# Design Optimization of IoT-Assisted Intelligent Education Soft Robot Based upon Improved GA

Authors: Qun Wu; Gaoqing Ji
Journal: Wireless Communications and Mobile Computing
 (2022)

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## Abstract

A soft robot is a kind of robot designed to simulate mollusks. It has the characteristics of degrees of freedom, strong adaptability, and high flexibility and safety. The main purpose of this paper is to study the intelligent education assistance of soft robots and then combine the application of improved genetic algorithm and the Internet of Things technology in soft robots to improve its performance and effect. Therefore, this paper designs the optimal guidance strategy through the NSGA genetic algorithm and then combines the improved genetic algorithm and the application of the Internet of Things technology in the flexible actuator and FEA actuator of the soft robot. In order to optimize the performance of the IoT-assisted intelligent education software robot based on the improved genetic algorithm, the genetic algorithm simulation test experiment, the rolling motion simulation experiment of the bionic software robot, and the inflating and exhausting experiment of the base section of the software robot are designed and analyzed. Through the analysis of the data obtained from the experiment, this paper finally designs a set of controlled experiments to verify its teaching ability. The experimental results show that the students’ evaluation of the IoT intelligent education software robot education method based on the improved genetic algorithm designed in this paper is 16.31 points higher than that of the traditional education method. Compared with the traditional teaching, the scores of the students after the IOT intelligent education software robot teaching based on the improved genetic algorithm is 11.16 points higher.


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## Body

## 1. Introduction

With the development of modern optimization theory, some new biological optimization algorithms have been highly evaluated and widely used, providing new ideas and methods for solving traditional optimization problems. These biological optimization algorithms include artificial neural network (ANN) and particle thermal algorithm (PSO), differential evolution algorithm (DE), simulated annealing algorithm (SA), and genetic algorithm (GA). Among them, GA is widely used for efficient, parallel processing and globalization optimization. The Internet of Things technology originated in the field of media and is the third revolution in the information technology industry. The Internet of Things refers to the connection of any object with the network through information sensing equipment according to the agreed protocol, and the object exchanges and communicates information through the information transmission medium to realize intelligent identification, positioning, tracking, supervision, and other functions.Soft robots have the characteristics of high degree of freedom, high adaptability, flexibility, and safety in theory, but they have many problems such as poor controllability and difficulty in modeling in practical applications. Most soft robots today are based on bioengineering, imitating natural creatures with shape and function. As more and more researchers focus on this field, software robotics will see a leap forward in the near future. If the improved genetic algorithm and the Internet of Things technology are combined and applied to the software robot that assists intelligent education, the accuracy of the operation and the teaching effect can be significantly improved.The innovation of this paper is that the optimal guidance strategy is designed through the NSGA genetic algorithm and then combined with the Internet of Things technology. It is used in the flexible actuators and FEA actuators of soft robots for intelligent education assistance. Then this paper designs an IoT-assisted intelligent education software robot based on an improved genetic algorithm. In this paper, the genetic algorithm simulation test experiment, the rolling motion simulation experiment of the bionic soft robot, and the inflating and exhausting experiment of the base section of the soft robot are designed and analyzed, and the experimental data is optimized for the soft robot.


## 2. Related Work

Engineering design often considers multiple differences in design and integrates them appropriately to arrive at the most ideal alternative. This concern is especially important in civil engineering construction projects. Babaei proposes a systematic approach called “Requirements-Based Design” to provide a directed multipurpose optimal design that considers all aspects of the project. His research developed an evolutionary fuzzy system for designing the structures considered, based on a combination of fuzzy logic and genetic algorithms [1]. His research is mainly based on the combination of fuzzy logic and genetic algorithm. If it can be combined with the Internet of Things, it will be closer to the theme of this paper. Tavakkoli-Moghaddam proposes a genetic algorithm (GA) for the redundancy assignment problem of series-parallel systems when the redundancy strategy can be chosen for a single subsystem. Most solutions to the general redundancy assignment problem assume that the redundancy policy for each subsystem is predetermined and fixed [2]. Dawid explores the idea of using artificial adaptive agents in economic theory. In particular, he uses genetic algorithms (GAs) to model the learning behavior of adaptive and bounded rational groups of agents interacting in economic systems [3]. Volkanovski proposed a new method to optimize the maintenance scheduling of power system generator sets. Maintenance planning minimizes risk by minimizing the annual value of Loss of Expected Load (LOLE), which is a measure of power system reliability. The method he proposed uses a genetic algorithm to obtain an optimal solution that minimizes the annual LOLE value of the power system during the analysis period [4]. The job shop scheduling problem (JSP) is one of the extremely difficult problems because it requires a very large combinatorial search space and there are some priority constraints between machines. Genetic algorithms (GAs) are considered to be one of the most powerful tools for solving such problems, especially for large-scale real-world problems. Tsujimura demonstrates its performance on a standard benchmark for job shop scheduling problems with two different fuzzy subset ranking methods [5]. In Release 13, 3GPP introduced a new narrowband radio technology called Narrowband Internet of Things (NB-IoT). NB-IoT is designed to support extremely low-power and low-cost devices under extreme coverage conditions. NB-IoT operates at a very small bandwidth and will provide connectivity to a large number of low data rate devices. Beyene highlights some key features introduced in NB-IoT and shows performance results from real experiments [6]. Soft robots are often inspired by biological systems composed of soft materials or powered by electroactive materials. Compared with traditional robots, the advantages of soft robots are safe human-computer interaction, adaptability to wearable devices, simple grasping system, etc. Due to its unique characteristics and advantages, soft robots have a wide range of applications. Lee reviews the latest research in soft robotics and its applications. The actuation systems of soft robots can be classified into three types: variable-length tendons, fluid actuation, and electroactive polymers (EAP) [7]. To sum up, most of the literature is about genetic algorithm-related applications. However, there are too few literatures related to the Internet of Things and soft robotics, and in-depth research on these two aspects is needed. The most important thing in the next research is to combine the application of genetic algorithm in IoT-assisted education and to apply the fusion results to soft robots.


## 3. IoT-Assisted Intelligent Education Software Robot Method Based on Improved Genetic Algorithm

### 3.1. Improved Genetic Algorithm

#### 3.1.1. Genetic Algorithm

Genetic algorithm [8, 9] was first proposed by a professor at the University of Michigan in the United States. Inspired by biological simulation technology, he proposed a probabilistic optimization technology based on evolution and genetic mechanisms—genetic algorithm. It is suitable for any kind of function without expression or with expression and has achievable parallel computing behavior; it can solve practical problems of any kind and has extensive application value. At present, the application research of genetic algorithm is very rich and has been cited by many disciplines [10]. Its research hotspot application areas are mainly concentrated in many aspects, as shown in Figure 1.Figure 1
Application areas of genetic algorithm.Genetic algorithm belongs to a class of evolutionary algorithms. It is a random search technology based on natural selection and natural genetic mechanism and is a biological heuristic random optimization method. Compared with other heuristic optimization methods, such as ant colony algorithm, artificial bee colony algorithm, particle swarm optimization algorithm, and differential evolution algorithm, genetic algorithm has many advantages, such as the flexibility in defining constraints, the ability to deal with continuous variables and discrete variables, the ability to deal with large search spaces, the ability to provide a variety of optimal solutions, and the ability to apply parallel computing techniques to reduce running time and so on. Genetic algorithms have been successfully applied to many optimization problems.


#### 3.1.2. Basic Principles of Genetic Algorithms

When the genetic algorithm is calculating, it first randomly selects a population and determines the evolution of chromosomes in the next population according to the adaptation to the environment. Through the operations of the chromosome selection operator [11], the crossover operator [12], and the mutation operator [13], individuals that are more adapted to the environment are generated, and the next generation of the population is more adapted to the environment. Through continuous iteration, the optimal solution is finally found.


