The Cherenkov Telescope Array (CTA) project aims to implement the world’s largest next generation of Very High Energy gamma-ray Imaging Atmospheric Cherenkov Telescopes devoted to the observation from a few tens of GeV to more than 100 TeV. To view the whole sky, two CTA sites are foreseen, one for each hemisphere. The sensitivity at the lowest energy range will be dominated by four Large Size Telescopes, LSTs, located at the center of each array and designed to achieve observations of high red-shift objects with the threshold energy of 20 GeV. The LST is optimized also for transient low energy sources, such as Gamma Ray Bursts (GRB), which require fast repositioning of the telescope. The overall design and the development status of the first LST telescope will be discussed.
Ionic polymer-metal composite (IPMC) is one of the electro-active polymer materials which respond to electric stimuli
with shape change. IPMC actuators can be activated with simple driving circuit and common control approach; however,
dynamic characteristics change from environmental conditions such as the temperature or humidity. The output force of
IPMC is very small, and the stress relaxation exists depending on the type of the counter-ions in the electrolyte.
Therefore, it is desirable to construct robust controllers and connection of multiple actuator units to obtain stable and
large output force. In this study, we apply a control method for cellular actuators to solve above problems. The cellular
actuator is a concept of the actuators which consist of multiple actuator units. The actuator units connect in parallel or
series, and each unit is controlled by distributed controllers, which are switched ON/OFF state stochastically depending
on the broadcast error signal which is generated in the central controller. In this paper, we verify the control performance
of the cellular actuator method through numerical simulations. In the simulations, we assume that the one hundred units
of IPMC connected in parallel, the output force is controlled to the desired value. The control performance is
investigated in the case of some mixed ratio of units whose counter-ions are Sodium (Na) ion or Tetraethylammonium
(TEA). As a result of simulation, it was confirmed that the tracking performance is improved by combining the fast
response actuator units of Na ions and the large output actuator units of TEA ions.