maxon motor UK office spoke with Philip Norman at Ross Robotics, who has created greater flexibility with his modular robots via innovative use of hub drives.
Ross Robotics specialises in remotely operated vehicles (ROVs) that are modular. The robots are designed to be made from generic parts to build robots small, medium and large. Tools and sensors are modular too and can be plugged on to suit the application. One robot can then perform different functions, which is highly unusual in the robotic world.
An unusual advantage
The latest modules offer greater flexibility than previously by using hub drives. Hub drives consist of motors and electronics inside a wheel case. These are stand-alone units, one of the advantages being that little maintenance is required. The speed and torque of the ROV can be changed quickly by swapping to a different hub drive. ‘The idea is to hide the complexity from the end-user to provide a range of performance options’ said Philip Norman, Research and Development Director of Ross, ‘If you want a police force robot to travel at 25 kmh or a bomb disposal unit to travel at 1 kmh, the hub drive will look the same from the outside but will be calibrated to perform to a specific task.’
Philip’s team are now using the maxon EC flat motor series with accompanying maxon gearboxes in each hub. Philip explained that initially they were using an alternative gearbox combined with a maxon motor. ‘We thought we needed a customised gearbox. This was expensive and we found they were prone to failure. We then tried an off-the-shelf maxon motor and maxon gearbox and it worked perfectly.’
The modular ROV’s have huge potential from mine inspection in South America to perimeter fence patrolling in Scandinavia. In agriculture, they can be used inside chicken farms. The robots are used to check the welfare of the birds. By using autonomous or remote-controlled navigation, onboard modular sensors can monitor the air quality, as well as the chicken distribution. Chicken aggression can be a big problem. Because robots are not imprinted as predators (unlike the human stockman) they can modify the behaviour of the birds by interacting with them, like ‘super hens’, allowing smaller birds to get to the feeders and drinkers. This is hugely beneficial for the birds’ welfare and results in improved commercial outcomes for the farmer.
The nuclear industry is using robots to explore areas hostile to humans. The robots can endure rough terrain and deploy modular sensors, LIDARs, cameras and Geiger counters to determine the quality of the environment. When equipped with suitable tool modules they also perform useful decommissioning tasks.
Ross Robotics offers a range of hub motors, depending upon customer requirements. They promise quality and reliability. ‘Our biggest worry is failure. No-one wants a call at 2 am from a customer in Australia to say that your robot has failed, and it’s affecting business’, says Philip. ‘This is why we use maxon products. maxon has a great reputation globally, we only have to say that the Hub has maxon motors and gearboxes in it and customers are reassured. If we want to deliver a quality product, the quality of our suppliers is paramount.’
Please contact Karen Whittaker, Marketing Manager maxon UK and Ireland, for more information.
maxon motor Australia tel. +61 2 9457 7477.
Left to right: maxon EC flat motor with gearbox; hub drive from Ross Robotics; and hub drive.
The maxon brushless flat motors are now available in combinations with planetary gearboxes, encoders and vented rotors for increased torque.
The recently released 90mm diameter Brushless DC ventilated motors from maxon gave power level increases from 160W to 600W within the same diameter. Two length options of 27.4mm and 39.9mm are selectable with two air cooling options. Four winding options are available for DC voltages varying from 12 to 60VDC. Continuous torque capability is up to 1610mNm from the motor alone and when combined with planetary, worm and helical gearhead options repeated peak torque levels of 650Nm have been achieved. High ratios and 25600qc integrated internal encoders make them extremely useful products for rotary joint applications such as robotics and industrial machinery actuators. Maxon can also manufacture custom versions with specific cable looms and rear shafts for mounting loads on both sides of the motor. The combination of the flat motors with high stiffness, low profile, zero backlash, trochoidal style gearheads also makes the complete drive suitable for wheel drive applications such as autonomous ground vehicles and warehouse logistic machinery.
maxon motor Australia tel. +61 2 9457 7477.
Many applications would benefit from a brushless motor without a sensor. A method developed by maxon is now setting new standards for precision and reliability.
Driving a brushless motor requires control electronics for precise commutation. However, this is possible only if the control electronics “know” the exact position of the rotor at all times. Traditionally, this information was provided by sensors, e.g. Hall sensors, installed inside the motor. But it can be done differently. Sensorless control methods use current and voltage information from the motor to determine the rotor position. The motor speed can then be derived from changes in the rotor position, and this information can be used for speed control. More advanced sensorless control methods can even control the current (torque) and the position. Leaving out the sensors has a range of benefits, such a lower cost and space savings, because cables, connectors, and sensitive electronic circuits become unnecessary.
