Thursday, April 30, 2009

Industrial Mechatronics Drive Unit

The Industrial Mechatronics Drive Unit (IMDU) is part of the new Mechatronic Controls Collection line of Quanser experiments. The system is 17.8 cm high, 30.5 cm long, 30.5 cm wide, and weighs 12.9 kg and, as illustrated in the image below, it has four external shafts. Two shafts are actuated through a 3:1 belt drive system with a DC Motor while the other two are passive. The position of each shaft can be measured using the high-resolution encoders. The built-in 150 W linear current controlled amplifiers that drives the DC motors are capable of supplying up to 10.0 A. So there is no need for an external amplifier.

The IMDU is a reconfigurable system and is extremely versatile. It is supplied with two inertial loads, five pulleys of different sizes, two belts, a backlash unit, and a friction unit. The inertia loads have adjustable weights: up to four can be placed and the location of each can be changed. By mounting the various pulleys on the different shafts and using the belts, a multitude of experiments can be performed. The device itself is supplied with four experiments: DC Motor Position Control, DC Motor Speed Control, Disturbance Rejection, and Haptic Knob. The IMDU can be run on a PC with the QuaRC control software through Matlab/Simulink.

The friction and backlash units can be used to add these corresponding effects to an output shaft. This permits the user to study the effects of real backlash and friction – not simulated. This lends itself well to control engineers who want to test their friction and backlash compensation or identification schemes.

To add to the list of experiments that can be performed on this device, a Web Winding Transport Module and a Multi-DOF Torsion Module are available. The web winding module can be added to the base IMDU system to convert the plant into a paper machine simulation. In this configuration, the goal is to process the paper as fast as possible without tearing the product. This is done by adjusting the tension and the rate of the spindles.

With the torsion module, the output of the motorized shaft is connected to a flexible coupling that is then connected to an inertial load (as pictured below). The challenge is to control the position of the output shaft while compensating for the joint flexibilities introduced by the torsional member. This reenacts common issues found in the real world, e.g. high-gear ratio harmonic drives.

Monday, April 20, 2009

One 3 DOF Gyroscope, Many Possible Experiments!

One of the great features of the Quanser 3 DOF Gyroscope is that while all three gimbals are free to rotate in space, each one can be fixed individually upon desire. This allows for many different possible configurations under which the device can be setup and controlled. For example by fixing the outer rectangular frame and the blue gimbal simultaneously, one can control the angle of the red gimbal by changing the speed of the rotor only. This is the classical reaction wheel experiment. Alternatively and as another possible experiment the red gimbal can be fixed, and the angle of the rectangular frame can be controlled by commanding the blue gimbal motor only! Of course the rotor has to be spinning at a certain RPM for this to happen. This experiment is a direct application of the gyroscopic effect.

Using QuaRC, interfacing to sensing and actuating elements of this hardware becomes as easy as dragging and dropping blocks into a Simulink model. Once a controller is designed for any desired configuration of the 3 DOF Gyroscope, real-time control, on-the-fly tuning, and data monitoring can all be done with the help of QuaRC and under the MATLAB environment.

The video below, shows the 3 DOF Gyroscope with its red gimbal fixed. In this configuration the angle of the outer rectangular frame is being controlled by commanding the blue gimbal motor only. The real-time plot shows the commanded signal versus the actual frame angle versus the simulated frame angle.

As another configuration, one can fix the outer rectangular frame and control the red gimbal orientation. The video below shows this configuration with the control signal being applied to the blue gimbal motor only as was the case with the previous configuration. The MATLAB Virtual Reality toolbox can be employed by QuaRC to run a real-time virtual environment simulation of the device in parallel to the actual controller commanding the plant.

Tuesday, April 14, 2009

QUARC: Hard-Real-Time Performance on a Windows PC

The next major release of QuaRC, version 2.0 which is currently under development, will support an additional target operating system, called INtime, in order to provide hard-real-time performance in a "one-PC solution", in which the user interface components and hard-real-time control are integrated on a single PC platform. INtime is a Real-Time Operating System (RTOS) developed by TenAsys which provides deterministic hard-real-time performance under Microsoft Windows.

The upcoming QUARC 2.0 is a result of Quanser's new partnership with TenAsys. QUARC's support for INtime has just been showcased during a Quanser-TenAsys joined demonstration at the TenAsys booth at the Embedded World 2009 Exhibition & Conference show in Nuremberg, Germany, at the beginning of March 2009.

The QUARC-INtime demonstration actually consisted of two fully-featured hard-real-time QUARC controllers running in INtime and interfacing to Windows on the same PC.

