This paper addresses the finite-time path following control problem for an under-actuated stratospheric airship with input saturation, error constraint, and external disturbances. To handle the adverse effect of input saturation, anti-windup compensators are employed and finite-time convergence of the saturated control solution is established. Error constraints of airship position and attitude are handled by incorporating a tan-type barrier Lyapunov function (TBLF) in guidance and attitude control schemes. Backstepping design is presented with the anti-windup compensators, the TBLF, and nonlinear disturbance observers which estimate the external disturbances. Stability analysis shows that the tracking errors of the airship position converge into a small set around zero within finite-time, the constrained requirements on the airship position and attitude are not violated during operation, and all closed-loop signals are guaranteed to be uniformly ultimately bounded. Compared with the conventional c...

Finite-time path following control for a stratospheric airship with input saturation and error constraint

Configurations, flight mechanisms, and applications of unmanned aerial systems: A review

The present paper is concerned with the dynamic modeling and design of control laws for a small non-rigid multi-rotor airship constituted of an oblate-spheroid helium balloon coupled with an electric-powered hexa-rotor airframe. The vehicle is assumed to operate in windless and low-speed conditions. A six-degree-of-freedom nonlinear dynamic model is derived for it using the Newton–Euler approach and considering, among other efforts, a restoring torque due to the displacement of the balloon’s center of buoyancy above the vehicle’s center of mass and the added-mass effect resulting from the air–structure interaction. Using the derived model and assuming a time-scale separation between the translational and rotational dynamics, the attitude and position control laws are designed separately from each other. Both laws are formulated using feedback linearization combined with control input saturation within appropriate parallelepipedal sets, which are carefully chosen to respect pre-defined bounds on the control torque, control force and maximum inclination angle. The effect of temperature and pressure fluctuations is taken into account through a parametric probabilistic approach, where Maximum Entropy Principle is used to construct a physically consistent stochastic model and Monte Carlo method is used as the stochastic solver to propagate the uncertainties through the system. Extensive simulation results show the effectiveness of the proposed control system and quantify the uncertainty of its performance over a wide range of local temperature and pressure.

Flight control of a hexa-rotor airship: Uncertainty quantification for a range of temperature and pressure conditions.

This paper presents a novel light-weighted Unmanned Aerial Vehicle (UAV), an over-actuated tilt-rotor quadrotor with an innovative control allocation technique, named as Fast Control Allocation (FCA). In this arrangement, every motor has its own independent tilting command angle. By using this novel approach, the aircraft enhances its yawing capability and increases one more actuation domain: forward/backward velocity. However, this approach generates a control allocation matrix with non-unique solutions, breaking the effectiveness matrix into two parts. The first one is created considering the yawing torque and forward/backward velocity, and the second one considers all aircraft dynamics, running iteratively until the convergence criteria are reached. The results showed a well designed UAV where the FCA convergence and robustness was visible, allowing reliable and safe flight conditions with low computational effort control boards.

Fast Real-Time Control Allocation Applied to Over-Actuated Quadrotor Tilt-Rotor

This paper presents the mathematical modeling and control of a finless airship that can fly at low altitudes in low wind conditions. Slow speed symmetrical airships can move freely in 3-dimensional air space with a vector propulsion system. The forces/moments of robotic arm are derived at center of gravity (CG) of the airship, and controllers are designed using classical control theory. An inner-outer loop strategy is proposed here in this paper; LQR based longitudinal and lateral controllers are designed for inner control loops while PI-based controllers are proposed for the height and velocity in outer guidance loop. The performance of the proposed scheme is validated through 6-degree of freedom nonlinear simulation having actuator dynamics and sensor models including measurement noises. Different scenarios are generated in nonlinear simulation to check the performance and robustness of the proposed scheme; simulation results validated the effectiveness of proposed scheme.

Modeling and control of unmanned finless airship with robotic arms.

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.

Modeling and Control of an Unmanned Airship with Sliding Ballast

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.

/pdf/unmanned-airship-design-with-sliding-ballast-modeling-and-3dxnnhbp6q.pdf

Unmanned airship design with sliding ballast: Modeling and experimental validation

Self-balancing robots can turn on the spot using differential steering with better efficiency than tracked or four-wheel drive robots, and they can be many times their width in height. However they have two major limitations: they cannot stand-up on their own and cannot climb stairs. In this paper, a novel design is proposed to address these issues. A single degree of freedom is added to the center of a four-wheel drive robot. This arm allows the robot to climb stairs and stand-up on its own. A model and simulation of the balancing and the stair-climbing process are derived and the stair-climbing is compared against experimental results with a prototype. It was shown that the model closely follows the trend of the experimental results and provides a basis for future studies on the concept.

https://www.ruor.uottawa.ca/bitstream/10393/32279/1/P19%20Robillard%2c%20Lanteigne.pdf

Development of Compact Self-Balancing Robot with Self-Standing and Stair-Climbing Capability

An energy harvesting device for use in a shipping container has a force-sensitive element displaceable in response to forces arising from deformation of the shipping container during movement thereof. An amplifier amplifies the resulting force or displacement of the force-sensitive element. A generator is responsive to the amplified force or displacement to generate electricity.

Dominic Robillard

Papers

Modeling and Control of an Unmanned Airship with Sliding Ballast

Unmanned airship design with sliding ballast: Modeling and experimental validation

Development of Compact Self-Balancing Robot with Self-Standing and Stair-Climbing Capability

Energy harvesting device for portable shipping containers