# Singulation of Objects in Cluttered Environment Using Dynamic Estimation of Physical Properties
## 7 Conclusions  
In this paper, a scattering technique for object singulation in a cluttered environment is proposed. The main idea was to design a virtual world simulator based on the estimation of physical properties of the environment. In order to obtain physical properties of the objects, an impulse-based approach was used along with image processing technique to acquire observable parameters from videos. A virtual world simulator was employed to perform scattering in a desired manner. Finally, the effectiveness of the proposed scattering algorithm was verified through real-world scattering experiments.  
It will be difficult to perform model-based object singulation for complex-shaped objects with a non-uniform pressure distribution. Our future aim is to combine the analytical model with deep learning. The neural networks will be trained based on the simulations of a virtual world for the general shape of objects (circular, triangular, cube). By performing enough training of scattering patterns, we can perform scattering of complex-shaped objects in the virtual world, which are not being used during training. Finally, the virtual world input will be fed to the robot to perform real-world object singulation.  
Another ongoing work is developing an analytical model to distinguish pushing and scattering. In the real world, objects are singulated through physical contact between the object and manipulator. However, due to conditions of contact, such as the strength and speed of interaction, material properties, or environment friction, contact between the object and manipulator may be maintained or not. If contact is maintained during motion, it is the case of pushing (quasi-static manipulation). Other than that, the resulting behavior will be complete separation, as in the case of scattering (dynamic manipulation). Developing a relevant analytical model would facilitate analysis and control singulation of objects.  
The following are available online at [[http://www.mdpi.com/2076-3417/9/17/3536/s1](http://www.mdpi.com/2076-3417/9/17/3536/s1)]([http://www.mdpi.com/2076-3417/9/17/3536/s1](http://www.mdpi.com/2076-3417/9/17/3536/s1)), Video S1: Singulation of objects in virtual and real world.  
Conceptualization: I.H.S. and B.-J.Y.; methodology: A.I. and B.-J.Y.; software: A.I. and S.-H.K.; writing--original draft preparation: A.I.; writing--review and editing: I.H.S. and Y.-B.P.; supervision: B.-J.Y.; experimentation: S.-H.K. and A.I.  
This research was funded by the Technology Innovation Program (or Industrial Strategic Technology Development Program) (grant number 20001856, Development of Robotic Work Control Technology Capable of Grasping and Manipulating Various Objects in Everyday Life Environment Based on Multimodal Recognition and Using Tools) funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea), by the Ministry of Trade, Industry and Energy (MI, Korea), and performed by the ICT-based Medical Robotic Systems Team of Hanyang University, Department of Electronic Systems Engineering was supported by the BK21 Plus Program funded by National Research Foundation of Korea (NRF). The APC was funded by grant number 20001856.  
The authors declare no conflict of interest.