Researchers from the Control Research Laboratory at the Sao Paulo State University, Brazil, study different approaches to control active suspension systems. They use Quanser Active Suspension platform to simulate and analyze the effectiveness of their control strategies. The team summarized their work in a paper "Sliding mode control for Active Suspension System with Data Acquisition Delay," recently accepted for publishing in the Mathematical Problems in Engineering Journal.
The paper addresses the issue of delays that may occur in the PC-based control of an active suspension system. The signal delays can occur, for example, in a network-based control system or due to slow slow data acquisition. The research team proposes using state predictors with sliding-mode control to take delays into account. Both continuous-time and a discrete-time methods are designed and implemented on the Quanser Active Suspension system. Based on the results from simulations and hardware tests, the paper evaluates the effectiveness of these control strategies.
Mechatronics Control Kit - or MechKit - is one of several experiments Quanser offers for hands-on teaching of control. Originally designed by Dan Block and Dr. Mark Spong at the University of Illinois at Urbana-Champaign, it has been popular for several years, thanks to its compact design and selection of control challenges. As technology evolves, the Mechatronics Control Kit needs to keep up. So here are the latest improvements our engineering team came up with to make this lab tool more effective for educators:
New peripherals improve MechKit's performance. To improve performance of the MechKit, we integrated new peripherals developed by Quanser: our new Q2-USB DAQ and VoltPAQ-X1 power amplifier. Plus swapping modular parts to set up a new experiment is now much easier.
QUARC integration enables rapid control prototyping Another new feature of the improved MechKit is the interface to QUARC. That makes changing parameters much easier and allows MechKit users to benefit from all the features of QUARC rapid control prototyping software and its seamless integration with MATLAB/Simulink.
More compact design All above mentioned improvements result in more compact and portable design. Sure, the MechKit got a bit smaller, but it also became more powerful.
It's not everyday that you find yourself driving on the moon and feeling the bumps and hills as your lunar buggy jumps around. But that's just what attendees at the IEEE CASE conference in Toronto got to experience last week. Earlier in the conference, we ran workshops on mechatronics design, unmanned vehicle experiments, and haptics led by our engineers, Amin Abdossalami, Derry Crimble, and Paul Karam.
Quanser's Hexapod was on display along with QUARC and the Active Suspension System. We displayed how the Hexapod could be used as a six degree of freedom motion platform, simulated vehicle motion.
Personally, the Hexapod is my favorite - it has a large payload capacity (250 kg), can be used as a shake table or parallel robot, can connect to a regular power supply, and uses a simple USB cable for data transfer. In our setup, we had it tied through QUARC to a visualization of a lunar surface. Attendees could sit on the Hexapod, grab a joystick, and go for a joy ride. As the controller was running, we had the ability to toggle on and off the active suspension of the lunar buggy and occupants were able to feel the moon bumps much more.
The Active Suspension Experiment was also on display - along with a virtual version of the experiment. It showed how students could design controllers to dampen out vehicle vibration.
The glue to these different systems was QUARC. QUARC can bring together complex systems and pair them with peripherals like joysticks, motion tracking cameras, and haptic devices. It can also allow someone to create a virtual environment to interact with their controller.
After the conference, ten lucky attendees had a chance to experience the magic behind the scenes and tour Quanser's headquarters, taking advantage of our open invitation earlier this summer.
Video shot by another one of our talented engineers, Pasha Javid
Back in 2009 we released the original Hexapod, a 6 DOF parallel robot capable of producing highly accurate motions while moving payloads of 100 kg. The device is currently in use around the world, serving research facilities and universities, with applications ranging from earthquake research to bite analysis of Saber Tooth Tiger.
Although the performance of the first version is excellent, we acted on a feedback from our customers to improve the Hexapod, so that it can meet their needs even better. Users were looking for higher payload capabilities and more compact system - and we delivered. We are pleased to announce that a new generation of the Quanser Hexapod is now available. The system has been made much more compact: all power amplification, brake logic, data acquisition and interfacing electronics have been moved into the base of the Hexapod. Whereas the original device required a separate Q8 interfacing card, two large rack-mount amplifiers with a set of five thick cables, all you need is now is a single USB cable to connect the Hexapod to your QUARC-enabled PC or laptop. The torque capacity of each of the six motors have been more than doubled, ultimately increasing the payload capacity to 250 kg. This was accomplished without losing any of the device's accuracy. At the same time, we improved the design of a passive joint to handle the increased payloads.
