A brushless DC motor for demanding operating room applications

A sterilizable EC-4pole 30 from maxon motor

A sterilizable EC-4pole 30 from maxon motor

A sterilizable EC-4pole 30 from maxon motor

maxon’s new brushless electric motor, the EC-4pole 30, delivers high torque (106 mNm) and is sterilizable – a perfect drive for hand-held surgical tools.

Swiss drive specialist maxon motor has developed a robust brushless DC motor for hand-held surgical tools: the EC-4pole 30. Featuring two pole pairs, this DC motor provides a nominal torque of 106 mNm and an output of 150 W. It has a hermetically sealed rotor, meaning that it can withstand over 1000 autoclave cycles.

Need to operate at overload? No problem!

The EC-4pole 30 is equipped with the special ironless maxon winding, which makes it highly efficient. Another key feature is that the torque and current behave linearly and the drive can be overloaded. It is available with an optional Hall sensor, as well as with a hollow shaft with a diameter of up to 4.1 millimeters.

With the EC-4pole 30, engineers get a first-class drive for surgical hand tools that work flawlessly under the tough conditions of operating rooms.

maxon offers a complete line of dc brushed and brushless motors, gearheads and controllers. Contact us to help find the right solution for your application. info@maxonmotor.com

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High performance drive in a small package

maxon's NEW brushless EC4mm motor and gearhead

maxon’s NEW brushless EC4mm motor and gearhead

maxon sets new standards in micro drives

maxon’s smallest DC brushless motor is only four millimeters in diameter and comes in two different lengths. Certified in accordance with ISO 13485, the new brushless micro drive is ideal for medical applications.

The EC 4 brushless DC motor is maxon motor’s ultra-compact solution to the market’s needs. As the smallest micromotor to come from the Swiss manufacturer, the EC 4 is only four millimeters in diameter. It is available in two lengths, with power ratings of 0.5 and 1 W. Equipped with an ironless maxon winding, the EC 4 stands out for its robust design, high power density, and energy efficiency.

EC4 measuring tool

EC4 measuring tool

maxon has the matching gearhead

Combined with the GP 4 planetary gearhead, the EC 4 becomes a compact drive for use in micropumps, analytic and diagnostic devices, and laboratory robots. Precise and reliable, it can adjust lenses, dispense fluids, or position sensing devices. All units meet the ISO 13485 medical standard, which makes this maxon micro drive the perfect choice for applications in medical technology.

maxon offers a complete line of dc motors, gearheads and controllers. Contact us to help find the right solution for your application. info@maxonmotorusa.com

Circulatory Support without Surgery for Heart Failure Patients

The cardiac pump is a mere 6 millimeters and 6.5 centimeters long. Image ©Procyrion

The cardiac pump is a mere 6 millimeters and 6.5 centimeters long. Image ©Procyrion

Intra-aortic pump powered by miniature brushless DC motors provides heart failure patients an aid to help hearts rest and heal.

Chronic heart failure patients draw hope from a new technology. A team of life science entrepreneurs in Houston, Texas has developed the first catheter-deployed circulatory assist device intended for long-term use. Procyrion, Inc.’s Aortix™ provides a minimally invasive treatment option for the more than two million chronic heart failure patients in the USA alone who are too sick for medication. This pre-clinical cardiologist tool dramatically reduces risks associated with circulatory support devices and enables treatment of younger, healthier patients before progressive damage occurs.

Assisting the natural function of the heart, the intra-aortic pump has been thoughtfully designed as an alternative to large, cumbersome surgical devices currently providing full circulatory support. Unlike these devices, Aortix provides minimal procedural risk. Measuring approximately 6 mm in diameter and 6.5 cm long, a cardiologist can deliver Aortix via a catheter in the femoral artery to the descending thoracic aorta. Once the catheter sheath is retracted, the self-expanding nickel-titanium anchors deploy to affix the pump to the aortic wall.

Aortix accelerates a portion of the body’s native blood flow within the pump and pushes it through fluid entrainment ports directed downstream. The jets entrain native aortic flow, transferring energy to the cardiovascular system and increasing blood flow to vital organs such as the kidneys. Additionally, in a model of chronic heart failure, Aortix decreased energy consumption of the heart by 39 percent, allowing the heart to operate more efficiently, encouraging cardiac rehabilitation and recovery.

