13 research outputs found
Soft robotic manipulators with proprioception
No full textAgriculture and horticulture depend heavily on human labor to perform tasks that are often dirty, hazardous, and highly repetitive. One reason for the lack of automation of these tasks is the absence of suitable robotic handling equipment. Rigid robotic manipulators are typically incapable of performing dexterous manipulation tasks such as harvesting apples as they lack the ability to adapt to objects of various shapes and sizes. Such robotic manipulators need a large number of sensors and actuators to overcome these challenges, making them overly complex and not very robust. Therefore, the development of robotic manipulators for dexterous manipulation tasks has begun to focus on morphological computation, in which at least some aspects of the control are outsourced to the body of the robot. Taking inspiration from grasping mechanisms in natural systems, the field of soft robotics attempts to address this problem by constructing robots from soft materials. Although soft robotics may be the key to realizing automation of dexterous manipulation tasks, the current commercially available soft robotic grippers are only capable of performing simple pick-and-place tasks with open-loop control. This limited capability is in large part due to a lack of techniques to endow these manipulators with a sense of self-movement and body position, known as proprioception. Proprioception is a simple problem for conventional robots with rigid members and discrete joints, as the body position can be easily reconstructed using the information from encoders in the robots’ joints. However, it is a highly challenging problem for soft robots with virtually infinite degrees of freedom and above all, no suitable off-the-shelf sensors…Materials and Manufacturin
Using soft robotics as a medium for gender accessible STEM education of preschoolers
No full textOnly 35 percent of the recent graduates are women. The figures are even lower for traditionally male dominated workforces such as engineering and robotics as women constitute only 12 percent of the engineering workforce. It is quite evident that we cannot ignore the gender equation when it comes to bringing in more equity in the workforce. As even the toys are heavily gendered, to take an example. Right from the way girls are prompted to play with Barbies and boys with G.I. Joes, this societal conditioning influences their future interest towards professions. In order to counter act the disparity in the STEM professions, a play based learning approach through the medium of soft robotics is used to get preschoolers equally interested towards the field of robotics in a gender-accessible manner. Silly Stompers consists of a reconfigurable base to which wide range of soft actuator blocks could be connected in various ways to create custom body movements. This provides a very tangible, screen-free, open ended experience for pre-schoolers through a fun way by allowing creating to create various pumping patterns. This provides compatibility with LEGO providing more open-ended outcomes. The learning outcomes mainly focus on constructive play and role play for pre-schoolers through the medium of soft inflatable actuators
Biomimetic design of a soft robotic fish for high speed locomotion
No full textWe present a novel DC motor driven soft robotic fish which is optimized for speed and efficiency based on experimental, numerical and theoretical investigation into oscillating propulsion. Our system achieves speeds up to 0.85 m/s, outperforming the previously reported fastest free swimming soft robotic fish by a significant margin of 27%. A simple and effective wire-driven active body and passive compliant body are used to mimic highly efficient thunniform swimming. The efficient DC motor to drive the system decreases internal losses compared to other soft robotic oscillating propulsion systems which are driven by one or multiple servo motors. The DC motor driven design allows for swimming at higher frequencies. The current design has been tested up to a tailbeat frequency of 5.5 Hz, and can potentially reach much higher frequencies.Accepted Author ManuscriptMaterials and ManufacturingInternet of Thing
Color-Based Proprioception of Soft Actuators Interacting with Objects
No full textActuators using soft materials feature a large number of degrees of freedom. This tremendous flexibility allows a soft actuator to passively adapt its shape to the objects under interaction. In this paper, we propose a novel proprioception method for soft actuators during real-time interaction with previously unknown objects. First, we design a color-based sensing structure that instantly translates the inflation of a bellow into changes in color, which are subsequently detected by a miniaturized color sensor. The color sensor is small and, thus, multiple of them can be integrated into soft pneumatic actuators to reflect local deformations. Second, we make use of a feed-forward neural network to reconstruct a multivariate global shape deformation from local color signals. Our results demonstrate that deformations of the actuator during interaction, including sigmoid-like shapes, can be accurately reconstructed. The accurate shape sensing represents a significant step toward closed-loop control of soft robots in unstructured environments.Materials and ManufacturingMechatronic Desig