#### 3.1.3. NSGA

NSGA [14, 15] is a genetic algorithm based on the concept of optimization. NSGA is the same as pure genetic algorithm in terms of selection operator, crossover operator, and mutation operator, but before executing the selection operator, it must be graded according to the superiority relationship between individuals. This is different from a pure genetic algorithm. According to the NSGA’s nondominant stratification approach, individuals are more likely to inherit in the next generation. However, the sharing strategy maintains the diversity of individual populations and prevents overbreeding of super-individuals. Flowchart of the NSGA algorithm is shown in Figure 2.Figure 2
Algorithm block diagram of NSGA.NSGA can quickly find Pareto fronts and maintain population diversity, but it still has some problems:(1)
The time complexity of NSGA is too high: because the nondominated sorting process of each generation is very complicated, the overall time complexity of the NSGA algorithm is too high. Too high time complexity will reduce the computational efficiency of the algorithm for large population size problems(2)
Lack of elite strategy: The elite strategy has great advantages in accelerating the operation of the genetic algorithm, and the elite strategy can store good individuals in layers to prevent the loss of the best individual(3)
It needs to specify shared parameters by itself: The traditional mechanism mainly relies on the sharing principle to ensure the diversity of the population, and the sharing mechanism needs to specify a sharing parameter, which is a difficulty of the mechanism


#### 3.1.4. Optimal Guidance Strategy

The best bootstrapping strategy [16] is the so-called genetic algorithm with bootstrap strategy, which achieves good results. The basic idea is very simple. In the process of genetic algorithm, if the evolutionary algebra or error meets certain conditions, the most suitable individuals will be saved, and the rest will be discarded and replaced by new random individuals [17]. The new individuals and the remaining most suitable individuals form a new group of individuals and perform corresponding evolutionary operations. In this way, it appears that a lot of useful information is lost on the surface, but in fact, because the best individuals are retained, the newly generated group not only conveys the excellent information of the previous generation group. And the new random individual introduces the new group with more new information, and the rest of the best individuals in the new evolution round will definitely take the lead in the new evolution round. At the same time, by introducing new information, the search space does expand, and the diversity of groups increases rapidly and efficiently.


### 3.2. Soft Robots

Soft robots [18, 19] are inspired by soft-bodied creatures that mimic nature. For example, invertebrate earthworms, worms, and other organs such as elephant trunks, octopus tentacles, and human hands are all imitated objects of soft robots. Traditional bionic robots are made of rigid parts, resulting in inherent defects in imitating the muscles of mollusks [20]. The soft bionic robot inherits the soft characteristics of soft biological, showing unprecedented adaptability, flexibility, and agility [21]. Robots are made of flexible materials, which have good inherent flexibility and can better simulate the motion of soft-bodied creatures through large deformation with multiple degrees of freedom and adapt to complex environments [22]. Figure 3 shows the application of the soft robot.Figure 3
Application of soft robot.At present, the research of soft robot focuses on the design, preparation, modeling, and control of the robot. In general, soft robotic systems include actuation systems, perception systems, drive electronics and computing systems. However, the modeling and control of soft robots are difficult because the intrinsic deformation of soft elastic materials is continuous, complex, and highly coupled. At present, there is no better model or planning control algorithm, and further exploration and practice are needed.


#### 3.2.1. Flexible Actuator

Soft robots can achieve their own movement through active deformation. By passively deforming to avoid obstacles and adapt to external obstacles, it has broad application prospects in the environment with narrow space and many obstacles. At the same time, soft robots have good flexibility and will not cause trauma to biological tissues and have gradually attracted the attention of medical workers. Therefore, it is necessary to study its preparation method.The preparation of pneumatic flexible actuators [23] should fully consider the influence of air cavity structure, location distribution, and wall thickness on the characteristics of flexible actuators. Due to the characteristics of the flexible material itself, the stiffness of the soft robot is not high. The introduction of the blocking system increases the stiffness of the soft robot and makes it suitable for more applications. The structure of the flexible actuator and the mold required for fabrication can be designed using 3D software. A suitable mathematical model was selected to describe the properties of the silicone material, and the 3D printing technology was used to make a mold, in which the silicone was molded, and the flexible actuator was prepared.Compared with other physical driving methods, the pneumatic driving method has the characteristics of fast response, high power density, and high bearing capacity. At the same time, due to the good flexibility of the material constituting the soft robot, the pressure is always maintained at a low level during pneumatic actuation. It not only enables the software robot to achieve the corresponding movement, but also has high security. Pneumatic-driven flexible actuators include pneumatic muscles and flexible actuators made of superelastic materials.(1)Action Principle. Pneumatic flexible actuators are usually made of superelastic materials, and a series of air cavities are usually distributed inside them. When the pressure gas is introduced into the air cavity, the air cavity expands, thereby producing movement. Therefore, it can realize the action control of the flexible actuator by controlling the gas pressure in the gas chamber. The air cavity structure, air cavity distribution, material type, and wall thickness of the flexible actuator all have an impact on the action characteristics of the flexible actuator. Therefore, the motion performance of the flexible actuator can be changed by changing the geometric characteristics and material properties of the flexible actuator.The action of the flexible actuator can also be realized by the mutual combination of different materials, as shown in Figure4. Normally, the two materials that make up the flexible actuator should have different stiffness. The material with lower stiffness is used as the deformation layer, the deformation layer contains air cavity, and the material with higher stiffness is used as the strain limiting layer.Figure 4
Action principle of sexual actuators composed of flexible materials of different materials.The motion principle of flexible actuators composed of different materials is that when pressure gas is introduced into the air cavity of the strain layer, the expansion degree of the strain layer will be greater than that of the strain confinement layer, resulting in bending. The strained layer is usually a flexible material such as Ecoflex series silica gel [24], and the material of the strain-limiting layer is usually PDMS, paper, etc.(2)Blocking the System. The blocking technique [25] is to transform a large number of particles between the fluid state and the solid state. As shown in Figure 5, if the particles are placed in a flexible capsule under normal conditions, due to the large gap between the particles, the friction between the particles is small, and the particles can flow arbitrarily. Therefore, it exhibits fluid-like behavior, in which flexible capsules encapsulating a large number of particles can produce arbitrary shape changes. When the air in the flexible bladder is expelled, a large number of particles are compressed together. At this time, due to the increase of the contact surface pressure between the particles, the friction force between the particles increases sharply. At this time, the particles cannot flow freely, so that the flexible air bag and a large number of particles show a certain stiffness as a whole and appear solid.Figure 5
Blocking technology.Particle blocking differs from traditional mechanical balancing. The coal blocks on the coal pile will reach a mechanical balance and maintain a static state without external interference, but once they are disturbed by the outside world, the coal blocks will roll down and cannot maintain the original equilibrium state. For a blocked system, the internal particles are aggregated together due to extrusion, thus exhibiting solid-state properties and reaching a stable equilibrium state. At this time, if there is disturbance in the outside world, due to the great friction between the particles, it can resist the disturbance of the outside world within a certain range and then maintain a state of equilibrium.


#### 3.2.2. FEA Actuator

FEA actuator [26] is a new type of highly scalable and adaptable, low-power soft actuator. The actuator is composed of a highly elastic shell and a nonstretchable highly flexible confinement layer, and the interior is driven by a low-pressure fluid. Once pressurized to a certain position, the drive requires little or no additional energy consumption to maintain its position. The actuator has the advantages of simple structure, low cost, and simple driving. However, due to its soft characteristics, low stiffness, and slow response, it is still complicated how to design a reasonable structure and adopt a reasonable control method to achieve a fast response.At present, the main application fields of FEA soft robots are motion robots, grippers, redundant manipulators, and exoskeletons. Because of its large deformation and theoretically infinite degrees of freedom, it can simulate the movement of organisms well. It can be used for all kinds of motion robots, such as worms, snakes, and earthworms. Because of its continuous deformation characteristics, it can adapt to the shape of the object through deformation and is used in the gripper, such as gripping claws and gripping arms. Because of the use of superelastic materials, it has soft characteristics and can change with the size of the entrance of the oral cavity and excretory cavity, reducing the invasive pain, and is used for redundant robotic arms, such as the pipeline of medical endoscopes. Because of its good passive flexibility and human-machine safety, it is used in medical exoskeletons, such as rehabilitation manipulators and power-assisted wearable devices. It can also be used in applications that do not require precise control, such as solar trackers.


### 3.3. Mechanical Modeling of the Flat Bending Actuator with Embedded SMA Wire

The mechanical model of the flat plate bending actuator embedded with SMA wire [27] is complex. In order to simplify the model, we make the following assumptions: (1) Because the topological structure of the flat curved structure embedded with double SMA wires and the flat curved structure embedded with a single SMA wire is symmetrical, therefore, in order to simplify the model, we only build a flat bending structure embedded with a single SMA wire. (2) The cross-section of the elastic substrate remains constant during the deflection of the actuator. (3) Since the mass of the SMA wire is much smaller than that of the elastic substrate, the inertial force of the SMA wire will be ignored. (4) Since the elastic substrate is very thin, the shear force of the elastic substrate is also ignored. Figure 6 is a simplified model of a flat bending actuator with a single SMA wire embedded. The model of the plate bending actuator embedded with SMA wire is established from two aspects, firstly, the mechanical modeling of the SMA linear actuator and then the establishment of the dynamic model of the elastic substrate.Figure 6
Schematic diagram of a flat bending actuator embedded with a single one-way memory effect SMA wire.


