CIMAR Research

Carl CraneCenter for Intelligent Machines and RoboticsUniversity of Florida

30 April 2012

Center for Intelligent Machines and RoboticsCollege of Engineering

Topics

• Autonomous ground vehicles– static obstacles, DARPA Grand Challenge– urban environment, DARPA Urban Challenge– autonomous convoy operations– automated range clearance

• Mechanisms– force & position control– variable stiffness suspensions– tensegrity mechanisms applied to wave energy harvesting

World Modeling (traversability grid)• 60 m 60 m grid with• grid resolution of 0.5 m 0.5 m

DARPA Grand Challenge

Problem Statement• given: a 225 km path defined by a series of waypoints

• navigate the entire path as quickly as possible

ladar

monocular vision ladar• sensors– pose

• Starfire GPS• Smiths Aerospace IMU

– obstacles• bumper height ladar

– terrain• two stationary ladar• image processing

Center for Intelligent Machines and RoboticsCollege of Engineering 4

Grand Challenge Technical Challenges

1. off-line path planning

2. detection of static obstacles

3. environment data represen-tation and sensor integration

4. localization

5. interprocess communication and coordination of multiple threads on multiple computers

6. reconciliation of differences in estimated global pose, a priori data, and sensed information

7. fault tolerance

Problem Statement• given: a road network data file and a mission file

• visit the waypoints listed in the Mission Data File while obeying traffic laws

• sensors– pose

• Novatel & Garmin GPS• GE Aerospace IMU

– obstacles & terrain• 6 Sick ladars• 2 long range ladars

– lane detection• 6 Bluefox cameras

Situation Assessment Specialist 1

Behavior Specialist 1

Smart Arbiter

Decision Broker

Intelligence Element

Receding Horizon

Controller

Primitive Driver

Control Element

Ladar 1Ladar 1

Ladar 1Ladar 1

Ladar 1Ladar 1 Camera 1 IMU GPS 1

Sensor Element

High Level Planner

Local World Model

Planning Element

FIN

DIN

GS

EVA

LUAT

EB

EHAV

IOR

S

SELECTBEHAVIOR

DARPA Urban Challenge

Center for Intelligent Machines and RoboticsCollege of Engineering 6

New Technical Challenges

1. pavement (road) detection and lane detection2. detection and classification of dynamic objects3. reconciliation of differences in estimated global pose, a priori data,

and sensed information4. determination of appropriate behavior mode5. smooth transition of vehicle control between behavior modes

Problem Statement• develop convoy with human operated lead vehicle and

robotic following vehicles

• implement the system without any use of GPS or radio communications between vehicles

• two approaches to measure distance and angle to lead vehicle

– tether based (Autonomous Solutions, Inc.)

– vision based (UF)• control algorithm guides

follower along relativepath of leader

Autonomous Convoy Operations

• tether approach • vision approach– infrared emitters attached to back of

leader vehicle– panning camera mounted on follower– measures distance and angle to leader

(exact same data as obtained by tether)

Problem Statement• automate the four steps of range clearance

• vegetation removal• surface clearance• mapping of subsurface objects• digging and removal of subsurface objects

• ladar based modeling of environment

Automated Range Clearance

• objects classified as– ground– vegetation– tree

• time study conducted in Wyoming which compares manned performance to teleoperation to autonomous operation

tree

ground

vegetation

Center for Intelligent Machines and RoboticsCollege of Engineering

Topics

• Autonomous ground vehicles– static obstacles, DARPA Grand Challenge– urban environment, DARPA Urban Challenge– autonomous convoy operations– automated range clearance

• Mechanisms– force & position control– variable stiffness suspensions– tensegrity mechanisms applied to wave energy harvesting

Problem Statement• simultaneously control the twists of freedom and the

wrenches of constraint for a body that is in contact with its environment

Approach• utilize a screw theory based approach whereby the

compliance matrix K is computed and used to relate a change in the contact wrench, , to the change in relative pose (twist), , as

• twists that correct wrench errors are added to twists that allow motion

• passive compliant mechanism attached to end of industrial robot

Simultaneous Force and Position Control

• active planar platform with compliance used to manipulate heavy loads

• device being applied to problem of attaching ordnance to a plane

• object must be maneuvered while limiting the contact force with the plane

w

ˆDˆ w K D

Problem Statement• Develop a suspension system that isolates a car body

from road disturbances by mechanically adjusting it’s effective stiffness

Approach• utilize a recently

designed variablestiffness springmechanism

• variable stiffness spring mechanism– effective spring stiffness varies as the pivot bar is

moved left and right

Variable Stiffness Suspensions

• suspension designed for automobiles • passing over speed bump at 40 mph

0 10 20 30 40 50 60 70 80 90-5

0

5

Rid

e C

omfo

rt

0 10 20 30 40 50 60 70 80 90-0.1

0

0.1D

efle

ctio

n

0 10 20 30 40 50 60 70 80 90-0.02

0

0.02

Roa

d H

oldi

ng

Distance (m)

TPSPassive VSSActive VSS

TPSPassive VSSActive VSS

TPSPassive VSSActive VSS

Problem Statement• recover electrical energy from ocean

Possible Approaches• Ocean Waves

• Ocean Tides

• Ocean Currents

• Thermal Gradients

• Salinity Gradients

• tensegrity– combination of elements in tension and compression– introduced by Snelson and Fuller in 1950’s– have been applied to architecture

Tensegrity Mechanisms used for Wave Energy Harvesting

• water particle motion • energy harvester concept