Assembling parts in an assembly line

An automotive final assembly line, comprising

• a transport system with one or more Automated Guided Vehicles (AGVs) to advance one or more parts along the final assembly line, and
• an assembly unit comprising:
• an industrial robot, the industrial robot comprising a base, a wrist, an end effector to be attached to the wrist, and a robot controller to control an automated assembly operation to be performed by the end effector on a part that is advanced or supported by one of the one or more AGVs along the assembly line, the robot controller comprising a visual servoing controller,
• a first real time vision system with a vision sensor mounted stationary in the assembly line to monitor a position of the AGV in a horizontal advance direction along the assembly line and to monitor oscillations of the AGV in a vertical direction, readings of the first real time vision system being provided to the visual servoing controller of the robot controller,
• a second real time vision system arranged to monitor a position of a target area of the part that is advanced or supported by the AGV along the assembly line, and
• a compliant behaviour system to allow compliant behaviour of the end effector in at least one direction,
• the output of the second real time vision system being connected to the robot controller, and the robot controller being configured to perform an assembly operation comprising:
• a displacement of the industrial robot or the end effector synchronized with an advance of the AGV along the assembly line in an advance direction, and a movement of the end effector of the robot synchronized with the vertical oscillations of the AGV, based on readings of the first real time vision system,
• a visual servoing process in which the movement of the end effector of the robot is controlled in real time based on readings of the second real time vision system, and
• a compliant behaviour process in which the movement of the end effector of the robot is controlled to allow compliant behaviour thereof.

A method for assembling parts in an assembly line, comprising:

• advancing a part along the assembly line with an Automated Guided Vehicle (AGV), the part having a target area at which an assembly operation is to be performed,
• providing a first real time vision system to monitor a position of the AGV in at least a horizontal advance direction and a vertical direction, the first real time vision system being stationary in the assembly line,
• providing an assembly unit comprising an industrial robot with an end effector and with a robot controller to control an automated assembly operation to be performed by the end effector at the target area of the part that is advanced by the AGV,
• the method further comprising, while the part is advancing,
• displacing the robot or the end effector of the robot synchronized with the advance of the AGV along the assembly line in the advance direction based on readings of the first real time vision system, and displacing the end effector of the robot in a vertical direction synchronized with vertical oscillations of the AGV based on readings of the first real time vision system, and
• performing the assembly operation at the target area with the industrial robot, the assembly operation performed with the industrial robot comprising
• a visual servoing process in which movement of the end effector of the robot is controlled in real time based at least on readings of a second real time vision system arranged to monitor a position of the target area, and
• a compliant behaviour process in which movement of the end effector of the robot is controlled at least to allow compliant behaviour of the end effector in at least one direction.