writing|Slow period hard core theoryedit|Slow period hard core theoryThe design of artificial robots is mainly rigid.Based on existing rigid body dynamics, they can be precisely controlledAnd demonstrated good performance in speed, intensity, and repetitive tasks

writing|Slow period hard core theory

edit|Slow period hard core theory

The design of artificial robots is mainly rigid.Based on existing rigid body dynamics, they can be precisely controlledAnd demonstrated good performance in speed, intensity, and repetitive tasks.

Basic Introduction

In recent years, robots have utilized soft materials to achieve safer human-computer interaction, better adaptability to complex terrain movements, and better self-protection ability in extreme environments.

Soft robots can simulate biological motion mechanisms more deeply than rigid robotsUnlimited possibilities have been opened up in the field of robotics.

At present, most soft robots are manufactured on a macro scale and driven by various novel driving mechanisms, which can be divided into three categories: variable length tendons, fluid driven, or electroactive polymers.

When it comes to precise operations or movements in limited space, soft robots need to be reduced to small sizes and powered or driven externally.

In this case,Magnetic control has demonstrated its unique advantages and has made contributions to the study of external force drivingMany different external forces are used to drive small robots, including swimming microorganisms and shrinking cells, through the sliding behavior of microorganisms, chemical reactions, temperature, light, pH, and remotely transmitted magnetic fields.

Among all these external forces,Magnetism is particularly important as it can provide wide area direct controlAllow various programming methods.

In addition, when robots are applied in the body, the control of robots driven by external forces such as microorganisms, chemical reactions, temperature, light, and pH is more complex. Therefore, choosing a magnetic field as the driving method for small soft robots is very suitable.

Although electromagnetic systems are more popular than permanent magnet systems, permanent magnet systems generate greater force at lower costs and provide greater flexibility. Therefore, this work adopts a permanent magnet system.

In nature,Many organisms have evolved legs to move their bodies to cope with complex terrain and various conditions. Currently, most small robots can only move in a simple way, such as rolling and crawling.

In the field of magnetic control, neodymium iron boron hard magnetic particles inside the legs are programmed to achieve a magnetic multi legged robot that crawls forward in a paddling manner.

Afterwards, someone designed aA million dollar soft robot inspired by starfish, capable of omnidirectional motion.However, there are still many shortcomings in the design of micro multi legged robots at present.

This is because the legs of micro robots can only achieve single joint movements, and the movements of these joints are determined before manufacturing.

writing

With the cooperation of these legs, the robot performs different motion modes.

Design and Manufacturing

Legs and/or feet are common in many living animals.These structures are used to support their weight and provide effective exercise,This allows them to continuously move to favorable environments.

In this work, we designed a new type of decorative column array soft robot to mimic the excellent capabilities of these biological systems.

By utilizing this design, robots can achieve the inherent comprehensive functions of a single legged animal, such as the adaptability of octopuses to various environments, and the excellent obstacle clearance ability of caterpillars.

The design principles of robots are:,On the basis of existing equipment, the size of the robot should be as small as possible,And the distribution of legs can be controlled.

As shown in Figure 1, the robot is designed as a soft body with predefined uniformly distributed slender legs. The body is made of pure silicon gel, and the legs are made of silicon iron mixture, driven by an external magnetic field.

Because only the legs of the robot have magnetic particles, the motion ability of the robot completely depends on the legs.writing

In addition, due to the inability to obtain uniformly saturated magnetization of neodymium iron boron, we use iron powder as the magnetic actuation source, which has biocompatibility and unique characteristics different from hard magnetic materials.

Figure 2 depicts the entire process of manufacturing a tetherless multi legged soft robot. They consist of the following steps: first, manufacturing composite molds using 3D printing technology.

The mold consists of two parts. The first part is a 3mm square plate with a length of 45mm. A series of through-holes with a diameter of 0.7mm are uniformly distributed in the center of the square plate. The second part is a square ring with a thickness of 3.5mm, which can be embedded with the square ring to form a complete mold.

After the mold is made,Starting to make magnetic legs using a combination of silicone and iron particles. Firstly, mix bottles A and B of silicone and iron powder in a 1:1:2 mass ratio in a plastic cup.

After stirring evenly, place the plastic cup in a vacuum to remove air for 5-7 minutes to minimize foaming. Then,Pour the silicon iron mixture into the square plate, ensuring that each through-hole is filled.

After scraping off the excess silicone, two pieces of cut acrylic acid (also coated with release agent) are clamped onto the square board with tape. After waiting for about 45 minutes, we removed the square piece from the magnet, mixed it with the square ring, and placed the mixed pure dragon skin 20 on top.

After the upper layer of pure silicone and the lower layer of magnetic doped silicone are completely cured and firmly bonded together, carefully remove the silicone from the mold using tweezers.