With all these improvements, the users get a system even stiffer than before.
Industry demand for mechatronic controls engineers has dramatically grown over the past decade. Today, industry is looking for a new kind of engineer, one with multidisciplinary and systems integration experience. It is becoming increasingly important for students to learn how electrical, mechanical, computer and control systems interact with one another.
Our engineers would like to invite you and your colleagues to get a more detailed demonstration of the Active Suspension, 3 DOF Gyroscope or any other plant from Quanser's new Mechatronic Controls Collection you wanted to explore. Simply register for any of the free webinars listed below to see the plants in action and get answers to questions about technical capabilities or how we can assist with funding. When you attend a webinar, you are entered to win a SONY Voice Recorder!
Hexapod is a 6 degree of freedom (6-DOF) full motion platform manufactured at Quanser. This high-fidelity device can combine six distinct motions simultaneously and is ready to meet various movement possibilities. It should be mentioned that typical motion platforms use hydraulic actuators making them very expensive and slow. Nevertheless, this seemingly complicated structure is taking advantage of fast response powerful electrical motors beside parallel mechanism. It enables the system to manipulate heavy loads (up to 150kg) over a relatively large workspace and frequency range. The kinematics and control are implemented by Quanser highly capable real-time software, QuaRC. From the main characteristics of this system one can name of fast response times, hardware and software safety measures, and simple maintenance.
The following video presents a driving simulator, as an application of the Hexapod, where some motion cues are applied to the operator in addition to the visual feedback from a virtual environment. In fact, the driver is receiving ultimate driving sensation such as vertical vibrations and realistic centrifugal forces. Who knows! Maybe the next stage is to simulate an aircraft using a flight simulator. And wait! You may be looking at an earthquake vibration test platform too.
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.
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.
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.
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.
Electrical: 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.
Controls: 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.
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.
The importance of cross-functional knowledge of engineers is emphasized more and more by industry - we read it in various articles, hear about it directly from industry representatives at various forums. Mechatronics,which combines and inter-connectes engineering disciplines like mechanical, electrical, computer and control engineering, is clearly addressing the need. Many universities recognize it - mechatronic programs are expanding - and many more universities are brainstorming the best ways how to start up such programs. Among them is Canada's Laurentian University.
A co-organizer of the ICMT 2008 Conference took the opportunity to raise an important question with the mechatronics experts from around the world that gathered at the conference to discuss and share the best international practices and expertise - how to create an innovative Mechatronic Program at the University. Dr. Markus Timusk and Dr. Brahim Chebbi brought to the round table discussion participants from Japan, England, Mexico, Germany, China, USA and Canada. Recognizing its leadership in Mechatronics, Robotics and Control, Quanser was also invited to join the discussion. The recommendation for the Laurentian Mechatronic Program was to build on local industry, its knowledge and experience. With mining being a major influence on the local economy, the program should have a slant towards heavy machinery and mining - in that way students would benefit from local expertise and could eventually support the community they got educated in. Another suggestion - build the program around multi-disciplinary mechatronic design projects and include a “keystone” project course, in which students will be exposed to often untaught intricacies of interfacing and mechatronics design.
We at Quanser took a step back and asked: what can we do to make sure that educators have teaching tools that will ensure industry gets engineers with cross-functional skills they need?
Design philosophy for developing any mechatronic system is based on understanding control principles. And that's Quanser comes in.This collection of five hands-on experiments are much-needed teaching tools to help students understand the control principles underlying all mechatronic sytems. All experiments in our Mechatronic Controls Collection are industry-driven and reflects the type of systems students will work with in industry after graduation. Our Active Suspension experiment, for example, teaches students by simulating a quarter car model. Another experiment from the collection - the 3 DOF Gyroscope allows to study dynamic properties of gyroscopes used in various practical applications such as control and guidance systems for air, sea and space vehicles. Completing the collection are Hexapod, 6 DOF motion platform capable of moving high loads at high accelerations within a small workspace, 2 DOF Planar Robot, a parallel roboticused to teach various robot concepts such as kinematics and calibration and Industrial Mechatronic Drives Unit (IMDU) with its Web Transport and Multi-DOF Torsion modules. With exception of IMDU - all completly new products. Stay tuned. More information on the new products will be posted soon on this blog.
Quanser's Active Suspension Quanser's 3 DOF Gyroscope
Quanser's Hexapod
The Industrial Mechatronics Drive Unit (
