Robert G. Landers. Manufacturing Automation and Control Laboratory (130 Toomey)

Transcription

1 Robert G. Landers Broad Areas of Research Interests: Controls applications and manufacturing automation Specific Research Interests: Modeling, analysis, monitoring, and control of manufacturing processes (metal cutting, friction stir welding, laser metal deposition, and freeze extrusion fabrication), control of alternative energy systems (hydrogen fuel cells and advanced batteries) and electro hydraulic systems, simulation systems for engineering education. Areas of Teaching Responsibility: Modeling, analysis, and control of dynamic systems, mechatronics, manufacturing automation Description of Scholarly Expertise: Manufacturing process control is the intelligent adjustment of process parameters to optimize manufacturing operations (e.g., minimize cycle time while not violating a set of machine and part quality constraints). In metal cutting operations, we have regulated the machining force and rejected chatter (i.e., the unstable interaction between the machining force process and structural vibrations). We are now working on parallel machining where multiple tools machine a single part simultaneously, but independently, and hierarchical control where individual equipment components are intelligently coordinated. In friction stir welding, we performance some of the first studies in the dynamic response of the force process and developed control techniques to regulate the forces to avoid wormholes to maintain excellent welding even when encountering gaps between the plates. We are now looking into creating a first-principles, control-oriented model of the friction stir welding process to predict forces and temperature. In laser metal deposition we developed a method to deposit uniform amounts of powder even as the motion system is accelerating and decelerating and we developed a layer-to-layer control methodology that was successfully applied to regulate melt pool temperature and part height. We are currently looking into extending existing models for multiple layers and using Iterative Learning Control to regulate the part morphology. In freeze extrusion fabrication of ceramics we did the first work in characterizing the dynamics of the paste extrusion process and we developed adaptive controllers that regulate the paste extrusion force even when air bubbles occur and as liquid phase migration changes the paste dynamic characteristics. We are now working on detailed analysis of the extrusion process using Fluent. A new branch of work is concerned with the diagnostics, dynamic modeling, and control of alternative energy systems. Specifically we are investigating hydrogen fuel cells and lithium ion batteries. We have built a table-top system to mimic a hybrid vehicle power architecture consisting of a hydrogen fuel cell and a lithium ion battery that run a motor. We are developing dynamic models of the system and looking into techniques to monitor the health of the fuel cell and battery, conduct thermal regulation, and perform power management under different loads. Manufacturing Automation and Control Laboratory (130 Toomey) Directed by Dr. Robert G. Landers, the MAC Lab contains a three axis machining center with an open architecture controller capable of course instruction, basic research projects, and low volume production. A parallel machine tool was built in the MAC Lab with funds from an NSF Major Research Instrumentation grant. The parallel machine tool has the ability to turn, mill, and drill cylindrical parts, or mill and drill prismatic parts, in one setup using two tools simultaneously and independently. The base machining center is a Mitsubishi 3 axis vertical machine tool (shown in Figure 1) with a 10 station tool changer and available coolant, lubrication, and air. The spindle power is 3 kw, the maximum spindle speed is 3,000 rpm, the x, y, and z axes have strokes of 0.6 m, 0.4 m, and 0.8 m, respectively, and maximum speeds of 1.0 m/s, 1.0 m/s, and 1.0 m/s, respectively. Each axis has a resolution of 1 μm. The machining center s closed architecture controller and proprietary electronics have been removed and replaced by a National Instruments Real Time control system (see description below). 1

