an integrated robotic laser range sensing system for automatic mapping of wide workspaces

An Integrated An Integrated Robotic Laser Range Robotic Laser Range Sensing System for Sensing System for Automatic Mapping Automatic Mapping of Wide Workspacesof Wide Workspaces

P. CurtisP. CurtisP. PayeurP. Payeur

University of OttawaUniversity of Ottawa

IntroductionIntroduction

• Range data acquisition of cluttered Range data acquisition of cluttered workspaces is tedious using currently workspaces is tedious using currently available point/line laser range scannersavailable point/line laser range scanners

• To create a practical 3-D model, range To create a practical 3-D model, range data from multiple view points are data from multiple view points are requiredrequired

• Through the use of a laser range finder Through the use of a laser range finder mounted on a robotic arm the data mounted on a robotic arm the data acquisition process is simplifiedacquisition process is simplified

IntroductionIntroduction

• Included software tools of both the laser Included software tools of both the laser range finder, and the robotic arm do not range finder, and the robotic arm do not allow for a seamless one step automatic allow for a seamless one step automatic processprocess

• Human interaction increases the probability Human interaction increases the probability of errors, and time required to acquire data, of errors, and time required to acquire data, and decreases repeatabilityand decreases repeatability

• The human interaction solution is therefore The human interaction solution is therefore not practical in an industrial environmentnot practical in an industrial environment

• Solution is to create a semi-autonomous Solution is to create a semi-autonomous system with a minimal amount of human system with a minimal amount of human interactioninteraction

EquipmentEquipment

• The equipment which is currently The equipment which is currently being applied to the problem is:being applied to the problem is:– CRS-Robotics F3 serial robotic CRS-Robotics F3 serial robotic

manipulator mounted upon a CRS 2m manipulator mounted upon a CRS 2m tracktrack

– Servo-Robot Jupiter laser line scannerServo-Robot Jupiter laser line scanner– Windows 2000 workstationWindows 2000 workstation

Robotic ArmRobotic Arm

• The CRS F3 The CRS F3 mounted on the 2m mounted on the 2m track provides 7 track provides 7 degrees of freedomdegrees of freedom

• The robotic arm is The robotic arm is controlled by a controlled by a CRS C500C CRS C500C controllercontroller

Robotic ArmRobotic Arm

• Interaction with the robotic arm Interaction with the robotic arm occurs via RS-232 asynchronous link occurs via RS-232 asynchronous link to the C500C controllerto the C500C controller

• The manufacturer supplied RAPL-3 The manufacturer supplied RAPL-3 language allows for the development language allows for the development of applications for the robotic of applications for the robotic systemsystem

Laser Range ScannerLaser Range Scanner

• The Jupiter laser line scanner exploits the The Jupiter laser line scanner exploits the well-known synchronized triangulation well-known synchronized triangulation technology developed at NRC.technology developed at NRC.

• This Laser Range scanner can acquire 256 This Laser Range scanner can acquire 256 or 512 points per scan along a single line.or 512 points per scan along a single line.


• The Servo-Robot Cami-Box controls The Servo-Robot Cami-Box controls the range scannerthe range scanner

• Interaction with the laser line Interaction with the laser line scanner occurs though a RS-232 scanner occurs though a RS-232 asynchronous link with the Cami-Boxasynchronous link with the Cami-Box

• The Jupiter laser line scanner was The Jupiter laser line scanner was chosen due to its large scan range chosen due to its large scan range (1m) and its physical attributes (light (1m) and its physical attributes (light and compact)and compact)


• The manufacturer The manufacturer supplied Winuser supplied Winuser software contains software contains functionality to functionality to acquire range images, acquire range images, but the data is saved but the data is saved to a proprietary to a proprietary format, and requires format, and requires too much human too much human interactioninteraction

System Hardware System Hardware IntegrationIntegration

• An Intel based An Intel based machine running machine running Windows 2000 Windows 2000 interfaces with the interfaces with the manipulator controller manipulator controller and with the Jupiter and with the Jupiter scanner controller via scanner controller via 2 RS-232 2 RS-232 asynchronous links.asynchronous links.

• The Jupiter scanner is The Jupiter scanner is mounted on the CRS mounted on the CRS F3 robotic F3 robotic manipulatormanipulator

System Software System Software Integration Integration

• Using the documentation for the CRS Using the documentation for the CRS C500C, the Servo-Robot Cami-Box, and the C500C, the Servo-Robot Cami-Box, and the Microsoft WIN32 API, software control Microsoft WIN32 API, software control modules were developed.modules were developed.

• Of particular note commands to move robot Of particular note commands to move robot joints, to turn on/off the laser line scanner, joints, to turn on/off the laser line scanner, and to acquire data were implementedand to acquire data were implemented

• An inverse kinematics solution was An inverse kinematics solution was developed based upon that developed by developed based upon that developed by W.M. Keck Virtual Factory Lab.W.M. Keck Virtual Factory Lab.

