## 3 Experimental Setup  
The setup shown in Figure 1 is used as a test bed. For the cylindrically continuum material, we use a two component silicone from [25] see Table 1, which is casted around the connectors for the top and bottom adapter plates; for further details on the construction process we refer to [18]. Four Dynamixel XH430-W350 motors are used in a symmetrical arrangement to ensure a uniform pretension of the continuum element. The tendons are guided under the center of the silicone and then directed to the respective outer pulley units by idler rollers. This pulley unit is also present in the upper assembly, whereby the steal tendon is then fixed with a terminal. The latter leads to our assumption for neglecting the influence of the tendon elasticities, see also Section 5.2.  
The forced oscillation is induced by another Dynamixel XM430-W350 by allowing it to rotate relative to the upper plate, supported by a thrust bearing. This rotation causes the lever arm and the weights attached to it to rotate. The rotation is captured by the integrated MPU9250 gyroscope/accelerometer of the ROBOTIS OpenCR1.0 board, whereby the filter of [26] is used to minimize the drift of the gyroscope. The time response of the filtered orientation angles \((\varphi,\chi,\psi)\) of the \(\mathcal{H}\) plate relative to the \(\mathcal{B}\) plate is used for further analysis, see Figure 3.  
In order to be able to guarantee a consistent initial condition, it is necessary to apply a defined pretension to the tendons at the beginning of each test series. This is achieved using a current-controlled routine that applies a pretension to the tendons up to a defined motor current value. Afterwards, the initial motor positions are stored and a final motor position is determined by means of a linearized matrix mapping and the desired pretension position. This final motor position is controlled by a proportional-integral position controller based on the actual pose and the target pose so that the top plate is parallel to that of the \(y\)-\(z\) plane in the \(\mathcal{H}\)-frame, see Figure 3. The effects of different pretensioning control methods provided by the used Dynamixels, i.e., position-controlled with and without motor current limit, solely current-controlled, can be found in the Supplementary Material S1.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Property** & **Dragon Skin\({}^{\oplus}\)** \\ \cline{2-3}  & **Type (Shore A)** & **20** \\ \hline Spec. weight [g/cm\({}^{3}\)] & 1.08 \\
100\% Young modulus [N/mm\({}^{2}\)] & 0.33 \\ Stiffness (Bending) [N m/rad] & 97.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Technical data of the continuum material being used, see also the online data sheet [[https://www.kaupo.de/shop/out/media/DRAGON_SKIN_SERIE.pdf](https://www.kaupo.de/shop/out/media/DRAGON_SKIN_SERIE.pdf)]([https://www.kaupo.de/shop/out/media/DRAGON_SKIN_SERIE.pdf](https://www.kaupo.de/shop/out/media/DRAGON_SKIN_SERIE.pdf)) (accessed on 4 June 2021) [25].  
Figure 4: Model for the characterisation of the dynamic properties of the continuum material. Input variables (magenta): \(\theta_{d},\Omega,p_{i}\). Measured torsion (red) \(\varphi\). System variables (black): \(d,k,\omega_{0},m,I_{m},l_{s}\). Geometry parameter (green): \(r\).