Decoupling the Eye: A Key toward a Robust Hovering for Sighted Aerial Robots

International audienceInspired by natural visual systems where gaze stabilization is at a premium, we simulated an aerial robot with a decoupled eye to achieve more robust hovering above a ground target despite strong lateral and rotational disturbances. In this paper, two different robots are compared for the same disturbances and displacements. The first robot is equipped with a fixed eye featuring a large field-of-view (FOV) and the second robot is endowed with a decoupled eye featuring a small FOV (about ±5°). Even if this mechanical decoupling increases the mechanical complexity of the robot, this study demonstrates that disturbances are rejected faster and the computational complexity is clearly decreased. Thanks to bio-inspired visuo-motor reflexes, the decoupled eye robot is able to hold its gaze locked onto a distant target and to reject strong disturbances by profiting of the small inertia of the decoupled eye

Miniature curved artificial compound eyes.

International audienceIn most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories

A miniature bio-inspired position sensing device for the control of micro-aerial robots

25th IEEE\\RSJ International Conference on Intelligent Robots and Systems (IROS), Algarve, PORTUGAL, OCT 07-12, 2012International audienceHere we present an example of a novel bio-inspired active vision system with a vibrating eye that can rotate freely by means of a miniature rotary piezo motor. Active micro-vibrations were applied to the eye by using an innovative micro-mechanism based on a tiny stepper motor. The hyperacuity of this inexpensive position-sensing device, which results from the active micro-vibrations, makes it capable of measuring the angular position of a contrasting edge. Among the many miniature rotary actuators available, piezomotors are often used when small size, low mass, great accuracy and high dynamics are required. The newly off-the-shelf miniature ultrasonic piezomotor presented in this study along with its position servo control system is supplied ready-integrated into a printed circuit board (PCB). The PCB Piezomotor (or PCBMotor) has many advantages, such as high torque (it requires no reducer), fast dynamics (the mechanical time constant is 3ms), a low mass (1gram) and a compact size (it is only 20mm in diameter and 2.6mm thick). The results of the tests conducted show that the performances of the PCBmotor connected to a custom-made miniature electronic driver make it a good alternative to the actuators classically used in robotic applications. In addition we present a simple visual processing, implemented onto a tiny microcontroller, composed of simple linear filtering and arithmetic operations. We show that our visual scanning sensor is a genuine position sensing device able to measure the relative angular position of a visual object with only two pixels and very few computational resources

A tiny lensless position sensing device for the tracking of active markers

International audienceActive markers tracking is performed using an innovative insect-based visual sensor. Without any optics and a field-of-view of about 60°, our novel miniature visual sensor is able to locate flickering markers (LEDs) with accuracy much greater than the one dictated by the pixel pitch. With a size of only 1cm3 and a mass of only 0.33g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. This small cubic position sensing device is composed of only three photosensors placed on each side of the cube, making this sensor very cheap and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at high frequency (>1kHz) with a precision of only few degrees. The simplicity, small size, low mass, and low power consumption of this optical sensor make it suitable for many applications in the field of cooperative flight of unmanned aerial vehicles, swarm robotics and more generally robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the infrared markers

Decoupling the eye: a Key toward of Robust Hovering for sighted Aerial Robots

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High Performance Optical Angular Position Sensing at Low-cost: a Bio-inspired Approach

10th IEEE Conference on Sensors, Limerick, IRELAND, OCT 28-31, 2011International audienceAccurate remote contactless angular sensing at high accuracy often requires emissive sensors with high energy consumption, complex processing and high cost. Thanks to active micro-vibrations applied to its elementary retina, our low-cost bio-inspired optical position sensing device is able to measure the angular position of a contrasting edge at low cost with hyperacuity. This sensor is able, for example, to estimate the elevation of a real edge such as the horizontal roof of a distant building with a resolution (0.025 degrees) at least 160-fold better than the sensors's static resolution (4 degrees), despite any changes in the contrast and illuminance. The visual processing algorithm is based on just a few linear filters and arithmetic operations, which require few computational resources. The high performances and low cost of this novel position sensing device make it suitable for applications in the fields of metrology, astronomy, robotics, automotive and aerospace