The cardiac pump is a mere 6 millimeters and 6.5 centimeters long. Image ©Procyrion

The cardiac pump is a mere 6 millimeters and 6.5 centimeters long. Image ©Procyrion

Procyrion has been working with maxon for almost two years to develop a motor for this unique and demanding application. The basis for the Aortix device is a maxon EC6 motor with some customization including the electrical lead, shaft length, and bearing assemblies – all designed to make the pump durable and biocompatible. maxon also designed a high efficiency motor core for this application, which extends battery life and produces less heat so it doesn’t adversely affect the circulating blood. In addition, maxon is working closely with Procyrion to implement a magnetic torque drive, so the motor could be mounted inside a hermetically sealed chamber. This configuration eliminates the possibility of blood entering the motor core. The magnetically coupled pump arrangement is a method sometimes used for giant pumps in the oil field, but because of maxon’s breadth of experience across multiple industries, the company was able to help the Procyrion team successfully transfer this technology to a miniature scale medical application.

Each Aortix device consists of a small, continuous flow pump mounted within a self-expanding anchoring system. The anchored pump attaches to a flexible power lead, which can be tunneled to a desired transdermal exit site or to a Transcutaneous Energy Transfer (TET) system for subcutaneous implantation without an indwelling power lead.

Presently, the device can operate for over eight hours on a single battery pack. The external battery pack and control unit have been designed to be “hot swappable”, meaning the battery can be changed without needing to stop the device. A variety of charging devices can be used.

“Aortix reduces the heart’s energy consumption by 39 percent.”

The Procyrion team has also built a TET charging system that enables the battery to be charged wirelessly. This design has the potential to significantly reduce the risk of infection, common with other implantable heart pumps.

Because traditional assist devices replace heart function rather than support it, device failure can be fatal. With Aortix, a partial support device which doesn’t obstruct native blood flow, failure is not life threatening. Should the pump fail, the device can easily be retrieved and replaced in another minimally invasive, catheter-based procedure.

Kenshiro: Strong robot with 160 muscles.

Kenshiro humanoid robot, maxon motor ag © 2013

Kenshiro humanoid robot, maxon motor ag © 2013

The tendon-controlled humanoid robot created by the University of Tokyo has more than 160 artificial muscles and is the result of many years of experience. Around 100 brushless maxon motors ensures that the only 1.58 m tall robot has humanlike movements.

The University of Tokyo has developed a tendon-controlled humanoid robot that is capable of very realistic humanlike movements. He is called Kenshiro – named after a well-known Japanese hero who was made famous in the 1980s manga comic series. During the development of the robot, the Japanese scientists used the human anatomy as its focus to create an artificial human that looks as natural as possible. “We wanted to understand the movements and appearance of humans and replicate it as closely as possible in Kenshiro,” explains Professor Kei Okada. At a height of 1.58 m and weighing 50 kg, the robot matches the stature of a 12-year old Japanese boy.

To imitate the very complex human anatomy made up of approximately 640 muscles, the scientists equipped Kenshiro with the most important human muscles: 50 in the legs, 76 in the torso, 12 in the shoulder and 22 in the neck. This robot has the greatest number of muscles ever installed in a humanoid robot. Kenshiro’s 160 individual tendon-controlled “muscles” make many humanlike movement patterns possible. Kenshiro can move his arms, legs and torso. He still has to learn how to walk properly. How does a robot learn humanlike movements? It’s simple: demonstrate a movement, he will then imitate it.A simple learning method, implemented by means of open source intelligent software and a mechanical interface. Learning how to walk requires more.

Kenshiro’s “bones” are made of aluminum and, as is the case in the human body, are movably connected to each other. The biggest challenges to the scientists, led by Professor Masayuki Inaba, was the robot’s weight at 50 kg. A replica with the size of an adult would weigh approximately 100 kg which means a higher load, higher energy requirements and slower movements.

93 motors for 160 muscles
The researchers from the Jouhou System Kougaku Laboratory (JSK) of the University of Tokyo decided on a drive system by maxon motor. Kenshiro’s 160 muscles use 93 maxon brushless DC motors. For those special muscles as in the abdominal and thoracic, only a single motor provides the necessary drive and it is that of the maxon brushless EC 16 and EC 22 motors. These electronically commutated servo motors stand out with excellent torque characteristics, high dynamics, an extremely wide speed range, and their very long service life. Strong brushless motors are required for the muscle movements, therefore 60 W to 100 W maxon motors are used. Another important criterion for the motor selection was the temperature development of the motor. It is not possible to install a cooling system in the robot. According to Professor Kei Okada, it was therefore very important that the motors dispense very little heat.