Sensorless controllers by maxon use three basic principles that are adapted specifically to maxon BLDC motors.
Principle 1: EMF method with zero crossing
The EMF method with determination of the zero crossing uses induced voltage (or EMF) in the non-powered phase during block commutation. The zero crossing happens in the middle of the commutation interval (fig. 1). The time delay to the next commutation point can be estimated from the preceding commutation steps.
The EMF method with zero crossing works only when the speed is high enough, because EMF becomes zero at standstill. Starting up the motor requires a special process, similar to step motor control, and must be configured separately. True sensorless commutation is possible only with motor speeds of 500–1000 rpm and up. The commutation step frequency is used for speed control. The limited feedback information puts some constraints on the motor dynamics, although this can be improved by integrating estimation methods into the control algorithm (observer, Kalman filter, etc.). The EMF method with zero crossing also has a range of benefits: It works for all brushless motor models, and it’s robust and cost-effective. The approach is used in many standard products, such as the maxon ESCON Module 50/4 EC-S.
Principle 2: Observer-based EMF method
Observer or model-based EMF methods use information about the motor current to determine rotor position and speed. The model-based approach yields a much higher resolution of the rotor position. This enables sinusoidal commutation (or FOC, field-oriented control), with all its benefits: Higher efficiency, lower heat generation, less vibration and noise. However, the observer-based EMF method also requires a minimum speed of several 100 rpm to function properly.
Principle 3: Magnetic anisotropy methods
Methods based on magnetic anisotropy deduce the rotor position from the motor inductance, which is minimal when the magnetic flows of the rotor and the stator are in parallel in the magnetic return (fig. 2). Measurement is achieved by means of brief current pulses, which do not cause the motor to move. Unlike EMF-based methods, this method also works at standstill or very low speeds, and it permits sinusoidal commutation. The measured signals are highly dependent on the motor type. The rotor position is determined in a model of the motor, which needs to be parameterised and adapted for each motor. Controllers based on magnetic anisotropy are therefore highly specific products – “plug and play” is not an option. The computation effort required for evaluating the rotor position also limits the maximum speed.
Why sensorless control?
In price-sensitive applications, the use of sensorless motors may reduce the cost. Hall sensors, encoders, cables, and connectors become unnecessary. Typical applications in this field are fans, pumps, scanners, mills, drills, and other fast-turning applications with a relatively modest control performance that do not require a tightly controlled start-up. For high quantities, a customised version of the EMF-based controller makes sense.
Cost optimisation for high control performance
Cost savings aren’t the only reason to choose sensorless control. Applications like door drives or bike drives require high controller performance. Jerk-free motor control from zero rpm is important, as are high dynamics and sinusoidal commutation for noise avoidance. All this needs to be realised without using an expensive encoder. Over the last few years, high-quality sensorless controllers based on the anisotropy method have become established, including maxon’s new High Performance Sensorless Control (HPSC, see below). However, the engineering effort required for adapting the model parameters can only be justified for quantities upward of a few hundred.
Rough ambient conditions
Sensorless control may also be required in situations where vulnerable sensor electronics need to be avoided in a motor. Examples include applications in very high or low ambient temperatures, cleaning and sterilisation in medical technology, or ionising radiation in space, nuclear facilities, or medical settings. The lower number of motor connectors also makes integration easier if space is limited.
The required control quality depends on the application. Which sensorless method fits best must be decided on a case by case basis. For example, hand-held dental tools for drilling or grinding need high speeds, while lower speeds and controlled torque are required for fixing screws in surgery.
There are three main reasons for choosing sensorless control: Cost savings, space savings, and operation in environments unfavorable to sensors. The EMF method with zero crossing determination is widespread in cost-sensitive applications that run at high speeds. Sensorless control from standstill and at low speeds requires more advanced methods. The implementation effort is greater and includes modelling and parameterisation. Cost savings are secondary. Field-oriented control yields a higher efficiency, less heat build-up, and a lower vibration and noise level. All these are advantages that come to bear especially in hand-held medical devices.
For further information please contact maxon motor Australia tel. +61 2 9457 7477.
maxon sensorless controllers
The HPSC Module 24/5 (High Performance Sensorless Control) is a new development from maxon, it is a platform of hardware and customer-specific software. HPSC is always a customised solution and therefore not a catalogue product.
