Ili Najaa Aimi Mohd Nordin

Development of bending soft actuator with different braided angles

In recent years, many researchers have been focusing on the different novel techniques in designing pneumatic soft actuator that can produce bending motion. This paper presents a novel soft actuator design; a combination of different braided angles of artificial muscle applied on a single chamber soft actuator to produce bending motion. The actuator construction is based on the theory of contraction and extension of artificial muscle. It comprises of fiber-reinforced inside silicone rubber and is capable to create one-sided bending motion. Analysis of nonlinear finite element method is conducted to predict the direction and bending angles of the actuator before a prototype of actuator is fabricated. Based on the results, the developed soft actuator can realize bending motion after standard pressure driving experiment is executed.

Two chambers soft actuator realizing robotic gymnotiform swimmers fin

This paper shows a study on two chambers soft actuator development and its application to an artificial soft actuator fin. Simulations of two chambers actuator are conducted using finite element method software and the bending angles produced are computed. Eleven designs are proposed and compared which differ in separating wall thickness, actuator thickness, fiber location, fiber materials, and rubber materials to analyze the optimal bending angle produced by the actuator. Two actuators are then fabricated and embedded at the ends of soft actuator fin to produce a traveling wave along the soft actuator fin. Soft actuator fin propels like gymnotiform swimmers and shows good linear motion.

3-D finite-element analysis of fiber-reinforced soft bending actuator for finger flexion

Towards the development of a safe, small, lightweight and human-friendly finger exoskeleton, device made from high elasticity material driven by pneumatic source; or simply known as soft actuator is currently being paid to attention. The study is to determine the optimum fiber-reinforced elastic soft actuator model to be employed in an exoskeleton for finger rehabilitation. Bending motion anticipated from a 3-D finite element actuator model is verified in the nonlinear finite element software, MARC™. The effectiveness of the proposed model is discussed based on the displacement data obtained from the large strain finite element analysis. Specific geometric properties, material properties, contact and boundary conditions related to the real experimental testing were applied to the analysis. Based on the results, the proposed model shows a good presentation of bending motion at applied pressure of 150 kPa. The behavior of bending motion which is greatly influenced by the angle of the fiber reinforced to the actuator is also discussed.

Simulations of fiber braided bending actuator: Investigation on position of fiber layer placement and air chamber diameter

Over recent years, studies on soft mechanism are rapidly being paid to attention especially in pneumatic actuator field. The actuator should provide sufficient force and flexibility in movement. The flexibility feature is vital in bending motion which needed in soft robotic actuation. There is no conventional fiber sleeve on single chamber actuator that can offer bending motion. In this paper, a new bending type actuator is introduced which the bending motion can be realized when braided fibers reinforcements on the cylindrical actuator rubber inner layer are formed from two different fiber angles. Two design parameters; position of fiber layer placement and air chamber diameter were varied and simulated to obtain the best specification of the proposed actuator design. The effects given by each design parameter were discussed and the dominant design parameter is also acknowledged from the FEM analysis. Significant bending motion was realized from the best model simulated. Actuator model with largest air chamber diameter and has the outermost position of fiber layer from the center point shows the highest bending capability.

Development of Flexible Bronchoscope Device Using Soft Actuator

Flexible bronchoscope or fiber optic bronchoscope (FOB) is commonly used for airway observation in lung diagnosis because of its easy, safe, and good tolerant technique. However, during intubation, FOB may lead to get jammed due to unpassed size. A novel soft-tip FOB development using soft actuator mechanism is proposed to solve the jamming problem. The study is focused on the design, fabrication, and implementation stages. The FOB design utilized a molding system that was drawn using SolidWorks and printed using 3D printer. The FOB fabrication used the printed mold to create the soft-tip by mixing the silicone rubber with its curing agent, pouring the mixture into the mold and solidifying them into the mold. The FOB initial implementation was performed by using tube and air compressor. Fabricating two types of soft actuator twisting and bending actuator developed a flexible bronchoscope using soft actuator. The result shows that the proposed soft-tip could move close to movement requirement after standard pressure driving experiment was executed.

Determination of non-linear material constants of RTV silicone applied to a soft actuator for robotic applications

SILASTIC P-1 Silicone, a hyper elastic material, supplied by Dow Corning® is considered for the current research of the development of a soft actuator. The uniaxial tensile testing and compression testing according to ASTM standards are conducted to find its mechanical material properties. The measured stress-strain data are then applied to three kinds of constitutive non-linear models and their respective non-linear material constants are computed by least square fit. The first order Ogden model shows the better agreement with the experimental data. The mechanical properties such as ultimate tensile strength, compressive strength, shear modulus and non-linear material constants of the selected material are finally presented which will further be used for the design and analysis of the soft actuator.

Non-Linear Finite Element Analysis of Biologically Inspired Robotic Fin Actuated by Soft Actuators

In this paper, a robotic fin was idealized with three rays, which are serially connected by thin flexible rubber membranes. Each ray consists a two chamber braided soft actuator operated by pneumatic pressure at the maximum of 20 kPa. The bending of the ray is achieved by alternating the supply of air to the chamber. The soft actuator bends to the right when the left chamber is pressurized and moves to the left when the right chamber is pressurized. The propulsive wave motion along the fin is thus achieved by oscillating the rays at the same frequency but in different phases. The finite element (FE) analysis was conducted in MARC®, nonlinear FE software, from which the lateral displacements of the rays and the corresponding effect on the membranes were measured. The wave amplitude of the fin was computed from the simulation results. The wave motion of the robotic fin and its corresponding pressure distributions were also observed and presented.

Numerical dynamic analysis of a single link soft robot finger

In this paper, a solid, single link soft robot finger was modeled with SILASTIC P-1 Silicone, supplied by Dow Corning®. The material is anon-linear hyper elastic, strain dependent, room temperature vulcanized (RTV) rubber. When the fingers are actuated for grasping and object manipulation, they vibrate with excessive amplitudes, which will disturb the precise positioning of the fingers. Vibration analysis through numerical simulation was conducted in ANSYS® V12. The first ten fundamental frequencies and their mode shapes were numerically computed and presented from modal analysis. The lowest natural frequency of the finger model was found to be 2.14 Hz. The dynamic stiffness of the finger model was then computed from the natural frequencies. It was found to be nonlinear in nature. The dynamic characteristics of the finger model during the excitation between 1 Hz and 1000 Hz were studied in transient analysis. The peak acceleration occurred at 9.3 Hz, while the peak velocity occurs at 3.75 Hz and 4.8 Hz with the magnitude of 0.013 mm/s.