Augmented-reality (AR) systems have been proposed for medical needle procedures as alternatives t... more Augmented-reality (AR) systems have been proposed for medical needle procedures as alternatives to restore the physician's natural perspective and head motion parallax that are lost when using standard imaging methods. AR systems have assumed a rigid needle, but in practice, a needle can experience large deflections which lead to significant errors. We combine an instrumented needle that measures bending deflections with optical tracking of the needle base for precision, and an AR system to provide users with precise 3D rendering of needle motion and deflection inside a body. In controlled tests, users guided a needle through 7 cm of tissue phantom to reach a 2 mm diameter target. We found that displaying needle shape allows users significantly reduce placement errors when compared to the rigid needle assumption. In addition, a new display technique called Tip Tangent Extrapolation (TTE), based on the sensed needle endpoint and direction, allowed users to further reduce errors resulting in 26% less error when compared to a rigid needle assumption.
An MR-compatible biopsy needle stylet is instrumented with optical fibers that provide informatio... more An MR-compatible biopsy needle stylet is instrumented with optical fibers that provide information about contact conditions between the needle tip and organs or hard tissues such as bone or tumors. This information is rendered via a haptic display that uses ultrasonic motors to convey directional cues to users. Lateral haptic cues at the fingertips improve the targeting accuracy and success rate in penetrating a prostate phantom. Although the original intent was for haptic cues to match the direction of contact forces and needle bending, more consistent results were obtained by using the cues as steering guidance (opposite to contact forces); accordingly this convention was adopted for the user experiments reported.
Journal of Medical Devices-transactions of The Asme, Mar 1, 2015
A passive, parallel master-slave mechanism is presented for magnetic resonance imaging (MRI)-guid... more A passive, parallel master-slave mechanism is presented for magnetic resonance imaging (MRI)-guided interventions in the pelvis. The mechanism allows a physician to stand outside the MRI scanner while manipulating a needle inside the bore and, unlike a powered robot, does not place actuators in proximity to the patient. The manipulator combines two parallel mechanisms based on the Delta robot architecture. The mechanism also includes a two-axis gimbal to allow for tool angulation, giving a total of five degrees of freedom so that the physician can insert and steer a needle using continuous natural arm and wrist movements, unlike simple needle guides. The need for access between the patient's legs and within the MRI scanner leads to an unusual asymmetric design in which the sliding prismatic joints form the vertices of an isosceles triangle. Kinematic analysis shows that the dexterity index of this design is improved over the desired workspace, as compared to an equilateral design. The analysis is extended to estimate the effect of friction and model the input:output force transmission. Prototypes, with final dimensions selected for transperineal prostate interventions, showed force transmission behavior as predicted by simulation, and easily withstood maximum forces required for tool insertion.
Haptic feedback of membrane puncture with an MR-compatible instrumented needle and electroactive polymer display
We present results of experiments with a haptic feedback device that imparts tangential deformati... more We present results of experiments with a haptic feedback device that imparts tangential deformations to the fingertips for displaying changes in force experienced by an MR-compatible optically-instrumented biopsy needle. The display is actuated using multiple layers of MR-compatible electroactive polymers stretched in a plastic frame. Users can use the device to sense events such as membrane puncture, as the needle is driven through a tissue phantom, with 98.9% reliability.
In this paper we present a trade study-based method to optimize the architecture of ReachBot, a n... more In this paper we present a trade study-based method to optimize the architecture of ReachBot, a new robotic concept that uses deployable booms as prismatic joints for mobility in environments with adverse gravity conditions and challenging terrain. Specifically, we introduce a design process wherein we analyze the compatibility of ReachBot's design with its mission. We incorporate terrain parameters and mission requirements to produce a final design optimized for mission-specific objectives. ReachBot's design parameters include (1) number of booms, (2) positions and orientations of the booms on ReachBot's chassis, (3) boom maximum extension, (4) boom cross-sectional geometry, and ( ) number of active/passive degrees-of-freedom at each joint. Using first-order approximations, we analyze the relationships between these parameters and various performance metrics including stability, manipulability, and mechanical interference. We apply our method to a mission where ReachBot navigates and gathers data from a martian lava tube. The resulting design is shown in Fig. .