#### 3.3.1. Balance Formula of SMA Linear Actuator

Based on the balance relationship between the three-dimensional force system and the moment, the vector relationship of the force balance of the SMA linear actuator is expressed by the following formula:(1)dFxdSSMA+fx=0.In the formula,Fa represents the internal force of the SMA wire, and the direction is the tangential direction along the central axis of the SMA wire. fx represents the distribution force of the elastic substrate acting on the SMA wire, which can be decomposed into two components along the normal direction and the tangential direction of the central axis of the SMA wire. SMA represents the arc length of the central axis of the SMA wire. So Fx and fx are represented by the following two formulas:
(2)Fx=Fxt,(3)fx=fkxk+ftxt.t represents the unit vector in the tangential direction, k represents the unit vector in the normal direction, and the unit vector in the tangential direction and the unit vector in the normal direction can be defined by the following formulas:
(4)k=1n∂t∂SSMA.Substituting Formulas (2) and (3) into Formula (1), we can get
(5)dFxdSSMA+ftxt+fkxk=0.Formula (5) can be simplified to get
(6)dFxdSSMAt+FxdtdSSMA+ftxt+fkxk=0,dFxdSSMAt+nFxk+ftxt+fkxk=0,dFxdSSMA+ftxt+nFx+fkxk=0.Since botht and k are nonzero vectors, the following two formulas can be obtained from Formula (5):
(7)dFxdSSMA+ftx=0,Fx+fkx1n=0,n represents the bending curvature of the SMA wire.


#### 3.3.2. Mechanical Model of Elastic Substrate

Since the mass of the elastic substrate [28] is much larger than that of the SMA wire, the inertial force of the elastic substrate during the motion cannot be ignored. The spatial position of any cross-section of the elastic substrate in the model can be represented by the vector rS,t. Considering that the forces and moments of elastic substrates are balanced at any cross-section, the formulas of their force balance and moment balance can be expressed by the following two formulas:
(8)dFdS+f=ρ0Xrx,(9)dMdS+dAdS×F+m=ρ0Iθtt.ρ0 represents the density of the elastic substrate, A represents the cross-sectional area of the elastic substrate, F represents the resultant force vector of the elastic substrate, f represents the distribution force of the SMA wire acting on the elastic substrate, and X is the space vector of the central axis of the elastic substrate. The stable motion of any point on the central axis of the elastic substrate can be converted into a velocity vt along the tangential direction of the central axis of the substrate and a velocity vk along the normal direction. rtt represents the inertial acceleration of any cross-section on the substrate, which can be simplified into the following formula:
(10)rt=vtt+vkk.rtt=∂vt∂tt+nv2tk+∂vk∂tk−nv2kvtt.Since the velocity (t) of any cross-section of the elastic substrate is very small during the deflection process, rn can be simplified as
(11)ru=∂vk∂t∙k.Since the resultant force vectorF received by the elastic substrate and the distributed force vector of the SMA wire on the elastic substrate can be expressed as
(12)F=F1q1+F2q2+F3q3,f=f1q1+f2q2+f3q3.q1,q2,q3 represents the space unit vector, respectively. The relationship between the space unit vector and the bending curvature of the elastic substrate can be expressed by the following formula:
(13)dqidS=ξijknjqn.ξijk is the space tensor, kj is the space bending curvature of the elastic substrate, i=j=n=1,2,3,ξ123=ξ231=ξ312=1, ξ132=ξ213=ξ321=−1.So Formula (8) can be simplified to
(14)dFidS+ξijknjFn+f1=ρ0Xrtt.SincedA/dS=1+qq3, m=d×f, where d is the distance vector from f to the central axis of the elastic substrate, q is the elongation d=d1q1+d2q2, i.e., d=dxqx,x=1,2, of the central axis of the elastic substrate. So Formula (9) can be simplified to
(15)dMidS+ξijknjMn−1+qξij3Fi+ξixndxfn=ρ0Iθtt.


### 3.4. IoT Technology

The Internet of Things [19] is an intelligent network that realizes the interconnection of all things. It can connect all items wirelessly or wiredly, making it possible to form a local area network or even access the Internet, making it more convenient to exchange information with each other. The basis of the Internet of Things is communication. Currently, the more commonly used technologies are Zigbee, Bluetooth, WIFI, Ethernet, UWB, and private radio frequency in various frequency bands. These communication means can not only play the role of data exchange, but also, the device can obtain additional parameters such as signal strength and electromagnetic wave flight time from these data streams. It provides more feedback on the working status of the node.IoT positioning technology is an important technology of the Internet of Things. Throughout the application field of the Internet of Things, positioning technology is widely used in logistics and transportation, manufacturing, transportation, mines, medical care, and other industries. Many of the information collected by the IoT sensor system will be difficult to exert its due value if there is no corresponding identification of the location information.


## 3.1. Improved Genetic Algorithm

### 3.1.1. Genetic Algorithm

Genetic algorithm [8, 9] was first proposed by a professor at the University of Michigan in the United States. Inspired by biological simulation technology, he proposed a probabilistic optimization technology based on evolution and genetic mechanisms—genetic algorithm. It is suitable for any kind of function without expression or with expression and has achievable parallel computing behavior; it can solve practical problems of any kind and has extensive application value. At present, the application research of genetic algorithm is very rich and has been cited by many disciplines [10]. Its research hotspot application areas are mainly concentrated in many aspects, as shown in Figure 1.Figure 1
Application areas of genetic algorithm.Genetic algorithm belongs to a class of evolutionary algorithms. It is a random search technology based on natural selection and natural genetic mechanism and is a biological heuristic random optimization method. Compared with other heuristic optimization methods, such as ant colony algorithm, artificial bee colony algorithm, particle swarm optimization algorithm, and differential evolution algorithm, genetic algorithm has many advantages, such as the flexibility in defining constraints, the ability to deal with continuous variables and discrete variables, the ability to deal with large search spaces, the ability to provide a variety of optimal solutions, and the ability to apply parallel computing techniques to reduce running time and so on. Genetic algorithms have been successfully applied to many optimization problems.


### 3.1.2. Basic Principles of Genetic Algorithms

When the genetic algorithm is calculating, it first randomly selects a population and determines the evolution of chromosomes in the next population according to the adaptation to the environment. Through the operations of the chromosome selection operator [11], the crossover operator [12], and the mutation operator [13], individuals that are more adapted to the environment are generated, and the next generation of the population is more adapted to the environment. Through continuous iteration, the optimal solution is finally found.


### 3.1.3. NSGA

NSGA [14, 15] is a genetic algorithm based on the concept of optimization. NSGA is the same as pure genetic algorithm in terms of selection operator, crossover operator, and mutation operator, but before executing the selection operator, it must be graded according to the superiority relationship between individuals. This is different from a pure genetic algorithm. According to the NSGA’s nondominant stratification approach, individuals are more likely to inherit in the next generation. However, the sharing strategy maintains the diversity of individual populations and prevents overbreeding of super-individuals. Flowchart of the NSGA algorithm is shown in Figure 2.Figure 2
Algorithm block diagram of NSGA.NSGA can quickly find Pareto fronts and maintain population diversity, but it still has some problems:(1)
The time complexity of NSGA is too high: because the nondominated sorting process of each generation is very complicated, the overall time complexity of the NSGA algorithm is too high. Too high time complexity will reduce the computational efficiency of the algorithm for large population size problems(2)
Lack of elite strategy: The elite strategy has great advantages in accelerating the operation of the genetic algorithm, and the elite strategy can store good individuals in layers to prevent the loss of the best individual(3)
It needs to specify shared parameters by itself: The traditional mechanism mainly relies on the sharing principle to ensure the diversity of the population, and the sharing mechanism needs to specify a sharing parameter, which is a difficulty of the mechanism


### 3.1.4. Optimal Guidance Strategy

The best bootstrapping strategy [16] is the so-called genetic algorithm with bootstrap strategy, which achieves good results. The basic idea is very simple. In the process of genetic algorithm, if the evolutionary algebra or error meets certain conditions, the most suitable individuals will be saved, and the rest will be discarded and replaced by new random individuals [17]. The new individuals and the remaining most suitable individuals form a new group of individuals and perform corresponding evolutionary operations. In this way, it appears that a lot of useful information is lost on the surface, but in fact, because the best individuals are retained, the newly generated group not only conveys the excellent information of the previous generation group. And the new random individual introduces the new group with more new information, and the rest of the best individuals in the new evolution round will definitely take the lead in the new evolution round. At the same time, by introducing new information, the search space does expand, and the diversity of groups increases rapidly and efficiently.


## 3.1.1. Genetic Algorithm

Genetic algorithm [8, 9] was first proposed by a professor at the University of Michigan in the United States. Inspired by biological simulation technology, he proposed a probabilistic optimization technology based on evolution and genetic mechanisms—genetic algorithm. It is suitable for any kind of function without expression or with expression and has achievable parallel computing behavior; it can solve practical problems of any kind and has extensive application value. At present, the application research of genetic algorithm is very rich and has been cited by many disciplines [10]. Its research hotspot application areas are mainly concentrated in many aspects, as shown in Figure 1.Figure 1
Application areas of genetic algorithm.Genetic algorithm belongs to a class of evolutionary algorithms. It is a random search technology based on natural selection and natural genetic mechanism and is a biological heuristic random optimization method. Compared with other heuristic optimization methods, such as ant colony algorithm, artificial bee colony algorithm, particle swarm optimization algorithm, and differential evolution algorithm, genetic algorithm has many advantages, such as the flexibility in defining constraints, the ability to deal with continuous variables and discrete variables, the ability to deal with large search spaces, the ability to provide a variety of optimal solutions, and the ability to apply parallel computing techniques to reduce running time and so on. Genetic algorithms have been successfully applied to many optimization problems.


