Swab and Monitoring Automation
Automated Robotic Swab and Monitoring Cell
Customer: Bechtel National, Inc.
Project Description
Raytheon Ktech was awarded a $4.6M design/build contract by Bechtel National, Inc. to design, fabricate, and acceptance test two sophisticated robotically controlled systems (Figure 1) used to decontaminate containers of vitrified waste, and then swab them to ensure the containers are sufficiently decontaminated to meet container storage and handling requirements. The “swab and decon” systems are part of the Low-Activity Waste (LAW) portion of the Hanford River Protection Project Waste Treatment Plant. The contract required that Raytheon Ktech, working with Bechtel’s plant engineers, first produce conceptual and then detailed engineering designs. Both systems were laid out in Raytheon Ktech’s high bay facility for acceptance testing prior to shipment to Hanford.
Figure 1. Swab and decontamination monitoring |
Conceptual Design
Raytheon Ktech’s conceptual design (Figure 2) utilized 6 Motoman UP50-XP robots: four each for the CO2 Decontamination Stations, and two each for the Swabbing Stations. The control approach was based upon the robust, widely used Motoman XRC controller. The controller was easily programmed and controlled through a teach pendant allowing remote operation and recovery of the robot. The controller has a robust communications capability from standard input/output (I/O) (digital and analog) to FieldBus (ProfiBus and DeviceNet). This allowed direct control by the ABB AC800M PLC. The control concept is one that uses the power of the ABB AC800M PLC as the supervisory control and the XRC as a profile program execution system with I/O processing. Utilized in the Decontamination Stations and Swabbing Stations, this concept allowed for effective use and minimized scope of training and trouble shooting.
Figure 2. Conceptual design of the
automated swab, decontamination,
and monitoring test cell. |
Hardware
The design utilizes four each Panjeris turntables (Figure 3) capable of carrying the stipulated 20,000 pound canister load. Amplifiers and control circuitry programmed and executed through the ProfiBus module resident in the Motoman XRC Robot Controller perform the control of the servomotors for acceleration, deceleration, speed, and position. Inductive and optical sensors are used to determine work cell process state and well-being. Process sensors and safety hardware is incorporated. The inductive sensors will position the end effectors to the required stand off distances. Other sensors include canister presence sensing at the turntable, end effector presence in the tool trays, swab presence in the end effector, and collision sensors at the end of the robot arm. There are two cameras in the each work cell that record the operation of the robots. The objective of the video monitoring system is to provide a visual record of the cleaning process. The Swabbing Stations require an elevator platform that will move the robot into a high and low position to allow for complete canister coverage with the swab end effector. These lifts were custom designed and built by Raytheon Ktech. Locking devices were incorporated to assure maximum robot accuracy. The I/O module in the XRC Controller controls the system.
Figure 3. Panjeris turn table integrated with the
motion of the robot. |
System Integration
Raytheon Ktech developed the design for the robotic control system based on the XRC controller and did not include a software intensive solution. The XRC controller will serve as a profile execution system where the PLC calls a profile that has been programmed into it. The profile is a saved teach pendant program that utilizes the power of the XRC controller to move the robot and sense the environment that the robot is working in using the I/O module, real-time sensor module, or the ProfiBus module to execute it. This profile call is performed from the AC800M PLC to the XRC controller using the ProfiBus connection between the two of them.
The XRC controller will serve as the processing controller for all data in the work cells. Connected directly to the controller are the various sensors, controllers, and scanners. The I/Os will be digital or analog, and other communication packets received and transmitted into and out of the controller will be over the ProfiBus connection.
After the design approval from Bechtel, Raytheon Ktech began procuring and manufacturing all of the hardware driven by the project quality requirements. Once the project received all the hardware, an integration effort of all systems began. Raytheon Ktech assembled and tested the hardware exactly as it would perform in the caves at the waste treatment plant. Compressed air simulated the CO2 blast cleaning system. A portable vacuum system simulated the effluent recovery flow rates. Raytheon Ktech built a mock canister to be dimensionally accurate, and the canister verified the operation of the robots. Sensors were tested and calibrated to verify that they can track the canister as it rotates and assist the robot in the location of the canister as it is lowered into the work cell by the overhead crane. Processes were developed and documented for recovery from various failure modes including robot arm failure.
