Abstract: The wheelchair is the major means of transport for
physically disabled people. However, it cannot overcome architectural
barriers such as curbs and stairs. In this paper, the authors proposed
a method to avoid falling down of a wheeled inverted pendulum type
robotic wheelchair for climbing stairs. The problem of this system
is that the feedback gain of the wheels cannot be set high due to
modeling errors and gear backlash, which results in the movement
of wheels. Therefore, the wheels slide down the stairs or collide with
the side of the stairs, and finally the wheelchair falls down. To avoid
falling down, the authors proposed a slider control strategy based on
skyhook model in order to decrease the movement of wheels, and a
rotary link control strategy based on the staircase dimensions in order
to avoid collision or slide down. The effectiveness of the proposed
fall avoidance control strategy was validated by ODE simulations and
the prototype wheelchair.
Abstract: In this paper, an magnetorheological (MR) mount with
fuzzy sliding mode controller (FSMC) is studied for vibration
suppression when the system is subject to base excitations. In recent
years, magnetorheological fluids are becoming a popular material in
the field of the semi-active control. However, the dynamic equation of
an MR mount is highly nonlinear and it is difficult to identify. FSMC
provides a simple method to achieve vibration attenuation of the
nonlinear system with uncertain disturbances. This method is capable
of handling the chattering problem of sliding mode control effectively
and the fuzzy control rules are obtained by using the Lyapunov
stability theory. The numerical simulations using one-dimension and
two-dimension FSMC show effectiveness of the proposed controller
for vibration suppression. Further, the well-known skyhook control
scheme and an adaptive sliding mode controller are also included in
the simulation for comparison with the proposed FSMC.
Abstract: This paper describes the development, modeling, and
testing of skyhook and MiniMax control strategies of semi-active
suspension. The control performances are investigated using
Matlab/Simulink [1], with a two-degree-of-freedom quarter car semiactive
suspension system model. The comparison and evaluation of
control result are made using software-in-the-loop simulation (SILS)
method. This paper also outlines the development of a hardware-inthe-
loop simulation (HILS) system. The simulation results show that
skyhook strategy can significantly reduce the resonant peak of body
and provide improvement in vehicle ride comfort. Otherwise,
MiniMax strategy can be employed to effectively improve drive
safety of vehicle by influencing wheel load. The two strategies can
be switched to control semi-active suspension system to fulfill
different requirement of vehicle in different stages.
Abstract: Active vibration isolation systems are less commonly
used than passive systems due to their associated cost and power
requirements. In principle, semi-active isolation systems can deliver
the versatility, adaptability and higher performance of fully active
systems for a fraction of the power consumption. Various semi-active
control algorithms have been suggested in the past. This paper
studies the 4DOF model of semi-active suspension performance
controlled by on–off and continuous skyhook damping control
strategy. The frequency and transient responses of model are
evaluated in terms of body acceleration, roll angle and tire deflection
and are compared with that of a passive damper. The results show
that the semi-active system controlled by skyhook strategy always
provides better isolation than a conventional passively damped
system except at tire natural frequencies.