Eric Lanteigne

An Experimental Study on a SMA Driven Pressurized Hyper-redundant Manipulator:

This study describes the design and fabrication of a pressurized hyper-redundant manipulator driven by high strain shape memory alloy (SMA) actuators. Hyper-redundant devices are characterized by repeating independently controlled structures connected in series; their architecture is comparable to that of a snake or worm. The proposed design is composed of four identical modules; each providing three degrees of freedom from three symmetrically positioned actuators. The manipulator stiffness and actuator return-force are controlled by pressurized air, injected at the base of the manipulator. Tests on a single unit module have demonstrated that the design could achieve rotations of over 50° and displacements of over 40% at a frequency of 1/20 Hz.

Hybrid Power Plant Design for a Long-Range Dirigible UAV

Unmanned aerial vehicle (UAV) dirigibles are well suited for surveillance and surveyance missions since they can hover and maintain lift without consuming energy and can be easily deflated for packaging and transportation. The challenge is developing a long endurance system while maintaining a low unit cost. This paper presents a novel hybrid power plant design that addresses both of these requirements. The lightweight design consists of a 4-stroke 14cc gasoline engine in-line with a brushless dc motor/generator and variable pitch propeller capable of producing a maximum power output of 250 W. A method was also developed to compare its performance and endurance to other power plant configurations that could be used in dirigible UAVs. Overall, the proposed hybrid power plant has 674% increase in energy density over that of a purely electric system, thereby proportionally increasing UAV flight time for the same power and weight.

Modeling and Control of an Unmanned Airship with Sliding Ballast

Generally underpowered, underactuated, and large in size, airships express difficulties in adverse atmospheric conditions and situations requiring rapid or precise maneuvers. In this paper, a novel miniature unmanned airship with a sliding ballast is presented to address the limited altitude maneuverability. Simulated and experimental tests demonstrate that the proposed architecture allows for large pitch variations and, when combined with forward facing thrusters, rapid changes in altitude thus facilitating autonomous landings or payload delivery. Operational advantages such as increased hull rigidity and concentrated hardware inherent to the vehicle design are also discussed.

A High-Fidelity Energy Efficient Path Planner for Unmanned Airships

This paper presents a comparative study on the effects of grid resolution, vehicle velocity, and wind vector fields on the trajectory planning of unmanned airships. A wavefront expansion trajectory planner that minimizes a multi-objective cost function consisting of flight time, energy consumption, and collision avoidance while respecting the differential constraints of the vehicle is presented. Trajectories are generated using a variety of test environments and flight conditions to demonstrate that the inclusion of a high terrain map resolution, a temporal vehicle velocity, and a spatial wind vector field yields significant improvements in trajectory feasibility and energy economy when compared to trajectories generated using only two of these three elements.

Unmanned airship design with sliding ballast: Modeling and experimental validation

Airships present many interesting opportunities for transport, surveillance and inspection but have seen little to no use in commercial or military unmanned applications. Generally underpowered, underactuated, and large in size, airships express difficulties in adverse atmospheric conditions or situations requiring rapid or precise maneuvers. In this paper, a miniature unmanned airship with a moving platform is presented to address the the limited altitude maneuverability of these vehicles. Simulated and experimental open-loop trajectories demonstrate that this architecture allows for large changes in vehicle pitch and, when combined with forward facing thrusters, rapid changes in altitude. Operational advantages such as increased hull rigidity and concentrated hardware inherent to the vehicle design are also discussed.

Experimental pitch control of an unmanned airship with sliding ballast

In this paper, the pitch control of a miniature unmanned airship using a sliding ballast is presented. The sliding ballast design has been developed to address the limited altitude maneuverability of lighter-than-air vehicles by allowing for large changes in vehicle pitch and, when combined with forward facing thrusters, rapid changes in altitude. Using the longitudinal position of the ballast as the control input, the vehicle behavior is simulated under various reference trajectories and wind disturbances. Preliminary experimental flight tests are then performed to evaluate the pitch controller performance.

Pitch control of an Oblique Active Tilting bi-rotor

This article presents the design and pitch control of an Oblique Active Tiling (OAT) fixed-pitch bi-rotor. The oblique arms of the bi-rotor allow faster pitch response due to gyroscopic torque, compared to other vertical take-off designs. The effect of the design parameters on flight are analyzed to provide general guidelines for the design of OAT bi-rotors. The non-linear model of a bi-rotor is simulated in Matlab and a simplified controller is implemented on a small scale model.

Optimal control for the trajectory planning of micro airships

The objective of this paper is to demonstrate the application of optimal control for generating dynamically constrained minimal time trajectories in micro unmanned airships. By design, airships are generally underactuated and underpowered limiting their maneuvering capabilities. Using a simplified dynamic model derived with experimentally derived coefficients, two trajectory planning simulations are solved using optimal control. The generated trajectories are then evaluated experimentally on a micro airship to demonstrate that optimal control can be used in open loop over short distances.

Efficient Cholesky Factor Recovery for Column Reordering in Simultaneous Localisation and Mapping

Simultaneous Localisation And Mapping problems are inherently dynamic and the structure of the graph representing them changes significantly over time. To obtain the least square solution of such systems efficiently, it is desired to maintain a good column ordering such that fill-ins are reduced. This comes at a cost since general ordering changes require the complete re-computation of the Cholesky factor. While some methods have obtained good results with reordering at loop closing, the changes are not guaranteed to be limited to the scope of the loop, leading to suboptimal performance. In this article, it is shown that the Cholesky factorisation of an updated matrix can be efficiently recovered from the previous factorisation if the permutations are localised. This is experimentally demonstrated on 2D SLAM datasets. A method is then provided to identify when such recovery is advantageous over the complete re-computation of the Cholesky factor. Furthermore, a hybrid algorithm combining factorisation recovery and re-computation of the Cholesky factor is proposed for dynamically evolving problems and tested on SLAM datasets. Steps where reordering occurs can be executed up to 67 % faster with the proposed method.

Design of a Link-Less Hyper-Redundant Manipulator and Composite Shape Memory Alloy Actuator

The design of a link-less hyper-redundant miniature manipulator driven by high strain SMA (shape memory alloy) actuators is the focus of this research. The manipulator is composed of four identical modules connected in series, each providing three degrees of freedom from three symmetrically positioned actuators. The manipulator is withheld by the action of a positive air pressure flow injected in structure at the base of the manipulator. The internal pressure give the manipulator its stiffness, provides the return force require by the SMA actuators and, to a certain extent, acts as a coolant during post-actuation. High strain rates are achieved by submitting the SMA material to bending stressed rather than pure tension. The controller is designed based on the principle of binary actuation, which eliminates the need for sensing equipment and feedback control. The compliant nature of the manipulator and its lightweight construction enable the manipulator to perform complex tasks in constrained environments