A two-fingered robot gripper with variable stiffness flexure hinges based on shape morphing

This paper presents a novel approach for developing robotic grippers with variable stiffness hinges for dexterous grasps. This approach for the first time uses pneumatically actuated pouch actuators to fold and unfold morphable flaps of flexure hinges thus change stiffness of the hinge. By varying the air pressure in pouch actuators, the flexure hinge morphs into a beam with various open sections while the flaps bend, enabling stiffness variation of the flexure hinge. This design allows 3D printing of the flexure hinge using printable soft filaments. Utilizing the variable stiffness flexure hinges as the joints of robotic fingers, a light-weight and low-cost two-fingered tendon driven robotic gripper is developed. The stiffness variation caused due to the shape morphing of flexure hinges is studied by conducting static tests on fabricated hinges with different flap angles and on a flexure hinge with flaps that are bent by pouch actuators subjected to various pressures. Multiple grasp modes of the two-fingered gripper are demonstrated by grasping objects with various geometric shapes. The gripper is then integrated with a robot manipulator in a teleoperation setup for conducting a pick-and-place operation in a confined environment

Tracking a moving sound source from a multi-rotor drone

We propose a method to track from a multirotor drone a moving source, such as a human speaker or an emergency whistle, whose sound is mixed with the strong ego-noise generated by rotating motors and propellers. The proposed method is independent of the specific drone and does not need pre-training nor reference signals. We first employ a time-frequency spatial filter to estimate, on short audio segments, the direction of arrival of the moving source and then we track these noisy estimations with a particle filter. We quantitatively evaluate the results using a ground-truth trajectory of the sound source obtained with an on-board camera and compare the performance of the proposed method with baseline solutions

Novel infinitely Variable Transmission allowing efficient transmission ratio variations at rest

Recent studies showed that Continuously Variable Transmissions (CVT) and Infinitely Variable Transmissions (IVT) can considerably improve the locomotion efficiency in legged robot. A CVT is a transmission whose ratio can be continuously varied and an IVT is a transmission whose ratio can be continuously varied from positive to negative values. However, efficient use of such transmissions in walking applications requires changing the transmission ratio at a minimal energy cost, even at rest, i.e. when the input shaft is not rotating. This contribution proposes a novel CVT and IVT principle which can achieve such ratio variations at rest. The presented CVT is a modified planetary gear, whose planets are conical and mounted on inclined shafts, and whose ring is made of contiguous diabolo-shaped rollers. This configuration enables the control of the transmission ratio by adjusting the point of contact between the cones and rollers that comprise the ring. A traditional planetary gear system can be added to the CVT to form an IVT

Magnetic-field-inspired Navigation for Soft Continuum Manipulator

Taking inspiration from the properties of magnetic fields, we propose a reactive navigation method for soft continuum manipulators operating in unknown environments. The proposed navigation method outperforms previous works since it is able to successfully achieve collision-free movements towards the goal in environments with convex obstacles without relying on a priori information of the obstacles' shapes and locations. Simulations for the kinematic model of a soft continuum manipulator and preliminary experiments with a 2-segments soft continuum arm are performed, showing promising results and the potential for our approach to be applied widely

Silicone-based Capacitive E-skin for Exteroception and Proprioception

Thin and imperceptible soft skins that can detect internal deformations as well as external forces, can go a long way to address perception and control challenges in soft robots. However, decoupling proprioceptive and exteroceptive stimuli is a challenging task. In this paper, we present a silicone-based, capacitive E-skin for exteroception and proprioception (SCEEP). This soft and stretchable sensor can perceive stretch as along with touch at 100 different points via its 100 tactels. In this paper, we present a novel algorithm that decouples global strain from local indentations due to external forces. The soft skin is 10.1cm in length and 10cm in width and can be used to accurately measure the global strain of up to 25% with an error of under 3%; while at the same time, can determine the amplitude and position of local indentations. This is a step towards a fully soft electronic skin that can act as a proprioceptive sensor to measure internal states while measuring external forces

Variable Stiffness Actuator applied to an active ankle prosthesis: Principle, energy-efficiency, and control

Series elastic actuators are very popular in rehabilitation robotics. Among other advantages, elastic elements between the actuator and the load permit to store and release energy during the task completion, such that the energy balance is improved and the motor power peak is decreased. In rhythmic tasks like walking, this reduces to design the spring stiffness such that it works at resonance. To comply with different gaits and cadences, it is therefore necessary to design Variable Stiffness Actuators (VSA). This paper proposes three contributions: (i) we apply a particular concept of VSA to an active ankle prosthesis; (ii) we discuss the relevance of using VSA to change the stiffness also within the gait cycle; and (iii) we elaborate some control strategies for this device. Our guideline is to track a mechanical design and a controller maximizing energy efficiency. We establish that a promising approach is simply to control the amount of energy stored in the elastic element

Autonomous view selection and gaze stabilization for humanoid robots

To increase the autonomy of humanoid robots, the visual perception must support the efficient collection and interpretation of visual scene cues by providing task-dependent information. Active vision systems allow to extend the observable workspace by employing active gaze control, i.e. by shifting the gaze to relevant areas in the scene. When moving the eyes, stabilization of the camera images is crucial for successful task execution. In this paper, we present an active vision system for task-oriented selection of view directions and gaze stabilization to enable a humanoid robot to robustly perform vision-based tasks. We investigate the interaction between a gaze stabilization controller and view planning to select the next best view direction based on saliency maps which encode task-relevant information. We demonstrate the performance of the systems in a real world scenario, in which a humanoid robot is performing vision-based grasping while moving, a task that would not be possible without the combination of view selection and gaze stabilization

Laparoscopic optical biopsies: in vivo robotized mosaicing with probe-based confocal endomicroscopy

Probe-based confocal laser endomicroscopy is a promising technology for performing minimally-invasive optical biopsies. With the help of mosaicing algorithms, several studies reported successful results in endoluminal surgery. In this paper, we present a prototype for making robotized optical biopsies on a variety of organs inside the abdominal cavity. We chose a macro-micro association, with a macropositioner, a micropositioner and a passive mechanical compensation of physiological motion. The probe is actuated by three hydraulic micro-balloons and can be moved on the surface of an organ to generate a mosaic. This paper presents the design and experimental results of a first in vivo trial on a porcine model

Ergonomic and gesture performance of robotized instruments for laparoscopic surgery

Shape and mechanical structure of instruments play a large part in the lack of ergonomics during laparoscopic surgery. Providing intra-abdominal mobility and rethinking handles design are two solutions to increase comfort and precision of gestures. Based on previous work that determined the optimal intra-abdominal kinematics, this study analyses the influence of handle design on both gesture and ergonomic performance. A virtual reality laparoscopic simulator was developed to perform an experimental comparison between two novel robotized instruments and standard ones. A group of 10 surgeons and 6 researchers in robotics carried out two representative surgical tasks with each instrument. Based on instrument and arm segments tracking, a gesture performance index and an ergonomic performance index were computed. The study demonstrates that distal mobilities combined with improved handle design and integration increase ergonomic level during laparoscopy and facilitate complex gestures