Training robots revolutionize therapy

Image © Dynamic Devices

Image © Dynamic Devices

When two Swiss robotics engineers developed a new computer-controlled leg press, they were thinking of athletes as their main target audience. Then it turned out that their Soft Robotic Training was surprisingly effective in the rehabilitation therapy of injuries and other physical conditions.

The device has little in common with the leg presses you see in gyms. Of course there is a seat and two pedals, but that is where the similarities end. Taking a seat on the Allegro (for Adaptive Leg Robot) means entering into the care of a unique, soft-robotic training partner. It is equipped with state-of-the-art industrial drive and safety components and a learning computer system. Human and machine work closely together – with astonishing results.

A pneumatic muscle is the core
Allegro is the brainchild of robotics experts Max Lungarella and Raja Dravid, founders of the company Dynamic Devices AG. They developed the first Allegro prototype in 2007 at the Artificial Intelligence Laboratory at the University of Zurich.

Their goal was to build a high-tech device for athletes, a highly dynamic machine that monitors and analyzes all workout sessions and makes suggestions for the next exercise. The core of the device is a pneumatic muscle that is able to deliver large forces to the pedals very quickly. This enables the machine to be used for a variety of challenging exercises.

Example: By pressing or pulling in with their legs, the user has to stay close to a line displayed on the screen. At the same time, the computer amplifies the effective forces, either gently or in the form of impacts. The user has to compensate these forces continuously, which is demanding but extremely effective. Not just the body is trained, but also the brain. “Our system supports this kind of dynamic interaction”, says Max Lungarella. The concept works even better than the two developers had at first imagined.

“Our system supports the dynamic interaction between brain and body.”
Max Lungarella, Dynamic Devices

More or less by chance, the two discovered that their training system had great effects on patients with neuro-muscular disorders or orthopedic conditions. On the Allegro machine, a number of patients were able to move their legs again in ways that didn’t seem possible. Stroke patients also made great progress in the restoration of their motor skills. These effects have now been corroborated in studies – a fact that motivated the developers of the softrobotic training device to focus primarily on rehabilitation. This is where maxon motors enter the stage.

In order to certify the Allegro as a medical device, it needed a critical safety feature: an adjustable stop that prevents the press from going past a certain angle. This is to protect the patient, especially those who are no longer able to fully bend their knees. A brushless EC 45 DC motor takes care of the individual positioning of the safety stop. Absolute reliability is an important, if not the most vital criteria for the drive. “With a maxon motor, we can be certain that this requirement is being fulfilled”, says Lungarella. Other important points include the compact design and integrated electronics of the flat motor.

Successful combination of drive and controller

Another maxon flat motor, an EC 90 with an outside rotor, is in charge of automatic seat positioning. Dynamic Devices combined the brushless motor with a planetary drive and an ESCON 50/5 servo controller. maxon drives are a key component of this training device, providing comfort and safety to the patient.

Success through a playful approach
Despite being a relatively new company, Dynamic Devices has achieved considerable success. Engineers, scientists, physicians, and therapists have collaborated to create a training device that gives many patients new hope for an improvement of their motor abilities. The decisive factor is the training aspect, which was traditionally relegated to a relatively minor role in rehabilitation therapy. If you sit down on the Allegro, you can expect to be challenged. If users are motivated to become better and score higher, their performance improves faster. Motivation is important, and that is why Dynamic Devices focuses on a playful approach. When patients use the pedals to control a simulated penguin sliding down a hill on its belly, trying to score as high as possible, they almost forget about the physical effort.

Some hospitals and rehabilitation centers are already using the new robotics-based training with more soon to follow. The next step is an expansion into the entire Eurozone. In addition, Max Lungarella and Raja Dravid are working to make their soft-robotic training device even more intelligent.

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Pancake Motors

Paul McGrath, Sales Engineer, discusses maxon’s line of dc brushless pancake motors. These motors feature external rotors and shafts and are available with or without Hall Sensors. They are ideal for use in robotics applications.

maxon 32 mm planetary gearhead for high radial loads.

maxon's 32 mm planetary gearhead for high radial loads.

maxon’s 32 mm planetary gearhead for high radial loads.

