Alexis Lussier Desbiens

Landing, perching and taking off from vertical surfaces

An approach is presented whereby small, unmanned aircraft can land on walls. The approach is demonstrated with a plane that uses an ultrasonic sensor to initiate a pitch-up maneuver as it flies toward a wall. The plane contacts the wall with spines that engage asperities on the surface. A non-linear suspension absorbs the kinetic energy while keeping the spines attached. A planar dynamic model is used to evaluate pitch-up maneuvers and determine suspension parameters that satisfy constraints on the contact forces for a range of flight velocities. Simulations conducted using the model are compared with data obtained using high-speed video and a force plate embedded in a wall.

Hybrid aerial and scansorial robotics

We present an approach that builds upon previous developments in unmanned air vehicles and climbing robots and seeks to emulate the capabilities of bats, insects and certain birds that combine powered flight with the ability to land and perch on sloped and vertical surfaces. As it approaches a wall, the plane executes an intentional pitch-up maneuver to shed speed and present its feet for landing. On contact, a nonlinear suspension dissipates the remaining kinetic energy and directs interaction forces toward the feet to engage small asperities on surfaces such as brick or concrete. The focus of the work in this paper is on the controller used for sensing a wall and executing vertical landing and take-off procedures and on the mechanisms developed for spine engagement and disengagement.

A wing characterization method for flapping-wing robotic insects

This paper presents a wing characterization method for insect-scale flapping-wing robots. A quasi-steady model is developed to predict passive wing pitching at mid-stroke. Millimeter scale wings and passive hinges are manufactured using the SCM fabrication processes. Flapping experiments at various frequencies and driving voltages are performed to extract kinematics for comparison with the quasi-steady predictions. These experiments examine the validity of the quasi-steady model and demonstrate the robustness of the wing characterization method. In addition, because time-averaged lift and drag are strongly correlated with flapping kinematics, quasi-steady prediction of wing kinematics directly leads to predictions of lift and drag generation. Given a flapping frequency and a driving voltage, the model computes the hinge stiffness that leads to optimal flapping kinematics. This reduces the number of flapping experiments required for wing characterization by a factor of four.

Efficient jumpgliding: Theory and design considerations

A dynamic model of a jump glider is presented and correlated with the results obtained with a prototype glider. The glider uses a carbon fiber spring and a main wing that pivots approximately parallel to the airflow during ascent and latches into place for a gliding descent. The robot demonstrates longer traveled distance than an equivalent drag-free ballistic mass. A detailed numerical and a simplified algebraic model are also introduced, which are useful for exploring design tradeoffs and performance. These models suggest ways to improve the traveled distance and indicate that with modest variations in the wing angle of attack during ascent, one can choose from a variety of launch angles to accommodate variations in ground friction without greatly compromising range.

Principles of microscale flexure hinge design for enhanced endurance

Articulation based on flexure hinges is increasingly popular in microrobotics because of the absence of Coulomb friction, ease of manufacturability, fluid motion, durability, and large angular ranges. However, the inherent flexibility of these hinges makes modeling very complex and specific to the particular engineering applications for which they were developed. In this paper we describe the development and testing of a simplified, versatile method for modeling the stress on a flexure hinge under multi-axis loads in order to maximize hinge lifespan. We also discuss other stress concentration reducing features and design rules that can be applied to more general flexure hinge designs to further extend hinge lifespan.

Design of a small and low-cost power management unit for a cockroach-like running robot

Without a properly designed power management unit, power failures are to be expected on systems raining on batteries. Unfortunately, there is no low cost fully configurable unit that is available on the market for small mobile robots. This paper presents the design of a power management unit for a six legged pneumatic robot that runs at a top speed of 1.11 m/s. The system consists of a main unit that acts as a fast charger, a power supply and a monitor of the energy left available to the robot. This unit communicates with small circuit embedded on each NiMH battery, which gives their level and stores the batterys parameters so that the charger can adapt its charging algorithm to batteries of different capacity or chemistry. Furthermore, this power management unfit takes advantage of the controller area network (CAN) and the PIC18F brain to act as a monitoring, fully configurable, remotely controllable and autonomous node.

Design of a Cockroach-Like Running Robot for the 2004 SAE Walking Machine Challenge

Captain Basile is a robot inspired from the cockroach and built to participate at the SAE Walking Machine Challenge 2004, an undergraduate competition of walking robots.

Design of a Passive Vertical Takeoff and Landing Aquatic UAV

With the goal of extending unmanned aerial vehicles mission duration, a solar recharge strategy is envisioned with lakes as preferred charging and standby areas. The Sherbrooke University Water-Air VEhicle (SUWAVE) concept developed is able to takeoff and land vertically on water. The physical prototype consists of a wing coupled to a rotating center body that minimizes the added components with a passive takeoff maneuver. A dynamic model of takeoff, validated with experimental results, serves as a design tool. The landing is executed by diving, without requiring complex control or wing folding. Structural integrity of the wing is confirmed by investigating the accelerations at impact. A predictive model is developed for various impact velocities. The final prototype has executed multiple repeatable takeoffs and has succeeded in completing full operation cycles of flying, diving, floating, and taking off.

Evaluating the Directional Stability of Alpine Skis through the Simulation of Ski Deformation during a Steady-State Turn

Directional stability is an important performance criterion for alpine skis and has been shown to correlate with the second moment of running surface pressure distribution. However, this stability index is complex to measure while skiing and is not practical for testing many skis. It therefore remains unclear what range one can expect in the variation of stability between commercially available skis. In this study, the mechanical properties of 179 skis were measured and the ski deformation was simulated during a steady-state turn to evaluate the stability index. The resulting data provide insight as to what values of stability, which ranged from 0.1 to 98 N m², are to be expected. A novel parameter, the product of the force required to flatten a ski and the square of its sidecut length, was introduced. Its high correlation with a ski’s stability suggests it can be used as an accurate predictor of stability.

Localization of RW-UAVs using particle filtering over distributed microphone arrays

Rotary-Wing Air Vehicles (RW-UAVs), also referred to as drones, have gained in popularity over the last few years. Intrusions over secured areas have become common and authorities are actively looking for solutions to detect and localize undesired drones. The sound generated by the propellers of the RW-UAVs is powerful enough to be perceived by a human observer nearby. In this paper, we examine the use of particle filtering to detect and localize in 3D the position of a RW-UAV based on sound source localization (SSL) over distributed microphone arrays (MAs). Results show that the proposed method is able to detect and track a drone with precision, as long as the noise emitted by the RW-UAVs dominates the background noise.