2022 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
Perceiving the environment through touch is important for robots to reach in cluttered environmen... more Perceiving the environment through touch is important for robots to reach in cluttered environments, but devising a way to sense without disturbing objects is challenging. This work presents the design and modelling of whisker-inspired sensors that attach to the surface of a robot manipulator to sense its surrounding through light contacts. We obtain a sensor model using a calibration process that applies to straight and curved whiskers. We then propose a sensing algorithm using Bayesian filtering to localize contact points. The algorithm combines the accurate proprioceptive sensing of the robot and sensor readings from the deflections of the whiskers. Our results show that our algorithm is able to track contact points with sub-millimeter accuracy, outperforming a baseline method. Finally, we demonstrate our sensor and perception method in a real-world system where a robot moves in between free-standing objects and uses the whisker sensors to track contacts tracing object contours.
Soft robotic hands can facilitate human–robot interaction by allowing robots to grasp a wide rang... more Soft robotic hands can facilitate human–robot interaction by allowing robots to grasp a wide range of objects safely and gently. However, their performance has been hampered by a lack of suitable sensing systems. We present a flexible and stretchable multi-modal sensor network integrated with a soft robotic hand. The design of wired sensors on a flexible metalized film was embodied through a manufacturing approach that uses both UV laser metal ablation and plastic cutting simultaneously to create sensor electrode and stretchable conductive wires in a Kirigami pattern into a single network. We evaluated the interconnects and sensors by measuring an impedance change to each external stimulus and showed that are not substantially affected by stretching the network. With the sensor sheet wrapped around a soft robotic gripper, we demonstrated several interaction scenarios, including a warm burrito for food handling, and a warm baby doll for medical applications.
In this paper we present a trade study-based method to optimize the architecture of ReachBot, a n... more In this paper we present a trade study-based method to optimize the architecture of ReachBot, a new robotic concept that uses deployable booms as prismatic joints for mobility in environments with adverse gravity conditions and challenging terrain. Specifically, we introduce a design process wherein we analyze the compatibility of ReachBot's design with its mission. We incorporate terrain parameters and mission requirements to produce a final design optimized for mission-specific objectives. ReachBot's design parameters include (1) number of booms, (2) positions and orientations of the booms on ReachBot's chassis, (3) boom maximum extension, (4) boom cross-sectional geometry, and (5) number of active/passive degrees-of-freedom at each joint. Using first-order approximations, we analyze the relationships between these parameters and various performance metrics including stability, manipulability, and mechanical interference. We apply our method to a mission where ReachBot navigates and gathers data from a martian lava tube. The resulting design is shown in Fig. 1.
Robotic manipulators navigating cluttered shelves or cabinets may find it challenging to avoid co... more Robotic manipulators navigating cluttered shelves or cabinets may find it challenging to avoid contact with obstacles. Indeed, rearranging obstacles may be necessary to access a target. Rather than planning explicit motions that place obstacles into a desired pose, we suggest allowing incidental contacts to rearrange obstacles while monitoring contacts for safety. Bypassing object identification, we present a method for categorizing object motions from tactile data collected from incidental contacts with a capacitive tactile skin on an Allegro Hand. We formalize tactile cues associated with categories of object motion, demonstrating that they can determine with > 90% accuracy whether an object is movable and whether a contact is causing the object to slide stably (safe contact) or tip (unsafe).