New design ensures smooth and true running.

maxon motor, the worldwide leader in high precision drives, has added two new gearheads to the already successful GP 32 program. Significant improvements have been made to the single-stage planetary gearhead: The planetary carrier has been reinforced, the bearings have been repositioned, and a ceramic version is now available.

With these new gearhead versions for high radial loads, maxon is now offering single-stage gearheads with extremely heavy-duty radial bearings. These versions are designed for applications such as toothed belt drives, applications that place enormous stress on the output stage due to the radial forces at work. The design of the GP 32 AR and GP 32 CR gearheads takes these forces into account. Both bearings of the output stage have been positioned as far apart as possible. As a result, radial forces of up to 140 N can be optimally compensated. The planetary carrier has been reinforced and given separate bearings. The axles of the planet gears are securely fixed in both halves of the planetary carrier. To achieve the maximum torque and life span, customers can select these axles in ceramic. The short-term permissible torque reaches up to 1.25 Nm.

The gearheads are available with output shafts in 6 mm and 8 mm diameters. These gearheads also feature smooth running and minimal fluctuation in friction characteristics. The planetary gearheads can be combined with various brushed, brushless, or flat motors in the maxon modular system.

For more information, visit our website at www.maxonmotorusa.com

maxon’s Brushless 90 mm flat motor with MILE Encoder

maxon’s Brushless EC 90 Flat with MILE Encoder

The ultra slim design of maxon’s EC 90 flat motor is now equipped with a MILE encoder. MILE (Maxon’s Inductive Little Encoder) is the world’s smallest inductive rotary encoder. Its operating principle is based on the detection of high-frequency inductivity which generates eddy current in an electrically conducting target. The advantage of a high-frequency inductive method of measurement includes high speed, high robustness towards dust or oil vapor and insensitivity against interferences pulses such as PWM controllers or motor magnets. 

This new EC 90 flat MILE is extremely precise with resolutions of up to 3200 impulses per turn and a remarkable high nominal torque of 517 mNm. This makes it the perfect choice in applications, such as door drives, logistic robots, or solar trackers. The motor is distinguished by optimal integration of the MILE encoder and combines state-of-the-art with the tried and tested features; flange pattern, fixation, and pin assignment. For additional information visit http://www.maxonmotorusa.com/

Getting Swinging Lights to Stop on a Dime

At the Royal Shakespeare Company’s refurbished venue, lightweight lights are hung from swinging cables. A unique design stops the swinging to put the spotlight on the actors.

The RSC Lightlock system operates using Newton’s third law of motion: every action has an equal and opposite reaction.

The RSC Lightlock system operates using Newton’s third law of motion: every action has an equal and opposite reaction.

The Royal Shakespeare Company recently went through a $200 million refurbishment at Stratford-upon-Avon. During that refurbishment, it was decided that the lighting system design needed to be approached differently than in the past, and had to be driven by health and safety concerns. For example, in the past, maintenance personnel had to climb scaffolding to where fixtures were mounted then, while strapped into a secure harness, reach to replace the bulbs or perform maintenance tasks. The reduction of bridges or trusses would eliminate the need for maintenance crews to work at such heights during routine work or when adjusting the lighting. The original idea was to be able to hang the lights from cables that could be lowered to the maintenance crew. By doing so, the RSC would be able to provide higher levels of safety, and save on maintenance times, both of which were expected to produce a cost savings.

Designing a system that would allow for the lights to be hung from cables created additional benefits. The new lighting system would be able to be used in a broader variety of theatre, TV, and film situations because the need for a heavy-duty mounting infrastructure had been eliminated. This advantage meant that the rigging would allow the lights to move virtually anywhere. No shot would be outside the capability of the moving lights. Plus, a lighting designer could choose to create the same design with smaller rigging requirements.

A Swinging Pendulum

The challenge in creating a lighting system that hangs from chains or cables is the pendulum effect. Once the light moves into place and is told to stop, the weight of the lighting apparatus causes it to continue to swing rather than stop where it’s supposed to be. This sends the spotlight all over the stage while it’s settling, which disrupts the performance at the least and, at the worst, ruins it.

