## 1 Introduction
Furthermore, to maximize the performance of TS hinges, optimizations with various design parameters were conducted with an experimentally validated physics-based model [18] and a multi-objective optimization [19]. Figure 1: Configuration of multi-layer TS hinges: (**a**) unfolding configuration, (**b**) folding configuration, (**c**) design parameters of multi-layer TS hinges. In the case of boom application of TS hinges, due to extreme slenderness of appendages deployed, it is susceptible to lose structural stability subjected to various micro-vibration excitation. Thus, its inherent mechanisms of single TS (STS) according to the equal-sense bending and the opposite-sense bending was experimentally investigated (see Figure 2a) [20, 21, 22]. Besides, various numerical simulation of STS was conducted by an equivalent beam modeling [23] and nonlinear analysis by FE simulation [21, 22, 24, 25]. Regarding the deployment performance of panels with TS hinge modeling, systematic optimization was conducted with constraints on the maximum latching forces, deployment time, and torque margin of the panels [26]. To make the correlation of deploying panels between test and analysis, the dynamic equation of the deploying solar arrays was derived and the motion was compared with the deployment test result of a Korean multi-purpose satellite (KOMPSAT-2) with multi-layer TS hinges (MLTS) (see Figure 2b). They found that there was some deviation due to the friction arising from the bungee cables of the Zero-G device [27, 28]. To minimize the friction from the zero-G device, [PERSON] et al. conducted a study on the development test device considering gravity compensation by air bearings to minimize friction [29], but still showed some deviation due to air-drag of large panels. The goal of this work is to investigate and validate the deployment motion of solar panels of TS hinges showing nonlinear hysteresis behavior by multi-body dynamics (MBD) with deployment tests considering friction compensation. For the MBD simulation, we used a commercial MBD software, RecurDyn [30] which simplifies the process of deriving the dynamics equation of motion. It is noted that, as mentioned earlier, TS hinges showed a path-dependent moment-rotation profile according to folding and unfolding that were hardly tractable in MBD modeling and also a time-consuming job in FE simulation, which were realized by the expression function in RecurDyn. The expression function distinguished the folding from unfolding by the sign of angular velocity of the revolute joints, and it determined the stiffness according to the sign of angular velocity similar to approaches in the references [26, 27, 28]. For the validation of the MBD model, several deployment tests were performed on the Zero-G device that simulates the space orbit environment by compensating gravity effect. However, even in the Zero-G device, when appendages were deployed or stowed, friction forces at the joints arising from the test set-up such as fine misalignment, and air resistance were unavoidable. To make a nice correlation between test and analysis, such effects have to be identified and properly compensated. Therefore, in this work, these frictions were substituted with the equivalent friction torques (EFTs) of the revolute joints, which were obtained by inverse analysis of simulation results referring to test results for the first 2 s and then it was applied to the MBD model for model validation. Figure 2: Typical moment–rotation profile of TS hinges: (**a**) single TS, (**b**) multi-layer TS. To the best of our knowledge, this kind of integrated approach, including the modeling of TS hinges, deployment testing of panels on the Zero-G device, and simulation and validation with friction compensation, has rarely tried before due to complexity of this work despite its importance in the relevant industry. Furthermore, a commercial MBD software was adopted to reduce the burden of modeling, making modeling process efficient for relevant engineers. The remainder of this paper is organized as follows.