Framework for Armature-Based 3D Shape Reconstruction of Sensorized Soft Robots in eXtended Reality
No full textSoft robots are typically intended to operate in highly unpredictable and unstructured environments. Although their soft bodies help them to passively conform to their environment, the execution of specific tasks within such environments often requires the help of an operator that supervises the interaction between the robot and its environment and adjusts the actuation inputs in order to successfully execute the task. However, direct observation of the soft robot is often impeded by the environment in which it operates. Therefore, the operator has to depend on a real-time simulation of the soft robot based on the signals from proprioceptive sensors. However, the complicated three-dimensional (3D) configurations of the soft robot can be difficult to interpret using traditional visualization techniques. In this work, we present an open-source framework for real-time 3D reconstruction of soft robots in eXtended Reality (Augmented and Virtual Reality), based on signals from their proprioceptive sensors. This framework has a Robot Operating System (ROS) backbone, allowing for easy integration with existing soft robot control algorithms for intuitive and real-time teleoperation. This approach is demonstrated in Augmented Reality using a Microsoft Hololens device and runs at up to 60 FPS. We explore the influence that system parameters such as mesh density and armature complexity have on the reconstruction's key performance metrics (i.e., speed, scalability). The open-source framework is expected to function as a platform for future research and developments on real-time remote control of soft robots operating in environments that impede direct observation of the robot
Rapid manufacturing of color-based hemispherical soft tactile fingertips
No full textTactile sensing can provide access to information about the contact (i.e.
slippage, surface feature, friction), which is out of reach of vision but
crucial for manipulation. To access this information, a dense measurement of
the deformation of soft fingertips is necessary. Recently, tactile sensors that
rely on a camera looking at a deformable membrane have demonstrated that a
dense measurement of the contact is possible. However, their manufacturing can
be time-consuming and labor-intensive. Here, we show a new design method that
uses multi-color additive manufacturing and silicone casting to efficiently
manufacture soft marker-based tactile sensors that are able to capture with
high-resolution the three-dimensional deformation field at the interface. Each
marker is composed of two superimposed color filters. The subtractive color
mixing encodes the normal deformation of the membrane, and the lateral
deformation is found by centroid detection. With this manufacturing method, we
can reach a density of 400 markers on a 21 mm radius hemisphere, allowing for
regular and dense measurement of the deformation. We calibrated and validated
the approach by finding the curvature of objects with a threefold increase in
accuracy as compared to previous implementations. The results demonstrate a
simple yet effective approach to manufacturing artificial fingertips for
capturing a rich image of the tactile interaction at the location of contact
Bonding between silicones and thermoplastics using 3D printed mechanical interlocking
No full textSilicones have desirable properties such as skin-safety, high temperature-resistance, and flexibility. Many applications require the presence of a hard body connected to the silicone. Traditionally, it has been difficult to create strong bonding between silicones and hard materials. In this study, a technique is presented to control the bonding strength between silicones and thermoplastics through mechanical interlocking. This is realized through a hybrid fabrication method where silicone is cast onto a 3D-printed mold and interlocking structure. The influence of the structure's design parameters on the bonding strength is explored through theoretical modeling and physical testing, while the manufacturability of the 3D-printed structure is ensured. A CAD tool is developed to automatically apply the interlocking structure to product surfaces. The user interface visualizes the theoretical strength of the cells as the designer adjusts the cell parameters, allowing the designer to iteratively optimize the structure to the product's load case. The bonding strength of the presented mechanical interlocking structure is more than 5.5 times higher than can be achieved with a commercially available primer. The presented technique enables custom digital design and manufacturing of durable free-form parts. This is demonstrated through application of the technique in over-molded products, airtight seals, and soft pneumatic actuators.Materials and ManufacturingMechatronic Desig