RSC’s team came up with a unique method of settling the lighting system after a move. After inventing the device, they needed a company to build and perfect the design. The RSC chose to work with Total Structures (Ventura, CA). The company not only helped with the design of what was eventually labeled as the RSC Lightlock system, but they also license it for manufacture and sales.

On stage, the lighting system must settle into place quickly and accurately so that the performance can go on smoothly and on time.

On stage, the lighting system must settle into place quickly and accurately so that the performance can go on smoothly and on time.

The final device was designed to eliminate the unwanted oscillation of the lightweight structures by using Newton’s third law of motion: for every action there is an equal and opposite reaction. The engineers decided to use use a heavy counterweight device that, mounted on an internal disc, swung in the opposite direction to the movement of the light. By accelerating and decelerating the balanced mass, or counterweight, at the appropriate moment of the swing cycle of the moving structure, the Lightlock would stop the motion. Essentially, the opposite reaction of the counterweight cancels out the movement of the light itself, stopping it in its tracks.

Nook Schoenfeld, from PLSN (Projection, Lights and Staging News) evaluated the Lightlock system independently from the company and said in a recent article, “The light swung 90 degrees and the truss barely swung. Within two seconds, the light beam and truss had settled on the focus target.” This is in opposition from moving the light without the Lightlock system, which took much longer. Later in his examination he added that, “The Lightlock really does work.”

Motion Control for Swinging Lighting Systems

The heavy counterweight, which swings in the opposite direction as the light, is rotated by a flat, brushless motor designed and manufactured by Maxon motor. The motor used is the EC 90, which is only 90mm in diameter. This motor was selected because the Lightlock device had to be small, while offering high performance and precision. The EC 90 Flat motor operates fast, and even with sudden, dramatic movements, can cancel out all unwanted motion in under a few seconds.

Maxon motor designs and manufactures the EC90 Flat motor used in the Lightlock system to swing the counterbalance into place.

Maxon motor designs and manufactures the EC90 Flat motor used in the Lightlock system to swing the counterbalance into place.

Maxon motor offers a full line of fractional horsepower moving coil DC motors and brushless motors ranging in size from 6mm to 90mm, and from 30 mW to 500W. They also offer gearheads, controllers, and accessories. Particularly, flat motors manufactured by Maxon Precision Motor provide long life along with their low profile package. The entire EC series of brushless motors are electronically commutated, which enables them to have extremely long motor life since there are no mechanical brushes to wear out. The motors incorporate ball bearings or ruby bearings that also add to the longevity of the motors, especially needed under such unique conditions where maintenance of the lighting system is routine. The flat motors were designed specifically for low profile applications like the Lightlock where size and weight are important selection criteria.

The Lightlock operates autonomously and needs no data inputs from an external source. It has an integrated track for half inch or M12 fixings that can be rigged with standard clamps and couplers or direct mount plates. The device also has an internal electronic safety device that prevents it from being rigged the wrong way. Plus the Lightlock self-calibrates every time it is powered up. The calibration takes only about 1.5 seconds to complete. The Lightlock is not affected by the high heat from the lighting fixtures.

One of the additional features of using Maxon motors is that the RSC Lightlock emits such low noise levels that allow it to be used for live performances. The overall Lightlock system measures approximately 20.3-inches wide by 16.9-inches deep, and only 3-inches high. It weighs only 31 pounds. The system draws a maximum of 150 watts of power. Multiple units can be incorporated for difficult lighting arrangements as well. In fact, according to Total Structures, the RSC Lightlock will remain effective for as many moving fixtures as required, however it may take slightly longer for the structure to come to rest.

For information:

maxon precision motors, inc.
101 Waldron Road
Fall River, MA 02720
P: 508-677-0520
F: 508-677-0530
S: http://www.maxonmotorusa.com

maxon’s EC 9.2 Flat motor

maxon's EC 9.2 Flat motor

maxon's EC 9.2 Flat motor

Large-scale torque in a small package

maxon motor launches its flat motor measuring Ø10 x 12.5 mm offering a high nominal torque of up to 0.83 mNm and a stall torque of up to 1.29 mNm. Its outer diameter of 10 mm includes a protective cover that serves as protection against contact and as mounting aid during installation of the motor. It is equipped with an 8-pole Neodymium permanent magnet and preloaded ball bearings.

