Space Robotics Developments

Automation and Robotics Section (TOS-MMA)

SPACE ROBOTICS DEVELOPMENTS for PLANETARY MISSIONS

Gianfranco Visentin, Automation and Robotics Section, European Space Agency Noordwijk, The Netherlands

21. August 1998

1

Automation and Robotics Section (TOS-MMA)

OUTLINE

• Planetary Exploration • Classification By Scale • Robotics Options By Scale – Robot Arms – Microrovers – Minirovers – Long-Range Rovers – Aerobots

• Conclusions 21. August 1998

2

Automation and Robotics Section (TOS-MMA)

Planetary Exploration

The scientific aims of in-situ planetary exploration can be divided in 2 categories: • Planet Characterisation: geology, geochemistry, detailed topography, weather and atmospheric composition • Exobiology Investigation: The search for traces of extant or extinct life The basic requirements for the tools used for planetary exploration are: • acquire measurements/samples • be close to places where measurements/samples can tell you more about your science 21. August 1998

3

Automation and Robotics Section (TOS-MMA)

The Robotics Advantage

ROBOT: “Etymology: Czech, from robota=compulsory labour, a device that automatically performs complicated often repetitive tasks” The main advantage of robots is the ability to carry out several tasks (in number and in nature) with the same basic equipment. Therefore the benefits of robotics can only be realised when - repetition of tasks (e.g. perform sampling several times) - execution of spatially diverse tasks (e.g. deployment, placement on different locations) is demanded 21. August 1998

4

Automation and Robotics Section (TOS-MMA)

A Classification Scale

A spatial scale of planetary scientific investigation provides an easy way to understand the applicability of different robotics concepts and their non robotic alternative Several Probes Released During Atmospheric Descent Montgolfiere

Ejection

Solar Airships

Booms Light Gas Balloons Long-range rovers Minirovers Microrovers Robot Arms 10

-1

10

0

10

1

10

2

10

3

10

4

10

5

10

6

21. August 1998

10

7

5

Automation and Robotics Section (TOS-MMA)

Robot Arms (1) A robotic arm provides a flexible means to: - deploy lander/rover subsystems (e.g. unlatch, unfold) - inspect lander/rover and surrounding planetary surface - deploy/apply instruments on the planetary surface - detach, collect and deposit planetary surface samples NASA/JPL used a robot arm based on an extendable boom on both Viking Mars landers (1976-1980) 21. August 1998

The Viking Robot arm in Stretched Configuration (Credit: NASA) 6

[m]

Automation and Robotics Section (TOS-MMA)

Robot Arms (2)

The NASA/JPL Mars Polar Lander featured a robot arm. This arm was designed to scoop soil from the planetary surface and to dump it into an analysis facility. Animation of Mars Polar Lander Surface Operations (Credit: NASA) 21. August 1998

7

Automation and Robotics Section (TOS-MMA)

Robot Arms (3)

A single robot may provide reach, dexterity and flexibility to replace several ad-hoc designed devices. The Beagle 2 lander (Mars Express) makes use of such robotic tool. The use of the arm allowed to produce a very high ratio between payload/lander mass (~20%) 21. August 1998

Animation of Deployment of the Beagle 2 robot arm

8

Automation and Robotics Section (TOS-MMA)

Microrovers (1) A Microrover provides reach beyond any appendage that could be installed on a lander and can be used to - inspect lander/rover and surrounding planetary surface - apply instruments on planetary surfaces - detach, collect and deposit planetary surface samples The NASA Sojourner microrover was a rocker-bogie wheeled rover. Its prime purpose was technology demonstrator, but it also performed soil mechanics tests and APXS measurements.

The Sojourner Rover at the end of sol 22 (credits NASA/JPL)

21. August 1998

9

Automation and Robotics Section (TOS-MMA)

Microrovers (2) Several other Microrovers have been proposed for different goals and with different principles of locomotion: Nanokhod (MPAe, ESA): a tethered, tracked rover to perform geochemistry investigation by applying 4 instruments to planetary surfaces (Mars, Mercury) This rover thanks to the use of a very thin tether achieves a ~very high payload/rover mass ratio (~50%) Nanokhod demo at the ESTEC Planetary Utilisation Terrain 21. August 1998

10

Automation and Robotics Section (TOS-MMA)

Microrovers (3)

The FrogBot (UniVR, JPL, ESA): hopping-tracked rover to perform geochemistry investigation. It uses a spring bow to propel itself into jumps several times its size. A single actuator is used to load the spring and to raise the rover after a landing. Additional tracks provide shortdistance, high precision positioning

FrogBot prototype (Credit: University of Verona)

21. August 1998

11

Automation and Robotics Section (TOS-MMA)

Microrovers (4)

Miro (ESA): a tethered, tracked rover to acquire and deliver to a lander, deep sub-surface samples. The rover has a 7 kg mass with and is equipped with a drilling and sampling subsystem (5 kg) capable of to acquire sample up to 2 m in depth. Miro prototype demo

21. August 1998

12

Automation and Robotics Section (TOS-MMA)

