3 research outputs found
Configuration and Fabrication of Preformed Vine Robots
Vine robots are a class of soft continuum robots that grow via tip eversion,
allowing them to move their tip without relying on reaction forces from the
environment. Constructed from compliant materials such as fabric and thin,
flexible plastic, these robots are able to grow many times their original
length with the use of fluidic pressure. They can be mechanically
programmed/preformed to follow a desired path during growth by changing the
structure of their body prior to deployment. We present a model for fabricating
preformed vine robots with discrete bends. We apply this model across
combinations of three fabrication methods and two materials. One fabrication
method, taping folds into the robot body, is from the literature. The other two
methods, welding folds and connecting fasteners embedded in the robot body, are
novel. Measurements show the ability of the resulting vine robots to follow a
desired path and show that fabrication method has a significant impact. Results
include bend angles with as little as 0.12 degrees of error, and segment
lengths with as low as 0.36 mm of error. The required growth pressure and
average growth speed of these preformed vine robots ranged from 11.5 to 23.7kPA
and 3.75 to 10 cm/s, respectively. These results validate the use of preformed
vine robots for deployment along known paths, and serve as a guide for choosing
a fabrication method and material combination based on the specific needs of
the task
Shared-Control Teleoperation Paradigms on a Soft Growing Robot Manipulator
Semi-autonomous telerobotic systems allow both humans and robots to exploit
their strengths, while enabling personalized execution of a task. However, for
new soft robots with degrees of freedom dissimilar to those of human operators,
it is unknown how the control of a task should be divided between the human and
robot. This work presents a set of interaction paradigms between a human and a
soft growing robot manipulator, and demonstrates them in both real and
simulated scenarios. The robot can grow and retract by eversion and inversion
of its tubular body, a property we exploit to implement interaction paradigms.
We implemented and tested six different paradigms of human-robot interaction,
beginning with full teleoperation and gradually adding automation to various
aspects of the task execution. All paradigms were demonstrated by two expert
and two naive operators. Results show that humans and the soft robot
manipulator can split control along degrees of freedom while acting
simultaneously. In the simple pick-and-place task studied in this work,
performance improves as the control is gradually given to the robot, because
the robot can correct certain human errors. However, human engagement and
enjoyment may be maximized when the task is at least partially shared. Finally,
when the human operator is assisted by haptic feedback based on soft robot
position errors, we observed that the improvement in performance is highly
dependent on the expertise of the human operator.Comment: 15 pages, 14 figure
A Comparison of Pneumatic Actuators for Soft Growing Vine Robots
Soft pneumatic actuators are used to steer soft growing "vine" robots while
being flexible enough to undergo the tip eversion required for growth. In this
study, we compared the performance of three types of pneumatic actuators in
terms of their ability to perform eversion, quasi-static bending, dynamic
motion, and force output: the pouch motor, the cylindrical pneumatic artificial
muscle (cPAM), and the fabric pneumatic artificial muscle (fPAM). The pouch
motor is advantageous for prototyping due to its simple manufacturing process.
The cPAM exhibits superior bending behavior and produces the highest forces,
while the fPAM actuates fastest and everts at the lowest pressure. We evaluated
a range of dimensions for each actuator type. Larger actuators can produce more
significant deformations and forces, but smaller actuators inflate faster and
can evert at a lower pressure. Because vine robots are lightweight, the effect
of gravity on the functionality of different actuators is minimal. We developed
a new analytical model that predicts the pressure-to-bending behavior of vine
robot actuators. Using the actuator results, we designed and demonstrated a 4.8
m long vine robot equipped with highly maneuverable 60x60 mm cPAMs in a
three-dimensional obstacle course. The vine robot was able to move around sharp
turns, travel through a passage smaller than its diameter, and lift itself
against gravity.Comment: 13 pages, 8 figures, 3 table