QuaRC-INtime demonstrations: LBS and 2-DOF Planar Robot

The first demonstrated system consisted of Quanser's Laser Beam Stabilization (LBS) unit, whose QUARC controller was solidly running at a 10-kHz sample rate while communicating with its corresponding Simulink model in Windows using external mode and updating on-the-fly, among others, a X-Y graph and a VRML 3-D graphical scene, both representing the laser beam regulated position.

The other demonstrated system was Quanser's latest state-of-the-art robotic device: the 2 DOF Planar Robot. The 2 DOF Planar Robot interfaced to the demo PC using a Q4 HIL card passed to INtime. It had its QUARC controller model running at 1 kHz in INtime and executing in parallel to the LBS, on the same PC. As an external user interface, a USB drawing tablet (a.k.a., pen pad) with stylus input was also connected to the PC. A Windows C# user application could collect the handwritten data and send it as position commands to the 2 DOF Planar Robot equipped with a pen end-effector, so that the captured handwriting (or signature) could be duplicated on an actual sheet of paper. The communication between the Windows user-developed C# application and the QUAaRC controller running in INtime was easily implemented using the QUARC Stream API.

Both LBS and 2 DOF Planar Robot models ran side-by-side using the INtime system timer and have proven themselves to be very stable during the 3-day long Embedded World conference. Preliminary performance measurements indicated observed latencies of ± 5 microseconds for both 10-kHz (LBS) and 1-kHz (2-DOF Planar Robot) controllers.

Therefore, QUARC for the INtime target has been demonstrated to give extremely promising hard-real-time performance while running alongside Microsoft Windows on the same PC.

Monday, April 13, 2009

Quanser Active Suspension

Quanser Active Suspension is a bench-scale plant to emulate a quarter-car model controlled by an Active Suspension mechanism.

The plant consists of three floors/plates on top of each other. The top floor resembles the vehicle body and is suspended over the middle plate with two springs and a tunable damper. A capstan drive high quality DC motor is also standing between the top and middle plates to emulate an active suspension mechanism. The top floor is instrumented with an accelerometer to measure the acceleration of the vehicle body relative to the plant ground. The middle plate is in contact with the bottom plate, i.e. the road, through a spring and a damper and constitutes the tire in the quarter-car model. The bottom floor provides the road excitation in the system. It is connected to a fast response DC motor so that the designer can simulate different road profiles.

When the road simulation motor turns, the torque created at the output shaft is translated, through the lead screw and gearing mechanism, to a linear force which results in the bottom plate's motion. The structure is made of steel and the three plates can smoothly slide along a stainless steel shaft using linear bearings. The motion of the two bottom plates is tracked directly by two high resolution optical encoders while a third encoder measures the motion of the top plate relative to the middle one. Such a scaled quarter-car structure has been designed to study critical aspects of Active Suspension control implementations.

Below, is a demo video of Quanser Active Suspension System in which the road simulator is coupled with a virtual terrain. Driving with and without haptic feedback is demonstrated in this video. Finally the demo is concluded with an open-loop vs. closed-loop response of the system to road disturbances.

Monday, April 6, 2009

Mechatronics Supports Robotics

Quanser's new 2 DOF Planar Robot is a primary example of a mechatronics system. How so you ask? As a graduate of University of Waterloo’s first mechatronics engineering class, hopefully I can shed some light. Let's look at the various disciplines considered to be part of mechatronics and see how they pertain to this particular product.

Mechanical: The system was designed to be mechanically robust. It uses heavy duty machined parts and zero-backlash harmonic drives. In order to make the robot slightly more interactive, a pen mechanism was added as an end-effector allowing the students see the path the robot has taken.

The robot's two degrees of freedom are driven by DC motors (coupled with aforementioned harmonic drives). Although not the focus of this particular experiment, electric motors are an integral part of most mechatronic systems. Also, the pen mechanism on the end-effector is actuated using a 12VDC solenoid.

Using position feedback from high resolution optical encoders, the system is controlled using Quanser's real-time control software, QuaRC. The system has built-in software watchdogs that allow students to develop controllers without posing the risk of damaging the mechanism in cases of instability.

When tied all together, this mechatronics system allows a series of robotic fundamentals to be taught in a safe, effective manner. These fundamentals include determining forward and inverse kinematics, dynamic properties of the system and developing a calibration routine. Any senior undergraduate or graduate students will certainly benefit from taking principles taught in class and applying them to a real, physical, interactive system.

Collaborative R&D - It's what we do!

