Everhart, T., "Neighboring Mobile Robot Cell with Drilling and Fastening," SAE Technical Paper 2017-01-2094, 2017.
Electroimpact, in collaboration with Boeing, has developed an advanced robotic assembly cell, dubbed “The Quadbots.” Using Electroimpact’s patented Accurate Robot technology and multi-function end effector (MFEE), each robot can drill, countersink, inspect hole quality, apply sealant, and insert fasteners into the part. The cell consists of 4 identical machines simultaneously working on a single section of the Boeing 787 fuselage, two on the left, and two on the right. These machines employ “collision avoidance” a new feature in their software to help them work more synchronously. The collision avoidance software uses positional feedback from external safety rated encoders mounted to the motors on the robot. From this feedback, safe spaces, in the form of virtual boundaries can be created. Such that a robot will stop and wait if the adjacent robot is in, or going to move into its programmed work envelope. Another feature of the collision avoidance is to limit robot speeds when they are occupying a zone slightly off the surface of the part. This allows the skin of the part to provide safe guarded space within the fuselage section, allowing a human element to be present. This is critical to the process as technicians run collars on each fastener before the machine moves onto the next hole to ensure adjacent hole clamp up for one up assembly. The production rate for this cell is so demanding, a 5th identical robot is required so that preventative maintenance can be done without interrupting production.