It is important to improve the natural frequency of test device to improve measurement accuracy. First-order frequency is basic frequency of dynamic model, which generally is the highest vibration energy of natural frequency. Taking vector force test device (VFTD) as example, a novel dynamic design method for improving first-order natural frequency by increasing structure stiffness is proposed. In terms of six degree-of-freedom (DOF) of VFTD, dynamic model of VFTD is built through the Lagrange dynamic equation to obtain theoretical natural frequency and mode shapes. Experimental natural frequency obtained by the hammering method is compared with theoretical results to prove rationality of the Lagrange method. In order to improve the stiffness of VFTD, increase natural frequency and meet the requirement of high frequency test, by using the trial and error method combined with curve fitting (TECF), stiffness interval of meeting natural frequency requirement is obtained. Stiffness of VFTD is improved by adopting multiple supports based on the stiffness interval. Improved experimental natural frequency is obtained with the hammering method to show rationality of the dynamic design method. This method can be used in improvement of first-order natural frequency in test structure.
 Liu, J., Meng, X.H., Zhang, D., Jiang, C., Han, X. (2017). An efficient method to reduce ill-posedness for structural dynamic load identification. Mechanical Systems and Signal Processing, 95, 273-285.
 Hessling, J.P. (2011). Propagation of dynamic measurement uncertainty. Measurement Science and Technology, 22 (10).
 Du, C., Zhang, J., Lu, D., Zhang, H., Zhao, W. (2016). A parametric modeling method for the pose-dependent dynamics of bi-rotary milling head. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 232, 797-811.
 Albrecht, A., Park, S.S., Altintas, Y., Pritschow, G. (2005). High frequency bandwidth cutting force measurement in milling using capacitance displacement sensors. International Journal of Machine Tools and Manufacture, 45, 993-1008.
 Li. Y.J., Wang, G.C., Zhang, J., Jia, Z.Y. (2012). Dynamic characteristics of piezoelectric sixdimensional heavy force/moment sensor for large-load robotic manipulator. Measurement, 45, 1114-1125.
 Qin, L., Jiang, C. (2011). Design and calibration of a novel piezoelectric six-axis force/torque sensor. In Seventh International Symposium on Precision Engineering Measurements and Instrumentation, SPIE 8321.
 Totis, G., Sortino, M. (2011). Development of a modular dynamometer for triaxial cutting force measurement in turning. International Journal of Machine Tools and Manufacture, 51, 34-42.
 Liu, X., Han, C., Wang, Y., Yang, T., Du, J., Zhu, M. (2016). Design of natural frequency adjustable electromagnetic actuator and active vibration control test. Journal of Low Frequency Noise, Vibration and Active Control, 35, 187-206.
 Scippa, A., Sallese, L., Grossi, N., Campatelli, G. (2015). Improved dynamic compensation for accurate cutting force measurements in milling applications. Mechanical Systems and Signal Processing, 54-55, 314-324.
 Ma, J., Song, A., Pan, D. (2013). Dynamic compensation for two-axis robot wrist force sensors. Journal of Sensors, 2013, art. ID 357396.
 Ren, Z.J., Sun, B.Y, Zhang, J., Qian, M. (2008). The dynamic model and acceleration compensation for the thrust measurement system of attitude/orbit rocket. In International Workshop on Modelling, Simulation and Optimization. IEEE, 30-33.
 Roj, J. (2013). Neural network based real-time correction of transducer dynamic errors. Measurement Science Review, 13 (6), 286-291.
 Law, M., Altintas, Y., Phani, A.S. (2013). Positiondependent multibody dynamic modeling of machine tools based on improved reduced order models. Journal of Manufacturing Science and Engineering, 135, 1-11.
 Li, X., Wang, X., Wang, J. (2016). A kind of Lagrange dynamic simplified modeling method for multi-DOF robot. Journal of Intelligent & Fuzzy Systems, 31, 2393-2401.
 Liu, M., Zhai, F., Chen, G., Li, Y., Guo, Z. (2016). Theoretical and experimental research on dynamics of the inner displaced indexing cam mechanism. Mechanism & Machine Theory, 105, 620-632.
 Sang, W.L., Mayor, R., Ni, J. (2006). Dynamic analysis of a mesoscale machine tool. Journal of Manufacturing Science and Engineering, 128, 194-203.