Development of a Soft Robotics Module for Active Control of Sitting Comfort
No full textSitting comfort is an important factor for passengers in selecting cars, airlines, etc. This paper proposes a soft robotic module that can be integrated into the seat cushion to provide better comfort experiences to passengers. Building on rapid manufacturing technologies and a data-driven approach, the module can be controlled to sense the applied force and the displacement of the top surface and actuate according to four designed modes. A total of 2 modules were prototyped and integrated into a seat cushion, and 16 subjects were invited to test the module’s effectiveness. Experiments proved the principle by showing significant differences regarding (dis)comfort. It was concluded that the proposed soft robotics module could provide passengers with better comfort experiences by adjusting the pressure distribution of the seat as well as introducing a variation of postures relevant for prolonged sitting.Technical SupportEmerging MaterialsMaterials and ManufacturingMechatronic Desig
Large area and flexible micro-porous piezoelectric materials for soft robotic skin
No full textThe need for flexible, highly sensitive tactile sensors that can fit onto curved surfaces is driving the conformable sensor materials research in the field of human–machine interactions. Here we report a new type of compliant piezoelectric active composite, a micro-porous polyurethane-PZT material, capable of generating a voltage output upon touch. The composites are synthesized with the aim of maximizing the piezoelectric sensitivity of particulate composite sensor materials. The goal is to reduce the dielectric constant of the polymer matrix and improve flexibility of conventional bulk piezo-composites, consisting of ceramic particles in a dense polymeric matrix, by adding a third (gaseous) phase to the system in the form of uniformly sized pores. The presence of the gaseous component in the polymer matrix in the form of well-distributed spherical inclusions effectively decreases the polymer dielectric permittivity, which increases the piezoelectric voltage sensitivity (g33) of the composite sensors significantly. The unique combination of dielectrophoretic structuring of PZT particles and the addition of a gaseous phase to the polymer resin results in the highest performance of the particulate composite sensors reported in the literature so far. The newly developed micro-porous composites show g33 value of 165 mV m/N that is twice that of the structured PZT-bulk PU composites (80 mV m/N) and more than five times the g33 value of bulk PZT ceramics (24–28 mV m/N). The capability of the flexible freestanding sensors for application in touch sensing devices for soft robotics is demonstrated
Diel plant water use and competitive soil cation exchange interact to enhance NH4 + and K+ availability in the rhizosphere
No full text© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Plant and Soil 414 (2017): 33-51, doi:10.1007/s11104-016-3089-5.Hydro-biogeochemical processes in the rhizosphere regulate nutrient and water availability, and thus ecosystem productivity. We hypothesized that two such processes often neglected in rhizosphere models — diel plant water use and competitive cation exchange — could interact to enhance availability of K+ and NH4+, both high-demand nutrients. A rhizosphere model with competitive cation exchange was used to investigate how diel plant water use (i.e., daytime transpiration coupled with no nighttime water use, with nighttime root water release, and with nighttime transpiration) affects competitive ion interactions and availability of K+ and NH4+. Competitive cation exchange enabled low-demand cations that accumulate against roots (Ca2+, Mg2+, Na+) to desorb NH4+ and K+ from soil, generating non-monotonic dissolved concentration profiles (i.e. ‘hotspots’ 0.1–1 cm from the root). Cation accumulation and competitive desorption increased with net root water uptake. Daytime transpiration rate controlled diel variation in NH4+ and K+ aqueous mass, nighttime water use controlled spatial locations of ‘hotspots’, and day-to-night differences in water use controlled diel differences in ‘hotspot’ concentrations. Diel plant water use and competitive cation exchange enhanced NH4+ and K+ availability and influenced rhizosphere concentration dynamics. Demonstrated responses have implications for understanding rhizosphere nutrient cycling and plant nutrient uptake.This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological & Environmental Research Terrestrial Ecosystem Science program under Award Number DE-SC0008182 to Z.G.C. and R.B.N
