Modular Research Rover and Gesture Control System for EVA

Steve McGuire, Joel Richter, Kevin SloanThe Pennsylvania State University

http://www.clubs.psu.edu/mars

Introduction

• The year is 2016. NASA formally proposes a manned Mars mission to launch within the next decade.

• Will this signal the turning point in space exploration from robotic exploration to manned exploration?

• Or does this mark the transition into a cooperative exploratory effort?

A model for robotic exploration on Mars

Mission Control for the Pathfinder Mission

This Isn’t Your Father’s Planetary Exploration...

• Hand gesture based control system - virtual reality gloves that can be integrated into an astronaut’s space suit will be used to control rovers and other robotic equipment

• Rover will be modular, and thus able to adapt to almost any situation

Approach/Problem Selection• When selecting a project, we looked for one that

would support:– Long term work– Development of a product that could be tested,

refined and demonstrated

• Desire to work in a new area, but on something feasible for a team of undergraduate students

• We were able to draw upon the experiences of a team member who spent a summer working at NASA Ames

Problem Definition

• Primary problem:Issue of field control of a rover on Mars– Preprogrammed missions are not flexible enough to

support in-field modifications– Astronauts on EVA cannot directly interface with rover

computers“Manual dexterity is also compromised by the bulky gloves, and so

creative ways of working with equipment and gathering samples must be developed.”

-EVA I Trip Report MDRS (Mars Desert Research Station); February 8, 2002

– Requiring a third party, namely a support crew at a base station, to assist in communications will take time away from other important tasks.

Reasons to Use a Glove•Keyboards, Mice and trackballs require interaction outside of the pressure suit

•Only minimal movement and flexibility required to operate the glove

•Thin, lightweight structure suitable for integration within pressure glove design

•Always available, yet unobtrusive

Problem Definition

• Secondary problem:Planned obsolescence– A typical rover is optimized for a specific

mission, or mission task– After that particular mission has been

completed, the rover is useless– Similar to planned reuse of orbital

communications hardware, we can reuse rover hardware

Why are we doing this?

• Actual rover needed for realistic tests of gesture-based control system

• Simulations only have so much fidelity

• Testbed for modularity concept

A Language for Control

• Requires expression for general tasks, yet simplicity for ease of learning

• Representation uses Moore model for operating points, Mealy for direct human interaction points

• Three states in basic design: Waiting, High Level Command, Direct Control

Current Implementation• Glove hardware: fiber optic based• Not focusing on autonomy; can collapse the high level

command state • Requires special “attention” and “done” commands to

prevent inadvertent activation or programming• Two hands only as orthogonal device controllers

Demos of Current Work

• Movie: Pioneer Rover in Action

• Demo: Something We Could Bring on a Plane

Limitations of Control System

• Glove measures only average finger flexion

• Limited gesture recognition ability– Discrete vs. Continuous Gestures– Increased programming complexity

Preliminary Rover Work

• As we started this project, we realized there was a lot we needed to learn in order to take design ideas and actually flesh them out

• Physical construction of the rover was a key issue because every detail had to be addressed

Rover Prototype Goals

• Teach the skills needed to design and build a high quality rover

• Allow for quick construction

• Stay within a fairly small budget

Rover Prototype Results

• Gained experience machining metal

• Learned the difficultly of joining pieces well

• Saw strengths and weaknesses of structural design so next design could be planned accordingly

• Similarity in size to future rover made it inconvenient to use as a demonstration tool of the glove control system

Future Work: Gesture Control

• Use two handed gestures, with gloves wired to a backpack laptop

• Expand state representation to be capable of controlling more peripherals: a universal language

• Expand into combined gestures (with both hands)

• Expand into semi-autonomous operations

The Next Rover: Red

• Testbed for glove control system

• Provide platform for robotics projects such as stereo vision and autonomous navigation

• Allow field testing of human factors to improve human-rover team interaction

• Demonstrate modularity

Red: an Overview

Rover Design Issues - Size

• A large rover is suited for independent missions– High speed, long range– Complicated and expensive, focus shifts away from

space science to applied engineering

• A small rover is suited for assisting humans in field work– Able to explore small places, unobtrusive when not in

use– Difficult to build because it requires very precise

engineering, expensive

Size Chosen

• Medium size was chosen– Balance of both size advantages– Easiest size to construct, allowing focus to be

on what the rover can do and not merely building the rover

– Dimensions are: 24” x 16” x 14”

Design Issues - Suspension

• Necessary to protect electronics from hard jolts and continuous vibrations

• Design fixes motors and axles on separate plate attached by shock absorbers to the payload section

Design Issues – Wheels vs. Treads

• Wheels– Steering mechanism difficult to design and construct– More efficient than treads but worse off-road handling

characteristics

• Treads– Difficult to attach to wheels and keep taut– Worse efficiency than but better performance on

rough terrain

• Decision: Treads

Modularity

• All rovers have many systems in common

• Differences emerge based on the purpose of the rover, such as the science package to be carried

Efficiency and Redundancy

• Only a small fraction of a rover’s mass is devoted to the payload

• Modules would reduce the number of rovers required without compromising the capabilities of the mission

• Redundancy is increased because failure of a base doesn’t disable the science capabilities of that rover

On-Board Computing: Our Approach

• Laptop will be a communications hub between user(s) and base

• Serial port expansion will allow laptop to interface with multiple microcontrollers

• Will also serve as main computing resource for computationally expensive processes, such as stereo vision

• Laptop screen will allow for advanced control interactions, as well more self-sustained field work

Microcontrollers

• Microcontrollers will receive direct commands from the laptop, and will interface with the electronics on-board

• For testing/prototyping stages, the Basic Stamp 2 will be used because of simplistic programming, which is ideal for testing other systems

• Final version of Red will utilize the Motorola 64HC11E9 microcontroller. It is much more difficult to use, but provides vast flexibility when compared to the Stamp

Stereo Vision

• Two Firewire cameras will be mounted on the front of the rover

• Early implementations will include rudimentary tracking algorithms, such as locating the user.

• More advanced tasks will deal with hazard detection and avoidance for autonomous navigation

Working Project Timeline

• Spring 2002: Basic development of applicable technologies, rover prototype, single glove basic motion control

• Fall 2002: Finalize rover design, continue development of control system

Working Project Timeline

• Spring 2003: Rover base fabrication, further control system implementations (i.e. two-hand control, more advanced control states), basic stereo vision tasks

• Summer 2003: Testing and verification of design

• Fall 2003-Spring 2004: Refinement and completion of base, module development, advanced user interface, autonomous navigation capabilities, further field testing

To Infinity, and Beyond…

While this project is currently outlined for the next 18 months, our work will open the door for countless opportunities. With a working rover and gesture control system in place, future groups will be able to build off of an open ended base system.

Questions?

Thank you.

The Penn State Mars Societyhttp://www.clubs.psu.edu/mars