## 3.1.2. Basic Principles of Genetic Algorithms

When the genetic algorithm is calculating, it first randomly selects a population and determines the evolution of chromosomes in the next population according to the adaptation to the environment. Through the operations of the chromosome selection operator [11], the crossover operator [12], and the mutation operator [13], individuals that are more adapted to the environment are generated, and the next generation of the population is more adapted to the environment. Through continuous iteration, the optimal solution is finally found.


## 3.1.3. NSGA

NSGA [14, 15] is a genetic algorithm based on the concept of optimization. NSGA is the same as pure genetic algorithm in terms of selection operator, crossover operator, and mutation operator, but before executing the selection operator, it must be graded according to the superiority relationship between individuals. This is different from a pure genetic algorithm. According to the NSGA’s nondominant stratification approach, individuals are more likely to inherit in the next generation. However, the sharing strategy maintains the diversity of individual populations and prevents overbreeding of super-individuals. Flowchart of the NSGA algorithm is shown in Figure 2.Figure 2
Algorithm block diagram of NSGA.NSGA can quickly find Pareto fronts and maintain population diversity, but it still has some problems:(1)
The time complexity of NSGA is too high: because the nondominated sorting process of each generation is very complicated, the overall time complexity of the NSGA algorithm is too high. Too high time complexity will reduce the computational efficiency of the algorithm for large population size problems(2)
Lack of elite strategy: The elite strategy has great advantages in accelerating the operation of the genetic algorithm, and the elite strategy can store good individuals in layers to prevent the loss of the best individual(3)
It needs to specify shared parameters by itself: The traditional mechanism mainly relies on the sharing principle to ensure the diversity of the population, and the sharing mechanism needs to specify a sharing parameter, which is a difficulty of the mechanism


## 3.1.4. Optimal Guidance Strategy

The best bootstrapping strategy [16] is the so-called genetic algorithm with bootstrap strategy, which achieves good results. The basic idea is very simple. In the process of genetic algorithm, if the evolutionary algebra or error meets certain conditions, the most suitable individuals will be saved, and the rest will be discarded and replaced by new random individuals [17]. The new individuals and the remaining most suitable individuals form a new group of individuals and perform corresponding evolutionary operations. In this way, it appears that a lot of useful information is lost on the surface, but in fact, because the best individuals are retained, the newly generated group not only conveys the excellent information of the previous generation group. And the new random individual introduces the new group with more new information, and the rest of the best individuals in the new evolution round will definitely take the lead in the new evolution round. At the same time, by introducing new information, the search space does expand, and the diversity of groups increases rapidly and efficiently.


## 3.2. Soft Robots

Soft robots [18, 19] are inspired by soft-bodied creatures that mimic nature. For example, invertebrate earthworms, worms, and other organs such as elephant trunks, octopus tentacles, and human hands are all imitated objects of soft robots. Traditional bionic robots are made of rigid parts, resulting in inherent defects in imitating the muscles of mollusks [20]. The soft bionic robot inherits the soft characteristics of soft biological, showing unprecedented adaptability, flexibility, and agility [21]. Robots are made of flexible materials, which have good inherent flexibility and can better simulate the motion of soft-bodied creatures through large deformation with multiple degrees of freedom and adapt to complex environments [22]. Figure 3 shows the application of the soft robot.Figure 3
Application of soft robot.At present, the research of soft robot focuses on the design, preparation, modeling, and control of the robot. In general, soft robotic systems include actuation systems, perception systems, drive electronics and computing systems. However, the modeling and control of soft robots are difficult because the intrinsic deformation of soft elastic materials is continuous, complex, and highly coupled. At present, there is no better model or planning control algorithm, and further exploration and practice are needed.


### 3.2.1. Flexible Actuator

Soft robots can achieve their own movement through active deformation. By passively deforming to avoid obstacles and adapt to external obstacles, it has broad application prospects in the environment with narrow space and many obstacles. At the same time, soft robots have good flexibility and will not cause trauma to biological tissues and have gradually attracted the attention of medical workers. Therefore, it is necessary to study its preparation method.The preparation of pneumatic flexible actuators [23] should fully consider the influence of air cavity structure, location distribution, and wall thickness on the characteristics of flexible actuators. Due to the characteristics of the flexible material itself, the stiffness of the soft robot is not high. The introduction of the blocking system increases the stiffness of the soft robot and makes it suitable for more applications. The structure of the flexible actuator and the mold required for fabrication can be designed using 3D software. A suitable mathematical model was selected to describe the properties of the silicone material, and the 3D printing technology was used to make a mold, in which the silicone was molded, and the flexible actuator was prepared.Compared with other physical driving methods, the pneumatic driving method has the characteristics of fast response, high power density, and high bearing capacity. At the same time, due to the good flexibility of the material constituting the soft robot, the pressure is always maintained at a low level during pneumatic actuation. It not only enables the software robot to achieve the corresponding movement, but also has high security. Pneumatic-driven flexible actuators include pneumatic muscles and flexible actuators made of superelastic materials.(1)Action Principle. Pneumatic flexible actuators are usually made of superelastic materials, and a series of air cavities are usually distributed inside them. When the pressure gas is introduced into the air cavity, the air cavity expands, thereby producing movement. Therefore, it can realize the action control of the flexible actuator by controlling the gas pressure in the gas chamber. The air cavity structure, air cavity distribution, material type, and wall thickness of the flexible actuator all have an impact on the action characteristics of the flexible actuator. Therefore, the motion performance of the flexible actuator can be changed by changing the geometric characteristics and material properties of the flexible actuator.The action of the flexible actuator can also be realized by the mutual combination of different materials, as shown in Figure4. Normally, the two materials that make up the flexible actuator should have different stiffness. The material with lower stiffness is used as the deformation layer, the deformation layer contains air cavity, and the material with higher stiffness is used as the strain limiting layer.Figure 4
Action principle of sexual actuators composed of flexible materials of different materials.The motion principle of flexible actuators composed of different materials is that when pressure gas is introduced into the air cavity of the strain layer, the expansion degree of the strain layer will be greater than that of the strain confinement layer, resulting in bending. The strained layer is usually a flexible material such as Ecoflex series silica gel [24], and the material of the strain-limiting layer is usually PDMS, paper, etc.(2)Blocking the System. The blocking technique [25] is to transform a large number of particles between the fluid state and the solid state. As shown in Figure 5, if the particles are placed in a flexible capsule under normal conditions, due to the large gap between the particles, the friction between the particles is small, and the particles can flow arbitrarily. Therefore, it exhibits fluid-like behavior, in which flexible capsules encapsulating a large number of particles can produce arbitrary shape changes. When the air in the flexible bladder is expelled, a large number of particles are compressed together. At this time, due to the increase of the contact surface pressure between the particles, the friction force between the particles increases sharply. At this time, the particles cannot flow freely, so that the flexible air bag and a large number of particles show a certain stiffness as a whole and appear solid.Figure 5
Blocking technology.Particle blocking differs from traditional mechanical balancing. The coal blocks on the coal pile will reach a mechanical balance and maintain a static state without external interference, but once they are disturbed by the outside world, the coal blocks will roll down and cannot maintain the original equilibrium state. For a blocked system, the internal particles are aggregated together due to extrusion, thus exhibiting solid-state properties and reaching a stable equilibrium state. At this time, if there is disturbance in the outside world, due to the great friction between the particles, it can resist the disturbance of the outside world within a certain range and then maintain a state of equilibrium.


### 3.2.2. FEA Actuator

FEA actuator [26] is a new type of highly scalable and adaptable, low-power soft actuator. The actuator is composed of a highly elastic shell and a nonstretchable highly flexible confinement layer, and the interior is driven by a low-pressure fluid. Once pressurized to a certain position, the drive requires little or no additional energy consumption to maintain its position. The actuator has the advantages of simple structure, low cost, and simple driving. However, due to its soft characteristics, low stiffness, and slow response, it is still complicated how to design a reasonable structure and adopt a reasonable control method to achieve a fast response.At present, the main application fields of FEA soft robots are motion robots, grippers, redundant manipulators, and exoskeletons. Because of its large deformation and theoretically infinite degrees of freedom, it can simulate the movement of organisms well. It can be used for all kinds of motion robots, such as worms, snakes, and earthworms. Because of its continuous deformation characteristics, it can adapt to the shape of the object through deformation and is used in the gripper, such as gripping claws and gripping arms. Because of the use of superelastic materials, it has soft characteristics and can change with the size of the entrance of the oral cavity and excretory cavity, reducing the invasive pain, and is used for redundant robotic arms, such as the pipeline of medical endoscopes. Because of its good passive flexibility and human-machine safety, it is used in medical exoskeletons, such as rehabilitation manipulators and power-assisted wearable devices. It can also be used in applications that do not require precise control, such as solar trackers.