JSK has been building various service robots and industrial robots since 1980 and today are focusing on their work with humanlike robots like Kenshiro. Just a

Service Robots Use Flat Motors

The Jaco2 service robot was designed and engineered by Kinova Robotics. Here, the robot shows well it handles fragile household items.  © 2014 Kinova Robotics

The Jaco2 service robot was designed and engineered by Kinova Robotics. Here, the robot shows well it handles fragile household items. © 2014 Kinova Robotics

Service robots being designed for the disabled must be reliable, safe, and easy to use. Having the right motion system components is essential for these highly specific applications.

Unlike industrial robots for manufacturing, service robots come with their own specification requirements aimed specifically at the end user, and the most discriminating user at that—a human being. That’s why designing and manufacturing service robots takes a particular set of skills and engineering expertise. For example, when Kinova Robotics (Quebec, Canada) creates designs for this market, they bring with them years of experience in the field. And although they’ve modified their robots over the years, as new products and systems become readily available, they are able to produce higher and higher quality and more useable products. Using the latest technologies allows Kinova to continue to advance their offerings to the public.

The company’s Jaco2 Robotic Arm has benefited from the company’s prior designs and forward thinking. Because of available technologies, the robotic arm provides a lightweight, quiet, and easily controlled device to the service industry. The Jaco2 robotic arm moves around six degrees of freedom through the use of six flat motors designed and manufactured by maxon precision motors (Fall River, MA). The arm was designed using six joints from a shoulder-type joint through to a functional wrist joint. The robot can manipulate a maximum payload of 1.5 kg at full extension, as well as a 2.5 kg payload at a mid-range extension. Both of these payloads are adequate for the needs of most disabled people in the process of living a normal life. The robotic arm device itself weighs only 5.3 kg, which was a very important specification for it to mount to a wheelchair without tipping it over. To maintain such a light weight, the company incorporated the lightweight and efficient flat motor series manufactured by maxon.

The Jaco2 easily mounts to a wheelchair and stays out of the way.  © 2014 Kinova Robotics

The Jaco2 easily mounts to a wheelchair and stays out of the way.
© 2014 Kinova Robotics

Because the first three joints have to handle the highest torque for movement of the extended arm as well as for lifting items the user needs, Kinova’s engineering team chose to use maxon’s EC 45 flat brushless DC motors. These motors provide an impressive maximum continuous torque of up to 134 mNm (19 oz-in) in a small, compact, but powerful 70 Watt package. And since the Jaco2 needed to fit inside the robotic arm itself, there had to be less heat generated through motor operation—a huge benefit of the EC flat motors. Although the EC 45s can operate at very high speeds, that was not a necessary requirement for the Jaco2 application. In order for the robotic arm to be manipulated efficiently, the device only needed to move at a speed of 20 cm per second, which translates to about 8 rpm maximum for the actuators’ outputs (about 1100 rpm for the motors).

The second three joints in the Jaco2 arm are also EC 45 flat motors, but are 30 Watt versions. Again, they were chosen to help keep heat dissipation at a minimum, since the motors were mounted inside the arm itself. Further, the flat motors were necessary because of the compact space allocated to the robot joints. The motor efficiencies offered by maxon motors were a critical point in selecting the EC series for the application. Plus, according to one member of the engineering team, maxon was open to slight customizations, which allowed the team to fit the motors to the application perfectly. Through the use of slip rings that were designed and manufactured in-house, each axis on the arm has infinite rotational capabilities. The arm incorporates Harmonic Drive® gears translating to a 1:136 ratio for the large actuators in joints one and three, a 1:160 ratio for the large actuator in joint two, and 1:110 ratio for the small actuators located in joints four, five and six.

The Jaco2 Service Robot uses three of maxon’s EC 32, 15 Watt motors to operate the finger of the robot. Kinova engineers provided an in-house design for the lead screw mechanisms incorporated inside the fingers. The linear actuators had to be very small due to the limited space available. The actuators were designed in-house because the company’s engineering team found that it was less expensive to design the lead screws they needed than to buy them off the shelf from another vendor. Although the flat motors have some minor degree of cogging, that did not affect the accuracy or other operations of the Jaco2 that would be critical to the user. Quiet operation of the motors only added to their overall appeal for the application, especially because of the human-robot interaction. The company wanted the device to be as transparent as possible to the user.