Microrovers (5)

SKORPION (NASA, UNIBremen, ESA): a 6 legged tethered rover to survey steep cliffs. The rover is used in conjunction with a long-range rover that provides access to the cliff rim. The rover makes uses of biologically inspired gait control. SKORPION on sand furrows (Credit: University of Bremen) 21. August 1998

13

Automation and Robotics Section (TOS-MMA)

Minirovers Minirovers have a size that allow them to endeavour into autonomous traverses on the planetary surface without support of a lander. They are capable to negotiate rather rugged terrains. They can be used to apply instruments to the planetary surface and to collect sample to be fed into the scientific payload that carry with them. The NASA MER mission will make animation of MER rover deployment use of two mini-rovers of 174 kg of (Credit: NASA) mass including 22 kg of payload 21. August 1998

14

Automation and Robotics Section (TOS-MMA)

Long-range Rovers (1) These are the largest rovers intended for planetary exploration. They are exposed to seasonal changes, due to their extremely long traverses and the long time they employ to cover them. For this they are likely to require non-solar power generation. Their long-range allow them to reach geological features that lay outside the landing ellipse. In order to investigate such features they may have childrobotic systems (microrovers, aerobots).

SKORPION mission (Credit: University of Bremen)

21. August 1998

15

Automation and Robotics Section (TOS-MMA)

Long-range Rovers (2)

The Russian Lunokhod-I and Lunokhod-II are the only long range rovers ever used. They operated on the Moon in 1970 and 1973 traversing a total of 10.54 Km and 37 km. They had 8-wheels, a rigid chassis and a mass of ~750 kg. 21. August 1998

The russian LUNOKHOD rover (Credits VNIITransmash) 16

Automation and Robotics Section (TOS-MMA)

Long-range Rovers (3)

The Russian Marsokhod was designed to fly on the Mars 92 mission. The mission was later scheduled in 96 and eventually it was cancelled. It had 6 cylindrical-conical wheels, an articulated body and could use peristaltic motion to overcome steep sandy slopes. It made use of RTGs to generate power.

Marsokhod testing in Kamchatka, Russia (Credit: VNII Transmash)

21. August 1998

17

Automation and Robotics Section (TOS-MMA)

Aerobots:

(1)

AERial ROBOTS (AEROBOTS) are another possible robotic means to carry out scientific investigation on planets with an atmosphere A classification divides them into: -Lighter Than Air (LTA) - Balloons, Montgolfieres and Airships -Heavier Than Air (HTA) - Fixed wing: Glider, Airplanes - Moving wing: Helicopters, Gyrocopters and Entomopters Due to their inherent simplicity, LTA are the best candidates for low cost missions 21. August 1998

18

Automation and Robotics Section (TOS-MMA)

Aerobots:

(2)

Light Gas Balloons These are the simplest aerobots: they consist of an envelope filled with gas lighter than the atmosphere. A gondola holding the payload hangs from the envelope - Zero-Pressure-Balloons have elastic envelopes and change height in the atmosphere due to thermal effects - Superpressure Balloons have fixed-volume envelope and maintain a more or less constant height. Montgolfieres These balloons are filled with the same gas of the atmosphere. Inside the envelope the gas is kept in some way at a temperature higher than the surrounding atmosphere.

21. August 1998

19

Automation and Robotics Section (TOS-MMA)

Aerobots:

(3)

Both Light Gas Balloons and Montgolfieres, rely on winds for their movement over the surface. This does not mean that these aerobots are hopelessly passive: -First of all localisation, measurement acquisition, storage and transmission are important autonomous tasks. -Furthermore these aerobots can autonomously drop probes to measure atmospheric or surface properties. -Finally some altitude control can be implemented to perform aerostatic navigation or even controlled touch-down. 21. August 1998

20

Automation and Robotics Section (TOS-MMA)

Aerobots:

CNES with participation of Russians and Americans built 2 superpressure balloons which were launched with the Russian VEGA missions in 1985. Filled with helium and carrying ~7 kg of payload they travelled for ~1/3 of the Venusian equator.

(4)

VEGA balloon (Credit: CNES)

21. August 1998

21

Automation and Robotics Section (TOS-MMA)

Aerobots: A Solar Mongolfiere was proposed for the Russian Mars 92 (then 94 and 96) mission. The montgolfiere envelope was attached at the top to a small helium balloon and had a guiderope attached to the bottom. During the day the balloon, heated by the Sun, would soar. At night its guide-rope would lay on the ground, with the montgolfiere held aloft by its balloon. Unfortunately due to financial constraints the montgolfiere contribution was cancelled 21. August 1998

(5)

Mars 92 Solar Montgolfiere (Credit: Planetary Society) 22

Automation and Robotics Section (TOS-MMA)

Conclusions

This presentation has shown some past and contemporary robotic developments for Planetary Exploration. These allow to support planetary missions with very different ranges of scientific investigation. Flexibility is the key benefit of robotics especially when applied to repetitive tasks. In a largely unknown environment this flexibility allows to adapt to the unknown and to have always a second-chance

21. August 1998

23