Research

Summaries of selected research projects:

 

A Lightweight High-Voltage Boost Circuit for Soft-Actuated Micro-Aerial-Robots (ICRA 2023, Accepted)
 
We developed a 127 mg boost circuit that can convert a 7.7 V DC input into a 600 V and 400 Hz output for driving a 120 mg dielectric elastomer actuator (DEA). The DEA is then assembled into a 158 mg aerial robot, which can demonstrate liftoff while carrying the boost circuit as a payload. The circuit was designed based on the well-known flyback topology and optimized through several iterations to achieve light weight. For the circuit fabrication, I used a diode-pulsed laser to ablate and cut the desired copper traces on a 0.13 mm thick copper-clad FR4 sheet and hand soldered all the components. The finished circuit has a dimension of 9.6 mm x 7.5 mm. The DEA is then assembled into a 158 mg aerial robot, which can demonstrate liftoff while carrying the boost circuit as a payload. 
 
 

 

A High‐Lift Micro‐Aerial‐Robot Powered by Low‐Voltage and Long‐Endurance Dielectric Elastomer Actuators (Advanced Materials, Cover Article)
 
We designed and fabricated a low voltage, high endurance, and power-dense DEA based on novel multiple-layering techniques and electrode material optimization. When operated at 400 Hz, the 143 mg DEA generates forces of 0.36 N and displacements of 1.15 mm. This DEA is incorporated into an aerial robot to demonstrate high performance. The robot achieves a high lift-to-weight ratio of 3.7, low hovering voltage of 500 V, and a long lifetime that exceeds 2 million actuation cycles. With 20 seconds of hovering time, and position and attitude error smaller than 2.5 cm and 2°, the robot demonstrates the longest and best performing flight among existing sub-gram aerial robots.  
 

 

 

 
Collision Resilient Insect-Scale Soft-Actuated Aerial Robots With High Agility (IEEE Transactions on Robotics, Best Paper)
 
We present a 665 mg aerial robot that is powered by novel dielectric elastomer actuators (DEA). The DEA achieves high power density (1.2 W/g) and relatively high transduction efficiency (37%). We further incorporate this soft actuator into an aerial robot to demonstrate novel flight capabilities. This insect-scale aerial robot has a large lift-to-weight ratio (>2.2:1) and it achieves an ascending speed of 70 cm/s. In addition to demonstrating controlled hovering flight, it can recover from an in-flight collision and perform a somersault within 0.16 s.
 

 

 

 
Shape Memory Alloy (SMA) Actuator With Embedded Liquid Metal Curvature Sensor for Closed-Loop Control (Frontiers in Robotics and AI)
 
We introduce a soft robot actuator composed of a pre-stressed elastomer film embedded with shape memory alloy (SMA) and a liquid metal (LM) curvature sensor. The soft sensor is thin and elastic and can track curvature changes without significantly altering the natural mechanical properties of the soft actuator. We show that the sensor can be incorporated into a closed-loop “bang-bang” controller to ensure that the actuator fully relaxes to its natural curvature before the next activation cycle. In this way, the activation frequency of the actuator can be dynamically adapted for continuous, cyclic actuation. Moreover, in the special case of slower, low power actuation, we can use the embedded curvature sensor as feedback for achieving partial actuation and limiting the amount of curvature change.