# Review of the Research Progress in Soft Robots
## 6 Conclusions and Prospects  
This paper introduces the driven methods and materials of soft robots, and the basic principles and characteristics of mainstream soft materials in 3D printing technology in detail by reviewing the relevant references on soft robots in the past 20 years, aiming to provide readers with some references on the driven principles of soft robots and 3D printing manufacturing. Then, aiming at the current studies, some problems existing in soft robots are summarized, such as the shortage of smart soft materials, the effective use of energy, the realization of the complex motion form of soft robots, the accuracy of the control motion, the actual modeling of the soft robot kinematics, high-efficiency and high-precision manufacturing of soft robots, and so on. Some suggestions are put forward as future research directions. Several suggestions are made to address the above problems:  
1. Developing new smart materials [140]. It is necessary to conduct in-depth studies on materials, chemistry, machinery, control and other disciplines, and new smart materials that are non-toxic, pollution-free, high stability, low cost, and large deformation for soft robots should be developed, so as to provide a variety of options for the applications of soft robots. 2. Developing 3D printing soft materials. More soft materials compatible with 3D printing should be developed to solve the limited range of printable soft materials. 3. Exploring new 3D printing technology. Traditional 3D printing methods restrict each other in manufacturing cost, printable materials, molding accuracy, printing speed, and universality, which poses new challenges to the 3D printing manufacturing technology of soft robots, and new 3D printing technology that can comprehensively take into account the above issues needs to be explored. In recent years, new technologies such as multi material 3D printing [130], embedded 3D printing [76], and 4D printing [141] have been developing. 4. Exploring the combination of multiple driven methods, the combination of multiple driven methods can make up for the shortcomings of a single driven method, and enable the soft robot to achieve more complex motion patterns. 5. Optimization of modeling techniques. The modeling needs to consider the multi-coupling problem to ensure the accuracy of the physical model of soft robots; for example, the finite element analysis software can be used to model and analyze the soft robots, and further optimize the design on the basis of ensuring the accuracy [140]. 6. Optimizing sensor control technology. Optimize sensor control technology to obtain accurate data feedback and meet the requirements of infinite degrees of freedom control. (7) Optimizing human-computer interaction techniques [140]. Optimizing the hardware and software design of the input and feedback equipment of soft robots, so as to better implement human-computer interaction techniques and facilitate people's control. (8) Reducing the production cost of soft robots. In terms of applications, currently, soft robots have good prospects in the field of medical and human health testing, but their production costs are still high, so the research of soft robots in low-cost and industrial production needs to be further advanced. (9) High-efficiency and high-precision manufacturing of soft robots. Explore the combination of high-efficiency 3D printing technology and high-precision 3D printing technology to meet the requirements of high-efficiency and high-precision manufacturing of soft robots. Therefore, the combination of multiple 3D printing methods with complementary advantages provides the possibility to realize high-efficiency and high-precision manufacturing of soft robots. In the future, soft robots will provide great assistance to people in expedition rescue in the hardest-hit areas, medical surgery and human skeletal replenishment, and even outer space exploration.