High Performance Optical Angular Position Sensing at Low-cost: a Bio-inspired Approach

10th IEEE Conference on Sensors, Limerick, IRELAND, OCT 28-31, 2011International audienceAccurate remote contactless angular sensing at high accuracy often requires emissive sensors with high energy consumption, complex processing and high cost. Thanks to active micro-vibrations applied to its elementary retina, our low-cost bio-inspired optical position sensing device is able to measure the angular position of a contrasting edge at low cost with hyperacuity. This sensor is able, for example, to estimate the elevation of a real edge such as the horizontal roof of a distant building with a resolution (0.025 degrees) at least 160-fold better than the sensors's static resolution (4 degrees), despite any changes in the contrast and illuminance. The visual processing algorithm is based on just a few linear filters and arithmetic operations, which require few computational resources. The high performances and low cost of this novel position sensing device make it suitable for applications in the fields of metrology, astronomy, robotics, automotive and aerospace

Visual Odometry and Low Optic Flow Measurement by Means of a Vibrating Artificial Compound Eye

4th International Conference on Biomimetic and Biohybrid Systems (Living Machines), Barcelona, SPAIN, JUL 28-31, 2015International audienceIn this study, a tiny artificial compound eye (diameter 15mm) named CurvACE (which stands for Curved Artificial Compound Eye), was endowed with hyperacuity, based on an active visual process inspired by the retinal micro-movements occurring in the fly's compound eye. A periodic (1-D, 50-Hz) micro-scanning movement with a range of a few degrees (5 degrees) enables the active CurvACE to locate contrasting objects with a 40-fold greater accuracy which was restricted by the narrow interommatidial angle of about 4.2 degrees. This local hyperacuity was extended to a large number of adjacent ommatidia in a novel visual processing algorithm, which merges the output signals of the local processing units running in parallel on a tiny, cheap micro-controller requiring very few computational resources. Tests performed in a textured (indoor) or natural (outdoor) environment showed that the active compound eye serves as a contactless angular position sensing device, which is able to assess its angular position relative to the visual environment. As a consequence, the vibrating compound eye is able to measure very low rotational optic flow up to 20 degrees/s and perform a short range odometry knowing the altitude, which are two tasks of great interest for robotic applications

Hyperacute Edge and Bar Detection in a Bioinspired Optical Position Sensing Device

International audienceWe present an improved bioinspired optical position sensing device, in which insect-based retinal microscanning movements are used to detect and locate contrasting objects such as edges or bars. The active microvibrations imposed upon the retina endow the sensor with hyperacuity. For the sake of clarity, this is demonstrated here for a two-pixel sensor, but the same principle could be applied to all pairs of neighboring photosensors in a focal plane array. The sensor is able to detect an edge or a bar present within its small field of view (4 degrees) and locate it with a resolution (0.025 degrees) 160-fold finer than the static resolution imposed by the pixel spacing. The sensor features the novel ability to establish whether it is actually facing an edge or a bar, based on the phase difference between the sinusoidally modulated signals of its two photoreceptors. The visual processing algorithm involves simple linear filtering and purely arithmetic operations requiring few computational resources. The complete theoretical framework is presented here, including an analytical model for the microscanning sensor. This high-performance, low-cost angular position sensing device could have many applications in fields such as metrology, astronomy, robotics, automotive design, and aerospace

HyperCube: A Small Lensless Position Sensing Device for the Tracking of Flickering Infrared LEDs

An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs) with an accuracy much greater than the one dictated by the pixel pitch. With a size of only 1 cm3 and a mass of only 0.33 g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. Only three photosensors are placed on each side of the cubic configuration of the sensing device, making this sensor very inexpensive and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at a high frequency (>1 kHz) with a precision of 0.5°. The minimalistic design in terms of small size, low mass and low power consumption of this visual sensor makes it suitable for many applications in the field of the cooperative flight of unmanned aerial vehicles and, more generally, robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the flickering infrared markers