SHS (Segment Handling System) is the subsystem implemented on the telescope. One of the key technologies of SHS is our force control technology applied to Segment Mirror Exchange Robot, which makes it possible to achieve safe and reliable mirror segment exchange as shown in Video 1.
Segment Handling System (SHS) is the subsystem that is planned to be permanently implemented on Thirty Meter Telescope (TMT) telescope structure that enables fast, efficient, semi-automatic exchange of M1 segments. TMT plans challenging segment exchange (10 segments per 10 hours a day). To achieve these, MELCO develops innovative SHS by accommodating Factory Automation (FA) technology such as force control system and machine vision system into the system. Force control system used for install operation, achieves soft handling by detecting force exerted to mirror segment and automatically compensating the position error between handling segments and primary mirror. Machine vision system used for removal operation, achieves semi-automatic positioning between SHS and mirror segments to be handled. Prototype experience proves soft (extraneous force ~300N) and fast (~3 minutes) segment handling. The SHS will provide upcoming segmented large telescopes for cost-efficient, effortless, and safe segment exchange operation.
For the Thirty Meter Telescope (TMT) that aims high-resolution and high-sensitivity observations for optical-infrared astronomy, detailed design is underway for Telescope Structure System (STR) including the mount control system and the segment handling system. The technical requirements for the STR system are very challenging on its performance and interface condition with telescope-mounted optics and observation instruments. The major challenging technical requirements include low flexure of mirror support structure and low optical path length variation due to gravitational deformation, high seismic performance against large earthquake, very accurate mount drive control for high tracking and guiding performance, and fast, safe and labor-saving segment exchange. To meet these technical requirements, Mitsubishi Electric Corporation (MELCO) has made a detailed design and technology development. In this paper, overview of major key technologies is introduced that is adopted for the TMT telescope structure in the detailed design and technology development.
Micro vibrations generated from some internal disturbance sources such as a reaction wheel degrades the pointing stability of an observation satellite. To suppress the pointing error, we have been developing an inertial stabilization unit. A prototype mechanism is designed based on concepts that it has non-contact actuators and sensors, and rotational leaf springs are applied to support a stabilized platform in order to meet two requirements which are precise drive and tolerance for launch load. Two kind of inertial sensors are installed on the platform to measure the attitude directly. Each of these two inertial sensors covers low or high bandwidth signal respectively. These signals will be able to be combined as one wideband signal to stabilize the platform in inertial space. In this paper, the developing prototype mechanism and control equipment are described and the basic evaluation results are reported. Less than 0.3urad as a drive precision and more than 100Hz as a local sensor control bandwidth are verified. The development of the system has not completely finished yet, but the basic performance is certified to meet the design specification. From now on, we continue to develop the unit. These future results can be applied to inter-satellite laser communication system.
An electric active polymer (EAP) using a dielectric elastomer is superior in the points of view of generated stress and
strain, response velocity, and energy efficiency. On the other hand, it is well known that a high polymer material has
creep properties. There is no research about creep of a dielectric elastomer actuator (DEA) as far as we know. It is
necessary to get a clear grasp of the creep properties of a DEA in order to design a DEA. The purpose of our research
was to investigate the creep characteristics and propose a mechanism of a DEA that can generate a large displacement
without creep deformation. At first, a sample element of a DEA was made and tested. As a result, it was found that creep
deformation was generated and accumulated by the repeated actions. Secondly, an element structure of a DEA was
proposed. The element had two driven areas on opposite sides and these two areas are actuated alternately. Therefore, the
proposed element worked as a vibration element. The repeated fatigue tests of the proposed vibration element gave proof
of the effectiveness against creep deformation. At last, a unit mechanism of a DEA was proposed. The proposed unit
mechanism was a combination of the vibration element and a ratchet mechanism. Through a performance test of the
proposed experimental unit mechanism, it was confirmed that the mechanism was able to be driven and the transport
velocity was changed by changing the drive frequency of the vibration element.