Motion planning for a multi-limbed climbing robot must consider the robot's posture, joint torque... more Motion planning for a multi-limbed climbing robot must consider the robot's posture, joint torques, and how it uses contact forces to interact with its environment. This paper focuses on motion planning for a robot that uses nontraditional locomotion to explore unpredictable environments such as martian caves. Our robotic concept, ReachBot, uses extendable and retractable booms as limbs to achieve a large reachable workspace while climbing. Each extendable boom is capped by a microspine gripper designed for grasping rocky surfaces. ReachBot leverages its large workspace to navigate around obstacles, over crevasses, and through challenging terrain. Our planning approach must be versatile to accommodate variable terrain features and robust to mitigate risks from the stochastic nature of grasping with spines. In this paper, we introduce a graph traversal algorithm to select a discrete sequence of grasps based on available terrain features suitable for grasping. This discrete plan is complemented by a decoupled motion planner that considers the alternating phases of body movement and end-effector movement, using a combination of sampling-based planning and sequential convex programming to optimize individual phases. We use our motion planner to plan a trajectory across a simulated 2D cave environment with at least 95% probability of success and demonstrate improved robustness over a baseline trajectory. Finally, we verify our motion planning algorithm through experimentation on a 2D planar prototype.
This report summarizes the evaluation of a controllable, instmmented compliant wrist. The design ... more This report summarizes the evaluation of a controllable, instmmented compliant wrist. The design of th< wrist and the concept of a remote center of compliance (RCC) have been described in an earlier repoil (CMU-Rl-TR-82-9). The wrist is mounted on a large industrial robot used to load precisely machined parts int( jigs and fixtures on computer controlled machine tools. The robot and the machine tools form part of ai automated cell in which machined parts can be produced with a minimum of human intervention. Loadinj parts into machine tools is essentially an assembly operation in which the parts are slid into clamps or fixture and for this reason the RCC techniques that have been developed for assembly robots can also be applied to ; machining cell. The wrist employs spherical springs with an adjustable stiffness that varies between 33 and 450 lb/incl (5.8xlO 3 and 7.9xlO 4 N/m). This allows the center of compliance to be projected over a range from 1.0 to 6.: inches (25 to 157 mm) out from the upper platform of the wrist. The wrist has 5^ degrees of freedom, beinj compliant in each direction except axial extension. Deflections of ± 0.18 inches (4.6 mm) in the radial plan< and 0.20 inches (5.1 mm) in compression are possible. The accuracy of the sensors over this working range i within 0.001 inches (0.025 mm) for translational motions and within 0.001 radians for rotational motions.
The International Journal of Robotics Research, 2018
This paper presents models of arrays of compliantly supported spines that attach to rough surface... more This paper presents models of arrays of compliantly supported spines that attach to rough surfaces. The applications include climbing and perching robots. Surfaces are characterized in terms of asperity distributions, which lead to stochastic models of spine force capabilities over a range of loading directions. Models cover unidirectional spine arrays and pairs of opposed arrays that withstand normal forces pulling away from a surface. Experiments on a variety of surfaces confirm the predicted behavior. For opposed spine arrays, the overall load capability also depends on the preloading strategy for applying internal forces. Insights from the analysis guide the design of spine array mechanisms to allow, for example, a small aerial platform to attach to walls and ceilings.
Micro-aerial vehicles (MAVs) face limited flight times, which adversely impacts their efficacy fo... more Micro-aerial vehicles (MAVs) face limited flight times, which adversely impacts their efficacy for scenarios such as first response and disaster recovery, where it might be useful to deploy persistent radio relays and quadrotors for monitoring or sampling. Thus, it is important to enable micro-aerial vehicles to land and perch on different surfaces to save energy by cutting power to motors. We are motivated to use a downward-facing gripper for perching, as opposed to a side-mounted gripper, since it could also be used to carry payloads. In this paper, we predict and verify the performance of a custom gripper designed for perching on smooth surfaces. We also present control and planning algorithms, enabling an underactuated quadrotor with a downward-facing gripper to perch on inclined surfaces while satisfying constraints on actuation and sensing. Experimental results demonstrate the proposed techniques through successful perching on a glass surface at various inclinations, including...
