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Safe human-robot interaction requires robots endowed with perception. This paper presents the design of a multi-modal sensory array for continuum robots, targeting operation in semi-structured confined spaces with human users. Active safety measures are enabled via sensory arrays capable of simultaneous sensing of proximity, contact, and force. Proximity sensing is achieved using time-of-flight sensors, while contact force is sensed using Hall effect sensors and embedded magnets. The paper presents the design and fabrication of these sensors, the communication protocol and multiplexing scheme used to allow an interactive rate of communication with a high-level controller, and an evaluation of these sensors for actively mapping the shape of the environment and compliance control using gestures and contact with the robot. Characterization of the proximity sensors is presented with considerations of sensitivity to lighting, color, and texture conditions. Also, characterization of the force sensing is presented. The results show that the multi-modal sensory array can enable pre and post-collision active safety measures and can also enable user interaction with the robot. We believe this new technology allows for increased safety for human-robot interaction in confined and semi-structures spaces due to its demonstrated capabilities of detecting impending collision and mapping the environment along the length of the robot. Future miniaturization of the electronics will also allow possible integration in smaller continuum and soft robots. [ABSTRACT FROM AUTHOR]

The navigation of magnetic medical robots typically relies on localizing an actuated, intracorporeal, ferromagnetic body and back-computing a necessary field and gradient that would result in a desired wrench on the device. Uncertainty in this localization degrades the precision of force transmission. Reducing applied force uncertainty may enhance tasks such as in vivo navigation of miniature robots, actuation of magnetically guided catheters, tissue palpation, as well as simply ensuring a bound on forces applied on sensitive tissue. In this paper, we analyze the effects of localization noise on force uncertainty by using sensitivity ellipsoids of the magnetic force Jacobian and introduce an algorithm for uncertainty reduction. We validate the algorithm in both a simulation study and in a physical experiment. In simulation, we observe reductions in estimated force uncertainty by factors of up to 2.8 and 3.1 when using one and two actuating magnets, respectively. On a physical platform, we demonstrate a force uncertainty reduction by a factor of up to 2.5 as measured using an external sensor. Being the first consideration of force uncertainty resulting from noisy localization, this paper provides a strategy for investigators to minimize uncertainty in magnetic force transmission. [ABSTRACT FROM AUTHOR]

Cochlear implant surgery is a procedure that requires delicate insertion of an electrode array into the inner ear. This paper reports the clinical motivation, design considerations, analysis, and design optimization of a new robot for electrode arrays insertion. This paper describes a new approach for coordinated insertion of perimodiolar electrode arrays in order to minimize shape discrepancy between the shape of the electrode array and the shape of the inner ear anatomy. A new design of a 3-degrees-of-freedom (DoF) parallel robot with wire-actuated prismatic legs is presented. The dimensional synthesis of the robot design was based on satisfying the accuracy, speed, system size, and workspace requirements. The robot prototype is validated experimentally to execute electrode insertions in plastic models of temporal bones. [ABSTRACT FROM PUBLISHER]

During exploration through tortuous unstructured passages by continuum robots, methods are required to minimize the force interaction between the environment and the robot along its length. This paper presents and evaluates an algorithm for compliant motion control of continuum robots subjected to multiple unknown contacts with the environment. A mapping of external wrenches to a generalized force in the configuration space of a multisegment continuum robot is presented and related to measured joint-level actuation forces. These measurements are applied as inputs to a low-level compliant motion controller. Friction and modeling uncertainties, presenting an unknown nonlinear deviation from the nominal system model, are corrected via a feed-forward estimate provided by a support vector machine. The controller is evaluated on Ø9 and Ø5 mm multisegment continuum robots. We quantify the minimal interaction forces needed to generate compliant motion and demonstrate the ability of the controller to minimize interaction forces during insertion through tortuous passages. [ABSTRACT FROM PUBLISHER]

In this paper, we present a novel kinematic-based framework for collision detection and estimation of contact location along multisegment continuum robots. Screw theory is used to define a screw motion deviation (SMD) as the distance between the expected and the actual instantaneous screw axis (ISA) of motion. The expected ISA is computed based on the unconstrained kinematics model of the robot, while the actual ISA is computed based on sensory information. Collisions with rigid environments at any point along the robot are detected by monitoring the SMD. Contact locations are estimated by the minimization of the SMD between the ISA that is obtained from a constrained kinematic model of the continuum robot and the one that is obtained from sensor data. The proposed contact detection and localization methods only require the relative motion of each continuum segment with respect to its own base. This strategy allows the straightforward generalization of these algorithms for an n -segment continuum robot. The framework is evaluated via simulations and experimentally on a three-segment multibackbone continuum robot. Results show that the collision-detection algorithm is capable of detecting a single collision at any segment, multiple collisions occurring at multiple segments, and total-arm constraint. It is also shown that the estimation of contact location is possible at any location along the continuum robot with an accuracy better than 20% of the segment nominal length. We believe this study will enhance manipulation safety in unstructured environments and confined spaces. [ABSTRACT FROM PUBLISHER]