System Software System Software IntegrationIntegration

• These modules were integrated together These modules were integrated together and a Windows GUI was developedand a Windows GUI was developed

• The GUI allows the entry of the following The GUI allows the entry of the following parameters:parameters:– starting position and orientation (which is starting position and orientation (which is

encoded into an homogeneous transformation encoded into an homogeneous transformation matrix - S)matrix - S)

– Scanning vector which defines the direction Scanning vector which defines the direction and magnitude of each step in a scan (also a and magnitude of each step in a scan (also a homogeneous transformation matrix – D)homogeneous transformation matrix – D)

– Number of steps in the scan (N)Number of steps in the scan (N)


• Using these limited Using these limited parameters it is parameters it is possible to scan a possible to scan a surface with a surface with a desired resolution desired resolution and sizeand size

• Data acquired is Data acquired is saved to a single saved to a single filefile


• The process to acquire a complete scan is as The process to acquire a complete scan is as follows:follows:

1.1. The current scan position (P) is determined by The current scan position (P) is determined by the starting transformation matrix (S), and the the starting transformation matrix (S), and the step transformation matrix (D) multiplied by step transformation matrix (D) multiplied by itself itself nn times, where times, where nn represents the current represents the current step number and is between 0 and N, in other step number and is between 0 and N, in other words the current position is:words the current position is:

P=SDP=SDnn

2. Once the scan position is computed, the robot 2. Once the scan position is computed, the robot inverse kinematics solution is used to generate inverse kinematics solution is used to generate the 7 joint valuesthe 7 joint values


3. The robot control module then moves each of 3. The robot control module then moves each of the joints to their respective angular positionthe joints to their respective angular position

4. Once the robot is finished moving, the laser is 4. Once the robot is finished moving, the laser is turned on, the line of data is acquired, and the turned on, the line of data is acquired, and the laser is turned off. The range data is kept in a laser is turned off. The range data is kept in a temporary memory with the corresponding temporary memory with the corresponding pose of the sensorpose of the sensor

5.5. The first 4 steps are repeated until n=NThe first 4 steps are repeated until n=N

6.6. Once the scanning trajectory is complete, the Once the scanning trajectory is complete, the operator clicks on a button on the graphical operator clicks on a button on the graphical interface to automatically save the acquired interface to automatically save the acquired data to a specified filedata to a specified file

Results – Using Human Results – Using Human InterationInteration

• Using the Manufacturer supplied Using the Manufacturer supplied software with human interaction for software with human interaction for each step in the scanning process, the each step in the scanning process, the time time to acquire 64 lines of data from a to acquire 64 lines of data from a series of 3 different viewing areas in a series of 3 different viewing areas in a large fixed environmentlarge fixed environment was on the was on the order of a day (excluding the merging of order of a day (excluding the merging of the data)the data)

• Results had a low repeatability and Results had a low repeatability and precision due to the manual driving of precision due to the manual driving of the manipulator to the desired positionthe manipulator to the desired position

Results – Using Semi-Results – Using Semi-Autonomous SystemAutonomous System

• Using the approach described, acquiring Using the approach described, acquiring 64 lines of data from 3 different view 64 lines of data from 3 different view points in a large fixed environment takes points in a large fixed environment takes about 2 hoursabout 2 hours

• Maximal precision is ensured throughout Maximal precision is ensured throughout the whole process, since registration the whole process, since registration precision is maintained for every precision is maintained for every position.position.

• Repeatability is increased due to the use Repeatability is increased due to the use of the computer controlled solution, and of the computer controlled solution, and its inherently high precisionits inherently high precision

Results – Sample DataResults – Sample Data

• The sample scan The sample scan (lower image) is of (lower image) is of the mock-up chair the mock-up chair (see upper image) (see upper image) and contains 64 and contains 64 lines at a 4mm line lines at a 4mm line spacing.spacing.

• The data The data visualization is visualization is through a matlab through a matlab script.script.

ConclusionsConclusions

• The improvement of the semi-The improvement of the semi-autonomous system over the previous autonomous system over the previous system of human interaction at each step system of human interaction at each step is primarily illustrated though the is primarily illustrated though the drastic improvement of acquisition time drastic improvement of acquisition time (about 5x improvement)(about 5x improvement)

• Precision and repeatability are ensured Precision and repeatability are ensured through the minimization of human through the minimization of human interaction in the data acquisition interaction in the data acquisition processprocess

Future WorkFuture Work

• Currently the manipulation of the robotic joints Currently the manipulation of the robotic joints occurs serially (i.e. one joint is moved at a occurs serially (i.e. one joint is moved at a time). By changing the design to allow all time). By changing the design to allow all joints to move simultaneously, a further joints to move simultaneously, a further increase in scanning speed can be realisedincrease in scanning speed can be realised

• Currently the laser line scanner is toggle on Currently the laser line scanner is toggle on and off for each line of data acquired. By and off for each line of data acquired. By leaving the laser on for the whole scan, a leaving the laser on for the whole scan, a further increase in scanning speed can be further increase in scanning speed can be realisedrealised

• Different scanning patterns are being Different scanning patterns are being investigated, as well as visualisation techniquesinvestigated, as well as visualisation techniques

Questions/Questions/AcknowledgmentsAcknowledgments

• E-mailE-mail– P. Curtis:P. Curtis: [email protected]@site.uottawa.ca– P. Payeur:P. Payeur: [email protected]@site.uottawa.ca

• The authors wish to acknowledge the The authors wish to acknowledge the support of the Canadian Foundation support of the Canadian Foundation for Innovation and the Ontario for Innovation and the Ontario Innovation Trust as well as the Faculty Innovation Trust as well as the Faculty of Engineering of the University of of Engineering of the University of Ottawa for their support that made Ottawa for their support that made this research work possible.this research work possible.

an integrated robotic laser range sensing system for automatic mapping of wide workspaces

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