, and the gripper can carry slung loads up to 28 times its weight. This new mechanism, including the kinematics, static behavior, control structure, and fabrication, is described in detail. A proof of concept prototype is designed, built, and tested. Experimental results are used to characterize performance and demonstrate the potential of these methods.

In this paper we present a study of a specific class of vibration-driven robots: the brushbots. In a bottom-up fashion, we start by deriving dynamic models of the brushes and we discuss the conditions under which these models can be employed to describe the motion of brushbots. Then, we present two designs of brushbots: a fully-actuated platform and a differential-drive-like one. The former is employed to experimentally validate both the developed theoretical models and the devised motion control algorithms. Finally, a coordinated-control algorithm is implemented on a swarm of differential-drive-like brushbots in order to demonstrate the design simplicity and robustness that can be achieved by employing a vibration-based locomotion strategy.

In this paper we introduce STEPPR (Sandia Transmission-Efficient Prototype Promoting Research), a bipedal robot designed to explore efficient bipedal walking. The initial iteration of this robot achieves efficient motions through powerful electromagnetic actuators and highly back-drivable synthetic rope transmissions. We show how the addition of parallel elastic elements at select joints is predicted to provide substantial energetic benefits: reducing cost of transport by 30 to 50 percent. Two joints in particular, hip roll and ankle pitch, reduce dissipated power over three very different gait types: human walking, human-like robot walking, and crouched robot walking. Joint springs based on this analysis are tested and validated experimentally. Finally, this paper concludes with the design of two unique parallel spring mechanisms to be added to the current STEPPR robot in order to provide improved locomotive efficiency.

In this paper we examine the dynamics of a unique type of jet propelled, spheroidal robot design. This robot uses jets angled inward into a diamond shape to achieve superior planar dynamics. We explore the role of the diamond configuration in avoiding nonminimum phase behavior and we examine the best vehicle aspect ratios for this type of robot design. We use a degree of controllability metric to illustrate the uncontrollable behavior of certain designs and also identify an optimal aspect ratio of 1.4. The paper concludes by incorporating these lessons into a new 5 degree-of-freedom prototype robot that provides substantial improvements over previous designs. This robot uses centrifugal pumps and fluidic valves to achieve high maneuverability and unique motions such as forward and reverse motions, sway translations, and turning in place. In addition, this design can achieve improved forward efficiency through the use of dual output-pumps and can perform these planar motions at various vehicle depths through the use of a closed loop depth control system.

A highly maneuverable, spheroid-shaped, underwater robot using appendage-free, multi-degree of freedom (DOF) propulsion technologies is presented. The vehicle is hydrodynamically unstable due to the Munk moment. The vehicle is stabilized by feedback control, rather than passive fins, which facilitates rapid turns and agile motions. The new design was motivated by nuclear reactor inspection and other applications where external appendages must be avoided. Two technical challenges are addressed in this paper. One is the development of a compact, multi-DOF propulsion system that generates multiaxis water jets and switches them rapidly. The other is the design of a jet configuration and control system that augments stability and achieves high maneuverability. A nonlinear hydrodynamic model is formulated, and its linearized dynamics are analyzed to attain insights into how jet direction influences controllability and stability. A prototype vehicle is built and used to verify these concepts. The integrated design method is implemented and shown to achieve stable motions, high maneuverability, and multidirectional capability.

In this paper we present a new type of spherical underwater robot that is completely smooth and uses jets to propel and maneuver. This robot is specifically designed for the direct visual inspection of water-filled infrastructure such as the inside of nuclear powerplants. The unique propulsion architecture consists of a single bidirectional centrifugal pump combined with two fluidic valves. The pump is used to produce a high velocity jet while the valves are used to quickly switch the jet between output ports. The spherical shape means that the robot is simple to model and control, maneuverable, and robust to collisions. The propulsion architecture is described in detail along with a rigid body model for maneuvering control. A novel valve PWM controller is used to achieve heading control, and the controller performance is confirmed with both simulation and experiments. Finally, experiments are used to illustrate the turning and diving performance of the robot.