Finally, we check the mobility of the legs. The last step is crucial because if we waste too much time on one of the intermediate steps, the iron silicon mixture will semi solidify and the internal iron particles will not be able to rearrange in the optimal direction.

kinematic analysis

3.1. Magnetic field distribution of rectangular permanent magnets

In order to gain a more intuitive understanding of the magnetic field,The magnetic field was simulated using finite element software. Figure 4 shows the distribution of magnetic field at the interface interface.

The parameters of the magnet are set to saturation state, so they are larger than the actual value. However, its magnetic field distribution in space provides us with a good reference.

3.2. Magnetic leg driving principle

Assuming that the diameter of the pure iron particles we use is approximately equal to the critical diameter, the domain structure of each particle can be considered as a single. Mix iron powder and silicone in a 1:1 mass ratio, and place the mixture in a 3D printing mold. Spray the mold with release agent before use.

During the solidification process of ferrosilicon powder, an external magnetic field is applied along the long axis of the support legs,Make the easy axis of the internal iron particles tend to align with the long axis of the support legs,The anisotropy of magnetization caused by manual intervention. In order to quantitatively study the driving ability of the leg, we measured the magnetization of the leg under different magnetic fields with a vibrating sample magnetometer.

3.3. kinematic analysis

Set the forwarding strategy of the multi legged robot to a series of repeated loops. The core of robot motion is to control the reciprocating motion of magnets related to the robot.

As shown in Figures 5 (a) - (d), at the beginning of a new cycle,The robot is stationary due to the balance between magnetic drag force and static friction.

Then, due to the deviation of the magnet, the tilted magnetic field acting on the robot's front leg generates a magnetic torque, causing the front half of the robot to flip upwards. The extreme value of this deformation depends on the vertical distance between the magnet and the robot, and the maximum value of the deviation distance is also the same.

Afterwards, the magnet returns and drags the robot forward until all legs of the robot return to the ground. It can be seen that the drag force generated between the magnet and the magnetic leg plays a decisive role in the robot's progress throughout the entire movement process.

However, thisIt does not mean that randomly placing magnets can cause the robot to move forward in a stable mode. In most cases, the robot will be pulled to the point where the magnetic potential energy is at its minimum, resulting in distorted posture and ultimately losing controllability.

In order to maintain the stability of the robot's posture, the relative position of the magnet and the robot cannot be too close or too far. Therefore, the motion of a multi legged robot is very similar to a puppet show, where magnetism serves as invisible lines and magnetic legs serve as the joints of the puppet.

experiment

writing57

When moving the bottom magnet in a certain way,The shape of the robot changes with its relative distance from the magnet.Research has found that only a small portion of the legs are consistently affected by the magnetic field during each exercise cycle, as shown in Figure 6.

When the magnet approaches a distance threshold horizontally from the front of the robot, the front of the robot will buckle in a short period of time and quickly reach a peak.

This is a delicate balance,The key to maintaining it is that the acceleration of the magnet moving forward must be greater than the acceleration of the robot moving forward.

However, each iteration of the magnet must reach a position that allows the robot to react. This makes it necessary for us to understand the exact distribution of the magnetic field around the magnet.

To illustrate how the magnetic field changes, we measured the precise distribution of the magnetic field in the workspace, as shown in Figure 7.

Finally,Tested the comprehensive motion ability of the robot in a multi terrain maze. As shown in Figure 8, there are multiple routes with different terrain settings in the maze, including speed bumps, shallow pits, slopes, humps, and narrow corners.

conclusion

Legs play a crucial role in animal movement as they provide sufficient physical support, higher mobility, and better ability to overcome obstacles.

writingRobots can move forward, backward, turn, and cross obstacles under the control of a magnetic field.

In addition,Analyzed the magnetic field distribution of the permanent magnet and the gait of the robot from the force perspectiveLaying the foundation for subsequent magnetic field control.

experiment30030

writing

[1] S. Chiaverini, B. Siciliano, O. Egeland, A control method of manipulator based on least square inverse kinematics, Journal of Mechanical Engineering. Control system. Technology 2 (2) (1994) 123-134.

[3] S. Sheikholeslami, A. Moon, E.A. Croft, Research on the Application of Robot Gestures in Human Computer Interaction, Journal of Human Computer Interaction. j. Robots. Res.36 (5-7) (2017) 699-720

[4] S. Hirose, Y. Umetani, Development of Flexible Manipulators, Mechanical Engineering. Mach Theory 13 (3) (1978) 351-359.

[5] D. Rus, M.T. Tolley, Design, Manufacturing, and Control of Soft Robots, Natural Sciences, 521 (7553) (2015): 467-475.

Disclaimer: The content of this article is sourced from the internet. The copyright of the text, images, and other materials belongs to the original author. The platform reprints the materials for the purpose of conveying more information. The content of the article is for reference and learning only, and should not be used for commercial purposes. If it infringes on your legitimate rights and interests, please contact us promptly and we will handle it as soon as possible! We respect copyright and are committed to protecting it. Thank you for sharing.(Email:[email protected])