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.
Emirates Team New Zealand are to partner with MND New Zealand (the Motor Neurone Disease Association of New Zealand) as the official charity of the Team for the 36th America’s Cup.
Emirates Team New Zealand June 18, 2019.
Motor Neurone Disease (MND) causes the muscles that enable us to move, speak, swallow and breathe to gradually stop working. New Zealand has the highest known rate of MND in the world, with an average of 2 people diagnosed each week and well over 300 people living with the condition.
Emirates Team New Zealand have first-hand experience witnessing the devastation of MND through team mate and former Emirates Team New Zealand Director and current Director of America’s Cup Event Ltd (ACE) Greg Horton.
“Greg has been and continues to be an undeniable inspiration to the team while fighting MND” said Emirates Team New Zealand CEO Grant Dalton.
“Whilst the disease is having a devastating effect on him physically he has always remained so strong and optimistic despite his personal hardship, he contributed to our success in winning the Cup in Bermuda, and he still manages to undertake his vital role towards the planning for the 36th America’s Cup in 2021.”
Greg is also a member of the National Council of the not-for-profit charity MND New Zealand which supports people living with MND, their family and carers and health professionals to enable them to have the best quality of life possible.
“MND New Zealand is a vital part of the support network for those with MND and their families. Emirates Team New Zealand put its hand up early after my diagnosis with team members offering support to me and my family in any way possible, and it is great to formalise a broader support basis today with Emirates Team New Zealand coming on board as our charity partner.” explained Horton.
MND New Zealand General Manager Carl Sunderland says it is a huge honour to be the Official Charity of Emirates Team New Zealand.
“We rely almost completely on the generosity of the New Zealand community to continue to provide free, personalised support to people living with MND, their carers and families and this partnership will help raise awareness of this devastating disease and the vital work we do.”
MND New Zealand also proudly funds vital research at the Centre for Brain Research at the University of Auckland and supports the latest genetics study led by Dr. Emma Scotter.
“MND New Zealand. Together with the Royal Society of NZ and several generous kiwi organisations and families, fund our research into the causes and possible cures of MND. Although the brain tissues of New Zealanders who die from MND show the expected signs of the disease, our research has uncovered a higher rate of MND in New Zealand than in the rest of the world. Our next step is a nationwide genetics study, also supported by MND New Zealand, to determine if our high rates relate to unique genetic factors in New Zealanders.” Said Dr Scotter.
As part of its support for MND New Zealand, Emirates Team New Zealand is giving MND New Zealand a full immersion day at Emirates Team New Zealand as an auction item to be auctioned off at The Grocery Charity Ball in September.
“Through Greg you can see the amazing work MND New Zealand do for the 300+ New Zealanders that are living with MND so we are really proud to be supporting them and everything they do” concluded Grant Dalton.
To make a donation to help MND New Zealand, please go to www.mnd.org.nz
For further information on DC motors for use in underwater and extreme environments please contact maxon motor Australia tel. +61 2 9457 7477.