Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

http://ieeexplore.ieee.org/iel5/5/31324/01456901.pdf

Microelectronic circuits

The 20th century's robotic systems have been made from stiff materials, and much of the developments have pursued ever more accurate and dynamic robots, which thrive in industrial automation, and will probably continue to do so for decades to come. However, the 21st century's robotic legacy may very well become that of soft robots. This emerging domain is characterized by continuous soft structures that simultaneously fulfill the role of robotic link and actuator, where prime focus is on design and fabrication of robotic hardware instead of software control. These robots are anticipated to take a prominent role in delicate tasks where classic robots fail, such as in minimally invasive surgery, active prosthetics, and automation tasks involving delicate irregular objects. Central to the development of these robots is the fabrication of soft actuators. This article reviews a particularly attractive type of soft actuators that are driven by pressurized fluids. These actuators have recently gained traction on the one hand due to the technology push from better simulation tools and new manufacturing technologies, and on the other hand by a market pull from applications. This paper provides an overview of the different advanced soft actuator configurations, their design, fabrication, and applications.

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Elastic Inflatable Actuators for Soft Robotic Applications

The compliance of soft grippers contributes to their great superiority over rigid grippers in grasping irregularly shaped objects and forming soft contact with environments. Due to a relatively small pressure, soft grippers lack the stiffness required for wider applications. Particle jamming has been frequently reported as a means of stiffness control. Unlike previous research using vacuum for particle jamming, this paper proposes a novel passive particle jamming principle that does not need any vacuum power or other control means. The proposed method is by simply patching a silicone rubber soft actuator and a pack (made of strain-limiting membrane) of particles to form an integral gripping finger. The inflation of the soft actuator applies a pressure to the particle pack causing particles inside it to jam. A larger squeezing pressure will result in tighter particle jamming, thus increasing the stiffness of the finger. The stiffness of the finger is controllable as it is proportional to the actuator's air pressure, which has been verified by experiments in this research. The stiffness can increase more than six fold when air pressure changes from 20 to 80 kPa in the experimental studies. The reported discovery may enhance the capabilities of soft robotic grippers so that more robotic picking operations could be performed by soft grippers.

Passive Particle Jamming and Its Stiffening of Soft Robotic Grippers

Soft robots have recently demonstrated impressive abilities to adapt to objects and their environment with limited sensing and actuation. However, mobile soft robots are typically fabricated using laborious molding processes that result in limited actuated degrees of freedom and hence limited locomotion capabilities. In this paper, we present a 3D printed robot with bellowed soft legs capable of rotation about two axes. This allows our robot to navigate rough terrain that previously posed a significant challenge to soft robots. We present models and FEM simulations for the soft leg modules and predict the robot locomotion capabilities. We use finite element analysis to simulate the actuation characteristics of these modules. We then compared the analytical and computational results to experimental results with a tethered prototype. The experimental soft robot is capable of lifting its legs 5.3 cm off the ground and is able to walk at speeds up to 20 mm/s (0.13 bl/s). This work represents a practical approach to the design and fabrication of functional mobile soft robots.

3D printed soft actuators for a legged robot capable of navigating unstructured terrain

A novel underactuated multi-fingered soft robotic hand for prosthetic application

The necessity of the soft gripping devices is increasing day-by-day in medical robotics especially when safe, gentle motions and soft touch are necessary. In this paper, a novel asymmetric bellow flexible pneumatic actuator (AFPA) has been designed and fabricated to construct a miniaturised soft gripper that could be used to grip small objects. The model of AFPA is designed using solid works and its bending motion is simulated in Abaqus software for optimisation and compared with experimental results. The actuator is fabricated using compression molding process that includes micromachining of the molds. Experiments conducted show the bending characteristics of the actuator at different pressures. The actuator shows excellent bending performance and the eccentricity in its design supports increased bending or curling motion up to a certain extent compared to normal bellows without eccentricity. The effects of profile shape and eccentricity on the actuator performance are analysed and the results are presented.

/pdf/asymmetric-bellow-flexible-pneumatic-actuator-for-miniature-52rvvlalec.pdf

Asymmetric Bellow Flexible Pneumatic Actuator for Miniature Robotic Soft Gripper

In the area of Robotics, the gripper plays a very important role as it is required to hold and place the object at the desired location. The requirements of gripper in terms of load capacity, and flexibility to adapt to the form of the object with tactile sensing capability which suit the strength of the object are necessary. Extensive research work is under way in the design of soft gripper or dexterous hand. An exhaustive survey of all such grippers conveys the idea of higher and higher sophistication with innumerable components and elaborate controls with programmable ability has been the outcome of research. Flexible micro actuators (FMA) proposed by earlier researchers are having two or more internal chambers and the internal pressure of each are controlled independently through flexible tubes which are connected to pressure control valves. The proposed actuator has a single internal chamber and is simple, compact and easy to manufacture. In this paper, a flexible microactuator (FMA) driven by a pneumatic/ hydraulic system with single internal chamber has been developed for robotic soft gripper. By proper selection and manufacturing of the asymmetric tube flexible actuator with reinforcement, a versatile dexterous hand can be fabricated which is suited for dynamic application closely approximating to the human hand. The present work has paved the way for extensive research on this innovative technique as it holds out the true potential for innumerable and very interesting application in various areas such as micro robots, pipeline inspection robots, underwater robots and walking robots‥

Robotic gripper driven by flexible microactuator based on an innovative technique

Human Gesture Recognition for Real-Time Control of Humanoid Robot

Renewable energy is vital for today's world since in the near future the non-renewable sources that we are using are going to get exhausted The solar vehicle is a step towards saving these non-renewable sources of energy A solar vehicle uses energy generated directly from PV panels and solar energy stored in the on-board battery The real-time solar power and the charged batteries are used to drive the electric motor and move the vehicle in reverse and forward directions This innovative solar vehicle, known as Amrita Surya Vahini, is a three wheeled solar auto rickshaw designed and fabricated without a differential mechanism by using BLDC hub motors directly coupled to the wheels The vehicle uses a 1200 Watt flexible solar panel which is placed not only on the roof top but also on the sides of the auto rickshaw The vehicle runs at a top speed of 50 km/hr and travels a distance of 80 to 120 km per battery charge with a cruising speed of 30 km/hr The manufactured solar auto rickshaw is a light weight and efficient, with a design that can be commercialised for the benefit of the society

Ganesha Udupa

Papers

A novel underactuated multi-fingered soft robotic hand for prosthetic application

Asymmetric Bellow Flexible Pneumatic Actuator for Miniature Robotic Soft Gripper

Robotic gripper driven by flexible microactuator based on an innovative technique

Human Gesture Recognition for Real-Time Control of Humanoid Robot

Design and manufacture of Amrita Surya Vahini — A solar auto rickshaw