IROS 2015 Papers

This paper presents a novel design for the soft continuum manipulator based on beehive structure. Our design inspiration derives from the beehive hexagon structure, which has some characteristics of compact layout, low material consumption, thinner thickness of wall, and higher structure strength. The manipulator includes several same modules which composed of many hexagon cell units, the deformation of these cell units synthesize the module macroscopic movement. By installing several modules in series, we can form the manipulator arm. For module fabrication, we adopt 3D printing technology and use the silicone rubber as the flexible material; these measures ensure that the complex shape of the module can be achieved and make the module easier to deform elastically. Based on pneumatic technology, we build the control system and verify its operation via some experiments. In the gravity environment, three-section (about 180mm long at uninflated state) manipulator's maximum bending angle reaches about 90°, its elongation is close to 2:1. We also do a five-section experiment to acquire the manipulator's motion under different section combinations. The experiments verified that the manipulator has both good flexibility and operational capabilities.

Modern robotic applications involve close contact to the human and consequently, require apart from performance a high degree of safety from their actuators. Further, the dexterous manipulation abilities of a human are not yet inherently realized by technical media. In this work a novel piezohydraulic actuator is presented aiming at a) high power density, b) human-like force/velocity characteristic, c) intrinsic passive safety and low reflected inertia, and d) high robustness. It is shown why the piezohydraulic actuation principle is appropriate to mimic the behavior of a human muscle and, as a consequence, desirable for robotic applications. A model of the actuator is also presented together with simulation and experimental results.

An increasing interest towards functionally independent and self-reconfigurable robots featured the research direction in the recent past. Such attention is well explained by the characteristics of flexibility and cost-effectiveness which distinguish these modular machines. This scenario framed the birth of many different devices characterized by simplicity of use and versatility. The present manuscript follows these trends by presenting a newly conceived device suitable for being used as a limb, as well as a planar two degrees of freedom manipulator. The features of both parallel and serial kinematic mechanisms have been exploited to the aim of obtaining a device as much as possible independent from the frame to whom it is connected. Formal aspects about position and velocity kinematics are addressed and a specifically built prototype is then used for experimental tests on the new limb.

For a robot serving in a complex environment such as in a restaurant, it is difficult to perform a task like tabletop object manipulation completely by itself, in that some information may be missing. An approach to deal with this is to use a tele-control system and method to control the robot or demonstrate. In this paper, a LeapMotion sensor based non-contact tele-control method is developed for a robot to perform tabletop object manipulation tasks. A coordinate system for mapping from the operation space of the LeapMotion sensor to the workspace of the robot is established. A gesture recognition and action generating algorithm is proposed for control or to demonstrate the motion to the robot. To evaluate the performance of the LeapMotion sensor and proposed method for tele-control of a robot, a comprehensive assessment index based on entropy weighting is proposed. Three common tele-control modes, including demonstration mode, teleoperation mode and semi-teleoperation mode, are developed on a PR2 robot. The experimental results show that the proposed tele-control system is more appropriate for use in task demonstration.

This paper presents a novel nonlinear compliant link. It has two major properties: bi-directionality and stiffening compliance. Bi-directionality means it can be stretched and compressed, and is realized by antagonistic arrangement of an extension spring and a compression spring. Stiffening compliance means it becomes stiffer as it is stretched, and is realized by asymmetric geometry. The links are parts of Simple Hand. Because Simple Hand gives limited space for links, current iteration of links is not obviously nonlinear. However, nonlinearity should be more obvious if links are designed for larger grippers.

This paper presents our work on design, modeling, and control of a meso-scale shape memory alloy (SMA) actuated torsion actuator for miniature robots. This novel torsion actuator is bi-directionally activated by a pair of antagonistic SMA torsion springs through alternate Joule heating. First, we present the mechanical design and fabrication approach of this miniature actuator. Then, we present the torsion spring mechanical model, SMA constitutive model, and kinematic and dynamic models, followed by the derivation of the quasi-static model of the actuator. Finally, the dynamic properties are tested by step response and sinusoidal tracking tests. A model-based controller is designed and its performance is evaluated by experiments.

This paper describes enhancements made to the distributed performance impact (PI) algorithm and presents the results of trials that show how the work advances the state-of-the-art in single-task, single-robot, time-extended, multiagent task assignment for time-critical missions. The improvement boosts performance by integrating the architecture with additional action selection methods that increase the exploratory properties of the algorithm (either soft max or e-greedy task selection). It is demonstrated empirically that the average time taken to perform rescue tasks can reduce by up to 8% and solution of some problems that baseline PI cannot handle is enabled. Comparison with the consensus-based bundle algorithm (CBBA) also shows that both the baseline PI algorithm and the enhanced versions are superior. All test problems center around a team of heterogeneous, autonomous vehicles conducting rescue missions in a 3-dimensional environment, where a number of different tasks must be carried out in order to rescue a known number of victims that is always more than the number of available vehicles.

