Tham khảo tài liệu 'robot manipulators, new achievements part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Robotic Machining from Programming to Process Control 37 compliant in normal to the path direction to make the tool constantly contact with the workpiece. Thus an accurate path could be generated automatically. During the machining process the force controller provides two more functions to achieve deformation compensation and CMRR. In both case robot is still under position control that is stiff at all directions. Deformation compensation is achieved by update the target position of position loop based on the measured process force and robot stiffness model while robot feed speed is adjusted to maintain constant spindle power consumption for CMRR. These two strategies are complementary to each other since CMRR adjusts robot speed at feed direction and deformation compensation adjusts the reference target at the rest of the directions. The detailed control strategies for process control of robotic machining will be explained in section four and five respectively. 3. Rapid Robot Programming Although extensive research efforts have been carried out on the methodologies for programming industry robots still only two methods are realistic in practical industrial application which are on-line programming jog-and-teach method and off-line programming Basanez Rosell 2005 Pires et al. 2004 . On-line programming relies on the experience of robot operators to teach robot motions by jogging the robot to the desired positions using teaching device usually teach pendent in real setup. Off-line programming generates the robot path from a CAD model of the workpiece in a computer simulated setup. The idea of programming by demonstration PbD has been proposed long time ago while requirement of additional hardware devices and complicated calibration process make it unattractive in practical applications. The major advantage of the PbD method proposed here is that no additional devices and calibration procedures are required. The only sensor implemented for force feedback is an ATI 6
