We develop tracking control laws for a rigid spacecraft using both thrusters and momentum wheels. The model studied comprises a rigid body with external thrusters and with N rigid axisymmetric wheels controlled by axial torques. The thruster torques and the axial motor torques are the controls used to track given attitude motions. Specifically, the thruster torques are used to implement the coa...

An antilock braking system (ABS) is one of the most important components in a road vehicle, which provides active protection during braking, to prevent wheels from locking-up and achieve handling stability steerability. The all-electric ABS without any hydraulic potential candidate for electric vehicles. To demonstrate examine algorithms, this article proposes single-wheel test bench, mainly in...

Locking devices are widely used in robotics, for instance to lock springs, joints or to reconfigure robots. This review paper classifies the locking devices currently described in literature and preforms a comparative study. Designers can therefore better determine which locking device best matches the needs of their application. The locking devices are divided into three main categories based ...

A control law for an Integrated Power/Attitude Control System (IPACS) for a satellite is presented in this paper. Four or more energy/momentum wheels in an arbitrary non-coplanar configuration and a set of three thrusters are used to implement the torque inputs. The energy/momentum wheels are used as attitude control actuators, as well as an energy storage mechanism, providing power to the spac...

A wheel is a graph made of a cycle of length at least 4 together with a vertex that has at least three neighbors in the cycle. We prove that the problem whose instance is a graph G and whose question is “does G contains a wheel as an induced subgraph” is NP-complete. We also settle the complexity of several similar problems.

for two given graphs g1 and g2, the ramseynumber r(g1,g2) is the smallest integer n such that for anygraph g of order n, either $g$ contains g1 or the complementof g contains g2. let tn denote a tree of order n andwm a wheel of order m+1. to the best of our knowledge, only r(tn,wm) with small wheels are known.in this paper, we show that r(tn,wm)=3n-2 for odd m with n>756m^{10}.

Safety of the wheels for high-speed train was investigated when the tread cleaner, which play a role in the increase of adhesion and the removal of dirt, is failed and stuck in wheel tread. The present study was performed on the basis of analyses of a combination of mechanical and thermal load due to the failure of tread cleaner during severe conditions. The finite element method was used to an...