There is an increasing need for the inspection of nuclear power plants worldwide. To access complex underwater structures and perform non-destructive evaluation, robots must be tetherless, compact, highly maneuverable, and have a smooth body shape with minimal appendages. A new water jet propulsion system using fluidic valves coupled with centrifugal pumps is developed for precision maneuvering. A hybrid control system that combines continuous pump regulation and discrete Pulse Width Modulation (PWM) of fluidic valves is proposed. This control scheme provides high accuracy, high bandwidth, and flexibility in maneuvering control. First, the functional requirements for nuclear power plant inspection are discussed, followed by the basic design concept of an inspection robot. Miniaturized Coanda-effect valves are designed and built based on CFD and mathematical analysis. The hybrid control system incorporating the pump/valve system is designed and tested. Experimental results illustrate that the hybrid control scheme holds substantial promise and is capable of very precise orientation control. Based on these, a full 4-DOF robot is designed, and its key components are described.

A highly maneuver able, compact vehicle for underwater precision inspection of complex structures is presented. The vehicle will have no appendages such as rudders, screws, and other external thrusters, which might get tangled and interfere with the underwater structure in a cluttered environment. A multi-axis, integrated thruster mechanism using Coanda-effect high-speed valves for switching the direction of jets can be encapsulated in a compact, egg-shaped body. Compared to traditional screw thrusters, these valves have improved dynamic performance in switching the jet stream direction. Furthermore, the reaction forces and moments due to switching can be substantially reduced. First, the principle of Coanda effect water jet valves is introduced, and its governing equations are obtained. Optimal dimensions and parameters producing a maximum of thrust are obtained, and are experimentally verified. Multiple Coanda-effect valves are then integrated into a tree structure to create a multi-axis thrust mechanism. A simple planar proof of concept prototype is built and tested.

Variable stiffness actuation and energy harvesting have been important yet separate challenges in robotics. Both functions are needed, however, for mobile robots on extended missions when actuators and generators must be used together. In this paper, we present a unique piezoelectric cellular system that combines motion generation and energy harvesting capabilities into a single, scalable device. Each of the discrete cellular units provides linear, contractile motion at 10% strain using the converse piezoelectric effect. These units may also be back-driven from environmental loading and thereby generate energy using the direct piezoelectric effect. Furthermore, each cell has the capability to toggle between a low stiffness ON state and a high stiffness OFF state, which allows an assembly of individual cells to tune both their static stiffness and structural resonant frequencies online. We demonstrate the effectiveness of our device for tuning both locomotion speed and the harvested power of an underwater flapping fin system.

A legged robot that moves across a steel structure is developed for steel bridge inspection. Powerful permanent magnets imbedded in each foot allow the robot to hang from a steel ceiling powerlessly. Although the magnets are passive, the attractive force is modulated by tilting the foot against the steel surface. This allows the robot to slide its feet along the surface using ¿Moonwalk¿ and ¿Shuffle¿ gait patterns. The robot can also detach its feet and swing them over small obstacles. These diverse walking patterns are created with a single servoed joint and 2 sets of simple locking mechanisms. Kinematic and static conditions are obtained for the under-actuated legged robot to perform each gait pattern safely and stably. A proof-of-concept prototype robot is designed, built, and tested. Experiments demonstrate the feasibility of the design concept and verify the analytical results.

The maneuvering performance of a robotic device designed to mimic the swimming motions of Thunniform swimmers is presented. In contrast to existing designs, this design achieves fish like locomotion through the use of a single actuator and a compliant body and tail. Experiments were performed using both biased swimming motions and coasted turns. During these experiments the Compliant Robotic Tuna (CRT) achieved steady swimming speeds of up to 0.37 body lengths/second, average turning rates of up to 12.6 degrees per second, and turning radii as low as 1 body length. In addition, this paper compares the measured maneuvering performance with the predictions of a simplified rigid body model that was derived using both theoretical and empirical techniques. The swimming motions studied in this paper were achieved using open loop mechanisms. Therefore the potential for performance improvements exists.