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Robotic Assembly

Robotic Assembly
  • Research Background
    • Because the assembly margin of a precision part is smaller than the position accuracy of robots, a robot based on position control cannot assemble precision parts. In order to solve this problem, an assembly strategy based on force control is suggested.
  • Research Objectives
    • Force control for an assembly task
    • Sensor compensation to eliminate effect of end-effector
    • An assembly task based on blind search
  • Research Output
    • Round peg-in-hole (Assembly margin: 0.08mm)
    • 김병상, 김영렬, 송재복, 손승우, 6축 머니퓰레이터를 이용한 임피던스 제어 기반의 원형 펙 조립 (Impedance Control based Peg-in-Hole Assembly using a 6 DOF Manipulator), 대한기계학회 논문집 A, 35권, 4호, pp. 347-352, 2011.04.
  • Control system of manipulator
    • Control system based on PC (CPU:dual core 3.0GHz)
    • Using an external timer for a real-time control (sampling time: 1 ms)
    • Using a motion controller for a position control (AJINEXTEK, PCI-N804)
            

  • Force control for an assembly task
    • Impedance control based on position control
    • Task space: impedance control using an admittance filter
    • Joint space: position control
            

  • Sensor compensation
    • Load identification: estimation of inertia parameters (mass, mass center)
    • Gravity compensation : compensation of gravity force of assembly parts
    • Contact force extraction
            

  • Sensor compensation: Load identification
    • Using F/T sensor data and manipulator pose data
    • Data acquisition operating only joint 5 and 6
    • Estimation error: below 5%

  • Sensor compensation: Gravity compensation
    • Computation of gravity force from current manipulator pose
    • Gravity compensation error: below 1N
            

  • Assembly strategy
    • Assembly strategy based on blind search
    • Contact detection based on sensing force
    • Hole detection using peg position