This paper presents design principles for compliant mechanisms used to support and load spines us... more This paper presents design principles for compliant mechanisms used to support and load spines used in climbing rough vertical surfaces. The design principles ensure that constraints associated with spine/surface interactions are satisfied and that when multiple spines are placed in contact with a surface they share the load without premature failures or spine overloading. The design principles are demonstrated with a compliant mechanism that has been used for robotic and human climbing on surfaces such as brick, stucco and concrete.
Bioinspiration is an increasingly popular design paradigm, especially as robots venture out of th... more Bioinspiration is an increasingly popular design paradigm, especially as robots venture out of the laboratory and into the world. Animals are adept at coping with the variability that the world imposes. With advances in scientific tools for understanding biological structures in detail, we are increasingly able to identify design features that account for animals' robust performance. In parallel, advances in fabrication methods and materials are allowing us to engineer artificial structures with similar properties. The resulting robots become useful platforms for testing hypotheses about which principles are most important. Taking gecko-inspired climbing as an example, we show that the process of extracting principles from animals and adapting them to robots provides insights for both robotics and biology.
Spurred by advances in manufacturing technologies developed around layered manufacturing technolo... more Spurred by advances in manufacturing technologies developed around layered manufacturing technologies such as PC-MEMS, SCM, and printable robotics, we propose a new analytic framework for capturing the geometry of folded composite laminate devices and the mechanical processes used to manufacture them. These processes can be represented by combining a small set of geometric operations which are general enough to encompass many different manufacturing paradigms. Furthermore, such a formulation permits one to construct a variety of geometric tools which can be used to analyze common manufacturability concepts, such as tool access, part removability, and device support. In order to increase the speed of development, reduce the occurrence of manufacturing problems inherent with current design methods, and reduce the level of expertise required to develop new devices, the framework has been implemented in a new design tool called popupCAD, which is suited for the design and development of complex folded laminate devices. We conclude with a demonstration of utility of the tools by creating a folded leg mechanism.
2014 IEEE International Conference on Robotics and Automation (ICRA), 2014
We present a robot capable of both (1) dynamically perching onto smooth, flat surfaces from a bal... more We present a robot capable of both (1) dynamically perching onto smooth, flat surfaces from a ballistic trajectory and (2) successfully transitioning to a climbing gait. Merging these two modes of movement is achieved via a mechanism utilizing an opposed grip with directional adhesives. Critical design considerations include (a) climbing mechanism weight constraints, (b) suitable body geometry for climbing and (c) effects of impact dynamics. The robot uses a symmetric linkage and cam mechanism to load and detach the feet while climbing. The lengths of key parameters, including the distances between each the feet and the tail, are chosen based on the ratio of required preload force and detachment force for the adhesive mechanism.
Gecko adhesion has inspired climbing robots and synthetic adhesive grippers. Distributing loads b... more Gecko adhesion has inspired climbing robots and synthetic adhesive grippers. Distributing loads between patches of adhesive is important for maximum performance in gecko-inspired devices, but it is unknown how the gecko distributes loads over its toes. We report in vivo measurements of stress distributions on gecko toes. The results are significantly non-uniform.
2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2013
Dynamic surface grasping is applicable to landing of micro air vehicles (MAVs) and to grappling o... more Dynamic surface grasping is applicable to landing of micro air vehicles (MAVs) and to grappling objects in space. In both applications, the grasper must absorb the kinetic energy of a moving object and provide secure attachment to a surface using, for example, gecko-inspired directional adhesives. Functional principles of dynamic surface grasping are presented, and two prototype grasper designs are discussed. Computer simulation and physical testing confirms the expected relationships concerning (i) the alignment of the grasper at initial contact, (ii) the absorption of energy during collision and rebound, and (iii) the force limits of synthetic directional adhesives.
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Papers by Mark Cutkosky