What’s special about this development: At standstill and at low speeds, magnetic anisotropy-based control technology is used first (principle 3). Then, when the speed is higher, a smooth transition to an observer-based EMF method (principle 2) follows. The module’s firmware is customised for every drive system. In a special tuning process, more than 120 parameters are automatically adjusted to each motor’s “fingerprint.” An example of the use of HPSC is the hand-held medical tool developed recently by maxon.
The ESCON Module 50/4 EC-S is the only sensorless controller from maxon that is listed in the product catalogue (block commutation with EMF method and zero crossing determination). The Sensorless Controller 24/1 is an alternative for the smallest EC motors (up to about 10 mm diameter). However, it is not listed in the catalogue or the e-shop.
New to the maxon motor Group, Parvalux bring unique combinations of AC motors fitted with multiple gearheads and sensors.
The SD series from Parvalux offers 240V AC solutions with the ability to mount multiple gearheads in the orientation to best suit the application. Combinations of inline planetary gearheads and right angle worm gearboxes not only offer flexibility of the shaft orientation for tight space constraints but also large variations in reduction ratio. This greatly increases the versatility of AC motors running in a fixed speed application. Made in the UK with high quality and backed up by the maxon group global sales and support network. The motors are available in single phase and three phase. The power range is from 315W to 8W and selection can be made between die cast zinc alloy or cast iron. Breaks, sensors, IEC flanges and foot mounts are all possible.
For further information please contact maxon Australia tel. +61 2 9457 7477.
From July 1, 2019 maxon dropped the word “motor” from its name.
maxon is evolving from a manufacturer of motors and components into a specialist for precision drive sys-tems. Known simply as maxon from 1 July, the company is changing its corporate structure to position it-self as a powerful group with a worldwide presence and the capability to respond to specific local de-mands. With a focus on five core markets – medical technology, aerospace, industrial automation, trans-portation & e-mobility and robotics. maxon drives are used wherever the requirements are particularly high, for example, in NASA’s Mars rovers, surgical power tools, humanoid robots and in precision industrial applications. maxon’s expertise beyond drive technology consists of mechatronics, battery management systems and software & cloud services. At maxon Australia, a fully integrated service is on offer with the introduction of Dr Carlos Bacigalupo who is an expert in controller integration, system analysis and configuration assistance.
For further information please contact maxon Australia tel. +61 2 9457 7477.
The European Space Agency (ESA) is working on a new system to enable easy docking between two spacecraft. maxon developed two special drive systems for this purpose.
Even though it’s been done many times before, the docking manoeuvre between two objects in space is always a delicate and potentially dangerous procedure. The speed is extremely high (about 28,000 km/h in case of the ISS), and corrections are difficult. For example, when the two objects are about to meet, manoeuvring thrusters can no longer be used, since their exhaust plumes can cause damage. To prevent harm, cargo transporters are caught by a robotic arm installed in the International Space Station (ISS) and berthed manually. Manned spacecraft on the other hand dock directly in a computer-controlled process.
This type of docking manoeuvre is going to become easier and safer in the future, so the European Space Agency (ESA) has commissioned its industry partners to design a new docking system called IBDM (International Berthing and Docking Mechanism). This conforms to the International Docking System Standard (IDSS), a standard on which the leading space agencies worldwide have agreed. The system will therefore be compatible with the ISS and most other spacecraft. The mechanism’s first missions will be with the Dream Chaser, a craft that looks like a compact version of the Space Shuttle and will soon perform cargo flights to the ISS. The craft is being developed by the Sierra Nevada Corporation.
Docking energy is absorbed
The IBDM is an androgynous coupling system. This means that the connector is identical on both sides. It consist of a hard inner ring (Hard Capture System) and a soft outer ring (Soft Capture System) that has six degrees of freedom and force sensors. The outer ring first absorbs the docking energy. Then the final airtight connection is made and secured by mechanical hooks which pull the two spacecraft tightly together.
SENER is in charge of developing and installing the Hard Capture System. The company is currently working on the qualification model, which is due for testing in 2020. “Then the IBDM needs to be used as quickly as possible on a supply flight for the ISS,” says SENER’s Gabriel Ybarra. One of the next steps would be to use it in NASA’s Lunar Space Station, which is planned to go into orbit around the moon and could serve as a launch point for manned missions to Mars in the future.