## 3.2.1. Flexible Actuator

Soft robots can achieve their own movement through active deformation. By passively deforming to avoid obstacles and adapt to external obstacles, it has broad application prospects in the environment with narrow space and many obstacles. At the same time, soft robots have good flexibility and will not cause trauma to biological tissues and have gradually attracted the attention of medical workers. Therefore, it is necessary to study its preparation method.The preparation of pneumatic flexible actuators [23] should fully consider the influence of air cavity structure, location distribution, and wall thickness on the characteristics of flexible actuators. Due to the characteristics of the flexible material itself, the stiffness of the soft robot is not high. The introduction of the blocking system increases the stiffness of the soft robot and makes it suitable for more applications. The structure of the flexible actuator and the mold required for fabrication can be designed using 3D software. A suitable mathematical model was selected to describe the properties of the silicone material, and the 3D printing technology was used to make a mold, in which the silicone was molded, and the flexible actuator was prepared.Compared with other physical driving methods, the pneumatic driving method has the characteristics of fast response, high power density, and high bearing capacity. At the same time, due to the good flexibility of the material constituting the soft robot, the pressure is always maintained at a low level during pneumatic actuation. It not only enables the software robot to achieve the corresponding movement, but also has high security. Pneumatic-driven flexible actuators include pneumatic muscles and flexible actuators made of superelastic materials.(1)Action Principle. Pneumatic flexible actuators are usually made of superelastic materials, and a series of air cavities are usually distributed inside them. When the pressure gas is introduced into the air cavity, the air cavity expands, thereby producing movement. Therefore, it can realize the action control of the flexible actuator by controlling the gas pressure in the gas chamber. The air cavity structure, air cavity distribution, material type, and wall thickness of the flexible actuator all have an impact on the action characteristics of the flexible actuator. Therefore, the motion performance of the flexible actuator can be changed by changing the geometric characteristics and material properties of the flexible actuator.The action of the flexible actuator can also be realized by the mutual combination of different materials, as shown in Figure4. Normally, the two materials that make up the flexible actuator should have different stiffness. The material with lower stiffness is used as the deformation layer, the deformation layer contains air cavity, and the material with higher stiffness is used as the strain limiting layer.Figure 4
Action principle of sexual actuators composed of flexible materials of different materials.The motion principle of flexible actuators composed of different materials is that when pressure gas is introduced into the air cavity of the strain layer, the expansion degree of the strain layer will be greater than that of the strain confinement layer, resulting in bending. The strained layer is usually a flexible material such as Ecoflex series silica gel [24], and the material of the strain-limiting layer is usually PDMS, paper, etc.(2)Blocking the System. The blocking technique [25] is to transform a large number of particles between the fluid state and the solid state. As shown in Figure 5, if the particles are placed in a flexible capsule under normal conditions, due to the large gap between the particles, the friction between the particles is small, and the particles can flow arbitrarily. Therefore, it exhibits fluid-like behavior, in which flexible capsules encapsulating a large number of particles can produce arbitrary shape changes. When the air in the flexible bladder is expelled, a large number of particles are compressed together. At this time, due to the increase of the contact surface pressure between the particles, the friction force between the particles increases sharply. At this time, the particles cannot flow freely, so that the flexible air bag and a large number of particles show a certain stiffness as a whole and appear solid.Figure 5
Blocking technology.Particle blocking differs from traditional mechanical balancing. The coal blocks on the coal pile will reach a mechanical balance and maintain a static state without external interference, but once they are disturbed by the outside world, the coal blocks will roll down and cannot maintain the original equilibrium state. For a blocked system, the internal particles are aggregated together due to extrusion, thus exhibiting solid-state properties and reaching a stable equilibrium state. At this time, if there is disturbance in the outside world, due to the great friction between the particles, it can resist the disturbance of the outside world within a certain range and then maintain a state of equilibrium.


## 3.2.2. FEA Actuator

FEA actuator [26] is a new type of highly scalable and adaptable, low-power soft actuator. The actuator is composed of a highly elastic shell and a nonstretchable highly flexible confinement layer, and the interior is driven by a low-pressure fluid. Once pressurized to a certain position, the drive requires little or no additional energy consumption to maintain its position. The actuator has the advantages of simple structure, low cost, and simple driving. However, due to its soft characteristics, low stiffness, and slow response, it is still complicated how to design a reasonable structure and adopt a reasonable control method to achieve a fast response.At present, the main application fields of FEA soft robots are motion robots, grippers, redundant manipulators, and exoskeletons. Because of its large deformation and theoretically infinite degrees of freedom, it can simulate the movement of organisms well. It can be used for all kinds of motion robots, such as worms, snakes, and earthworms. Because of its continuous deformation characteristics, it can adapt to the shape of the object through deformation and is used in the gripper, such as gripping claws and gripping arms. Because of the use of superelastic materials, it has soft characteristics and can change with the size of the entrance of the oral cavity and excretory cavity, reducing the invasive pain, and is used for redundant robotic arms, such as the pipeline of medical endoscopes. Because of its good passive flexibility and human-machine safety, it is used in medical exoskeletons, such as rehabilitation manipulators and power-assisted wearable devices. It can also be used in applications that do not require precise control, such as solar trackers.


## 3.3. Mechanical Modeling of the Flat Bending Actuator with Embedded SMA Wire

The mechanical model of the flat plate bending actuator embedded with SMA wire [27] is complex. In order to simplify the model, we make the following assumptions: (1) Because the topological structure of the flat curved structure embedded with double SMA wires and the flat curved structure embedded with a single SMA wire is symmetrical, therefore, in order to simplify the model, we only build a flat bending structure embedded with a single SMA wire. (2) The cross-section of the elastic substrate remains constant during the deflection of the actuator. (3) Since the mass of the SMA wire is much smaller than that of the elastic substrate, the inertial force of the SMA wire will be ignored. (4) Since the elastic substrate is very thin, the shear force of the elastic substrate is also ignored. Figure 6 is a simplified model of a flat bending actuator with a single SMA wire embedded. The model of the plate bending actuator embedded with SMA wire is established from two aspects, firstly, the mechanical modeling of the SMA linear actuator and then the establishment of the dynamic model of the elastic substrate.Figure 6
Schematic diagram of a flat bending actuator embedded with a single one-way memory effect SMA wire.


### 3.3.1. Balance Formula of SMA Linear Actuator

Based on the balance relationship between the three-dimensional force system and the moment, the vector relationship of the force balance of the SMA linear actuator is expressed by the following formula:(1)dFxdSSMA+fx=0.In the formula,Fa represents the internal force of the SMA wire, and the direction is the tangential direction along the central axis of the SMA wire. fx represents the distribution force of the elastic substrate acting on the SMA wire, which can be decomposed into two components along the normal direction and the tangential direction of the central axis of the SMA wire. SMA represents the arc length of the central axis of the SMA wire. So Fx and fx are represented by the following two formulas:
(2)Fx=Fxt,(3)fx=fkxk+ftxt.t represents the unit vector in the tangential direction, k represents the unit vector in the normal direction, and the unit vector in the tangential direction and the unit vector in the normal direction can be defined by the following formulas:
(4)k=1n∂t∂SSMA.Substituting Formulas (2) and (3) into Formula (1), we can get
(5)dFxdSSMA+ftxt+fkxk=0.Formula (5) can be simplified to get
(6)dFxdSSMAt+FxdtdSSMA+ftxt+fkxk=0,dFxdSSMAt+nFxk+ftxt+fkxk=0,dFxdSSMA+ftxt+nFx+fkxk=0.Since botht and k are nonzero vectors, the following two formulas can be obtained from Formula (5):
(7)dFxdSSMA+ftx=0,Fx+fkx1n=0,n represents the bending curvature of the SMA wire.


