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This study investigates the impact of economic policy uncertainty on corporation innovation in innovative cities. The study sheds light on different results from the previous literature by testing the moderator effects of entrepreneurial risk appetite on such impact.

A static panel estimator is applied to a Chinese sample of 416 firm-year observations from 2010 to 2019. This paper uses regression model to test the impact of uncertainty on enterprise innovation in innovative cities, and to test the regulatory role of entrepreneurial risk appetite. For a series of robustness analysis conducted by the author to deal with endogeneity, the results are robust.

The author finds reliable evidence that the economic policy uncertainty can promote corporations to invest more in R&D in innovative cities. In addition, the role of the entrepreneurial initiative is significant, and there is a positive moderating effect of entrepreneurial risk appetite between policy uncertainty and corporation innovation.

From a practical point of view, this study examines the impact of economic policy uncertainty on corporation innovation in innovative cities for the first time. It emphasizes the role of entrepreneurial risk-taking in the development of corporation innovation in Shenzhen, an innovative city. This research is of great significance to the formulation of government policies and the innovative choice of entrepreneurs. In addition, the research shows that the entrepreneurial risk appetite in innovative cities can have a positive impact on enterprise innovation. Therefore, when formulating policies, the government should take the subjective factors of entrepreneurs into account and support enterprises with innovation potential. The evidence of this study also helps entrepreneurs make innovative decisions and enhance their confidence in enterprise development.

By studying the impact of economic policy uncertainty on enterprise innovation under the regulation of enterprise risk appetite, this study shows the subjective and positive role of entrepreneurs in risk grasp in innovative cities for the first time. In addition, it fills the gap of the impact of policy uncertainty on innovative urban enterprises. In fact, although it is traditionally believed that economic policy uncertainty has a negative impact on enterprise innovation, the sensitive findings of this study reveal completely different results from previous studies.

The purpose of this paper is to propose a two-degrees-of-freedom wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism based on spring, in order to improve the robot’s athletic ability, load capacity and rigidity, and to ensure the coordination of multi-modal motion.

First, based on the rotation transformation matrix and closed-loop constraint equation of the parallel trunk joint mechanism, the mathematical model of its inverse position solution is constructed. Then, the Jacobian matrix of velocity and acceleration is derived by time derivative method. On this basis, the stiffness matrix of the parallel trunk joint mechanism is derived on the basis of the principle of virtual work and combined with the deformation effect of the rope driving pair and the spring elastic restraint pair. Then, the eigenvalue distribution of the stiffness matrix and the global stiffness performance index are used as the stiffness evaluation index of the mechanism. In addition, the performance index of athletic dexterity is analyzed. Finally, the distribution map of kinematic dexterity and stiffness is drawn in the workspace by numerical simulation, and the influence of the introduced spring on the stiffness distribution of the parallel trunk joint mechanism is compared and analyzed. It is concluded that the stiffness in the specific direction of the parallel trunk joint mechanism can be improved, and the stiffness distribution can be improved by adjusting the spring elastic structure parameters of the rope-driven branch chain.

Studies have shown that the wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism based on spring has a great kinematic dexterity, load-carrying capacity and stiffness performance.

The soft-mixed structure is not mature, and there are few new materials for the soft-mixed mixture; the rope and the rigid structure are driven together with a large amount of friction and hindrance factors, etc.

It ensures that the multi-motion mode hexapod mobile robot can meet the requirement of sufficient different stiffness for different motion postures through the parallel trunk joint mechanism, and it ensures that the multi-motion mode hexapod mobile robot in multi-motion mode can meet the performance requirement of global stiffness change at different pose points of different motion postures through the parallel trunk joint mechanism.

The trunk structure is a very critical mechanism for animals. Animals in the movement to achieve smooth climbing, overturning and other different postures, such as centipede, starfish, giant salamander and other multi-legged animals, not only rely on the unique leg mechanism, but also must have a unique trunk joint mechanism. Based on the cooperation of these two mechanisms, the animal can achieve a stable, flexible and flexible variety of motion characteristics. Therefore, the trunk joint mechanism has an important significance for the coordinated movement of the whole body of the multi-sport mode mobile robot (Huang Hu-lin, 2016).

In this paper, based on the idea of combining rigid parallel mechanism with wire-driven mechanism, a trunk mechanism is designed, which is composed of four spring-based wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism in series. Its spring-based wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism can make the multi-motion mode mobile robot have better load capacity, mobility and stiffness performance (Qi-zhi et al., 2018; Cong-hao et al., 2018), thus improving the environmental adaptability and reliability of the multi-motion mode mobile robot.