This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.

Coverage control for mobile sensing networks

A highly versatile soft gripper that can handle an unprecedented range of object types is developed based on a new design of dielectric elastomer actuators employing an interdigitated electrode geometry, simultaneously maximizing both electroadhesion and electrostatic actuation while incorporating self-sensing. The multifunctionality of the actuator leads to a highly integrated, lightweight, fast, soft gripper with simplified structure and control.

/pdf/versatile-soft-grippers-with-intrinsic-electroadhesion-based-10fu4b42iq.pdf

Versatile Soft Grippers with Intrinsic Electroadhesion Based on Multifunctional Polymer Actuators

The Ecological Approach to Visual Perception

We describe a prototype 75 g micro quadrotor with onboard attitude estimation and control that operates autonomously with an external localization system The motivation for designing quadrotors at this scale comes from two observations First, the agility of the robot increases with a reduction in size, a fact that is supported by experimental results in this paper Second, smaller robots are able to operate in tight formations in constrained, indoor environments We describe the hardware and software used to operate the vehicle as well our dynamic model We also discuss the aerodynamics of vertical flight and the contribution of ground effect to the vehicle performance Finally, we discuss architecture and algorithms to coordinate a team of these quadrotors, and provide experimental results for a team of 20 micro quadrotors

/pdf/towards-a-swarm-of-agile-micro-quadrotors-2fehv2bsdt.pdf

Towards a swarm of agile micro quadrotors

For aerial robots, maintaining a high vantage point for an extended time is crucial in many applications. However, available on-board power and mechanical fatigue constrain their flight time, especially for smaller, battery-powered aircraft. Perching on elevated structures is a biologically inspired approach to overcome these limitations. Previous perching robots have required specific material properties for the landing sites, such as surface asperities for spines, or ferromagnetism. We describe a switchable electroadhesive that enables controlled perching and detachment on nearly any material while requiring approximately three orders of magnitude less power than required to sustain flight. These electroadhesives are designed, characterized, and used to demonstrate a flying robotic insect able to robustly perch on a wide range of materials, including glass, wood, and a natural leaf.

http://science.sciencemag.org/content/sci/352/6288/978.full.pdf

Perching and takeoff of a robotic insect on overhangs using switchable electrostatic adhesion.

Micro Aerial Vehicles (MAVs) with perching capabilities can be used to efficiently place sensors in aloft locations. A major challenge for perching is to build a lightweight mechanism that can be easily mounted on a MAV, allowing it to perch (attach and detach on command) to walls of different materials. To date, only very few systems have been proposed that aim at enabling MAVs with perching capabilities. Typically, these solutions either require a delicate dynamic flight maneuver in front of the wall or expose the MAV to very high impact forces when colliding head-first with the wall. In this article, we propose a 4.6 g perching mechanism that allows MAVs to perch on walls of natural and man-made materials such as trees and painted concrete facades of buildings. To do this, no control for the MAV is needed other than flying head-first into the wall. The mechanism is designed to translate the impact impulse into a snapping movement that sticks small needles into the surface and uses a small electric motor to detach from the wall and recharge the mechanism for the next perching sequence. Based on this principle, it damps the impact forces that act on the platform to avoid damage of the MAV. We performed 110 sequential perches on a variety of substrates with a success rate of 100%. The main contributions of this article are (i) the evaluation of different designs of perching, (ii) the description and formal modeling of a novel perching mechanism, and (iii) the demonstration and characterization of a functional prototype on a microglider. (See accompanying video and http://lis.epfl.ch/microglider/perching.mpg.)

/pdf/a-perching-mechanism-for-micro-aerial-vehicles-50oeabv2h6.pdf

A perching mechanism for micro aerial vehicles

Genetic control methods of mosquito vectors of malaria, dengue, yellow fever, and Zika are becoming increasingly popular due to the limitations of other techniques such as the use of insecticides. The sterile insect technique is an effective genetic control method to manage insect populations. However, it is crucial to release sterile mosquitoes by air to ensure homogeneous coverage, especially in large areas. Here, we report a fully automated adult mosquito release system operated from an uncrewed aerial vehicle or drone. Our system, developed and tested in Brazil, enabled a homogeneous dispersal of sterile male Aedes aegypti while maintaining their quality, leading to a homogeneous sterile-to-wild male ratio due to their aggregation in the same sites. Our results indicate that the released sterile males were able to compete with the wild males in mating with the wild females; thus, the sterile males were able to induce sterility in the native female population. The use of drones to implement the sterile insect technique will lead to improvements in areal coverage and savings in operational costs due to the requirement of fewer release sites and field staff.

/pdf/field-performance-of-sterile-male-mosquitoes-released-from-3jg8q0cig8.pdf

Field performance of sterile male mosquitoes released from an uncrewed aerial vehicle

With the ongoing rise of soft robots there emerges a need for new soft robotic technologies that can cope with hyper-flexibility and stretchability. In this paper, we describe our developments on enabling controllable adhesion, namely electroadhesion, for the use in soft robots. We present a method to manufacture stretchable electroadhesive pads and characterize their performance when stretching the pad more than double its original length. Our results suggest that the normal detachment force per area slightly decreases with the stretching, while the shear detachment force per area increase with the stretch ratio. These results imply that stretchable electroadhesive pads have higher adaptivity to a given task compared to non-stretchable pads, because the stretchable pads are adaptable in terms of their mechanical stiffness as well as their adhesive force.

/pdf/stretchable-electroadhesion-for-soft-robots-584uq2md2x.pdf

Stretchable Electroadhesion for Soft Robots

To date, most modular robotic systems lack flexibility when increasing the number of modules due to their hard building blocks and rigid connection mechanisms. In order to improve adaptation to environmental changes, softness on the module level might be beneficial. However, coping with softness requires fundamental rethinking the way modules are built. A major challenge is to develop a connection mechanism that does not limit the softness of the modules, does not require precise alignment and allows for easy detachment. In this paper, we propose a soft active connection mechanism based on electroadhesion. The mechanism uses electrostatic forces to connect modules. The method is easy to implement and can be integrated in a wide range of soft module types. Based on our experimental results, we conclude that the mechanism is suitable as a connection principle for light-weight modules when efficiency in a wide range of softness, tolerance to alignment and easy detachment are desired. The main contributions of this article are (i) the qualitative comparison of different connector principles for soft modular robots, (ii) the integration of electroadhesion, featuring a novel electrode pattern design, into soft modules, and (iii) the demonstration and characterization of the performance of functional soft module mockups including the connection mechanism.

/pdf/active-connection-mechanism-for-soft-modular-robots-3fupf0vui4.pdf

Active Connection Mechanism for Soft Modular Robots

We developed an automatic method to extract the parameters of the 7 times 50 m Stroke Efficiency Test for swimming based on a wrist worn acceleration sensor device. In the wrist acceleration signal we detect characteristic swim events such as wall push-offs, wall-strikes and strokes. Based on this information we compute the distance per stroke and the swimming velocity. The upper error bounds of our automatic method are 1.67% for the velocity and 1.33% for the time per stroke. The velocity measurement accuracy is of comparable order to the manual accuracy. The automatic method clearly outperforms the manual measurement for the time per stroke extraction.

/pdf/an-automatic-parameter-extraction-method-for-the-7-50m-37hap3lykt.pdf

Jürg Markus Germann

Papers

A perching mechanism for micro aerial vehicles

Field performance of sterile male mosquitoes released from an uncrewed aerial vehicle

Stretchable Electroadhesion for Soft Robots

Active Connection Mechanism for Soft Modular Robots

An automatic parameter extraction method for the 7×50m Stroke Efficiency Test