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Technology

Testing an OpNav Rig

Testing an OpNav RigAn appropriate function that inputs the base-line, focal length, resolution & depth will help define the “hardware rig”. You will still require test footage to be used for development of relevant control algorithms. Destructive testing of this rig is kind “easy” though prohibitively expensive.

However all we really need is video footage, at a reasonably high resolution, calibrated for accurate height from the “surface” – these when put together can simulate a free/controlled fall onto the lunar surface without actually destroying the test rig itself. So, the keywords are absolutely no damage to the test rig, Controlled fall/ Movement, Video footage, lunar surface simulations.

To make things easier, its easy to rotate the fall axis by 90 deg and make it horizontal, therefore instead of falling, the rig moves closer to the wall, which is pretending to be the floor 🙂

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Optical Navigation Rigs

Different baselines would pose different resolutions in visual odometry. Placing number of cameras might solve the problem but that is an overkill. Thanks to the variable focal length / Optical zoom feature of the conventional cameras a two camera stereo rig with a different baseline can be realized by having a longer baseline stereo rig with variable focal length.

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Optical Navigation 101

Compact-er, lighter, great resolution on digital cameras today make them a great choice for fully & semi-autonomous navigation systems, especially in space. Starting with the basics...

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Classical trajectories to the Moon

Till date there have been 75 planned missions for Moon, 10 of those did not quite make it.

In 1959 Luna-1 was man’s first attempt to reach the Moon – Luna-1 took a 36 hour trajectory and missed Moon by about 6000 km at a speed of over 2.5 km/s. Interestingly Luna-1 went on to become the first ever “artificial planet”. Yeah, that’s right, it missed moon, got slingshot into an orbit around Sun. If it has enough battery to talk back to base station, there would have been some really interesting data and pics to be had back then!

While Luna-1 & 2 took a 36 hour trajectory, with Luna-3 a 3 day trajectory was the preferred option. Luna-9 went to an Earth Parking orbit, followed by a 3 day trajectory as did all remaining Luna missions. Luna-16 used a 3 day trajectory and orbited around the Moon before de-orbiting onto Lunar Surface. It was the first artificial craft to land and retrieve a sample from Moon. In case you want to develop a robotic mission to the Moon, blindly follow the Russians.

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TI Locomotion 101 – Testbed Rovers

As telerobotics continues to be the favourite method of planetary exploration, rover technology continues to be redefined and innovative concepts are making their way into development test models. Here we take a look at some of the these promising rover concepts and technologies.

ExoMars is a joint ESA-Russian astrobiological exploration mission to Mars. The ExoMars rover mobility system shall be using a 6-wheel “3-bogie” design, similar to the rocker bogie, which evolved from the RCL-E platform developed by Kucherenko et al., which was iterated to the now existing 3-Bogie design by Michaud et al. It is still under development, and is scheduled to be launched sometime in 2018.

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TI Locomotion 101 – Past Rover Missions

If there is an adage which signifies what all teams are attempting to do, it is, Standing on the Shoulders of Giants. As engineers, we do not intend to reinvent the wheel, but actually stand on the shoulders of these huge giants, who’ve been there, done that! Now that’s our actual design philosophy, top secret! 😉

Lunokhods
Talking of giants, there’s no better way to start than with the first ones. They literally translate into moon walkers, and we are sure that they would have given Michael Jackson some competition on the lunar surface 😛 When Luna 17 landed at the Sea of Rains or Mare Imbrium, and rolled down the ramp a peculiar bucket-shaped 750-kg Lunokhod 1, it heralded a new era of space exploration via telerobotics. Weighing in at a massive 750 kg, Lunokhod was a rugged-design-SUV of sorts, with half a metre wheels and a decent obstacle capacity (maximum height/depth of obstacle rover is able to cross) of 40 cm. A metallic wire mesh tire rim and titanium grousers gave it more than enough traction, and the huge body weight and that tire size, the motors had to be pretty heavy duty for overcoming frictional torque. Lunokhod 1 clocked 10,540 m while conducting TV camera surveys and lunar soil tests, before it was lost to comm. failure.

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TI Locomotion 101 – Wheel Design

Wheel Design

Wheel design and selection is central to any mobility system. Any rover is said to possess a high degree of mobility in natural terrain only if it can surmount obstacles that are large in comparison to the wheel size. A rover must have enough traction from the rear wheels to push the front wheels against an obstacle, so that enough reaction force is generated on the front wheels to climb up it.

Typically, a four wheeled rover cannot climb over obstacles larger than a wheel radius due to the above mentioned fact.  Without sufficient traction, the wheels slip and enough thrust is not generated to keep the front wheels in contact with the obstacle. The JPL-developed rocker bogie suspension solves this issue by having an intermediary set of wheels, hence while climbing, four wheels are always stationary at all time.

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TI Locomotion 101 – Design Philosophy & Considerations

Design Philosophy
The term “design philosophy” may sound really vague and open ended, but for a complex project of this scale with multiple interdependencies, it is important to strategize a design plan in order to stay on track. So, what actually is a design philosophy? Well, it’s certainly not about Confucianism or Advaita Vedanta. Simply put, it is how you envision the design to develop and evolve in stages. Technically, design philosophy defines the course of design – from conceptual sketches at brainstorming sessions to trade off studies that narrow down options. From developing a preliminary design leading to a final detailed design after multiple iterations based on simulations, to prototyping which finally leads to integrated fabrication and testing.

TI Locomotion 101 - Design Philosophy & Considerations

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