Research

1. Bio-mimetic robot

1) Quadrupedal robot

• Compared to wheel-based robots, biomimetic robots that consist of multi degrees of freedom show better performance in overcoming obstacles. In particular, snake robots have the potential to overcome various obstacles.

• Quadnake is a quadruped robot with 24 degrees of freedom. Quadnake can perform the locomotion of snake robots using their redundant degree of freedom. These motions can be implemented to overcome obstacles including, narrow gaps.

• Pybullet simulation of Quadnake was conducted. Based on these simulation results, the hardware specification of Quadnake was improved by changing actuators near the body. Through these improvements, Quadnake could implement more complex motions.    

     2) Snake robot 

• The snake robot has multiple joints and can perform various motions because of its high degree of freedom. Also, it can pass through narrow spaces and climb pipes by using its long and thin body.

• The snake robot is driven through MATLAB and Simulink, and angle and current values can be measured in real time. In the future, we plan to perform feedback control through the angle, current value, or the value measured through an additional sensors.

• Servo motors are combined with supporters and placed in series to make a snake robot. Driving assistant mechanism was produced to prevent the robot from rolling down on a slope.    

    3) Jumping robot 

• Recently, diverse research has actively been conducted to control the posture of jumping robots using an inertial tail mechanism. However, the inertial tail mechanism has a high probability of collision with obstacles.

• The momentum wheel mechanism was used to achieve the same attitude control performance while reducing the volume of the inertial tail. The reason is that the momentum wheel can produce a large control output despite a small control input and the size of the momentum wheel is lower than the inertial tail mechanism.

• To verify the performance of the momentum wheel mechanism, we proposed a jumping robot with a momentum wheel mechanism and performed a dynamic analysis, simulation, and experiments on a jumping robot with a momentum wheel mechanism.  

  4) Robotic bird 

• A flying robot that mimics the wing flapping mechanism of small birds like crows and magpies. The robot implements the Articulated Wing structure, a structure in which wings articulate in the middle like a real bird when flapping their wings.

• In the Articulated wing structure, the wings fold when the wings go up, unfold when they come down, and the area that pushes the air is different, so the wings themselves can generate lift.  As a result, the robot shows high flight stability and energy efficiency even in small size.

• The implemented bird robot has high flight performance and quietness by applying an articulated wing mechanism making the robot suitable for reconnaissance mission and terrain exploration.

2. Robotic hand and manipulator

1) Robot gripper for industry

• The industrial gripper developed today has a simple shape and can only perform particular tasks, and the development of an anthropomorphic robot hand is essential to complement this. Research is being conducted on developing a high-performance anthropomorphic robot hand that mimics various parts of the human hand.

• Measuring the force and torque applied to the gripper wrist is essential for the use of the industrial gripper. By utilizing the principle of a parallel robot capable of 6-degree-of-freedom movement and force control, it is possible to develop a compliant gripper wrist that can measure the deformed position, angle, and force.

2) Soft gripper 

2-1) CFH finger & Humanoid robot hand 

• In this study, an anthropomorphic(humanoid) robot hand was developed that can absorb shocks in various directions and has a large payload by using a crossed flexure hinge (CFH) structure.

• In order to check whether CFH is a suitable structure for human hand joints, the problem was analyzed through a 6x6 stiffness matrix. To reinforce weak rigidity, a new structure, paired-CFH (p-CFH) structure, was proposed and applied to the joint.

• A quantitative impact test was performed to confirm the shock absorption rate of the anthropomorphic robot hand developed using the CFH structure. It was proved that the impact can absorb 46.7% more than the existing pin joint-based robotic hand due to the compliance of the hinge itself.  In addition, it was confirmed that various objects of unspecified shape were stably grasped without motor control in a shape-adaptive method.

    2-2) Pneumatic finger 

• In this study, the soft gripper can mimic human hand’s multiple motion by focusing on the air chamber design and position.The soft actuator consists two or three air chambers, that makes it possible to grasp an object and rotate it.

• To make a soft gripper for performing various motion by adding the chambers includes rotating any object on the initial place, where the object was except grasping and by their position in soft finger

• We used the finite element method (FEM) method to design the most effective model, and later these results were compared with results from experiments. 

