6,180 research outputs found
Bipedal Hopping: Reduced-order Model Embedding via Optimization-based Control
This paper presents the design and validation of controlling hopping on the
3D bipedal robot Cassie. A spring-mass model is identified from the kinematics
and compliance of the robot. The spring stiffness and damping are encapsulated
by the leg length, thus actuating the leg length can create and control hopping
behaviors. Trajectory optimization via direct collocation is performed on the
spring-mass model to plan jumping and landing motions. The leg length
trajectories are utilized as desired outputs to synthesize a control Lyapunov
function based quadratic program (CLF-QP). Centroidal angular momentum, taking
as an addition output in the CLF-QP, is also stabilized in the jumping phase to
prevent whole body rotation in the underactuated flight phase. The solution to
the CLF-QP is a nonlinear feedback control law that achieves dynamic jumping
behaviors on bipedal robots with compliance. The framework presented in this
paper is verified experimentally on the bipedal robot Cassie.Comment: 8 pages, 7 figures, accepted by IROS 201
Time and Energy Managed Operations (TEMO): Cessna Citation II Flight Trials
From 9-26 October 2015 the Netherlands Aerospace Centre (NLR) in
cooperation with Delft University of Technology (DUT) has executed Clean Sky flight
trials with the Cessna Citation II research aircraft. The trials consisted of several
descents and approaches at the Eelde airport near Groningen, demonstrating the
TEMO (Time and Energy Managed Operations) concept developed in the Clean Sky
Joint Technology Initiative research programme as part of the Systems for Green
Operations (SGO) Integrated Technology Demonstrator.
A TEMO descent aims to achieve an energy-managed idle-thrust
continuous descent operation (CDO) while satisfying ATC time constraints, to
maintain runway throughput. An optimal descent plan is calculated with an advanced
on-board real-time aircraft trajectory optimisation algorithm considering forecasted
weather and aircraft performance. The optimised descent plan was executed using
the speed-on-elevator mode of an experimental Fly-By-Wire (FBW) system connected
to the pitch servo motor of the Cessna Citation II aircraft. Several TEMO conceptual
variants have been flown. It has been demonstrated that the TEMO concept enables
arrival with timing errors below 10 seconds. The project was realised with the
support of CONCORDE partners Universitat Politècnica de Catalunya (UPC) and
PildoLabs from Barcelona, and the Royal Netherlands Meteorological Institute
(KNMI).Peer ReviewedPostprint (published version
- …