Transcript
Navigation Subsystem Real-Time Vehicle Guidance Project TA: Mark Gilbertson 2016
Table of Contents • Logistic Considerations • Navigation Overview • Track Map • Navigation Subsystem Assignment • Programming Help
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Logistic Considerations • “Hello Word” interim report. • Use paragraphs, not bullet points. • Color indicators require color printers… • Don’t copy the assignment text. • Label figures. • Don’t print double sided. 3
Logistic Considerations • Include “ME5286” in the subject of all your emails to the TA. • Send emails with your questions to the TA. • Grades can be discussed at office hours or other nonclass times.
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Navigation Overview
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What is Navigation? • Determination of vehicle’s state vector – Position – Speed – Heading
• Used with knowledge about the track • Relationship between vehicle and track 6
Why do we need it?
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continued
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Location Methods • Global Navigation Satellite Systems (GNSS)
– Example: DGPS (Differential Global Positioning System, most common for vehicle navigation) – Provides latitude and longitude
• Inertial Sensors
– Laser ring gyros – Mechanical gyros – Mechanical linear sensors
• Imaging
– Captures ground speed – Identifies landmarks – Identifies obstacles
• Compass • LIDAR and SONAR
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SAFETRUCK Sensors • GPS – Location in “State Plane Coordinate System” – In meters
• Speed – Straight-line speed – Meters per second
• Heading – In radians – You need to characterize sensor orientation 10
State Plane Coordinate System •
A set of 124 geographic zones or coordinate systems designed for specific regions of the United States
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Ignores the curvature of the Earth – Each zone is assumed to be flat
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Cartesian coordinates
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Measured in meters – Arbitrary zero position – Northing (y) – Easting (x)
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Our coordinate system: Minnesota Central
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Track Map
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Map Structure • Map is made up of road centerline data – Linear segments connecting (x,y) location pairs
• Map is split in to sections each with: – Section ID – Speed limit (m/s) – Number of data points (in that section) – Center line data (x,y) – Next and previous section info
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previous next_ 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 1 0 1 0 1 0
POINT_X POINT_Y speed 1 823338 350990.7 1 823347.1 350986.1 1 823356.7 350982.5 1 823366.6 350980.2 1 823376.7 350979 1 823387 350979.1 1 823397.1 350980.4 1 823407 350982.9 1 823416.5 350986.6 1 823425.5 350991.4 1 823433.9 350997.2 1 823442.3 351003.3 1 823449.6 351009.6 2 823449.6 351009.6 2 823457.8 351015.1 2 823466.5 351019.5
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30 30 30 30 30 30 30 30 30 30 30 30 30 35 35 35
Using the Map • Test track data is stored in a file • Accessible through CLData class – Defined in LoadCenterLine.cpp and .h – Pre-written, don’t edit
• Map data must be read in and stored locally – Takes too long to make map queries in real time 14
Programmatic Map Access • Lots of info on course website – http://me.umn.edu/courses/me5286/vehicle/Simulation/map.shtml
• Basic Steps – Find the number of sections – For each section, find: • Number of points • Speed limit • Next section to find
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Initialization Algorithm • Truck can start anywhere • An algorithm should be proposed and implemented to bring the truck back to the track – Need to relate starting location to track – Which segment or centerline point are you on?
• Algorithm must be robust • Make sure the algorithm is general – Works with different tracks
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Navigation Subsystem Assignment
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Requirements • Read map data using the provided functions – Using MNroad track – Print to file (Don’t just copy-paste from .csv) – Create a map of the track – Plot speed limit vs % distance along track • 0 to 1.00 or 0% to 100%
• Create an initialization algorithm – Do not implement (yet) 18
Deliverable • Single document – Memo-format – Turn in a hard copy on February 17, at the beginning of class – As an appendix, include your commented code
• Document your ability to read in the map • Include the required plots – One showing a map of the track, with the different track sections clearly designated visually (Color) – One showing the speed limit plotted against percent distance down the track
• Discuss your initialization algorithm 19
Programming Help
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Pointers • Very Important • Very Confusing • You will want to (re)-learn this stuff
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File I-O • Functions used in C: – fopen() – fclose() – fprintf() – fscanf()
• Use them to read/write from/to files • Look up functions online for exact syntax 22
File I-O Example • Declare pointer to file as type FILE • Example: FILE *file_id; int ndays = 7; file_id = fopen(“name.txt”,“w”); fprintf(file_id,“There are %d days \ in a week”,ndays); fclose(file_id);
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Static Variables • Declare in header or outside function • Used to share variables – Between functions – Between function calls – Maintains value through re-initialization.
• Declare using static keyword 24
Questions
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