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Research on Snake Robots

Snake robots, whose shape are similar to real snakes, are expected to be suitable for variety of tasks as serch and rescue operations, pipe inspection, and so on. In Matsuno Lab., we are aiming at making theoritical foundation of the control of this kind of robots, with consideration of practical applications.

  • Control of a snake robot on complex environment
  •     Gait design method
        Movement on rough terrain
        Moving over a flange on a pipe
  • Control Strategy for a Snake Robot
  •     Locomotion Control for a Snake Robot
        Cooperative Control for a Snake Robot
        Climbing on a Cylindrical Surface of a Snake Robot
        Jumping Control for a Snake Robot
  • Researches on Snakes’ Locomotion by Snake Robots
  •     A Study on Sinus-Lifting Motion Used by Snakes in Nature
  • A snake-like robot using the screw drive mechanism
  •     A screw drive unit
        Front-Unit-Following Control
  • Amphibious Snake-like Robot with Screw Drive Mechanism
  •     Various Movement
        Autonomous Trajectory Tracking of Center of Mass of the Robot

    Control of a snake robot on complex environment

    We are studying how to control snake robots in complex environments such as disaster sites and plant facilities. Currently we are primarily studying on moving, but we are aiming to develop into work.

    Gait design method

    We proposed a method of designing the target form of a snake robot by combining simple shapes such as straight line, circular arc and helix. In addition, the target form is realized by approximating the form of a snake robot to the target form. With this method, it is possible to intuitively design complicated movements.


    GaitDesignMethod.png

    Movement on rough terrain

    Using the above gait design method, we designed a crawler-gait to move on rough terrain. With this crawler-gait, the snake robot behaves like a large crawler belt, so it can easily propell even if it is an unknown rough terrain.

    Moving over a flange on a pipe

    Using the above gait design method, we designed a gait that climbs over a flange on pipe. With this method, snake robot can get over the flange by locally lifting the body while helically wrapping around a vertical pipe to prevent slipping down.

    We ran simulations to verify the control method.


    MovingOverFlange.png

    Reference

  • Tatsuya Takemori, Motoyasu Tanaka, Fumitoshi Matsuno, Gait Design of a Snake Robot by Connecting Simple Shapes, 2016 IEEE International Symposium on Safety, Security and Rescue Robotics, pp. 189 – 194, 2016
  • 竹森達也, 田中基康, 松野文俊, “ヘビ型ロボットの複雑環境における運動設計と制御”,第17回システムインテグレーション部門講演会

  • Control Strategy for a Snake Robot

    Despite of its very simple string-like body without legs, a snake can realize many kinds of locomotion such as lateral undulation and pole climbing. We are studying snake-like robots to achieve the similar locomotion as real snakes, or even more difficult movements that cannot be achieved by real snakes.

    Locomotion Control

    By making use of its redundancy, we can solve a variety of problems that coincide with trajectory tracking tasks of a snake-like robot. For example, if the redundancy is used properly, a snake-like robot with passive wheels can avoid falling into undesirable shapes (an arc, a straight line, and so on), which are called singularities and make it impossible for a snake-like robot to locomote.

    Movie 1. Singularity avoidance using redundancy



    If the redundancy isn't used (shown in the left side of the movie), a snake-like robot will fall into a singularity and get stuck. On the other hand, if we make use of the redundancy (right side of the movie), a snake-like robot will continue to traverse by lateral undulation.

    Movie 2. 3-dimensional trajectory tracking



    When the reference trajectory is 3-dimensional, we also have to control the robot to prevent it from falling down. Without this control (movie case1), a snake-like robot will fall down during the maneuver, but with this control (movie case2), the robot can avoid it.

    Reference

  • 佐藤,田中,松野,“動力学モデルに基づく蛇型ロボットの軌道追従制御”,計測自動制御学会論文集,Vol.42, No.6, pp.651-658,2006.
  • M. Tanaka, F. Matsuno,“Experimental study of Redundant Snake Robot Based on Kinematic Model”, Proc. IEEE Int. Conf. on Robotics and Automation, Apr/2007.
  • 田中,松野,“3次元ヘビ型ロボットの冗長性を利用した制御”,計測自動制御学会論文集,Vol.44,No.12,2008.
  • M. Tanaka, F. Matsuno,“Control of 3-dimensional snake robots by using redundancy”, Proc. IEEE Int. Conf. on Robotics and Automation, May/2008.
  • Cooperative Control

    By lifting up the head and some links that follow it, a snake-like robot can be used like a robot arm. We have proposed a cooperative control method that enables multiple snake-like robots to cooperate to carry an item, by controling contact forces, with their heads used like robot arms. Without force control (movie 1), snake-like robots cannot hold the item because contact forces act in different directions. With force control (movie 2), we can keep the direction of the contact forces to have the robots hold the item and carry it cooperatively.

    Movie 1. Without force control



    Movie 2. With force control



    We conducted experiments to verify the proposed method with the real robots shown below.


    ./photo/2_snake_robot.JPG

    Reference

  • 田中,吉川,松野,“2台のヘビ型ロボットの協調制御”,日本ロボット学会誌,Vol.24,No.3,pp.400-407, 2006.
  • M. Tanaka, F. Matsuno,“Cooperative Control of Three Snake Robots”, Proc. IEEE Int. Conf. on Intelligent Robots and Systems, Oct/2006.
  • 田中,松野,“3次元ヘビ型ロボットの協調制御”,第25回日本ロボット学会学術講演会,1F35,Sep/2007.
  • Climbing on a Cylindrical Surface

    A snake can climb up a pole-like structure such as a tree by winding around it. A snake-like robot, which uses similar locomotion mechanism, may also be able to move on a cylindrical surface in the same way. We have proposed a control method for a snake-like robot to track a reference trajectory on a cylindrical surface by winding movement.

