The Vine Robot is a vine-like, growing soft robot that can be used to navigate cluttered environments. Traditionally, biomimetic robots draw inspiration from the animal kingdom and use locomotion to achieve mobility. The vine robot, however, was inspired by members of the plant kingdom. Much like the common ivy, it is able to achieve mobility through growth rather than locomotion.

     The vine robot is grounded through a base station, where the unused length of robot material is stored until required. Once a fluid is used to pressurize the base, the inner chamber’s pressure enables forward growth through lengthening at the tip. It is important to note that unlike snakes and earthworms, the robot does not slide as it grows; it has no movement relative to its surroundings. As a result, it is able to move through the environment with ease, especially in constrained environments where friction would have normally hindered movement in a sliding robot. The vine robot can also be steered through reversible or non-reversible means as it grows. This allows it to navigate environments with obstacles and reach its target location (Figure 1).

Figure 1: Basic Concept for Vine Robot Movement

Growth and Eversion

Figure 2: Growth and Tip Eversion

 

     Eversion refers to the process of turning the tubular roll of plastic — the body of the vine robot — inside-out as the robot grows (Figure 2). Vine robot growth is primarily pressure-driven. This means that pressure enables the turning inside-out of the plastic by “pushing” material out during actuation.

     Prior to launching the robot, the unused material is stored in a spool within the base station. Create enough pressure and the inverted tubing will inflate to form a cylinder. Increase the pressure and the robot will begin lengthening as the spool unwinds and material everts, or turns inside out. In models that include robot retraction, the spool is motorized to rewind material into the spool but may also be used to restrict growth to a particular rate.

Steering

     Methods for steering the vine robot vary based on the type of robot and the desired reversibility. The “Build One” section will show you how to build a pre-formed vine robot. This type of vine robot does not have active steering. However, you can have turns pre-programmed before launching and its soft body is compliant enough to use the environment as anchor or redirection points. On the other hand, the teleoperated version uses a set of three pneumatic artificial muscles to do active steering.

 

 

The Pre-Formed Vine Robot

This website focuses on the design and construction of pre-formed vine robots. For design and construction of actively steered vine robots, we will post additional information as it becomes available.

Figure 3: A mechanically pre-programmed path

This model of the vine robot follows a pre-programmed path. It requires that you enforce predetermined turns on the robot prior to launching and will only follow that path (Figure 3). As a result, some knowledge of the area being explored or task is necessary.

Figure 4: Close up of a turn formed by pinching and taping the plastic tube

Fortunately, enforcing turns is simple and merely requires a piece of tape. A small strip of tape is used to shorten any side of the robot body and this will cause the robot to turn at either shallow or sharp angles (Figure 4).

Before launching, variables under your control include:

  • Robot Diameter
  • Angle of Approach
  • Turn Locations
  • Turn Angles

During operation, variables under your control include:

  • Growth Rate
  • Retraction Rate
  • Robot Stiffness (pressure and motor dependent)

See “Case Studies” to see a pre-formed robot in action.

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