### 3.3.2. Mechanical Model of Elastic Substrate

Since the mass of the elastic substrate [28] is much larger than that of the SMA wire, the inertial force of the elastic substrate during the motion cannot be ignored. The spatial position of any cross-section of the elastic substrate in the model can be represented by the vector rS,t. Considering that the forces and moments of elastic substrates are balanced at any cross-section, the formulas of their force balance and moment balance can be expressed by the following two formulas:
(8)dFdS+f=ρ0Xrx,(9)dMdS+dAdS×F+m=ρ0Iθtt.ρ0 represents the density of the elastic substrate, A represents the cross-sectional area of the elastic substrate, F represents the resultant force vector of the elastic substrate, f represents the distribution force of the SMA wire acting on the elastic substrate, and X is the space vector of the central axis of the elastic substrate. The stable motion of any point on the central axis of the elastic substrate can be converted into a velocity vt along the tangential direction of the central axis of the substrate and a velocity vk along the normal direction. rtt represents the inertial acceleration of any cross-section on the substrate, which can be simplified into the following formula:
(10)rt=vtt+vkk.rtt=∂vt∂tt+nv2tk+∂vk∂tk−nv2kvtt.Since the velocity (t) of any cross-section of the elastic substrate is very small during the deflection process, rn can be simplified as
(11)ru=∂vk∂t∙k.Since the resultant force vectorF received by the elastic substrate and the distributed force vector of the SMA wire on the elastic substrate can be expressed as
(12)F=F1q1+F2q2+F3q3,f=f1q1+f2q2+f3q3.q1,q2,q3 represents the space unit vector, respectively. The relationship between the space unit vector and the bending curvature of the elastic substrate can be expressed by the following formula:
(13)dqidS=ξijknjqn.ξijk is the space tensor, kj is the space bending curvature of the elastic substrate, i=j=n=1,2,3,ξ123=ξ231=ξ312=1, ξ132=ξ213=ξ321=−1.So Formula (8) can be simplified to
(14)dFidS+ξijknjFn+f1=ρ0Xrtt.SincedA/dS=1+qq3, m=d×f, where d is the distance vector from f to the central axis of the elastic substrate, q is the elongation d=d1q1+d2q2, i.e., d=dxqx,x=1,2, of the central axis of the elastic substrate. So Formula (9) can be simplified to
(15)dMidS+ξijknjMn−1+qξij3Fi+ξixndxfn=ρ0Iθtt.


## 3.3.1. Balance Formula of SMA Linear Actuator

Based on the balance relationship between the three-dimensional force system and the moment, the vector relationship of the force balance of the SMA linear actuator is expressed by the following formula:(1)dFxdSSMA+fx=0.In the formula,Fa represents the internal force of the SMA wire, and the direction is the tangential direction along the central axis of the SMA wire. fx represents the distribution force of the elastic substrate acting on the SMA wire, which can be decomposed into two components along the normal direction and the tangential direction of the central axis of the SMA wire. SMA represents the arc length of the central axis of the SMA wire. So Fx and fx are represented by the following two formulas:
(2)Fx=Fxt,(3)fx=fkxk+ftxt.t represents the unit vector in the tangential direction, k represents the unit vector in the normal direction, and the unit vector in the tangential direction and the unit vector in the normal direction can be defined by the following formulas:
(4)k=1n∂t∂SSMA.Substituting Formulas (2) and (3) into Formula (1), we can get
(5)dFxdSSMA+ftxt+fkxk=0.Formula (5) can be simplified to get
(6)dFxdSSMAt+FxdtdSSMA+ftxt+fkxk=0,dFxdSSMAt+nFxk+ftxt+fkxk=0,dFxdSSMA+ftxt+nFx+fkxk=0.Since botht and k are nonzero vectors, the following two formulas can be obtained from Formula (5):
(7)dFxdSSMA+ftx=0,Fx+fkx1n=0,n represents the bending curvature of the SMA wire.


## 3.3.2. Mechanical Model of Elastic Substrate

Since the mass of the elastic substrate [28] is much larger than that of the SMA wire, the inertial force of the elastic substrate during the motion cannot be ignored. The spatial position of any cross-section of the elastic substrate in the model can be represented by the vector rS,t. Considering that the forces and moments of elastic substrates are balanced at any cross-section, the formulas of their force balance and moment balance can be expressed by the following two formulas:
(8)dFdS+f=ρ0Xrx,(9)dMdS+dAdS×F+m=ρ0Iθtt.ρ0 represents the density of the elastic substrate, A represents the cross-sectional area of the elastic substrate, F represents the resultant force vector of the elastic substrate, f represents the distribution force of the SMA wire acting on the elastic substrate, and X is the space vector of the central axis of the elastic substrate. The stable motion of any point on the central axis of the elastic substrate can be converted into a velocity vt along the tangential direction of the central axis of the substrate and a velocity vk along the normal direction. rtt represents the inertial acceleration of any cross-section on the substrate, which can be simplified into the following formula:
(10)rt=vtt+vkk.rtt=∂vt∂tt+nv2tk+∂vk∂tk−nv2kvtt.Since the velocity (t) of any cross-section of the elastic substrate is very small during the deflection process, rn can be simplified as
(11)ru=∂vk∂t∙k.Since the resultant force vectorF received by the elastic substrate and the distributed force vector of the SMA wire on the elastic substrate can be expressed as
(12)F=F1q1+F2q2+F3q3,f=f1q1+f2q2+f3q3.q1,q2,q3 represents the space unit vector, respectively. The relationship between the space unit vector and the bending curvature of the elastic substrate can be expressed by the following formula:
(13)dqidS=ξijknjqn.ξijk is the space tensor, kj is the space bending curvature of the elastic substrate, i=j=n=1,2,3,ξ123=ξ231=ξ312=1, ξ132=ξ213=ξ321=−1.So Formula (8) can be simplified to
(14)dFidS+ξijknjFn+f1=ρ0Xrtt.SincedA/dS=1+qq3, m=d×f, where d is the distance vector from f to the central axis of the elastic substrate, q is the elongation d=d1q1+d2q2, i.e., d=dxqx,x=1,2, of the central axis of the elastic substrate. So Formula (9) can be simplified to
(15)dMidS+ξijknjMn−1+qξij3Fi+ξixndxfn=ρ0Iθtt.


## 3.4. IoT Technology

The Internet of Things [19] is an intelligent network that realizes the interconnection of all things. It can connect all items wirelessly or wiredly, making it possible to form a local area network or even access the Internet, making it more convenient to exchange information with each other. The basis of the Internet of Things is communication. Currently, the more commonly used technologies are Zigbee, Bluetooth, WIFI, Ethernet, UWB, and private radio frequency in various frequency bands. These communication means can not only play the role of data exchange, but also, the device can obtain additional parameters such as signal strength and electromagnetic wave flight time from these data streams. It provides more feedback on the working status of the node.IoT positioning technology is an important technology of the Internet of Things. Throughout the application field of the Internet of Things, positioning technology is widely used in logistics and transportation, manufacturing, transportation, mines, medical care, and other industries. Many of the information collected by the IoT sensor system will be difficult to exert its due value if there is no corresponding identification of the location information.


## 4. Performance Test Experiment of IoT-Assisted Intelligent Education Software Robot Based on Improved Genetic Algorithm

### 4.1. Genetic Algorithm Simulation Test Experiment

Five typical test functions in MATLAB are selected to test the three algorithms of SAG, AGA, and MPAGA. The advantages and disadvantages of each algorithm can be visually analyzed from the test results. This subsection excludes simulation errors due to individual special cases by changing the population size, the maximum number of genetic iterations, and increasing the number of simulations of the test function. In the process of testing the function to find the optimal solution, the optimal solution searched, that is, the function value when the algorithm reaches convergence, is given a range error of 0.6%. When the searched solution is within this range, the algorithm is considered to be convergent. The test function is simulated for 100 times, and the results are compared and analyzed. The experimental results are shown in Tables1–6.Table 1
Experimental results of convergence times with a population size of 40.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA1251001001002502313763504546874500038550302383Table 2
Experimental results of average convergence algebra with a population size of 40.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA125544250353823350323321450——45550373918Table 3
Experimental results of convergence times when the population size is 100.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA12510010010021006154903100636592410054715100343289Table 4
Experimental results of average convergence algebra with a population size of 100.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA12542732100262321310021691341009232415100322716Table 5
Experimental results of convergence times with a population size of 200.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA12510010010022007466973200636510042001230835200584991Table 6
Experimental results of average convergence algebra with population size of 200.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA1253222200202321320018211342008745405200262513The average number of iterations in the table is used to represent the average of the number of iterations that the optimization algorithm achieves the optimal value within a given number of iterations. In order to prevent the situation that the global optimum cannot be found due to too few genetic iterations, the iteration of the multivariate multipeak function is increased to 100, and the population size is 100.It can be seen from the table that for the simple test function of one variable, the three algorithms can converge quickly, and the convergence probability reaches 100%. But for complex multivariate functions, it exhibits different characteristics. When the population size is 40, due to the limited number of iterations (50), AGA and SGA converge less times, and even for test function 4, the convergence times are zero. For test functions 2 and 5, the SGA algorithm has more convergence times than the AGA algorithm, but the average convergence algebra is earlier. When the population size is 100, the number of genetic iterations increases to 100, the convergence probability of the three algorithms is improved, the average convergence algebra is also reduced, and the probability of MPAGA algorithm is increased by 6% to 33%. When the population size is 200, for test functions 2, 3, and 5, the convergence probability of MPAGA algorithm is close to the limit. Therefore, there is no significant improvement, and the convergence probability for test function 4 is increased by about 12%.From the data comparison, it can be seen that the iterative convergence times of MPAGA, AGA, and SGA proposed in this paper all increase significantly with the increase of population size, and the average convergence algebra also shows a decreasing trend.In order to show the differences between SGA, AGA, and MPAGA more clearly, when the population size is 100, the data of 100 experiments for each test function are drawn as Figure7.Figure 7
Convergence probability and average number of iterations under three algorithms.
(a)
Convergence probability(b)
Average convergence iterationsFrom the graph, it can be clearly seen that MPAGA has more convergence times than SGA and AGA in 100 trials, and the cut-off algebra to search for the optimal solution is earlier.