All the motors in the arm are daisy-chained using a single cable that runs through the system. The tight form factor dictated the size and type of motor the company could use, and they were able to match their needs to maxon devices. The Jaco2 uses 18 to 29 VDC for operation at 25 W nominal power (100 W peak power). Control of the arm is performed through an RS485 (internal) and CANBUS (external) protocol. The system comes with two expansion card connectors for future use. The controller features redundant security on each actuator/finger, redundant error check in actuators and control system, position and error calculation performed every 0.01 seconds, Cartesian and angular trajectory control, and force and torque control options.

Each Jaco2 Robotic arm is controlled easily directly through the user’s wheelchair control or through a user-friendly joystick, which provides the precision necessary for the human-robot interaction needed for the disabled person. All the software required for the system was written by the Kinova Robotics engineering team so that the operation of the Jaco2 met all their in-house specifications and goals. The software runs on Windows, Linux Ubuntu, and ROS, and was written using C# and C++.

Please smile with maxon motors.

© dannas - Fotolia.com

© dannas – Fotolia.com

Digital SLR cameras can deliver extremely sharp photos – regardless of whether the photographer is a professional or a hobbyist. Not only does the skill of the photographer, but also the technology inside the camera play a key role. maxon drive systems help to create lightning-fast images.

With its Leica S system, camera manufacturer Leica offers a unique combination of performance features for digital photography. It combines the image quality of a medium-format camera with the handling, speed and flexibility of a small-format camera. The lenses used in the Leica S system have a built-in dedicated processor for controlling the auto focus. The lenses are also available with a central shutter for maximum flexibility when using a flash. Besides the focal-plane shutter, which is integrated in the camera, the central shutter is one of two common designs. The central shutter is typically located at a “central” position in the lens assembly, between the optical lens elements. It consists of several blades arranged around the optical axis in a concentric pattern. When the shutter release of the camera is pressed, the blades snap back from this axis synchronously and let the light fall on the sensor.

With SLR cameras, the central shutter first closes after the shutter release, because all the settings were made with an open shutter. The mirror swings up, then the central shutter opens for the duration of the exposure before closing again. Finally, the mirror swings back into the path of light, and the shutter opens. Even though it employs the classic solution of mechanical springs for the efficient storage of potential energy, the central shutter is a piece of cutting-edge technology. The tensioned-spring principle contributes significantly to the extremely compact dimensions.

Small motor for high tension
The springs are tensioned by a specially developed maxon motor with a high-precision overrunning clutch and release their stored energy to activate the shutter blades when the shutter release is depressed. A specially constructed solution prevents the blades from rebounding when the shutter is opened or closed. A microprocessor-controlled pawl and ratchet mechanism controls the shutter cycle via two electromagnetically activated plungers.

The gear motor of maxon motor is used for tensioning three springs that store the energy for the central shutter. A maxon A-max 12 motor is used as the base motor. The gearhead is an all-new development and is adapted to the available space. This presented a special challenge to the gear motor in the central shutter of the Leica lens. What was needed and developed was a very compact, enclosed and sealed custom version of the gearhead with perpendicular power transmission to toothed gear of the central shutter through a crown gear, for a life span of more than 100,000 releases.

Wing-flapping Aircraft Hovers and Flies

The Nano Hummingbird’s string-based flapping mechanism geometry shown illustrates the mechanism configuration (top), then the forestroke (2nd and 3rd from top) motions and backstroke (4th and 5th from top) motions.

The Nano Hummingbird’s string-based flapping mechanism geometry shown illustrates the mechanism configuration (top), then the forestroke (2nd and 3rd from top) motions and backstroke (4th and 5th from top) motions.

Life-sized hummingbird-like unmanned surveillance aircraft weighs two-thirds of an ounce, including batteries and video camera.

The Nano Hummingbird (Figure 1) is a miniature aircraft developed under the Nano Air Vehicle (NAV) program funded through the Defense Advanced Research Projects Agency (DARPA). DARPA was established to prevent strategic surprise from negatively impacting U.S. national security and to create strategic surprise for W.S. adversaries by maintaining the technological superiority of the U.S. military. The agency relies on diverse performers to apply multi-disciplinary approaches to advance knowledge through basic research, and create innovative technologies that address current practical problems through applied research.

For the Nano Hummingbird project, technical goals for the effort were set out by DARPA as flight test milestones for the aircraft to achieve by the end of the contract effort. The Nano Hummingbird met all – and exceeded many – of the milestones (see sidebar), even though the goal was never to replicate a hummingbird exactly, but to learn from its remarkable flying qualities, and then develop an aircraft that would look, fly, and sound as much like a real hummingbird as possible.