    We ran simulations to verify the control method.


    makitsuki.jpg

    In the pole climbing task, we have to take it into account how to avoid slipping down, as well as singularity avoidance. By controling the force to wind around the pole, the robot can track the reference trajectory without slipping.

    Movie 1. Pole climbing control of a snake-like robot



    Reference

  • H. Tsukano, M. Tanaka, F. Matsuno, “Control of a Snake Robot on a Cylindrical Surface Based on a Kinematic Model”, SYROCO, Sept/2009.
  • Jumping control

    There are some snakes that have a high ability to jump. If we can succeed to let a snake robot jump, we can make snake robots with comparatively higher motion capacities, furthermore, we may acquire a clearer understanding on why snakes can jump. The type of snake robot that we focus on has the property of friction anisotropy. Because of this, the shape of the part of robot’s body which attaches to the ground, functions as a support base part for jumping, is crucial when considering whether the robot will slip or not when it starts to jump. Slipping backward causes less movement in desired direction and is not efficient. Therefore, we have to consider what kind of shape is optimal. Here, we have achieved to propose a cost function to decide which shape is optimal for jumping, and figured out it. Consequently, we succeeded to attain a jumping motion for a snake robot without slipping too much.



    Reference

  • K. Hoshino, M. Tanaka, F. Matsuno, “Optimal Shape of a Snake Robot for Jumping”, Proc. IEEE Int. Conf. on Robotics and Automation, May/2010.

  • Researches on Snakes’ Locomotion by Snake Robots

    Snakes are normally found to move wrigglingly with all parts of their bodies attaching to the ground. However, snakes which move according Sinus-lifting motion, moving forward while lifting parts of their bodies which twist mostly, and snakes which move according Side-winding motion, moving sideward while lifting some parts of their bodies are also discovered in nature. The reason why snakes use these kinds of motions may be that they consume less energies while moving in these ways. We focus on energies used while moving, check whether this hypothesis is correct or not by using a snake-like robot from an engineering view, and try to explain why snakes in nature apply these motions.

    A Study on Sinus-Lifting Motion Used by Snakes in Nature

    We define three kinds of energies used while moving. One is used to wriggle, the second one is used to lift some parts of the body, the last one aims to hold lifted parts. We have checked whether Sinus-lifting motion will appear or not based on minimization of the total energy used to move for a same distance by using a snake robot. As a result, we found that snake robots will move by Sinus-lifting motion under the similar condition as real snakes.



    Reference

  • Satoshi Toyoshima and Fumitoshi Matsuno: “A Study on Sinus-lifting Motion of a Snake Robot with Energetic Efficiency”, Proc.IEEE Int. Conf on Robotics and Automation, pp.2673-2678, May, 2012.

  • A snake-like robot using the screw drive mechanism

    A snake-like robot using the screw drive mechanism is expected to be useful for search and rescue operations, pipe inspection, and so on. The advantage of the robot is that it can move in any direction by coupling the unit called a screw drive unit developed in Matsuno Lab. in various forms.


    ./photo/nejihebi.JPG

    A screw drive unit

    There are two types of screw drive units. One is the left screw drive unit which generates propulsion force diagonally to the left. The other is the right screw drive unit which generates propulsion force diagonally to the right. A snake-like robot using the screw drive mechanism is made by connecting these two kinds of units. This robot can move along a complex path by bending its 2 DOF joints.


    ./photo/nejiunit1.JPG

    Front-Unit-Following Control

    To facilitate the operation, we have proposed and applied the control called Front-Unit-Following Control. In this control, an operator control the robot in narrow space because only the operator has to give the command for the head unit of the robot, and the commands for the rest of the units are calculated automatically in order to follow the path of the preceding unit.

    MOVIE1. Omni-directional movement



    MOVIE2. Circular trajectory tracking



    Reference

  • Hara, M., Satomura, S., Fukushima, H., Kamegawa, T., Igarashi, H., & Matsuno, F. (2007, April). Control of a snake-like robot using the screw drive mechanism. In Robotics and Automation, 2007 IEEE International Conference on (pp. 3883-3888). IEEE.
  • Ariizumi, R., Fukushima, H., & Matsuno, F. (2011, September). Front-unit-following control of a snake-like robot using screw drive mechanism based on past velocity commands. In Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on (pp. 1907-1912). IEEE.
  • Fukushima, H., Satomura, S., Kawai, T., Tanaka, M., Kamegawa, T., & Matsuno, F. (2012). Modeling and Control of a Snake-Like Robot Using the Screw-Drive Mechanism. Robotics, IEEE Transactions on, 28(3), 541-554.

  • Amphibious Snake-like Robot with Screw Drive Mechanism

    Underwater and 2-link version of the screw driven snake robot has been produced in our laboratory in 2016. This robot is expected to be helpful in underwater inspection and rescue missions. Since this robot does not need to have undulating locomotion for other snake like robots, it can enter narrow spaces like pipes. Robot has 3 actuators consisting of 2 motors to drive 2 screws and 1 motor to give yaw joint angle.


    ScrewDriveUnit.png

    Just like the land version, this robot also has 2 different screw drive units consisting of left and right screws. Thanks to its screw propulsion, this robot can move laterally additional to longitudinal movement.


    ScrewDriveUnit2.png

    Various Movement

    In this video, you can see different types of movement of the robot. The robot is controlled by a human through joystick.

    MOVIE1. Various Movement

    Autonomous Trajectory Tracking of Center of Mass of the Robot

    In this video, the robot’s joint angle was fixed for sake of simplicity and its Center of Mass was controlled to follow a trajectory using feedback linearization PD control.

    MOVIE2. Autonomous Trajectory Tracking of CoM