The actuator is the heart of a machine. It profoundly restricts the output power, force, speed, and even shape and size of the machine. We cannot emphasize the importance of developing actuators too much. For future lightweight, compliant, agile, and dexterous robots, my work is currently focused novel actuators such as electrostatic film actuators, electrostatic adhesion, IPMC, and SMA. Using these new techniques on actuators, we build robots with unique features such as ultra-low profile, lightweight, and great flexibility, which cannot be achieved from conventional motors.
From millimeter-scale insects to meter-scale vertebrates, several animal species exhibit multimodal locomotive capabilities in aerial and aquatic environments. To develop robots capable of hybrid aerial and aquatic locomotion we require versatile propulsive strategies that reconcile the different physical constraints of airborne and aquatic environments. Furthermore, transitioning between aerial and aquatic environments poses significant challenges at the scale of microrobots where interfacial surface tension can be substantial relative to the weight and forces produced by the animal/robot. Here we report the design and operation of an insect-scale robot capable of flying, swimming, and transitioning between air and water. This 175 mg robot employs a multi-modal flapping strategy to efficiently locomote in both fluids. Once the robot swims to the water surface, lightweight electrolytic plates produce oxyhydrogen from the surrounding water that is collected by a buoyancy chamber. Increased buoyancy force from this electrochemical reaction gradually pushes the wings out of the water while the robot maintains upright stability by exploiting surface tension. A sparker ignites the oxyhydrogen and the robot impulsively takes off from the water surface. This work analyzes the dynamics of flapping locomotion in an aquatic environment, identifies the challenges and benefits of surface tension effects on microrobots, and further develops a suite of new meso-scale devices that culminate in a hybrid, aerial-aquatic microrobot.
When a robot weighs 1.6g and is several centimeters long, it faces opportunities and challenges unique to its scale. Leveraging on surface tension, the robot can easily move along the surface of water. On the other hand, it needs to overcome the inhibiting surface tension force when it wants to transition into or come out of water. This is the first centi-metered scaled robot that can freely transition between land, the surface of water, and underwater.
Using the novel actuators electrostatic actuators and electrodense films (instead of conventional motors and magnets) for actuation and latching respectively, we build ultra-thin (2.5 mm high), flexible (no rigid component) climbing robots (distinguished them from the conventional rigid clumsy climbing robots), which can be applied to the inspection in a narrow gap or confined space.
Multiple-segment flexible and soft robotic arms composed by ionic polymer–metal composite (IPMC) flexible actuators exhibit compliance but suffer from the difficulty of path planning due to their redundant degrees of freedom, although they are promising in complex tasks such as crossing body cavities to grasp objects. We propose a learning from demonstration method to plan the motion paths of IPMC based manipulators, by statistics machine-learning algorithms. To encode demonstrated trajectories and estimate suitable paths for the manipulators to reproduce the task, models are built based on Gaussian Mixture Model and Gaussian Mixture Regression respectively. The forward and inverse kinematic models of IPMC based soft robotic arm are derived for the motion control. A flexible and soft robotic manipulator is implemented with six IPMC segments, and it verifies the learned paths by successfully completing a representative task of navigating through a narrow keyhole.
Traditional rigid robotic hand manipulator has been used in many field nowadays due to its advantages of large gripping force and stable performance. However, this kind of rigid manipulator is not suitable for gripping fragile objects since it is motorized and force control can be a problem. It is also not suitable to grip object with different shapes since the manipulator is rigid and not compliant. In this study, a novel manipulator with gripping capability is designed and fabricated. The manipulator combines electrostatic adhesion actuation with soft manipulators. The manipulator has high flexibility and can be compliant to different shapes due to the property of the materials. It is very promising to do delicate manipulations in industry field and biomedical field.
- Built a model for localization and tracking of multiple sound sources
- Designed and fabricated the mechanical structures and the circuit of microphone arrays for sound-source localization and tracking