Quanser's new 6DOF Hexapod is a perfect example of what drives us at Quanser - Collaborative Engineering. Dr. Venkat Krovi at SUNY came to Quanser in search of a research platform he required. Working with his original specs and after a few iterations between Quanser and his research team, the 6DOF Hexapod concept was born!

Corresponding via phone and web, we developed a model of the Hexapod's capabilities. We allowed for certain parameters to be adjustable (such as lengths, transmission ratios and power). Dr. Krovi and his team varied the parameters until his required capabilities were met. The Quanser Hexapod team then setoff to design the new device.

Working with Quanser ensures researchers that their device will be delivered as part of a complete system. Using our modular and parallel approach to design, the hexapod utilizes our existing linear current amplifier's (2x QPA), our DAQ system (Q8) and our real-time control software QuaRC. In addition to these standard Quanser components, we also developed a motor brake control unit to engage the hexapod brakes when the joints are at their limits - this ensures that the powerful motors do not damage the device or worse, the load on the hexapod.

Once the prototype was manufactured and tested, we invited Dr. Krovi and his team to Quanser for training and demonstration of the device. They spent a full day at Quanser, first learning about Quarc and its features, then onto the Q8 and its capabilities and finally on the complete Hexapod system. Although the device met the original design specs, Dr. Krovi quickly noted that the rotational workspace was not exactly what he originally had in mind.

We brainstormed with his team to address this concern, and came up with a suitable solution – allow the hexapod legs to be adjustable. The final Hexapod design that was shipped to Dr. Krovi incorporated the adjustable lengths. Today, he is the first recipient of that latest in Quanser’s product line – the 6DOF Hexapod! Watch this short demo to see Hexapod in action.

Thursday, April 2, 2009

Skills Engineering Graduates Need to Succeed - An Expert Opinion

Is there a gap between what engineering students learn and the skills industry needs? Leading academics and industry professionals will discuss the skills engineering graduates need to succeed on June 17th at this year's ASEE Annual Conference. Quanser and The MathWorks are hosting a panel discussion titled Helping to Teach Engineers Real World Skills with Hands-on Labs. The dynamic panelists who will be sharing their unique perspective include:

Dr. Chaouki Abdallah is a professor and the chair of the Electrical and Computer Engineering Department at the University of New Mexico. Professor Abdallah conducts research and teaches courses in the general area of systems theory with focus on control, communications, and computing systems. His research has been funded by NSF, AFOSR, NRL, national laboratories (SNL, LANL), and by various companies.

Dr. Marcia O'Malley is currently an Assistant Professor in the Mechanical Engineering and Materials Science Department at Rice University. She holds a joint appointment in Computer Science at Rice, and is an Adjunct Assistant Professor in Physical Medicine and Rehabilitation at Baylor College of Medicine. Her research interests include physical human robot interaction, robot-assisted rehabilitation, nanorobotic manipulation, and educational haptics.

Dr. Mark Spong is a Dean of the Erik Jonsson School of Engineering and Computer Science and the Lars Magnus Ericsson Professor in Electrical Engineering at the University of Texas at Dallas. His research interests are in nonlinear control theory and robotics. He has published over 250 technical articles in control and robotics and is co-author of four books.

Dr. Jacob Apkarian is CTO of Quanser. Jacob taught Electrical Engineering at the University of British Colombia and held senior engineering and management positions at Lyndhurst Hospital and Spar Aerospace. He founded Quanser in 1990 to enhance and advance control theory education. He made the company world-renown in the academic and research realms and achieved reputation as a global leader in the development of real-time control systems and services for industry. His main interest remains in research and development where he explores new ideas in control and create imaginative and industry-driven teaching and research plants.

James H. Hughes is a Training Manager at The Apprentice School of Northrop Grumman Shipbuilding - Newport News, responsible for academics and continuing education of graduates. Prior to joining The Apprentice School, James was as Assistant Professor at the School of Education and Psychology at North Carolina State University. James has a doctorate in education from the University of North Carolina at Chapel Hill.

Andy Mastronardi joined Freescale Semiconductor in September of 1999 and is Global Director of the Freescale University Programs. Prior to Freescale, Andy spent 26 years in the education industry, both as a teacher and in educational publishing. Andy holds a BS from SUNY Potsdam and a MS from Long Island University.

Terri Morse is the Engineering, Operations & Technology Director at The Boeing Company. She’s had engineering and management positions developing systems such as Flight Controls, Autopilot/Auto throttle, Flight Management Systems, and many others. She’s been part of the design teams for various airplanes, including 777 and 787 airplane. In addition, she has been leader of the Define aspect of the Phantom Works Lean & Efficient (L&E) Thrust responsible for developing the next generation processes and design tools for use across the Boeing Company.