Editor's Choice


New docking system for space rendezvous

Third Quarter 2019 Editor's Choice Electrical switching & drive systems & components

The European Space Agency (ESA) is working on a new system to enable easy docking between two spacecraft. maxon motor developed two special drive systems for this purpose. Even though it has 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 the case of the International Space Station (ISS), and correc-tions 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 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 International Berthing and Docking Mechanism (IBDM). The mechanism’s first missions will be with the Dream Chaser, a craft that will soon perform cargo flights to the ISS.

Docking energy is absorbed

The IBDM is an androgynous coupling system. This means that the connector is identical on both sides. It consists 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. “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, especially with regard to safety, because the docking mechanism can also cope with manned flights,” continues Ybarra. “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 drive specialist maxon for several years.”

For the hard capture system maxon developed an EC 32 flat motor with two windings and a GPX 22 UP planetary gearhead. There are twelve maxon drive systems powering the locking hooks. Each consists of two brushless EC-4pole 30 motors and a GPX 42 UP gearhead. maxon’s engineers have developed two drives 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 additionalstator 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.

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 Hans Burri, DNH Tradeserve, +27 11 468 2722, [email protected], www.dnhtrade.co.za



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Compressed air treatment do’s and don’ts
Artic Driers International Editor's Choice Pneumatic systems & components
As a long-established importer and manufacturer of air dryers, Artic Dryers often sees the results of poor installation and issues with aftercoolers that create serious problems in air drying systems.

Read more...
Process control system for the entire plant lifecycle
Siemens South Africa Editor's Choice
The automation of process plants has been characterised by IT silos for a long time. The high level of IT security required was achieved through strict isolation from the outside world. However, this made unlocking the opportunities for digitalisation very difficult. This is a compelling reason to opt for Simatic PCS neo – Siemens’s completely web-based process control system with state-of-the-art IT security concepts.

Read more...
Celebrating 65 years: rebuilding and redefining its legacy
Axiom Hydraulics Editor's Choice News & events
Founded in 1959 by Neill Simpson, Axiom Hydraulics has grown into one of South Africa’s elite hydraulic companies. Over the past six and a half decades they’ve weathered many challenges, but none as devastating as the fire of 2023.

Read more...
Monitoring the health of systems
SA Gauge Editor's Choice Shaft power components
Pressure and temperature gauges are vital instruments in various industries. However, they are susceptible to failures that can compromise their accuracy and reliability. When these gauges fail, the consequences can be severe.

Read more...
PC-based control for advanced hydrogen storage technology
Beckhoff Automation Editor's Choice Electrical switching & drive systems & components
The proportion of renewable energies from solar, wind and water is rising continuously. However, sufficient storage options are of the essence to use these energies as efficiently as possible. GKN Hydrogen offers a particularly compact and safe option, low-pressure metal hydride hydrogen storage systems with PC-based control from Beckhoff.

Read more...
Axiom reaches new heights
Axiom Hydraulics Editor's Choice Electrical switching & drive systems & components
When Rula Bulk Handling could not source a cable tensioner large enough for a new cableway, the engineers knew they had to come up with an inventive solution. After discovering that no such tensioner was immediately available, Rula approached Axiom Hydraulics and ifm to assist with building their own.

Read more...
At least 60 million strokes
Horne Technologies Editor's Choice Electrical switching & drive systems & components
Designing and constructing compact automation systems is one of the core activities of the Austrian machine manufacturer, STIWA. Its modular LTM-CI system has been optimised for small parts assembly. Linear and rotating micromotors from Faulhaber perform key tasks in these systems.

Read more...
Pushing technological boundaries with Festo Electric Automation solutions
Festo South Africa Editor's Choice
In the ever-evolving landscape of Industrial Automation, Festo Electric Automation solutions are at the forefront of a revolution, fundamentally reshaping production paradigms. As a global leader in automation, Festo focuses on intelligent connectivity to reduce costs, save time, and increase efficiency and convenience for customers.

Read more...
Perfect balance for every race
Horne Technologies Editor's Choice Electrical switching & drive systems & components
It goes without saying that success in Formula 1 requires a top driver. However, their chance of achieving a place on the podium depends on the car, which in turn depends on three essential factors: engine, tyres and aerodynamics. To find the optimum balance, the racing teams test models of their bolides in the wind tunnel. At Sauber, the adjustable components are moved on the model and in the test chamber using FAULHABER motors.

Read more...
MeerKAT radio telescope array
Editor's Choice News & events
Leading consulting engineering and infrastructure advisory practice, Zutari is continuing its involvement with the world-leading MeerKAT radio telescope array, where it has played a leading role since the project first broke ground.

Read more...