6 research outputs found
Co-Design Optimisation of Morphing Topology and Control of Winged Drones
The design and control of winged aircraft and drones is an iterative process
aimed at identifying a compromise of mission-specific costs and constraints.
When agility is required, shape-shifting (morphing) drones represent an
efficient solution. However, morphing drones require the addition of actuated
joints that increase the topology and control coupling, making the design
process more complex. We propose a co-design optimisation method that assists
the engineers by proposing a morphing drone's conceptual design that includes
topology, actuation, morphing strategy, and controller parameters. The method
consists of applying multi-objective constraint-based optimisation to a
multi-body winged drone with trajectory optimisation to solve the motion
intelligence problem under diverse flight mission requirements. We show that
co-designed morphing drones outperform fixed-winged drones in terms of energy
efficiency and agility, suggesting that the proposed co-design method could be
a useful addition to the aircraft engineering toolbox
Whole-Body Trajectory Optimization for Robot Multimodal Locomotion
The general problem of planning feasible trajec-tories for multimodal robots is still an open challenge. This paper presents a whole-body trajectory optimisation approach
that addresses this challenge by combining methods and tools developed for aerial and legged robots. First, robot models that enable the presented whole-body trajectory optimisation framework are presented. The key model is the so-called robot centroidal momentum, the dynamics of which is directly related to the models of the robot actuation for aerial and terrestrial locomotion. Then, the paper presents how these models can be employed in an optimal control problem to generate either terrestrial or aerial locomotion trajectories with a unified approach. The optimisation problem considers robot kinematics, momentum, thrust forces and their bounds. The overall approach is validated using the multimodal robot iRonCub, a flying humanoid robot that expresses a degree of terrestrial and aerial locomotion. To solve the associated optimal trajectory generation problem, we employ ADAM, a custom-made open-source library that implements a collection of algorithms for calculating rigid- body dynamics using CasADi
Torque and velocity controllers to perform jumps with a humanoid robot: theory and implementation on the iCub robot
Jumping can be an effective way of locomotion to overcome small terrain gaps
or obstacles. In this paper we propose two different approaches to perform
jumps with a humanoid robot. Specifically, starting from a pre-defined CoM
trajectory we develop the theory for a velocity controller and for a torque
controller based on an optimization technique for the evaluation of the joints
input. The controllers have been tested both in simulation and on the humanoid
robot iCub. In simulation the robot was able to jump using both controllers,
while the real system jumped with the velocity controller only. The results
highlight the importance of controlling the centroidal angular momentum and
they suggest that the joint performances, namely maximum power, of the legs and
torso joints, and the low level control performances are fundamental to achieve
acceptable results
Modeling and Control of Morphing Covers for the Adaptive Morphology of Humanoid Robots
This article takes a step to provide humanoid robots with adaptive morphology
abilities. We present a systematic approach for enabling robotic covers to
morph their shape, with an overall size fitting the anthropometric dimensions
of a humanoid robot. More precisely, we present a cover concept consisting of
two main components: a skeleton, which is a repetition of a basic element
called node, and a soft membrane, which encloses the cover and deforms with its
motion. This article focuses on the cover skeleton and addresses the
challenging problems of node design, system modeling, motor positioning, and
control design of the morphing system. The cover modeling focuses on
kinematics, and a systematic approach for defining the system kinematic
constraints is presented. Then, we apply genetic algorithms to find the motor
locations so that the morphing cover is fully actuated. Finally, we present
control algorithms that allow the cover to morph into a time-varying shape. The
entire approach is validated by performing kinematic simulations with four
different covers of square dimensions and having 3x3, 4x8, 8x8, and 20x20
nodes, respectively. For each cover, we apply the genetic algorithms to choose
the motor locations and perform simulations for tracking a desired shape. The
simulation results show that the presented approach ensures the covers to track
a desired shape with good tracking performances
Centroidal Aerodynamic Modeling and Control of Flying Multibody Robots
This paper presents a modeling and control frame-work for multibody flying robots subject to non-negligible aero-dynamic forces acting on the centroidal dynamics. First, aero-dynamic forces are calculated during robot flight in different operating conditions by means of Computational Fluid Dynamics (CFD) analysis. Then, analytical models of the aerodynamics coefficients are generated from the dataset collected with CFD analysis. The obtained simplified aerodynamic model is also used to improve the flying robot control design. We present two control strategies: compensating for the aerodynamic effects via feedback linearization and enforcing the controller robustness with gain-scheduling. Simulation results on the jet-powered humanoid robot iRonCub validate the proposed approach