Dual systems for maximum safety
This is a challenging project for the engineers at SENER: “We first needed to fully understand all the requirements set by ESA and NASA and figure out how to fulfill these requirements. And especially with regard to safety, because the docking mechanism can also cope with manned flights.” As well as being lightweight and delivering the required torque, the electrical drives that are used must also be extremely reliable. This is why SENER has been working with the drive specialist maxon for several years.
maxon’s engineers have developed two drives for SENER that can be used to execute a huge variety of functions. This first drive consists of two brushless EC-4pole motors and a GPX UP gearhead. Twelve of these actuators power the locking hooks in the IBDM docking mechanism. The second drive combines a flat motor with a planetary gearhead. It is used in eleven places, to manage the plug-in connections and the retaining eyes, as well as other ancillary functions.
As the IBDM docking mechanism is a flight-critical application, redundant drive systems are required. The backup must function even if the primary drive fails. This is often solved by means of a backup motor that can take over in an emergency. This is the approach used for the locking hook actuator. For the other drive system however, the maxon engineers found a different, unconventional solution: an additional stator is used instead of an extra motor. The flat motor therefore has two stators and hence two windings, each of which is capable of independently driving the rotor – an ingenuous solution, which guarantees safety while saving space.
Gabriel Ybarra praises the collaboration with maxon: “The team understands our requirements and is very quick with design modifications.” Moreover, both partners have a passion for mechatronic systems. “It feels great to be involved in the entire cycle, from design to production and testing. This makes it extremely interesting. And when the system moves for the first time, it’s like watching your children take their first steps.”
For more information contact maxon motor Australia tel. +61 2 9457 7477.
maxon has been selected to supply the optical filter changer system for what will soon be the largest wide field telescope in the world. The project, involving five French research laboratories, requires motors and controllers capable of working to an accuracy of 1/10th of a millimetre.
With its 8.4-meter mirror and 3.2 gigapixel camera (making it the biggest digital camera in the world), the Large Synoptic Survey Telescope (LSST) is a project that is defined by superlatives. Its mission? To extend the boundaries of the visible universe but also to tirelessly survey and map the universe for the next 10 years from the observatory on the summit of Cerro Pachón in Chile.
The LSST: the product of expertise from all over the world
To achieve its mission, the Large Synoptic Survey Telescope will photograph the entire sky several times each week, allowing it to catalogue changes and measure the movement of the celestial bodies. Its astronomical surveys will contribute to studies designed to elucidate the structure and evolution of the Solar System and Milky Way. The findings will also be applied in various research projects dedicated to unlocking the mysteries of dark matter and dark energy.
Coordinated by the USA, the project has a budget of some USD 675 million (approximately EUR 600 million). Almost twenty countries will contribute to analysis of results with inputs from research laboratories from all around the world. Alongside the United States and Chile, France is playing an active part in the construction of the telescope through the French National Institute of Nuclear and Particle Physics (IN2P3).
Precision engineering in the service of astronomy
The telescope is installed on the 2,680 meter-high summit of Cerro Pachón, a site chosen for its very low levels of atmospheric and luminous interference. It is housed in a dome that is 30 meters in diameter and 17 meters high. The dome is fully motorised, so that the telescope can be rotated to successively point in all possible directions.
The telescope itself consists of three main elements. The first of these is the mount with which the telescope is precisely positioned in preparation for observations. Then there is the optical element, which is made up of three curved, aspherical mirrors, the largest of which has a diameter of more than 8 meters. Finally, there is the digital camera, which is one of the project’s centrepieces.
This camera is built around a 3.2 billion pixel digital sensor that is chilled to -100°C. This is sensitive to a particularly broad range of light, from near ultraviolet to near infrared, so that photometric measurements can be carried out across the entire spectrum. Finally, the camera incorporates a system of optic filters that enable users to select the fraction of the light spectrum that they wish to observe.
Fast-action optical filter changer
All astronomical survey telescopes incorporate a filter changer but most of the systems currently in use are too slow to meet the ambitious performance requirements of the LSST, demanding changeover 15 times faster than that of other instruments of a similar size.
A team of five French laboratories therefore collaborated in the development of a robotic system capable of placing a new filter over the imaging camera in only a few minutes. In meeting this challenge, the team had to deal with major technical constraints, starting with the integration of the automatic filter changer, as all of its components had to be housed in the body of the camera. And there it must remain perfectly stable, even in the event of a strong earthquake.
The team designed a device capable of handling the extremely costly filters – each with a diameter of 75 cm and weighing almost 40 kg – with an accuracy of a tenth of a millimetre. The centre piece of the device is a carousel that can be loaded with up to five filters and present one of them for use in less than 20 seconds. In addition, there is an automatic mechanism for loading/unloading a filter onto the camera and another mechanism for loading filters within the camera. Together, these three elements go to make up the automatic filter changer.