2 Figure 1: Three Axis Machining Center with Open Controller in the Manufacturing Automation and Control Laboratory at Missouri S&T. Schematics of the proposed parallel machine tool in two configurations are provided in Figure 2. Two modular towers, mounted on the x axis slide, on either side of the main spindle provide the capability for parallel machining. With lathe tools mounted on each tower (see Figure 2a), the machine tool will be able to parallel turn cylindrical parts. With the sub spindles mounted on each tower (see Figure 2b), the machine tool will be able to parallel mill/drill cylindrical or prismatic parts. Note that both tools are able to perform off axis milling/drilling of cylindrical parts. The left tower consists of a Gilman hardened way slide (HWS M1 6) mounted on a Kistler (9253B) plate dynamometer. The lathe tool, or sub spindle, is mounted on the slide, depending on the desired configuration (i.e., parallel turning of parallel milling/drilling). The slide is oriented in the y direction. Coupled with the machining center s x and z axis motions, the tool on the left tower will have three degrees of freedom. The right tower consists of two integrated, orthogonal Gilman hardened way slides (horizontal: HWS M1 6 and vertical: HWS M1 6) mounted on a Kistler (9253B) plate dynamometer. The lathe tool, or sub spindle, is mounted on the vertical slide, depending on the desired configuration. The horizontal slide is oriented in the x direction and the vertical slide is oriented in the z direction. Coupled with the machining center s y axis motion, the tool on the right tower will have three degrees of freedom. A group of specially designed collets will be constructed to hold cylindrical parts and another group of specially designed collets will be constructed to hold prismatic parts; thus, multiple parts can be machined in one setup. Note that the dynamometers provide the means to accomplish process modeling, monitoring, and control. 2

3 (a) (b) Figure 2: Schematic of Parallel Machine Tool in Parallel Turing Configuration (a) and Parallel Milling/Drilling Configuration (b). When a cylindrical part is being machined, the machining center s x and z axes provide the required radial and longitudinal, respectively, feed for the left tower. The additional x and z slides on the right tower provide the radial and longitudinal, respectively, feeds for that tower. Since the right tower is on top of the machining center s x axis, the motion of the additional horizontal and vertical slides compensate whenever the tool in the left tower moves, and vice versa. Therefore, tight coupling between the motions of the two towers exists. When a prismatic part is being machined, or a cylindrical part is being milled/drilled, the machining center s x and z axes and the additional y axis on the left tower provide the required three axes of motion for that tower. The machining center s y axis and the additional x and z axes on the right tower provide the required three axes of motion for that tower. Again, the motion of one tower requires adjustments in the motion of the other tower. Note that the main spindle allows prismatic parts to be machined on multiple faces. The modular control system architecture shown in Figure 3 will allow the project team to implement the rapid development systems. The control system consists of two processors. Processor P1 is a non real time processor where control programs are developed and simulated, and downloaded to P2 via an Ethernet connection. Processor P1 is also responsible for the operator interface and, during the operation of the machining centers, the operator can issue commands such as feed rate and spindle overrides. Monitoring information of the machining centers and the metal cutting processes is sent to processor P1 (not in real time) during the operation for display. Processor P2 is a real time processor running the National Instruments Real Time operating system. Processor P2 is equipped with high count digital I/O cards, analog output cards, multifunction cards for analog input, counter/timer cards for quadrature encoding, and signal conditioning cards for antialiasing of all analog signals. This processor is responsible for the velocity and position control of the spindles and axes, respectively, as well as the discrete control required for the axis homing, coolant management, etc. 3

4 Processor P1: Non Real-Time Controller Processor P2: Real-Time Controller supervisory controller interpolation servo controller process controller process monitoring digital input/output counter/ timers analog output analog input signal conditioning encod amps curr Discrete Machine Tool Components Linear Axes and Spindles Part proximity sensors dynamometers Figure 3: Schematic of Modular Machining Center Control System Architecture. Alternative Energy Control Research Laboratory (207 Toomey) The Alternative Energy Control Research Laboratory (AECR Lab) was established by Robert G. Landers for alternative energy education and control research purposes at Missouri University of Science and Technology (Missouri S&T). Currently the AECR lab has a hydrogen fuel cell advanced battery hybrid tabletop system under construction. The hybrid system shares the same structure with hydrogen fuel cell vehicles so that the knowledge and experience the students acquired by experimenting on the tabletop system can be applied in other similar systems. A schematic of the system is shown in Figure 4. 4

