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Soft robot shape estimation with IMUs leveraging PCC kinematics for drift filtering

Stella, F. (author), Della Santina, C. (author), Hughes, Josie (author)

The control possibilities for soft robots have long been hindered by the need for reliable methods to estimate their configuration. Inertial measurement units (IMUs) can solve this challenge, but they are affected by well-known drift issues. This letter proposes a method to eliminate this limitation by leveraging the Piecewise Constant...

journal article 2024

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Input Decoupling of Lagrangian Systems via Coordinate Transformation: General Characterization and its Application to Soft Robotics

Pustina, P. (author), Della Santina, C. (author), Boyer, Frederic (author), De Luca, Alessandro (author), Renda, Federico (author)

Suitable representations of dynamical systems can simplify their analysis and control. On this line of thought, this article aims to answer the following question: Can a transformation of the generalized coordinates under which the actuators directly perform work on a subset of the configuration variables be found? We not only show that the...

journal article 2024

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Model and Control of R-Soft Inverted Pendulum

Caradonna, Daniele (author), Pierallini, M. (author), Della Santina, C. (author), Angelini, Franco (author), Bicchi, Antonio (author)

Soft robots enable safe and robust operations in unstructured environments. However, the nonlinearities of their continuum structure complicate the accomplishment of classic robotic tasks, such as pick and place. In this work, we propose the R-Soft Inverted Pendulum, a Soft Inverted Pendulum (SIP) actuated only by a revolute joint at the base...

journal article 2024

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Model Predictive Path Planning of AGVs: Mixed Logical Dynamical Formulation and Distributed Coordination

Xin, Jianbin (author), Wu, Xuwen (author), D'Ariano, Andrea (author), Negenborn, R.R. (author), Zhang, Fangfang (author)

Most of the existing path planning methods of automated guided vehicles (AGVs) are static. This paper proposes a new methodology for the path planning of a fleet of AGVs to improve the flexibility, robustness, and scalability of the AGV system. We mathematically describe the transport process as a dynamical system using an ad hoc mixed...

journal article 2023

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P-satI-D Shape Regulation of Soft Robots

Pustina, P. (author), Borja, Pablo (author), Della Santina, C. (author), De Luca, Alessandro (author)

Soft robots are intrinsically underactuated mechanical systems that operate under uncertainties and disturbances. In these conditions, this letter proposes two versions of PID-like control laws with a saturated integral action for the particularly challenging shape regulation task. The closed-loop system is asymptotically stabilized and...

journal article 2023

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Robust Jumping with an Articulated Soft Quadruped via Trajectory Optimization and Iterative Learning

Ding, J. (author), Sels, Mees A.van Loben (author), Angelini, Franco (author), Kober, J. (author), Della Santina, C. (author)

Quadrupeds deployed in real-world scenarios need to be robust to unmodelled dynamic effects. In this work, we aim to increase the robustness of quadrupedal periodic forward jumping (i.e., pronking) by unifying cutting-edge model-based trajectory optimization and iterative learning control. Using a reduced-order soft anchor model, the...

journal article 2023

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Distributed Nonlinear Trajectory Optimization for Multi-Robot Motion Planning

Ferranti, L. (author), Lyons, L. (author), Negenborn, R.R. (author), Keviczky, T. (author), Alonso-Mora, J. (author)

This work presents a method for multi-robot coordination based on a novel distributed nonlinear model predictive control (NMPC) formulation for trajectory optimization and its modified version to mitigate the effects of packet losses and delays in the communication among the robots. Our algorithms consider that each robot is equipped with an...

journal article 2023

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Dynamic Optimization Fabrics for Motion Generation

Spahn, M. (author), Wisse, M. (author), Alonso-Mora, J. (author)

Optimization fabrics are a geometric approach to real-time local motion generation, where motions are designed by the composition of several differential equations that exhibit a desired motion behavior. We generalize this framework to dynamic scenarios and nonholonomic robots and prove that fundamental properties can be conserved. We show...

journal article 2023

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On the stability of the soft pendulum with affine curvature: open-loop, collocated closed-loop, and switching control

Trumic, Maja (author), Della Santina, C. (author), Jovanovic, Kosta (author), Fagiolini, Adriano (author)

This letter investigates the stability properties of the soft inverted pendulum with affine curvature - a template model for nonlinear control of underactuated soft robots. We look at how changes in physical parameters affect stability and equilibrium. We give conditions under which zero dynamics corresponding to a collocated choice of the...

journal article 2023

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Field Model Identification and Control of a Mobile Electromagnet for Remote Actuation of Soft Robots

Riccardi, A. (author), Furtado, Guilherme P. (author), Sikorski, Jakub (author), Vendittelli, Marilena (author), Misra, Sarthak (author)

The actuation of miniaturized robots through external magnetic fields has great potential for medical applications. The controllability properties of the miniaturized robots are affected by magnetic field generation modality. In this work, the magnetic field of a mobile electromagnet, notably capable to generate a desired magnetic field in...

journal article 2023

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A Provably Stable Iterative Learning Controller for Continuum Soft Robots