### 4.2. Simulation Experiment of Rolling Motion of Bionic Software Robot

The rolling motion is to analyze the characteristics of the rolling motion of the soft robot through the visual simulation interface of ADAMS. Since the soft robot only rolls on a two-dimensional plane, the motion direction of the soft robot is not changed during the movement process, so only the horizontal and vertical motions of the center of mass of the soft robot are considered. Figure8 is a simulation timing diagram of a group of soft robot rolling motions. The initial state of the soft robot remains stable, and when the spring force generates the driving force, the body of the soft robot begins to deform. It rolls forward under the force of gravity. When the rolling speed of the robot reaches the maximum value, the spring force of the former group is rapidly reduced to zero, and the spring force of the latter group immediately generates a driving force, which makes the soft robot generate a continuous rolling motion forward. It can be seen from the simulation sequence diagram that a single group of spring force cannot cause the robot to roll continuously, and the soft robot must realize the rolling of the soft robot through the alternating application of each group of spring force. By adjusting the application time of the spring force, the rolling motion of the soft robot can reach the optimal value. The displacement and velocity of its center of mass on the x- and y-axes are shown in Figure 9.Figure 8
Simulation sequence diagram of rolling motion of soft robot.Figure 9
Rolling motion results of the soft robot.
(a)
Movement displacement and velocity of the center of mass of the soft robot in thex-axis direction(b)
Movement displacement and velocity of the center of mass of the soft robot in they-axis directionIn order to better analyze the rolling motion characteristics of the soft robot when it deforms, a single set of spring force is applied to the soft robot to analyze the motion characteristics. In the motion simulation, thex-axis direction is the forward direction of the rolling motion of the soft robot, and the y-axis is the motion direction of the center of mass of the soft robot perpendicular to the x-axis. In the graph of the movement displacement and velocity of the center of mass of the soft robot in the x-axis direction, the red curve represents the movement displacement. It can be seen that the motion displacement of the robot reaches the maximum value at 1.3 s and then gradually decreases. By differentiating the motion displacement, the motion velocity of the center of mass of the soft robot in the x-axis direction is obtained, which is represented by the blue curve in the figure. The speed of the soft robot is not constant during the rolling process; the speed of the robot reaches the maximum value at 0.9 s and then gradually decreases to zero at 1.3 s. Then the soft robot starts to decrease, and its speed reaches the maximum at 1.75 s. It can be seen that the application time of the next set of spring force should be 1.3 s, so that the rolling motion speed of the soft robot can be kept at the maximum value. The motion of the soft robot is the driving force generated by the change of the center of mass and the use of gravity to do work. Therefore, it is necessary to study the change of the center of mass of the soft robot in the direction of gravity through simulation. In the graph of the movement displacement and velocity of the center of mass of the soft robot in the y-axis direction and the direction of gravity, it can be seen that the movement displacement and velocity of the center of mass of the soft robot in the y-axis direction are relatively small. But the fluctuations are very large. This is mainly because the soft-body robot adopts a pseudo-rigid body model, and the change of its outer contour is not continuous and smooth, which makes its motion have more burrs. At 0.9 s, the displacement of the center of mass in the y-axis direction reaches the maximum value, while the velocity is zero. At 1.3 s, the displacement and velocity of the center of mass in the y-axis direction are both zero. At this time, if the next set of springs does not generate a driving force, the robot will roll back. Therefore, the application time of the next set of spring force cannot exceed 1.3 s at the latest; otherwise, the robot cannot produce continuous rolling.


## 4.1. Genetic Algorithm Simulation Test Experiment

Five typical test functions in MATLAB are selected to test the three algorithms of SAG, AGA, and MPAGA. The advantages and disadvantages of each algorithm can be visually analyzed from the test results. This subsection excludes simulation errors due to individual special cases by changing the population size, the maximum number of genetic iterations, and increasing the number of simulations of the test function. In the process of testing the function to find the optimal solution, the optimal solution searched, that is, the function value when the algorithm reaches convergence, is given a range error of 0.6%. When the searched solution is within this range, the algorithm is considered to be convergent. The test function is simulated for 100 times, and the results are compared and analyzed. The experimental results are shown in Tables1–6.Table 1
Experimental results of convergence times with a population size of 40.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA1251001001002502313763504546874500038550302383Table 2
Experimental results of average convergence algebra with a population size of 40.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA125544250353823350323321450——45550373918Table 3
Experimental results of convergence times when the population size is 100.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA12510010010021006154903100636592410054715100343289Table 4
Experimental results of average convergence algebra with a population size of 100.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA12542732100262321310021691341009232415100322716Table 5
Experimental results of convergence times with a population size of 200.
Test functionNumber of iterationsConvergence timesSGAAGAMPAGA12510010010022007466973200636510042001230835200584991Table 6
Experimental results of average convergence algebra with population size of 200.
Test functionNumber of iterationsMean convergence algebraSGAAGAMPAGA1253222200202321320018211342008745405200262513The average number of iterations in the table is used to represent the average of the number of iterations that the optimization algorithm achieves the optimal value within a given number of iterations. In order to prevent the situation that the global optimum cannot be found due to too few genetic iterations, the iteration of the multivariate multipeak function is increased to 100, and the population size is 100.It can be seen from the table that for the simple test function of one variable, the three algorithms can converge quickly, and the convergence probability reaches 100%. But for complex multivariate functions, it exhibits different characteristics. When the population size is 40, due to the limited number of iterations (50), AGA and SGA converge less times, and even for test function 4, the convergence times are zero. For test functions 2 and 5, the SGA algorithm has more convergence times than the AGA algorithm, but the average convergence algebra is earlier. When the population size is 100, the number of genetic iterations increases to 100, the convergence probability of the three algorithms is improved, the average convergence algebra is also reduced, and the probability of MPAGA algorithm is increased by 6% to 33%. When the population size is 200, for test functions 2, 3, and 5, the convergence probability of MPAGA algorithm is close to the limit. Therefore, there is no significant improvement, and the convergence probability for test function 4 is increased by about 12%.From the data comparison, it can be seen that the iterative convergence times of MPAGA, AGA, and SGA proposed in this paper all increase significantly with the increase of population size, and the average convergence algebra also shows a decreasing trend.In order to show the differences between SGA, AGA, and MPAGA more clearly, when the population size is 100, the data of 100 experiments for each test function are drawn as Figure7.Figure 7
Convergence probability and average number of iterations under three algorithms.
(a)
Convergence probability(b)
Average convergence iterationsFrom the graph, it can be clearly seen that MPAGA has more convergence times than SGA and AGA in 100 trials, and the cut-off algebra to search for the optimal solution is earlier.