5 Figure 4: Fuel cell Tabletop System Schematic. The fuel cell battery hybrid tabletop system includes the following major components: a Horizon H 200 hydrogen fuel cell, a RFE 8F10 Lithium ion battery, two AALBORG GFC17 mass flow controllers for hydrogen and oxygen flow rate control, two Omega IP211 X15 pressure regulators, a V Infinity VHK200W DC DC converter, an Advanced Motion Controls BX30A8 servo drive, two MagMotor C40 e 500 motors for load emulation, a Matlab xpc based data acquisition and control system. The H 200 hydrogen fuel cell consists of 48 cells and has a rated power of 200W (28V@7.2A). The xpc based data acquisition and control system consists of a host PC, Dell Optiplex 760, and a xpc target, which is equipped with two National Instruments data acquisition cards, PCI 6711 and PCI 6040E. The PCI 6711 card has 4 12 bit high speed analog output channels which can used for control of actuators in the tabletop system, such as mass flow controllers, pressure regulators, etc. The PCI 6040E is capable of measuring 16 analog input signals with a 12 bit resolution, which can be used to measure feedback from the temperature sensors, pressure transducers, etc. A schematic of the data acquisition and control system is shown in Figure 5. 5

6 Figure 5: Fuel Cell Battery Hybrid Tabletop System Data Acquisition and Control System Schematic. Caterpillar Mechatronics Laboratory (201 Toomey) Directed by Drs. Krishnamurthy and Robert Landers, the Caterpillar Mechatronics Laboratory (CAT Lab) was established in the Missouri S&T Mechanical and Aerospace Engineering (MAE) department in 2004 with a gift of approximately $250,000 from the Caterpillar Foundation. The CAT Lab consists of a variety of electro mechanical and electro hydraulic systems that are utilized for instructional activities in a variety of courses including ME 211: Linear Systems, ME 279: Automatic Control of Mechanical Systems, ME 301: Mechatronics, ME 355: Automation in Manufacturing, and ME 381: Mechanical and Aerospace Control Systems. The foundation of this laboratory is the eight electro hydraulic benches (see Figure 6). These benches, which consist of components found on Caterpillar machinery, are used by student to conduct modeling and control experiments of industrial grade electro hydraulic systems. The benches have two actuation components, a cylinder and a motor, which can be regulated automatically or can be controlled via a manual or an electronic joystick. The cylinder has a displacement sensor and the motor has a speed sensor. Pressure, flow, and temperature sensors are also available to compute measurements at different points in the system. The electro mechanical systems consist of a modular double cart pendulum system, which can be configured in a variety of ways to conduct different laboratories, and a mini three axis motion control system that will be outfitted to perform meso manufacturing operations such as machining. Cylinder ECM Joy Stick Accumulator Pilot Valve Spool Valve EH Relief Valve Pump Manual Control Valve Manifold Motor Figure 6: Electro hydraulic Workbench (shown without hoses) in Caterpillar Mechatronics Laboratory. 6

7 The control systems for all electro mechanical and electro hydraulic systems in the CAT Lab are developed in Matlab Simulink and then downloaded to an xpc TargetBox for implementation. The electro hydraulic system is controlled electronically by the combination of a Caterpillar Electronic Control Module (ECM) and an xpc TargetBox. The ECM, manufactured by Caterpillar, is designed to interface directly with the sensors and actuators found on the bench. It reads sensor data in the form of either a PWM signal or an analog voltage and relays them to the xpc TargetBox via a CAN (Controller Area Network) connection. It also receives actuation instructions via the CAN connection and can produce specified current signals to power actuators through its onboard PWM amplifiers. The xpc TargetBox, contains the computer hardware on which control logic is executed. It utilizes a special purpose operating system allowing for real time, low latency execution of controller code. When connected to the ECM via the CAN connection, the TargetBox will receive sensor data from the ECM, execute a controller based on that sensor data, and send output signals back to the ECM through the CAN connection. The electro mechanical systems are controlled in the same manner as the electro hydraulic systems, expect the ECM is not utilized. Instead electro mechanical system actuators and sensors are directly connected to analog I/O, digital I/O, and counter/time boards in the TargetBox. 7