More Like this

1. Hybrid vine robot with internal Steering-Reeling Mechanism enhances system-level capabilities

   https://doi.org/10.1109/LRA.2021.3072858  

   Haggerty, David Arthur ; Naclerio, Nicholas ; Hawkes, Elliot Wright ( January 2021 , IEEE Robotics and Automation Letters)

   Continuum robots have high degrees of freedom and the ability to safely move in constrained environments. One class of soft continuum robot is the “vine” robot. This type of robot extends from its tip by everting or unfurling new material, driven by internal body pressure. Most vine robot examples store new body material in a reel at their base, passing it through the core of the robot to the tip, and like many continuum robots, steer by selectively lengthening or shortening one side of the body. While this approach to steering and material storage lends itself to a fully soft device, it has three key limitations: (i) internal friction of material passing through the core of the robot limits its length in tortuous paths, (ii) body buckling as the robot's body material is re-spooled at the base can prevent retraction, and (iii) constant curvature steering limits the robot's poses and object approach angles in a given workspace. This letter presents a hybrid soft-rigid robotic system comprising a soft vine robot body and a rigid, mobile, internal steering-reeling mechanism (SRM); this SRM is equipped with a reel for material storage, a bending actuator for steering, and is capable of actuating themore »robot at any point along its length. This hybrid configuration increases reach along tortuous paths, allows retraction, and increases the workspace. We describe the motivation for the device, generate its mathematical models, present its methods of operation, and verify experimentally the models we developed and the performance improvements over previous vine robots.« less
2. Tractable and Intuitive Dynamic Model for Soft Robots via the Recursive Newton-Euler Algorithm

   https://doi.org/10.1109/RoboSoft54090.2022.9762215  

   Jensen, Spencer W. ; Johnson, Curtis C. ; Lindberg, Alexa M. ; Killpack, Marc D. ( April 2022 , IEEE International Conference on Soft Robotics (RoboSoft))

   Because of the complex nature of soft robots, formulating dynamic models that are simple, efficient, and sufficiently accurate for simulation or control is a difficult task. This paper introduces an algorithm based on a recursive Newton-Euler (RNE) approach that enables an accurate and tractable lumped parameter dynamic model. This model scales linearly in computational complexity with the number of discrete segments. We validate this model by comparing it to actual hardware data from a three-joint continuum soft robot (with six degrees of freedom represented in a constant curvature kinematic model). The results show that this RNE-based model can be computed faster than real-time. We also show that with minimal system identification, a simulation performed using the dynamic model matches the real robot data with a median error of 3.15 degrees.
3. Modeling of Soft Robotic Grippers Integrated With Fluidic Prestressed Composite Actuators

   https://doi.org/10.1115/1.4052699  

   Zhou, Yitong ; Headings, Leon M. ; Dapino, Marcelo J. ( June 2022 , Journal of Mechanisms and Robotics)

   Abstract Soft robotic grippers can gently grasp and maneuver objects. However, they are difficult to model and control due to their highly deformable fingers and complex integration with robotic systems. This paper investigates the design requirements as well as the grasping capabilities and performance of a soft gripper system based on fluidic prestressed composite (FPC) fingers. An analytical model is constructed as follows: each finger is modeled using the chained composite model (CCM); strain energy and work done by pressure and loads are computed using polynomials with unknown coefficients; net energy is minimized using the Rayleigh–Ritz method to calculate the deflected equilibrium shapes of the finger as a function of pressure and loads; and coordinate transformation and gripper geometries are combined to analyze the grasping performance. The effects of prestrain, integration angle, and finger overlap on the grasping performance are examined through a parametric study. We also analyze gripping performance for cuboidal and spherical objects and show how the grasping force can be controlled by varying fluidic pressure. The quasi-static responses of fabricated actuators are measured under pressures and loads. It is shown that the actuators’ modeled responses agree with the experimental results. This work provides a framework for themore »theoretical analysis of soft robotic grippers and the methods presented can be extended to model grippers with different types of actuation.« less
4. Modeling Variable Curvature Parallel Continuum Robots Using Euler Curves

   https://doi.org/10.1109/ICRA.2019.8794238  

   Gonthina, Phanideep S. ; Kapadia, Apoorva D. ; Godage, Isuru S. ; Walker, Ian. D. ( May 2019 , 2019 International Conference on Robotics and Automation (ICRA))

   In this paper, we propose and investigate a new approach to modeling variable curvature continuum robot sections, based on Euler spirals. Euler spirals, also termed Clothoids, or Cornu spirals, are those curves in which the curvature increases linearly with their arc length. In this work, Euler spirals are applied to the kinematic modeling of continuum robots for the first time. The approach was evaluated using the sections of numerous continuum robots, including two novel parallel continuum robots. Each robot consists of three parallel sections, each with three thin, long McKibben actuators. These sections are poorly modeled by the widely used constant curvature kinematic model. The constant curvature and Euler spiral models were compared and the Euler spiral method was seen to be a significantly better match for a wide range of configurations of the robot hardware.
5. Grasp Analysis and Manipulation Kinematics for Isoperimetric Truss Robots

   https://doi.org/10.1109/ICRA48506.2021.9561332  

   Hammond, Zachary M. ; Usevitch, Nathan S. ; Follmer, Sean ( May 2021 , 2021 IEEE International Conference on Robotics and Automation (ICRA))

   Soft isoperimetric truss robots have demonstrated an ability to grasp and manipulate objects using the members of their structure. The compliance of the members affords large contact areas with even force distribution, allowing for successful grasping even with imprecise open-loop control. In this work we present methods of analyzing and controlling isoperimetric truss robots in the context of grasping and manipulating objects. We use a direct stiffness model to characterize the structural properties of the robot and its interactions with external objects. With this approach we can estimate grasp forces and stiffnesses with limited computation compared to higher fidelity finite elements methods, which, given the many degrees-of-freedom of truss robots, are prohibitively expensive to run on-board. In conjunction with the structural model, we build upon a literature of differential kinematics for truss robots and apply it to the task of manipulating an object within the robot’s workspace.