Tech

Under software control, Luke has demonstrated opening and closing the throttle +/- 10 degrees. This 'dithering' action is made using a simple algorithm and can be customised so as to prevent the super-cold liquid oxygen ball valve from sticking, prior to launch.





Luke's work is advancing nicely with a PCB layout for throttle control hardware. We'll attempt to make the make the board dimensions and positions of the mounting holes identical between the Rutex R2020 and the throttle control board, so they can be stacked together making them more space efficient.





After analysing design proposals, Roy suggested providing two sensing potentiometers for valve positioning. This would provide redundancy in case one is damaged and increase valve position accuracy when the results of both are combined. Roy's proposal is to have the two cams, which are connected to the throttle position sensing potentiometers, offset by 45 degrees. Nice throttle control work being done Numbatters!

Fortunately the variable throttle control technology we're developing for ASRI's Ausroc 2.5 is also transferable to the descent stage motor of the White Label Space lunar lander, so it's a win all round for our GLXP partner WLS, the Australian Space Research Institute, and us.

With parts for development provided by ASRI, Luke Weston has built a 60 V power supply for testing the motor which will drive the gearhead that will control the RP1 valve, and thus throttle propellent to the rocket engine.

After some simple testing, Luke has also tuned the Rutex R2020 servo drive board so as to give it full control of the motor / gearhead assembly, as seen below:





Along with this great work, Luke has also prepared some preliminary code for an AVR (Arduino) to control the throttle motor via the Rutex servo board, and done a marvellous job of updating the relevant documentation on the Wiki.

Ultimately, through Luke's and the rest of the build team's efforts, we'll prepare avionics to take instructions on a CAN bus and translate these to valve positions which will control propellant flow into the Ausroc A2.5 rocket engine, and thus thrust. All a bit exciting really

Andy Gelme of the Lunar Numbat build team has prepared this post of his recent endeavours:

Continuing on from the initial launches of a Class C rocket, the Lunar Numbat build team has been making steady progress towards launching more sophisticated avionics, along with an audio/video feed, as part of a Class G rocket.

A crucial part of the journey has been, not just creating the hardware and software, but bringing more capability and experience to the effort, in the form of organization, equipment and most importantly ... people with specialist skills.

For a long time, we've been contemplating the need for a shared space or workshop, expensive electronics equipment and mechanical manufacturing capabilities beyond that which individuals can typically justify or afford. These sorts of facilities are available in universities and specific types of government or commercial organizations, but they are much less accessible to smaller communities of individual developers.

At the end of March 2009, a Wired magazine article propelled the concept of HackerSpaces into the popular zeitgeist. So, it was an natural step to create the first HackerSpace in Melbourne, Australia, aka the "Connected Community".

The Connected Community HackerSpace was formed and operates independently of Lunar Numbat. A HackerSpace is much broader in scope than even a space technology project, to the point of hacking any object in any domain in any conceivable fashion is fair game. Fortunately, there is significant overlap in the types of people involved in both groups, the skills and equipment required and the artifacts created.

An advantage of the HackerSpace is that it attracts a larger community of hobbyists and professionals. These people may not be as focused or as passionate about the research and development of space technology as the Lunar Numbat team. Although, sometimes they are even more passionate. However, their skills can directly or indirectly contribute to the Lunar Numbat effort, due to the deeply embedded culture of sharing. This collaboration is enhanced by both groups utilizing commodity, open-source hardware and software. The power of open-source hardware and software communities is evident in the growing number of developers using the Arduino platform or BeagleBoard for increasingly sophisticated projects.

Since it's inception, the HackerSpace has been meeting regularly and working on a variety of projects. Many of the projects have been founded by HackerSpace members, often initiated prior to the HackerSpace and operating independently. In addition, the HackerSpace is introducing new members to those projects and bringing them up-to-speed with fundamental skills, such as PCB design and manufacture. New members also bring additional skills such as amateur radio experience, CNC milling machine design, construction using composite materials or hard-core hardware and software engineering ... and, even rocketry

Lunar Numbat will benefit from this infusion of new blood into HackerSpace and the Class G rocket development has been one of the projects around which HackerSpace members can gravitate and apply their skills.

Project progress and technical discussions have been captured on the Connected Community HackerSpace web-site and project artifacts placed in social coding repositories, such as the popular GitHub, as follows ...

• Class G rocket project


• Class G rocket hardware design


• Aiko: Modular event-driven software framework

A key outcome will be to deliver re-usable hardware and software components. In part, this is driving us to create general purpose frameworks, like Aiko, which provide a modular, event-driven abstraction on top of specific hardware / software platforms, like the Arduino. This is so that we can produce high-quality embedded applications and software components that encapsulate a given set of hardware devices.

In the longer term, this collaboration between the Connected Community HackerSpace and Lunar Numbat, along with the resulting re-usable hardware and software artifacts, provides a strong foundation for undertaking the next phases of Lunar Numbat beyond the current Class G rocket launch milestone.

An ingenious 'tethered marsupial rover' that would spend most of its time attached to a larger vehicle until it is needed is being investigated by NASA.

From Space.com:

The Axel rover prototype is built like a yo-yo; its tether is wrapped around its central axle. The other end of the tether would be attached to a larger, conventional rover robot, like the Spirit and Opportunity rovers on Mars. The Axel rover solves a problem that bedevils these conventional robots. When Spirit, for example, encounters a crater, it cannot descend and explore.

According to Pablo Abad-Manterola, one of the contributing CalTech students:

"Right now, it's really risky for astronauts or robots, for example, like Spirit an Opportunity to go into craters. The ground is too loose and the slopes are too steep. So it's too risky for those robots to get into those craters and perform any interesting science. So this robot would be very useful for those types of scenarios, where you can really dive into those craters, pick up some samples, and really analyze them and tell us something really new and interesting about Mars or the moon, for example."

Small, nippy and smart is all the rage. Go Lunar Numbat!

Spirit and Opportunity, the wildly successful Martian rovers have an Australian contribution.

Both are driven by 39 DC micromotors supplied by Maxon Motor Australia.

Each rover is equipped with 39 DC motors from Swiss drive specialists, Maxon motor Australia. The precision drives are used for driving the robotic arms, rock drilling, operating the cameras, the steering mechanism, and for the 6 wheels that drive the heavy vehicles (each weighing nearly 180kg) over the planet’s surface.

The motors are standard products with diameters of 20 and 25mm that deliver more than 90% efficiency. Minor modifications were required to enable rovers to cope with the harsh conditions. The equipment has to be able to withstand temperature changes on the surface of Mars, which can range from around -120°C to +25°C, vibrations and the special atmosphere.

Worthy of investigation.