In this paper, a novel constrained tendon-driven serpentine manipulator (CTSM) suited for minimally invasive surgery is presented. It comprises of a flexible backbone, a set of controlling tendons and a constraint. In the CTSM not only the curvature of the bending section can be controlled but also the length. Specifically, the curvature is controlled by the tendons, and the length is controlled by a constraint tube, which is translational and is concentric with the flexible backbone. The kinematic model of the CTSM is developed based on the piecewise constant curvature assumption. Analysis shows that by introducing the translational constraint both the workspace and dexterity of the manipulator are improved. The stiffer the constraint the larger the workspace expansion and the smaller the dexterity enhancement. A prototype is developed and the experimental results validate the design idea and analysis.

The next generation of ambient assisted living services will be based on eco-systems or organizations of intelligent artificial agents embodied in companion robots and smart objects. To provide, anywhere and anytime, smart assistance services to people, these agents need to be endowed with advanced knowledge representation, reasoning and communication capabilities. In this paper, we propose a distributed cognitive architecture allowing to integrate seamlessly the actors of the ambient system and an expressive model for commonsense knowledge representation and reasoning on events. This model allows a common description of the actors in an open world and a management of interactions with humans using natural language. A scenario dedicated to the cognitive assistance of frail people is implemented and analyzed for validation purposes of the proposed approach.

One of the challenging problems in human-robot shared control is the algorithms for force rendering due to uncertain human behavior. Common adaptive and optimal control techniques may not be readily applied to a number of popular haptic devices, since the required state space models are not available. In addition, the invoked control algorithms should meet the requirements of a human-in-the-loop control problem and be fast enough for such haptic applications. Thus, this paper proposes a novel combination of model predictive control (MPC) and neural networks to overcome the aforementioned problems. First, the robot is modeled by a multilayer perceptron (MLP) network. The model has been trained with a set of data created with reasonably considered all possible robot variations in a virtual environment (VE). Afterwards, an MPC is developed with the aid of artificial neural networks and genetic algorithm (GA) to find the optimized force required for a typical task model. Such optimal force calculation with the MPC approach has been carried out for a variety of reference points of a task. Then another MLP network is trained to find the optimal required forces for a reasonably fast and smooth performance. The results show the effectiveness of this approach compared to classical impedance controllers in increasing user performance.

In this paper we present a new single port robotic system particularly designed for single port access surgery in the field of colon cancer. In contrast to most state of the art systems the two intracorporeal manipulator arms are set up using a parallel kinematic structure with 5DOF, which are integrated into a shaft of 38mm in diameter. The parallel kinematic structure and its workspace are discussed in detail. As a unique feature, the kinematics uses the translation and rotation of three rods per manipulation arm. Using a parallel kinematic approach enables dynamic, stiff and precise movements which are needed to generate a realistic haptic feedback. The results of several performed circle tests are presented showing the ability of performing precise and dynamic movements with speeds of up to 327 mm/s and under load condition of 4 N.

In this paper, we present a new robotic uterine positioner for total laparoscopic hysterectomy. The robot is designed to actively position the patient's uterus during surgery, a lengthy and tedious task that is traditionally performed by a human assistant. Safety is simply the most important concern when developing robots for surgical purposes; we address this concern in the design of our robot from a mechanical perspective. To this end, we develop a 3-DOF robotic uterine positioner with an in-body remote center of motion (RCM); this key feature allows to prevent injuries to the patient when large motions occur at the cervix. A linearly-actuated arc-guided RCM mechanism is introduced to guarantee the rigidity and stability of the robot; The system's design allows to manipulate the uterus in a decoupled manner, thus control complexity can be reduced. Passive safety mechanisms are also implemented in all DOF of the robot in order to limit the interaction forces with the patient. Experiments, including an ex-vivo test conducted with cadaver, are conducted to verify the robot's performance.

In this paper, a new passivity-based technique is proposed to analyze and guarantee the stability of haptics-enabled telerobotic rehabilitation systems where there is a possibility of having more sources of non-passivity than communication delays. In practice, the difficulty of therapeutic exercises should be tuned taking into account the stage of physical disability. However, tuning the difficulty and intensity should not violate the stability of patient-robot interaction. This usually puts conservative prefixed limits on the allowable exercise intensity. In this paper, patient-robot interaction safety is studied in the context of Strong Passivity Theory (SPT). Our goal is to ultimately relax the limitation on the allowable robotic therapies while preserving system stability. The proposed stabilizing scheme does not try to make the entire non-passive component passive. This allows the therapist to have freedom in injecting energy into the system for assistive therapies while ensuring safe patient-robot interaction. In this paper, the case of telerobotic rehabilitation is considered. Experimental implementation and evaluation are presented to support the proposed theory.