## 4.2. Simulation Experiment of Rolling Motion of Bionic Software Robot

The rolling motion is to analyze the characteristics of the rolling motion of the soft robot through the visual simulation interface of ADAMS. Since the soft robot only rolls on a two-dimensional plane, the motion direction of the soft robot is not changed during the movement process, so only the horizontal and vertical motions of the center of mass of the soft robot are considered. Figure8 is a simulation timing diagram of a group of soft robot rolling motions. The initial state of the soft robot remains stable, and when the spring force generates the driving force, the body of the soft robot begins to deform. It rolls forward under the force of gravity. When the rolling speed of the robot reaches the maximum value, the spring force of the former group is rapidly reduced to zero, and the spring force of the latter group immediately generates a driving force, which makes the soft robot generate a continuous rolling motion forward. It can be seen from the simulation sequence diagram that a single group of spring force cannot cause the robot to roll continuously, and the soft robot must realize the rolling of the soft robot through the alternating application of each group of spring force. By adjusting the application time of the spring force, the rolling motion of the soft robot can reach the optimal value. The displacement and velocity of its center of mass on the x- and y-axes are shown in Figure 9.Figure 8
Simulation sequence diagram of rolling motion of soft robot.Figure 9
Rolling motion results of the soft robot.
(a)
Movement displacement and velocity of the center of mass of the soft robot in thex-axis direction(b)
Movement displacement and velocity of the center of mass of the soft robot in they-axis directionIn order to better analyze the rolling motion characteristics of the soft robot when it deforms, a single set of spring force is applied to the soft robot to analyze the motion characteristics. In the motion simulation, thex-axis direction is the forward direction of the rolling motion of the soft robot, and the y-axis is the motion direction of the center of mass of the soft robot perpendicular to the x-axis. In the graph of the movement displacement and velocity of the center of mass of the soft robot in the x-axis direction, the red curve represents the movement displacement. It can be seen that the motion displacement of the robot reaches the maximum value at 1.3 s and then gradually decreases. By differentiating the motion displacement, the motion velocity of the center of mass of the soft robot in the x-axis direction is obtained, which is represented by the blue curve in the figure. The speed of the soft robot is not constant during the rolling process; the speed of the robot reaches the maximum value at 0.9 s and then gradually decreases to zero at 1.3 s. Then the soft robot starts to decrease, and its speed reaches the maximum at 1.75 s. It can be seen that the application time of the next set of spring force should be 1.3 s, so that the rolling motion speed of the soft robot can be kept at the maximum value. The motion of the soft robot is the driving force generated by the change of the center of mass and the use of gravity to do work. Therefore, it is necessary to study the change of the center of mass of the soft robot in the direction of gravity through simulation. In the graph of the movement displacement and velocity of the center of mass of the soft robot in the y-axis direction and the direction of gravity, it can be seen that the movement displacement and velocity of the center of mass of the soft robot in the y-axis direction are relatively small. But the fluctuations are very large. This is mainly because the soft-body robot adopts a pseudo-rigid body model, and the change of its outer contour is not continuous and smooth, which makes its motion have more burrs. At 0.9 s, the displacement of the center of mass in the y-axis direction reaches the maximum value, while the velocity is zero. At 1.3 s, the displacement and velocity of the center of mass in the y-axis direction are both zero. At this time, if the next set of springs does not generate a driving force, the robot will roll back. Therefore, the application time of the next set of spring force cannot exceed 1.3 s at the latest; otherwise, the robot cannot produce continuous rolling.


## 5. Experiment Analysis of IoT-Assisted Intelligent Education Software Robot Based on Improved Genetic Algorithm

### 5.1. Experimental Analysis of Inflating and Exhausting of the Base Section of the Soft Robot

In the case of no external load, the basal section and the tail section were, respectively, carried out four times of inflatable experiments and exhaust experiments to measure the relationship between L and P. The experimental data of charging and exhausting of the base section are shown in Figure10.Figure 10
Experimental results.
(a)
Soft robot basal segment inflation experiment(b)
Exhaust experiment of the base section of the soft robotIt can be observed that the standard deviation S does not exceed 0.24 mm in the four repeated inflation and exhaust experiments, so the repeatability of the experiment is good. It can be seen that the experimental curve of charging and exhausting is numerically lower than the theoretical simulation curve. The main reason is that there are embedded springs in the base section and the inner ring and outer ring of the tail section of the soft robot. The two coils of springs hinder the elongation of flexible materials under the action of air pressure, while the theoretical simulation ignores the influence of the springs (the wire diameter of the spring is only 0.8 mm, and the number of coils is 30). At the same time, due to the damping characteristics of the rubber material, the exhaust experiment curve and the inflation experiment curve cannot be completely overlapped. The vulcanization process of the soft robot requires a high temperature and high pressure environment, and the mandrel is prone to bending deformation under high pressure. In the process of demolding and cooling to room temperature, the nonuniform deformation of the structure is easy to exist, which will eventually affect the fitting of the experimental results and the theoretical simulation.


### 5.2. Test Analysis of IoT-Assisted Intelligent Education Software Robot Based on Improved Genetic Algorithm

The data obtained through the experiment optimizes the IoT-assisted intelligent education software robot based on the improved genetic algorithm designed in this paper and then analyzes its role in medical practice education. Therefore, this paper designs a set of control experiments; two groups are 10 medical students, and then the experimental group is taught by the Internet of Things-assisted intelligent education software robot based on improved genetic algorithm, and the other group is taught by traditional education methods. The student evaluation and teaching effect obtained from the experiment are shown in Figure11.Figure 11
Results of the control experiment.
(a)
Student evaluation(b)
Teaching effectIt can be seen from the figure that the students’ evaluation score for the traditional education method is 76.48 points, while the students’ evaluation score for the IoT intelligent education software robot education method based on the improved genetic algorithm designed in this paper is 92.79 points. It can be seen that the software robot education method designed in this paper is 16.31 points higher than the traditional education method. The score of students after the traditional teaching method was 81.33, and the score of the students after the teaching of the IoT intelligent education software robot based on the improved genetic algorithm was 92.49. It can be seen that the teaching effect of the software robot designed in this paper is 11.16 points higher than the traditional teaching effect. It can be seen from the experimental results that the student evaluation and teaching effect of the IoT intelligent education software robot based on the improved genetic algorithm designed in this paper have been improved to varying degrees.


## 5.1. Experimental Analysis of Inflating and Exhausting of the Base Section of the Soft Robot

In the case of no external load, the basal section and the tail section were, respectively, carried out four times of inflatable experiments and exhaust experiments to measure the relationship between L and P. The experimental data of charging and exhausting of the base section are shown in Figure10.Figure 10
Experimental results.
(a)
Soft robot basal segment inflation experiment(b)
Exhaust experiment of the base section of the soft robotIt can be observed that the standard deviation S does not exceed 0.24 mm in the four repeated inflation and exhaust experiments, so the repeatability of the experiment is good. It can be seen that the experimental curve of charging and exhausting is numerically lower than the theoretical simulation curve. The main reason is that there are embedded springs in the base section and the inner ring and outer ring of the tail section of the soft robot. The two coils of springs hinder the elongation of flexible materials under the action of air pressure, while the theoretical simulation ignores the influence of the springs (the wire diameter of the spring is only 0.8 mm, and the number of coils is 30). At the same time, due to the damping characteristics of the rubber material, the exhaust experiment curve and the inflation experiment curve cannot be completely overlapped. The vulcanization process of the soft robot requires a high temperature and high pressure environment, and the mandrel is prone to bending deformation under high pressure. In the process of demolding and cooling to room temperature, the nonuniform deformation of the structure is easy to exist, which will eventually affect the fitting of the experimental results and the theoretical simulation.


## 5.2. Test Analysis of IoT-Assisted Intelligent Education Software Robot Based on Improved Genetic Algorithm

The data obtained through the experiment optimizes the IoT-assisted intelligent education software robot based on the improved genetic algorithm designed in this paper and then analyzes its role in medical practice education. Therefore, this paper designs a set of control experiments; two groups are 10 medical students, and then the experimental group is taught by the Internet of Things-assisted intelligent education software robot based on improved genetic algorithm, and the other group is taught by traditional education methods. The student evaluation and teaching effect obtained from the experiment are shown in Figure11.Figure 11
Results of the control experiment.
(a)
Student evaluation(b)
Teaching effectIt can be seen from the figure that the students’ evaluation score for the traditional education method is 76.48 points, while the students’ evaluation score for the IoT intelligent education software robot education method based on the improved genetic algorithm designed in this paper is 92.79 points. It can be seen that the software robot education method designed in this paper is 16.31 points higher than the traditional education method. The score of students after the traditional teaching method was 81.33, and the score of the students after the teaching of the IoT intelligent education software robot based on the improved genetic algorithm was 92.49. It can be seen that the teaching effect of the software robot designed in this paper is 11.16 points higher than the traditional teaching effect. It can be seen from the experimental results that the student evaluation and teaching effect of the IoT intelligent education software robot based on the improved genetic algorithm designed in this paper have been improved to varying degrees.


## 6. Conclusions

This paper mainly studies the design of a software robot based on improved genetic algorithm to assist intelligent education in the Internet of Things environment and studies the basic principle of genetic algorithm. Then, this paper mainly designs the optimal guidance strategy based on NSGA genetic algorithm and then combines the application of Internet of Things technology in software robots. Therefore, this paper studies the flexible actuators and FEA actuators in soft robots. By combining the application of the improved genetic algorithm and the Internet of Things technology in the intelligent auxiliary education of the soft robot, this paper designs a software robot based on the improved genetic algorithm to assist the intelligent education in the environment of the Internet of Things. This paper also designs the genetic algorithm simulation test experiment and the rolling motion simulation experiment of the bionic soft robot. By analyzing the experimental data, the education of the soft robot designed in this paper is optimized, and then the paper analyzes the inflating and exhausting experiments of the base section of the soft robot. Finally, this paper designs a set of controlled experiments to study the educational effect of the software robot based on the improved genetic algorithm to assist intelligent education in the Internet of Things environment. The experimental results show that the teaching effect of the software robot based on the improved genetic algorithm to assist intelligent education in the Internet of Things environment will be greatly improved compared with the traditional medical education method.



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*Source: 7265308-2022-04-20.xml*