System Identification I

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.

In the past few years, soft robotics has rapidly become an emerging research topic, opening new possibilities for addressing real-world tasks Perception can enable robots to effectively explore the unknown world, and interact safely with humans and the environment Among all extero- and proprioception modalities, the detection of mechanical cues is vital, as with living beings A variety of soft sensing technologies are available today, but there is still a gap to effectively utilize them in soft robots for practical applications Here, the developments in soft robots with mechanical sensing are summarized to provide a comprehensive understanding of the state of the art in this field Promising sensing technologies for mechanically perceptive soft robots are described, categorized, and their pros and cons are discussed Strategies for designing soft sensors and criteria to evaluate their performance are outlined from the perspective of soft robotic applications Challenges and trends in developing multimodal sensors, stretchable conductive materials and electronic interfaces, modeling techniques, and data interpretation for soft robotic sensing are highlighted The knowledge gap and promising solutions toward perceptive soft robots are discussed and analyzed to provide a perspective in this field

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201800541

Toward Perceptive Soft Robots: Progress and Challenges

A soft, mobile, morphing robot is a desirable platform for traversing rough terrain and navigating into small holes. In this work, a new paradigm in soft robots is presented that utilizes jamming of a granular medium. The concept of activators (as opposed to actuators) is presented to jam and unjam cells that then modulate the direction and amount of work done by a single central actuator. A prototype jamming soft robot utilizing JSEL (Jamming Skin Enabled Locomotion) with external power and control is discussed and both morphing results and mobility (rolling) results are presented. Future directions for the design of a soft, hole traversing robot are discussed, as is the role and promises of jamming as an enabling technology for soft robotics.

/pdf/jsel-jamming-skin-enabled-locomotion-3vk7tzgs4v.pdf

JSEL: Jamming Skin Enabled Locomotion

Flexible instruments, i.e. instruments presenting a great number of degrees of freedom and able to perform snake-like movements when avoiding obstacles, can find a lot of applications in the medical field. On the other hand, flexible fluidic actuators, i.e. actuators having a flexible inflatable structure and actuated by fluid, present interesting features regarding medical applications. Therefore, this paper proposes to use these actuators to develop medical flexible instruments. Firstly, the advantages and drawbacks linked to the use of flexible fluidic actuators are listed and a discussion about the miniaturization of fluidic actuators peripherics (such as valves) is led. Next, a literature review of the existing flexible fluidic actuators is established. It can serve as basis to develop flexible instruments based on these actuators.

Towards flexible medical instruments: Review of flexible fluidic actuators

Current virtual reality systems are not enough to realize a force feedback system for hands, arms, legs and so on. Furthermore, due to the ageing in Japanese society and the decreasing birthrate, an increasing problem of providing nursing care for the elderly has occurred. As a result, it is necessary to develop systems to aid in nursing care. The actuators required for such systems, need to be flexible so as not to injure the human body. The purpose of our study is to develop a flexible and lightweight actuator which can be safe enough to be mounted on the human body. In this paper, we proposed and tested rodless type of flexible pneumatic cylinder. The cylinder consists of a flexible tube as a cylinder or rod, steel balls as a piston and a duralumin slide stage that has balls and rollers. We investigated the characteristics of the tested cylinder. We also applied the tested cylinder as a rotary actuator of master-slave robot arm. As a result, we found that the tested cylinders had a “self holding function for positioning” under condition of no supply pressure. We confirmed that the tested cylinder was useful to apply as a wearable actuator with the advantages of flexibility, lightweight and easier positioning.

/pdf/development-of-a-rodless-type-flexible-pneumatic-cylinder-fmiivv08gj.pdf

Development of a Rodless Type Flexible Pneumatic Cylinder and Its Application

Development of a Simple-structured Pneumatic Robot Arm and its Control Using Low-cost Embedded Controller

Development of Wearable Pneumatic Actuator and Multiport Pressure Control Valve

Current virtual reality systems are not enough to realize a force feedback system for hands, arms, legs and so on. Furthermore, due to the ageing in Japanese society and the decreasing birthrate, an increasing problem of providing nursing care for the elderly has occurred. As a result, it is necessary to develop systems to aid in nursing care. The actuators necessary for such systems, need to be flexible so as not to injure the human body. The purpose of study is to develop a flexible and lightweight actuator which can be safe enough to be mounted on the human body. In this paper, a new type of McKibben artificial muscle that had a long stroke of more than 80% of its original length was proposed and tested. A long stroke lifting motion of a load with mass of 6 kg was realized. As results of experiments, it was found that the generated force was related to sealing characteristics of the actuator. The construction of the slide stage of the actuator was modified and the generated force of the actuator was improved.

Shujiro Dohta

Papers

Development of a Rodless Type Flexible Pneumatic Cylinder and Its Application

Development of a Simple-structured Pneumatic Robot Arm and its Control Using Low-cost Embedded Controller

Development of Wearable Pneumatic Actuator and Multiport Pressure Control Valve

Development of McKibben Artificial Muscle with a Long Stroke Motion

Development of Smart Inner Diameter Sensor for Position Control of Mckibben Artificial Muscle