The work presents the development and evaluation of a novel foot sole for humanoid robots. For humanoid locomotion the foot sole is important for absorbing impacts. In contrast to the simple planar rubber pad foot sole that is conventionally used in humanoid robots this paper introduces a new foot sole design in which the dissipation of energy during collision is done effectively using a viscous air damping sole mechanism that provides better reduction of the ground impact forces. The paper describes the principle of the foot sole and provides details of its design and implementation. Experimental trials were performed with the child size humanoid robot, COMAN, wearing the proposed feet to validate their performance during landing and walking. The results demonstrate that the proposed new passive damping mechanism can reduce effectively the ground reaction impact forces and oscillations while maintaining the foot/body posture.

Tactile sensing is of fundamental importance for object manipulation and perception. Several sensors for hands have been proposed in the literature, however, only a few of them can be fully integrated with robotic hands. Typical problems preventing integration include the need for deformable sensors that can be deployed on curved surfaces, and wiring complexity. In this paper we describe a fingertip for the hands of the iCub robot, each fingertip consists of 12 sensors. Our approach builds on previous work on the iCub tactile system. The sensing elements of the fingertip are capacitive sensors made from a flexible PCB, and a multi-layer fabric that includes the dielectric material and the conductive layer. The novelty the proposed sensor lies in incorporating the multi-layer fabric technology into a small fingertip sensor that can be attached to the hands of a humanoid robot. The new sensors are more robust. The manufacturing is easier and relies on industrial techniques for the fabrication of the components, which results in higher repeatability. We performed experimental characterization of the sensor. We show that the sensor is able to detect forces as low as 0.05 N with no cross-talk between the taxels. We identified some hysteresis in the response of the sensor which must be taken into account if the robot exerts large forces for a long period of time. The taxels have spatially overlapping receptive fields, this has been demonstrated to be a useful property that allows hyperacuity.

Vessel maintenance entails periodic visual inspections of internal and external parts of the hull in order to detect the typical defective situations affecting metallic structures. Nowadays, robots are becoming more and more important regarding these inspection tasks, since they can collect the requested information and, thus, prevent humans from performing tedious, and even dangerous tasks because of places hard to reach for humans. A Micro Aerial Vehicle (MAV) fitted with vision cameras can be used as part of an automated or semi-automated inspection strategy. The resulting collection of individual images, however, does not permit the surveyor to get a global overview of the state of the surface under inspection, apart from the fact that the defects can be separated into different consecutive images. Image mosaicing can certainly help in this case. To this end, in this paper, we propose a novel image mosaicing approach able to deal with this kind of scenarios. Our solution employs a graph-based registration method from which relevant topological relationships between (overlapping) images are found. This graph is built according to a visual index based on a Bag-of-Words (BoW) scheme making use of binary descriptors for speeding up the image description process. At the end of the paper, we report about the results of a number of experiments that validate our approach, including the outcome of defect detectors working directly over the mosaic.

Artefacts that are present in images taken from a moving rolling shutter camera degrade the accuracy of absolute pose estimation. To alleviate this problem, we introduce an addition linear velocity in the camera projection matrix to approximate the motion of the rolling shutter camera. In particular, we derive a minimal solution using the Gröbner Basis that solves for the absolute pose as well as the motion of a rolling shutter camera. We show that the minimal problem requires 5-point correspondences and gives up to 8 real solutions. We also show that our formulation can be extended to use more than 5-point correspondences. We use RANSAC to robustly get all the inliers. In the final step, we relax the linear velocity assumption and do a non-linear refinement on the fuli motion, i.e. linear and angular velocities, and pose of the rolling shutter camera with all the inliers. We verify the feasibility and accuracy of our algorithm with both simulated and real-world datasets.

Robots are often equipped with 2D laser-rangefinders (LRFs) and cameras since they complement well to each other. In order to correctly combine the measurements from both sensors, it is required to know their relative pose, that is, to solve their extrinsic calibration. In this paper we present a simple, quick and effective minimal solution for the extrinsic calibration problem. Our approach does not require any onpurpose calibration pattern: it bases on the observation of an orthogonal trihedron, which is profusely found as corners in human-made scenarios. The proposal is validated with synthetic and real experiments, showing better performance than existing alternatives. An implementation of our approach is made available as open-source software.

This paper presents the design, fabrication, modeling, and demonstration of a micro spherical rolling and flying robot, with a total mass and payload of 35 g and 10 g, respectively. The micro aerial terrestrial robot (ATR) has the ability to fly through the air or roll on the ground, for applications that include search and rescue, mapping, and surveillance. Its unique size makes is easily portable and enables the robot to enter and maneuver around in tight spaces such as air ducts. The design centers around a micro-quadcopter encased in a lightweight spherical exoskeleton that can rotate about the quadcopter. The spherical exoskeleton offers agile ground locomotion while maintaining characteristics of a basic aerial robot in flying mode. Details of the system modeling, design and fabrication are discussed, including the robot's turning capabilities over ground and the lightweight spring-steel exoskeleton. The prototype ATR is experimentally validated in aerial and terrestrial mode, and results show that the ATR traveling over the same distance in rolling mode is 260 percent more efficient than a traditional flying-only robot and in flying mode the system is only 39 percent less efficient. Experimental results also demonstrate transition between modes of locomotion and curved, rolling trajectories.