Hoa Phung

A small biomimetic quadruped robot driven by multistacked dielectric elastomer actuators

A kind of dielectric elastomer (DE) material, called ‘synthetic elastomer’, has been developed based on acrylonitrile butadiene rubber (NBR) to be used as a dielectric elastomer actuator (DEA). By stacking single layers of synthetic elastomer, a linear actuator, called a multistacked actuator, is produced, and used by mechatronic and robotic systems to generate linear motion. In this paper, we demonstrate the application of the multistacked dielectric elastomer actuator in a biomimetic legged robot. A miniature robot driven by a biomimetic actuation system with four 2-DOF (two-degree-of-freedom) legged mechanisms is realized. Based on the experimental results, we evaluate the performance of the proposed robot and validate the feasibility of the multistacked actuator in a locomotion system as a replacement for conventional actuators.

Printable monolithic hexapod robot driven by soft actuator

Aiming to apply soft actuators in driving a walking robot, the design, fabrication and locomotion of a bio-inspired printable hexapod robot are studied. The robot mimics the insects design and walking posture by driving six legs with alternating tripod gait which provides its locomotive adaptability on flat terrains. The versatile movements of the robots leg are achieved by using soft and multiple degree-of-freedom actuators. The actuators are made by dielectric elastomers with a simple mechanism based on antagonistic configuration. By using 3D printing method, the actuator can be embedded into the frame of the robot and a control system is developed. Finally, the robots locomotion is successfully demonstrated with variable speeds and stride lengths.

A highly sensitive dual mode tactile and proximity sensor using Carbon Microcoils for robotic applications

This paper presents a highly sensitive dual mode tactile and proximity sensor for robotic applications that uses Carbon Microcoils (CMCs). The sensor consists of multiple electrode layers printed on a Flexible Printed Circuit Board (FPCB) and a dielectric substrate into which the CMCs are dispersed. The dielectric layer is simply put on the top of the FPCB. Thus, the sensor provides ease of fabrication and robustness against repetitive external contacts because the dielectric layer protects the electrodes. The electrical properties of the sensor are changed when an object approaches or touches the sensor. The sensor uses a capacitive sensing mode for tactile sensing and an inductive sensing mode for proximity sensing. CMCs amplify the change of the sensor signal because of electrical impedance formed by the CMCs, and thus, the sensitivity of the sensor increases. We fabricate the prototype sensor with the dimensions of 30 × 30 × 0.6 mm3, and with 3 mm spatial-resolution. The sensor detects the applied pressure up to 330 kPa and the distance of an object as much as 150 mm away.

Development of a smart handheld surgical tool with tactile feedback

This paper presents a handheld surgical tool adapting a tactile feedback system. The tool consists of a 3-degree-of-freedom (DOF) force sensor and three tactile displays. The sensor is easily embedded in the tool by adopting the capacitive transduction principle. The sensor measures the direction and magnitude of the 3-DOF force applied to the tool tip. The fingertip grasping the tool is stimulated by the tactile display to transmit the contact force information measured by the sensor. The tactile display is actuated by employing a soft actuator technology based on a dielectric elastomer actuator such as a type of electroactive polymer actuator. In this work, a prototype of the tool is designed and fabricated. Its performance is experimentally validated.

Biomimetic printable hexapod robot driven by soft actuator

This paper presents the preliminary design of a biomimetic printable hexapod robot driven by soft actuators. The robot mimics the insects design with six legs and shows the capability of versatile locomotion on flat terrains by using alternating tripod gait. The soft and multiple degree-of-freedom (multi-DOF) actuators based on dielectric elastomer provide required motions of the robot with a simple mechanism based on antagonistic configuration. The fabrication of the robot is effectively implemented by 3D printing method. In addition, a control system is built to provide various locomotion and walking speeds for the robot and its operation is demonstrated.

Highly sensitive proximity and tactile sensor based on composite with dielectric elastomer and carbon microcoils

This work presents a dual purpose sensor for collecting proximity and tactile information by using a composite with dielectric elastomer (DE) and Carbon Micro Coils (CMC). CMC is a coil-like carbon microstructure with the size of several hundred micrometers, and its electrical characteristics change with the distance between the object or via physical contact. Especially, the impedance change of the composite depending on the distance can be used as the principle for proximity sensing. We present a method to process the materials by using dielectric materials and additives. A prototype of the sensor is fabricated and its feasibility is experimentally validated.

A highly flexible, stretchable and ultra-thin piezoresistive tactile sensor array using PAM/PEDOT:PSS hydrogel

This paper presents a highly flexible, stretchable and ultrathin piezoresistive tactile sensor array, which can be attached to a tactile display actuator array [1] without any influence on its motion. Its operational principal is based on the resistance changing of a tactile cell array prepared by blending a precise conductive polymer — Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) with Polyacrylamide (PAM) hydrogel. Through comparing the characteristics of the blended hydrogel mixed between PAM and PEDOT with different ratios 2.5:1; 3:1; 3.5:1 respectively, the 2.5:1 ratio is the appropriate sample selected as the sensor design. Then, the 12×8 tactile sensor array were fabricated by dropping the conductive hydrogel into the cavity of two electrodes cast on Sylgard 184 substrates (PDMS), which is flexible and thin — around 800μm thickness in total. Finally, a primary measuring circuit using Wheatstone Bridge with a low-pass filter, an amplifier, and a signal processing circuit are also built to demonstrate the sensor s performance successfully.

Design and fabrication of compliant proximity-tactile sensor using carbon micro coils

This paper presents a stretchable proximity-tactile sensor (PTS) using Carbon Micro Coils (CMC). The PTS consists of pairs of multiple active electrodes and a common ground electrode on the same plane. Thus, the sensor is tolerable to the repetitive contacts from external forces. The top layer consists of dielectric elastomer substrate mixed with 5% of CMC, so that it can respond to the proximity and tactile stimuli. Electrodes are located under the top layer and optimally organized to reduce the number of wirings. The sensor is fabricated by molding and casting methods. As the result, a 4 × 4 sensor prototype is made and its performance are experimentally evaluated.