Pierallini, M. (author), Stella, F. (author), Angelini, Franco (author), Deutschmann, Bastian (author), Hughes, Josie (author), Bicchi, Antonio (author), Garabini, Manolo (author), Della Santina, C. (author)

Fully exploiting soft robots' capabilities requires devising strategies that can accurately control their movements with the limited amount of control sources available. This task is challenging for reasons including the hard-to-model dynamics, the system's underactuation, and the need of using a prominent feedforward control action to...

journal article 2023

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Robotic Skill Mutation in Robot-to-Robot Propagation During a Physically Collaborative Sawing Task

Maessen, Rosa E.S. (author), Prendergast, J.M. (author), Peternel, L. (author)

Skill propagation among robots without human involvement can be crucial in quickly spreading new physical skills to many robots. In this respect, it is a good alternative to pure reinforcement learning, which can be time-consuming, or learning from human demonstration, which requires human involvement. In the latter case, there may not be...

journal article 2023

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Contour Moments Based Manipulation of Composite Rigid-Deformable Objects With Finite Time Model Estimation and Shape/Position Control

Qi, Jiaming (author), Ma, Guangfu (author), Zhu, J. (author), Zhou, Peng (author), Lyu, Yueyong (author), Zhang, Haibo (author), Navarro-Alarcon, David (author)

The robotic manipulation of composite rigid-deformable objects (i.e., those with mixed nonhomogeneous stiffness properties) is a challenging problem with clear practical applications that, despite the recent progress in the field, it has not been sufficiently studied in the literature. To deal with this issue, in this article, we propose a...

journal article 2022

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Deep-Learning-Based Compliant Motion Control of a Pneumatically-Driven Robotic Catheter

Wu, D. (author), Ha, Xuan Thao (author), Zhang, Yao (author), Ourak, Mouloud (author), Borghesan, Gianni (author), Niu, Kenan (author), Trauzettel, F. (author), Dankelman, J. (author), Menciassi, Arianna (author), Poorten, Emmanuel Vander (author)

In cardiovascular interventions, when steering catheters and especially robotic catheters, great care should be paid to prevent applying too large forces on the vessel walls as this could dislodge calcifications, induce scars or even cause perforation. To address this challenge, this paper presents a novel compliant motion control algorithm...

journal article 2022

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Feedback Regulation of Elastically Decoupled Underactuated Soft Robots

Pustina, P. (author), Della Santina, C. (author), De Luca, Alessandro (author)

The intrinsically underactuated and nonlinear nature of continuum soft robots makes the derivation of provably stable feedback control laws a challenging task. Most of the works so far circumvented the issue either by looking at coarse fully-actuated approximations of the dynamics or by imposing quasi-static assumptions. In this letter, we...

journal article 2022

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An experimental validation of the polynomial curvature model: identification and optimal control of a soft underwater tentacle

Stella, F. (author), Obayashi, Nana (author), Della Santina, C. (author), Hughes, Josie (author)

The control possibilities for soft robots have long been hindered by the lack of accurate yet computationally treatable dynamic models of soft structures. Polynomial curvature models propose a solution to this quest for continuum slender structures. Nevertheless, the results produced with this class of models have been so far essentially...

journal article 2022

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Learning to Pick at Non-Zero-Velocity from Interactive Demonstrations

Mészáros, A. (author), Franzese, G. (author), Kober, J. (author)

This work investigates how the intricate task of a continuous pick & place (P&P) motion may be learned from humans based on demonstrations and corrections. Due to the complexity of the task, these demonstrations are often slow and even slightly flawed, particularly at moments when multiple aspects (i.e., end-effector movement,...

journal article 2022

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Actuating Eigenmanifolds of Conservative Mechanical Systems Via Bounded or Impulsive Control Actions

Della Santina, C. (author), Calzolari, Davide (author), Giordano, Alessandro Massimo (author), Albu-Schaffer, Alin (author)

Eigenmanifolds are two-dimensional submanifolds of the state space, which generalize linear eigenspaces to nonlinear mechanical systems. Initializing a robot on an Eigenmanifold (or driving it there by control) yields hyper-efficient and regular oscillatory behaviors, called modal oscillations. This letter investigates the possibility of...

journal article 2021

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Efficient and Goal-Directed Oscillations in Articulated Soft Robots: the Point-to-Point Case

Bonacchi, Luigi Bono (author), Roa, Maximo A. (author), Sesselmann, Anna (author), Loeffl, Florian (author), Albu-Schaffer, Alin (author), Della Santina, C. (author)

Introducing elasticity in the mechanical design can endow robots with the ability of performing efficient and effective periodic motions. Yet, devising controllers that can take advantage of such elasticity is still an open challenge. This letter tackles an instance of this general problem, by proposing a control architecture for executing...

journal article 2021

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Exciting efficient oscillations in nonlinear mechanical systems through Eigenmanifold stabilization

Della Santina, C. (author), Albu-Schaeffer, Alin (author)

Nonlinear modes are a well investigated concept in dynamical systems theory, extending the celebrated modal analysis of linear mechanical systems to nonlinear ones. This letter moves a first step in the direction of combining control theory and nonlinear modal analysis towards the implementation of hyper-efficient oscillatory behaviors in...

journal article 2021