Over ninety percent of the design and fabrication of the aircraft and its support systems was completed by AeroVironment Inc. (Monrovia, CA). The aim of the project was to use as many off-the-shelf components as possible. The challenge for the completed project was to provide controlled precision hovering and fast forward flight using a two-wing, flapping-wing craft that also carried its energy source and a video camera as payload.

To this stage of the project, the Nano Hummingbird is capable of climbing and descending vertically, flying sideways left and right, flying forward and backward, as well as rotating clockwise and counterclockwise, all while under remote control. The prototype is handmade and has a wingspan of 16 cm (6.5-in) tip-to-tip, and a total flying weight of 19 grams (2/3 ounce), which is less than the weight of a common AA battery.

The prototype includes all the systems required for flight: batteries, motors, communications systems, and video camera. It can also be fitted with a removable body fairing, which is shaped to look like a real hummingbird. Even though the aircraft is larger and heavier than an average hummingbird, it is still smaller and lighter than the largest hummingbird currently found in nature.

The typical flight endurance of the final Nano Hummingbird is between five and eleven minutes, depending on how the aircraft is outfitted with batteries and payload. It is expected that with planned weight reductions and system efficiency improvements that the flight endurance could effectively double.

The hummingbird has an onboard stability and control system that allows seamless and simple remote piloting of hover flight to fast forward flight. It is configured with a micro, color video camera that transmits continuous real-time video to the pilot operator during the flight and is displayed on a small LCD screen on the hand control unit. In the future, AeroVironment plans to develop collision avoidance capabilities to allow for semi-autonomous indoor flying, video aided navigation; GPS aided navigation, and long range communications.

Significant effort was spent miniaturizing the flapping and control mechanisms while maintaining stiffness and precision. Flapping wing designs are heavily influenced by the unsteady aspects of the flapping motion, both structurally and aerodynamically. A large number of possible degrees of freedom in the kinematics of the system made the design problem a complicated one. Nonetheless, based on earlier ornithopter wing design research, a flexible membrane was ultimately used, which allowed the wing to passively deform, since active control of wing shape was infeasible.

Quantitative analysis of the wings was based around the metric of thrust per motor shaft power, as mechanism power consumption is not readily separable from the aerodynamic power. So, shaft power was converted from motor input voltage and current using well-tested model of the drive motor, which was manufactured by maxon precision motors (Fall River, MA). Generally the names of
vendors and component part numbers are held as confidential, but according to Matthew Keenon, Nano Air Vehicle Project Manager, “We can say that the main propulsion motor was supplied as a stock part from maxon precision motors, we just can’t say which model was selected at this time.”

maxon motors provides its customers with a complete line of DC brushed and DC brushless motors to choose from. What makes them unique is their ability to provide a non-cogging brushless DC motor down to less than 6 mm long. Because their motors offer high torque to speed ratios, and low-power versions, they are ideal for unique applications in fields from medical and aerospace to robotics and consumer products. Their motors were used in the Nano Hummingbird for their efficiency and longevity, among other key characteristics.

The final string-based flapping mechanism uses a continuously rotating crankshaft driven by the maxon motor. The pin on the crankshaft (Figure 2 a and b) is attached to two strings, each connected to two pulleys that are mounted on the wing hinge flapping axes. When the motor turns the crankshaft, the pulleys oscillate. Two additional strings connected to the pulleys keeps them (and the wings) matched in phase. This design helped to minimize vibration and maximize thrust.

In all, the Nano Hummingbird is a successful project that is continually under adjustment and innovation. AeroVironment has been involved in the project since its inception, and is excited about the advances made in this technology.

SIDEBAR:

-The Nano Hummingbird technical goals performed:
-Demonstrated precision hover flight within a virtual two-meter diameter sphere for one minute.
-Demonstrated hover stability in a wind gust flight that required the aircraft to hover and tolerate a two-meter per second (five miles per hour) wind gust from the side, without drifting downwind more than one meter.
-Demonstrated a continuous hover endurance of eight minutes with no external power source.
-Flew and demonstrated controlled, transition flight from hover to eleven miles per hour fast forward flight and back to hover flight.
-Demonstrated flying from outdoors to indoors and back outdoors through a normal-sized doorway.
-Demonstrated flying indoors “heads-down” where the pilot operated the aircraft only while looking at the live video image stream from the aircraft, without looking at or listening to the aircraft   directly.
-Flew the aircraft in hover and fast forward flight with bird-shaped body and bird-shaped wings.

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