An ideal motor drive for medical technology applications where space limitations may be a concern. Other features include high nominal torque and lifespan-optimized bearings. Also available with or without Hall sensors. The drive meets medical technology’s quality standard ISO 13485 meaning it conforms to the rigid quality requirements and guaranteed traceability of individual components.

Humanoid Robotic Hand Moves

Five-fingered hand

Five-fingered hand

The human hand is undoubtedly one of the most universal and complex tools of nature. Researchers have been studying the characteristics and special features of this evolutionary design for years. Now the findings of this research are being used and implemented for the robotic hand of the future.

Rapid progress in the development of robotic hands that replicate human movement has progressed to the design of delicate grippers with fingers and thumbs. This accomplishment is no longer a vision but a reality, meaning that multi-fingered hands may soon be available for use in the daily work environment. At the moment only simple, yet robust, two- or three-fingered grippers are being used, leading the charge for the more complex, five-fingered hands that will be able to carry out intricate tasks. Progress in microelectronics and micromechanics allows a multi-fingered hand to be produced with separately controllable fingers and joints that replicate the human hand. The complex mechanics and control electronics required for this can even be constructed, to a certain extent, using standard commercial components.

The German Aerospace Centre (DRL) has developed a robotic hand in conjunction with the Harbin Institute of Technology (HIT). Thanks to micro and precise drive technology and high-performance bus technology, this development is sets new standards for sensitive gripper hands that replicate human ones. Compared with its predecessor, the DRL-HIT-Hand I, the new DLR-HIT Hand II has five fingers, each with four joints and three degrees of freedom. The hand is also smaller and lighter. Four fingers are required for clasping conical parts, and a thumb is used as an outer support. The mechanical range of movement must be properly controlled and monitored to enable the hand to be used fully. High-performance information channels are essential.

The motors in the DRL-HIT Hand II fit directly into the fingers. Particular attention has been paid to the control processor’s information with respect to positioning and operating data. This allows the discrete drive to show its strengths in situ. Every finger joint is fitted with a self-developed non-contacting angle sensor and a torque sensor. Due to the application, both sensors must resolve very quickly.

A high-speed bus transmits the data flow. Rapid feedback — comparing target and actual value is crucial for the function of the controller, particularly in precise and delicate applications. Besides data volume, speed of transfer is also vital, which is why an internal real-time 25 Mbps high-speed bus, based on FGPAs (Field Programmable Gate Arrays), was developed for the application. Only three leads are required for the external serial connection of hand and control processor. The actual controls — a signal processor on a PCI insert card — is integrated into a standard PC. The user-friendly interface provides a way for the hand to be controlled at the PC, with all sensor data displayed on the screen.

EC flat motor designed and manufactured by maxon precision motors.

EC flat motor designed and manufactured by maxon precision motors.

Each finger needs several drives, and each of those must be controlled separately. In this instance, 15 brushless DC motors with Hall sensors are used for each hand. Maxon motor’s EC 20 flat drives were designed in because they are inexpensive, commercially available, products offering a high power density in a compact size. The motors, including Hall sensors, create a unit that is only 10.4 mm long with an outer diameter of 21.2 mm. Each motor weighs 15 g. The motors are mounted with harmonic drive gears from the HDUC 05 range, which have the same diameter as the motor. The three-watt motors are available in a 12 or 24 V version and provide maximum torque of 8.04 mNm. Good dynamic behaviour and preloaded ball bearings ensure precise response behaviour of control commands, including changing the direction of rotation. The digital Hall sensors always report the actual position to the controller accurately. The motors idle at 9,300 rpm.

Thanks to compact drive technology with feedback and rapid data transfer per bus technology, the new DLR-HIT Hand II can be controlled very sensitively and precisely. Micromechanics and microelectronics complement each other, which allows for standard components to be used to produce well-designed products that would have been previously unimaginable, even with expensive special developments.

For information:
maxon precision motors, Inc.
101 Waldron Road
Fall River, MA 02720
P: 508-677-0520
F: 508-677-0530
S: http://www.maxonmotorusa.com

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