Compactness, reliability, support
It is in this context that the French National Institute of Nuclear and Particle Physics (LPNHE) sought expert support from MDP – maxon France. The online configurator and associated technical documentation posted on the maxon website served as a starting point for identifying the initial components suitable for integration in the system.
In the course of further exchanges, the suitability of solutions from MDP – maxon France was validated, and the use of the same supplier for the motor/controller combination meant that there would be no compatibility issues. For example, the carousel and the automatic filter changer use maxon EC40/GP42 and RE40/GP52C drive motors along with an EPOS2 70/10 modular digital positioning controller.
Among the various criteria adopted by the teams working on the LSST were the compactness of the components, motors, gearheads and controllers – an essential factor as these had to integrated in the heart of the camera – combined with complete reliability. Indeed, the filter changer must be able to function continuously, with maintenance limited to a period of 2 weeks every 2 years when operation of the telescope is interrupted for re-aluminisation of its mirrors.
The demanding nature of the work carried out on the optical filter changer reflects the ambition of the project and gives some idea of the extent of collaboration required among the various stakeholders in the LSST. For its part, maxon is delighted that its online configurator, its motors, and its electronic systems have contributed to the successful realisation of such a technical and scientific challenge!.
For more information contact maxon motor Australia tel. +61 2 9457 7477.
New industrial series IP65 hollow shaft right angle gearmotor.
Featuring high power density this 60mm diameter 400W 48V brushless DC motor and right angle helical bevel gear combination can deliver 25Nm of torque. Loads can be mounted traditionally via keyway or coupling and also through-shaft clamp collar fittings can be used. The brushless DC motor’s rear cable entry housing contains a 5000cpt 3 channel encoder and a DC holding brake for safety critical power failure load holding. Two different 48V windings allow for high speed and low current preferences making control selection easy and cost effective. All surfaces are gasketed, all bearings are rubber sealed and cables are grommeted for industrial operation in harsh environments making the drive particularly suitable for oil and gas, mining and agriculture applications.
For more information please contact maxon motor Australia tel. + 61 2 9457 7477.
maxon DC motors are currently on Mars, helping collect vital information on the Red Planet.
On November 26, 2018 NASA’s InSight rover touched down on Mars. maxon DC motors went straight into action to unfold the two solar panels, securing the energy supply that operates the all-important probe. There are two main instruments onboard InSight, a seismometer to measure potential quakes on Mars and a heat sensor designed to drill down five meters into the ground. The sensor was developed by German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Its rod digs into the hard soil using a hammer mechanism, driven by a DCX motor from maxon. The rate of boring down strongly depends on the composition of the soil, which hasn’t been ideal, the rod hit an obstruction in the very first hammering cycle. However, the engineers at DLR are confident these complexities can be overcome and that the sensor will reach the projected depth.
To efficiently drive the penetrometer into the ground, the DC motor needed to withstand forces in excess of 400 g – and more than 100,000 times. It took a number of variations and failed tests to find the right solution. The result is a standard DCX 22 motor, greatly modified with additional welding rings, bearing welds and specially shortened brushes. The GP 22 HD gearhead, on the other hand, only needed Mars-specific lubrication.
InSight’s mission is to carry out several measurements over a period of two years and provide insights into Mars and the formation of Earth. The mission is being conducted by the Jet Propulsion Laboratory (JPL) for NASA.
For more information on DC motors and gearheads that withstand exceptionally harsh environments, strong vibrations and extreme temperatures contact maxon motor Australia tel. +61 2 9457 7477.
maxon motor have achieved higher levels of power density for their 4 pole brushless gearmotors.
Up to 96% efficiency and 5Nm from a gearhead that is only 22mm diameter. This new series of ultra-power gearheads has been perfectly matched with a 4 pole 120W brushless DC motor and a 1000cpt 3 channel encoder. With the exception of maxon motors specialist oil filled heavy duty gearboxes the new series gives the highest torque levels available from 22mm. Intermittent torque ratings have increased from 3.8 to 6.5Nm with a maximum speed input of 10,000rpm. The pictured combination is the first of the series supplied to customers in Australia and also exhibits a custom shaft with key and keyway. Additionally, the motor is fitted with temperature sensors in contact with the winding to allow the brushless DC 4 pole motor to be pushed to its continuous thermal capacity. A sealed bearing system and continuous welding of inline components protect the assembly for use in harsh environments and give optimal assembly strength making the gearmotor series particularly suitable for Aerospace applications.
For more information contact maxon motor Australia tel. +61 9457 7477.