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Sensing and Control for Robust Grasping with Simple Hardware
Robots can move, see, and navigate in the real world outside carefully structured factories, but they cannot yet grasp and manipulate objects without human intervention. Two key barriers are the complexity of current approaches, which require complicated hardware or precise perception to function effectively, and the challenge of understanding system performance in a tractable manner given the wide range of factors that impact successful grasping. This thesis presents sensors and simple control algorithms that relax the requirements on robot hardware, and a framework to understand the capabilities and limitations of grasping systems.Engineering and Applied Science
Soft Robot-Assisted Minimally Invasive Surgery and Interventions: Advances and Outlook
Since the emergence of soft robotics around two decades ago, research interest in the field has escalated at a pace. It is fuelled by the industry's appreciation of the wide range of soft materials available that can be used to create highly dexterous robots with adaptability characteristics far beyond that which can be achieved with rigid component devices. The ability, inherent in soft robots, to compliantly adapt to the environment, has significantly sparked interest from the surgical robotics community. This article provides an in-depth overview of recent progress and outlines the remaining challenges in the development of soft robotics for minimally invasive surgery
Inter-finger Small Object Manipulation with DenseTact Optical Tactile Sensor
The ability to grasp and manipulate small objects in cluttered environments
remains a significant challenge. This paper introduces a novel approach that
utilizes a tactile sensor-equipped gripper with eight degrees of freedom to
overcome these limitations. We employ DenseTact 2.0 for the gripper, enabling
precise control and improved grasp success rates, particularly for small
objects ranging from 5mm to 25mm. Our integrated strategy incorporates the
robot arm, gripper, and sensor to manipulate and orient small objects for
subsequent classification effectively. We contribute a specialized dataset
designed for classifying these objects based on tactile sensor output and a new
control algorithm for in-hand orientation tasks. Our system demonstrates 88% of
successful grasp and successfully classified small objects in cluttered
scenarios
Development of PVDF tactile dynamic sensing in a behaviour-based assembly robot
The research presented in this thesis focuses on the development of tactile event sig¬
nature sensors and their application, especially in reactive behaviour-based robotic
assembly systems.In pursuit of practical and economic sensors for detecting part contact, the application
ofPVDF (polyvinylidene fluoride) film, a mechanical vibration sensitive piezo material,
is investigated. A Clunk Sensor is developed which remotely detects impact vibrations,
and a Push Sensor is developed which senses small changes in the deformation of a
compliant finger surface. The Push Sensor is further developed to provide some force
direction and force pattern sensing capability.By being able to detect changes of state in an assembly, such as a change of contact
force, an assembly robot can be well informed of current conditions. The complex
structure of assembly tasks provides a rich context within which to interpret changes
of state, so simple binary sensors can conveniently supply a lot more information than
in the domain of mobile robots. Guarded motions, for example, which require sensing a
change of state, have long been recognised as very useful in part mating tasks. Guarded
motions are particularly well suited to be components of assembly behavioural modules.In behaviour-based robotic assembly systems, the high level planner is endowed with
as little complexity as possible while the low level planning execution agent deals with
actual sensing and action. Highly reactive execution agents can provide advantages by
encapsulating low level sensing and action, hiding the details of sensori-motor complexity from the higher levels.Because behaviour-based assembly systems emphasise the utility of this kind of quali¬
tative state-change sensor (as opposed to sensors which measure physical quantities),
the robustness and utility of the Push Sensor was tested in an experimental behaviourbased system. An experimental task of pushing a ring along a convoluted stiff wire is
chosen, in which the tactile sensors developed here are aided by vision. Three differ¬
ent methods of combining these different sensors within the general behaviour-based
paradigm are implemented and compared. This exercise confirms the robustness and
utility of the PVDF-based tactile sensors. We argue that the comparison suggests
that for behaviour-based assembly systems using multiple concurrent sensor systems,
bottom-level motor control in terms of force or velocity would be more appropriate
than positional control. Behaviour-based systems have traditionally tried to avoid
symbolic knowledge. Considering this in the light of the above work, it was found
useful to develop a taxonomy of type of knowledge and refine the prohibition
Variable stiffness robotic hand for stable grasp and flexible handling
Robotic grasping is a challenging area in the field of robotics. When interacting with an object, the dynamic properties of the object will play an important role where a gripper (as a system), which has been shown to be stable as per appropriate stability criteria, can become unstable when coupled to an object. However, including a sufficiently compliant element within the actuation system of the robotic hand can increase the stability of the grasp in the presence of uncertainties. This paper deals with an innovative robotic variable stiffness hand design, VSH1, for industrial applications. The main objective of this work is to realise an affordable, as well as durable, adaptable, and compliant gripper for industrial environments with a larger interval of stiffness variability than similar existing systems. The driving system for the proposed hand consists of two servo motors and one linear spring arranged in a relatively simple fashion. Having just a single spring in the actuation system helps us to achieve a very small hysteresis band and represents a means by which to rapidly control the stiffness. We prove, both mathematically and experimentally, that the proposed model is characterised by a broad range of stiffness. To control the grasp, a first-order sliding mode controller (SMC) is designed and presented. The experimental results provided will show how, despite the relatively simple implementation of our first prototype, the hand performs extremely well in terms of both stiffness variability and force controllability
A review on model-based and model-free approaches to control soft actuators and their potentials in colonoscopy
Colorectal cancer (CRC) is the third most common cancer worldwide and responsible for approximately 1 million deaths annually. Early screening is essential to increase the chances of survival, and it can also reduce the cost of treatments for healthcare centres. Colonoscopy is the gold standard for CRC screening and treatment, but it has several drawbacks, including difficulty in manoeuvring the device, patient discomfort, and high cost. Soft endorobots, small and compliant devices thatcan reduce the force exerted on the colonic wall, offer a potential solution to these issues. However, controlling these soft robots is challenging due to their deformable materials and the limitations of mathematical models. In this Review, we discuss model-free and model-based approaches for controlling soft robots that can potentially be applied to endorobots for colonoscopy. We highlight the importance of selecting appropriate control methods based on various parameters, such as sensor and actuator solutions. This review aims to contribute to the development of smart control strategies for soft endorobots that can enhance the effectiveness and safety of robotics in colonoscopy. These strategies can be defined based on the available information about the robot and surrounding environment, control demands, mechanical design impact and characterization data based on calibration.<br/
Modelado de sensores piezoresistivos y uso de una interfaz basada en guantes de datos para el control de impedancia de manipuladores robóticos
Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Arquitectura de Computadores y Automática, leída el 21-02-2014Sección Deptal. de Arquitectura de Computadores y Automática (Físicas)Fac. de Ciencias FísicasTRUEunpu
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