A research paper by scientists at the University of Coimbra proposed a soft robotic hand that composed of soft actuator cores and an exoskeleton, featuring a multimaterial design aided by finite element analysis to define the hand geometry and promote finger's bendability. The new research paper, published on Aug. 8 in the journal Cyborg and Bionic Systems, presented the development, fabrication, and control of a bioinspired soft robotic hand and demonstrated finite element analysis can serve as a valuable tool to support the design and control of the hand's fingers.
"Recent research led to impactful achievements in functional designs, modeling, fabrication, and control of soft robots. Nevertheless, the full realization of life-like movements is still challenging to achieve, often based on trial-and-error considerations from design to fabrication, consuming time and resources. Using finite element analysis to support the design process, saving time and resources", explained study author Pedro Neto, a professor at the University of Coimbra. The finite element analysis comprising (a) hyperelastic behavior of the soft materials, (b) finite rotation and large strain of the exoskeleton and actuators, and (c) frictional contact between exoskeleton and actuators. "This integrated solution will make soft robotic hands more available to people, at a reduced cost, avoiding the time-consuming design-fabrication trial-and-error processes", said authors. Thus, they proposed a soft robotic hand that composed of soft actuator cores and an exoskeleton, featuring a multimaterial design aided by finite element analysis to define the hand geometry and promote finger's bendability.
Soft robots can be fabricated by using multiple materials and using different manufacturing processes, ranging from silicone molding to 3D printing. 3D printing methods bring significant benefits in design and fabrication, making it easy to introduce complex geometries within soft robots, accelerating/automating the fabrication process, and reducing its cost. "3D printing allows the introduction of sensing and control elements within the robot, promoting innovation in multiple application domains", said Alves.
The study authors showed that the multimaterial soft actuators are designed and fabricated at a reduced cost and time effort, using standard fabrication processes such as molding and single-step 3D printing. The ON–OFF controller, while simple, keeps the set fingers bending angles stable, even in the presence of leaks. The robotic hand demonstrated dexterity and capability to grasp objects with different shapes, weights, and sizes.
"The reinforcement in a circumferential direction guarantees the actuator's elongation and consequently the fingers bent when inside the exoskeleton. The robotic hand achieved an interesting dexterity level, being able to grasp objects of different shapes and sizes. Nevertheless, it struggles to grasp heavier objects featuring slippery surfaces, showing a concentrated deformation at the base of the fingers while the thumb motion is constrained. In addition, depending on the grasping surface and geometry, there exists mechanical interference between the fingers. Since the soft hand is highly nonlinear, with most variables of interest being coupled between themselves, future work will be dedicated to an in-depth analysis of the grasping phenomena together with further standardization of testing benchmarks," said Alves. Totally, this soft robotic hand is accessible and can be built at a reduced cost, avoiding the time-consuming design-fabrication trial-and-error processes, and inspiring innovation around it.
Authors of the paper include Samuel Alves, Mihail Babcinschi, Afonso Silva, Diogo Neto, Diogo Fonseca, Pedro Neto
Portuguese national funds through FCT—Fundação para a Ciência e a Tecnologia (grant numbers UIDB/00285/2020, LA/P/0112/2020, and 2022.13512.BD).
The paper, "Integrated Design Fabrication and Control of a Bioinspired Multimaterial Soft Robotic Hand" was published in the journal Cyborg and Bionic Systems on Aug 8, 2023, at DOI: 10.34133/cbsystems.0051.
