I. INTRODUCTION  
A. The development of robotic peg-in-hole assembly  
B. The motivation and purpose of this paper  

II. ROBOTIC PEG-IN-HOLE ASSEMBLY SYSTEM  
A. Mating parts  
B. Sensing system  
C. Manipulators  

III. CONTACT MODEL-BASED CONTROL STRATEGIES  
A. Contact state recognition with analytical model  
B. Contact state recognition with statistical model  
C. Compliant control  

IV. CONTACT MODEL-FREE LEARNING STRATEGIES  
A. LFD  
B. LFE  

V. DISCUSSION AND CONCLUSION  
A. Open questions in the field of robotic peg-in-hole assembly?  
B. Potential future work