    2-3) Wearable globe

• In this study, we proposed a new method, the ring-pull mechanism, to overcome the disadvantages of existing wearable robotic gloves. By attaching a ring to the metacarpophlangeal(MCP) joint of the finger, the ring-pull mechanism supplements the grasping force of the user, while reducing the weight of the entire wearable robotic glove system. 

• The main body of the developed RPSG is composed of single polymer silicon, a soft material, and is driven by tendon-driven actuation. The tendon path is secured through a tube attached to the palm that matches the direction of the flexor digitorum superficialis(FDS). 

• The RPSG increased the subject's grasping force by 25.69% on average, and the %MVIC data analysis demonstrated that the activation of FDS decreased by about 23.51%.

3. Mechatronics system 

    1) Sensors and actuator 

• we are not only conducting research on the application of  various sensors on the robotic field, but also conducting research on the development of various sensors.

• In particular, we are researching and developing various sensors and actuators using the electromagnetic field principle, and we have the original technology for the design and analysis of LVDT, a high-precision displacement sensor and we also have several patents and technology transfer records. In addition, we have developed various types of electromagnetic actuators such as BLDC motors, induction motors and linear actuators.

• In addition, we are conducting research on various displacement and force sensors using the elasticity of flexible materials.

2) Micropatterning system 

• With the development of mobile sensors and biosensors, ultrafine process technology that can generate ultrafine patterns and has mass production capability has garnered attention recently.

• We devised the the impact print-type hot embossing process that can create user-defined micropatterns with various widths and depths in real-time on various types of polymer films.  Thanks to the multi-header and control algorithm, this process can generate repetitive patterns in real-time, and it can adjust the pattern resolution by controlling the pattern extraction interval.

• The proposed method is thus expected to be widely applicable to industrial fields that require microscale user-defined patterns such as mobile sensors and biosensors.

3) Personal Off-the-ground(OTG) Mobility

• This research  suggests a prototype of a personal off-the-ground(OTG) mobility system. This was carried out jointly by DGIST and KAERI, and was supported by KEIT's Alchemist Research Project. The project was a competitive project and our research team took first place among 6 research teams.

• Through this study, the goal was to develop a non-contact transportation system that can be used by individuals, and to do this, a new mechanism that can increase agility by using two air cushion flotation devices, which resemble a bi-copter drone system, was proposed. 

4. Artificial intelligence for robotics

1) Safe-HRC with ML & Vision

• As the 4th Industrial Revolution occurs, there is a change in factories into a smart factory where robots and people work together in the same space. Therefore, various studies are being conducted to ensure human safety.

• Among them, many studies have been conducted on preventing collisions between humans and cooperative robots in advance through active safety guarantee methods.

• We are conducting a study that combines various sensors and cameras with machine learning to allow robots to avoid humans. Through this study, it is expected that even if humans and robots perform work in the same space, robots will be able to enter our lives safely.

    2) AI based approaches for mobile robots 

• Recently, many AI-based approaches have been applied to mobile robots. We utilize these approaches for motion planning, environment recognition, pose estimation, etc.

• Imitation learning was used to enhance the performance of the obstacle-avoiding algorithm. The imitation-learning-based algorithm showed a higher success rate in dynamic and static obstacle avoidance compared to the rule-based algorithm.

• To estimate 6-DOF poses for mobile robots such as snake robots, vision markers are used along with ROS system integration. 

5. Autonomous locomotion 

1) Biomimetic RL Controller for mobile robots

• Recently, artificial neural network libraries and related SW tools have been developed, increasing the accessibility of artificial intelligence development. Among the studies conducted using artificial neural networks, in the case of DL or ML, learning is performed by a supervised learning method that requires a large amount of data.

• We are conducting research to speed up this learning through a powerful physics engine and simulators, and through this, we are pursuing to develop an effective controller for multi degree-of-freedom snake robots.

• If a controller of the snake robot with non-linear dynamics can be implemented through reinforcement learning, it is expected that the snake robot will be operated in a variety of environments than the existing controllers that simply generate repetitive movements.

     2) Path tracking and obstacle avoiding of mobile robots 

• Snake robots are attracting attention as small disaster response robots because they can overcome various and narrow terrain. However, their driving directions are not intuitive, so they have high operational difficulties.

• This study proposes a driving direction estimator of a 3-dimensional wheel-less snake robot for autonomous locomotion, such as path tracking and obstacle avoiding.