Final Presentation Prime Mobility Group Group Members: Fredrick Baggett William Crick Sean Maxon Project Advisor: Dr. Elliot Moore
Jan 19, 2016
Final PresentationPrime Mobility Group
Group Members:Fredrick BaggettWilliam CrickSean Maxon
Project Advisor:Dr. Elliot Moore
WHATWHAT: Adding Autonomous Functionality to a Power Wheelchair
WHYWHY: To assist disabled individuals in homes, hospitals, and healthcare institutions.
SCOPESCOPE: Prototype proof of concept
Assisted Driving Mode Assisted Driving Mode - Chair will prevent head on collisions and block user commands that increase the likelihood of a collision.
Target Following Mode Target Following Mode - Chair will autonomously follow a person wearing a predefined target symbol.
USB Camera
Laptop
CompactRIO
Embedded Controller
LIDARRange Finder
Joystick
PowerWheelch
air
SICK LMS-291 180 degree Field of View 75 Hz motor speed 1° angular resolution 13.33 ms response time 30 meter range
““Laser Range Finder”Laser Range Finder”
Target Emblem
L C R
Low Frequency PWMExperimentally Determined
ParametersPiecewise Linear Proportional
Target
Pulse width
Camera Image
Turning Radius
Left Turn Proportional Control
Right Turn Proportional Control
LabVIEW Front Panel, Displayed on Laptop
What we tested: Collision Avoidance Object Detection Target Tracking Target Following
How we tested: Set up obstacles and measured the
distances at which they were detected. Designed a target and measured the
tracking and following specifications in different lighting conditions.
Feature DescriptionProposed
SpecificationActual
Specification
Collision Avoidance
Front Distance (Stationary)
> 0.5 m 1.28 m
Front Distance (Moving)
>10 cm
Side Clearance > 10 cm 12 cm
Object Detection
Range 0.1 m – 5 m 0.1 m – 4.5 m
Field of View 180° 180°
Target Tracking
Range 0.5 m – 3 m 0 m – 7 m
Field of View 45° 65°
Target Following
Linear Speed ≤ 3 km/h 2.4 km/h
Angular Speed 20° per sec 16° per sec
Heading Deviation < 20° 7°
Problems SolutionsLIDARLIDAR reported
‘ghost’ points caused by reflections
Mounted the LIDAR at a 10° downward angle.
Mounted the LIDAR at a 10° downward angle.
Chair drifts Chair drifts to the right when in motion
Shifted the center camera region to the right to compensate.
Shifted the center camera region to the right to compensate.
SlowSlow acquisition rateacquisition rate for LIDAR data causes delayed
response
Increased the length of the front LIDAR zone.
Increased the length of the front LIDAR zone.
Voltage regulation Voltage regulation issues
• USB webcam with laptop in place of Ethernet camera.• Removed Shaft Encoders.
• USB webcam with laptop in place of Ethernet camera.• Removed Shaft Encoders.
Shaft encodersShaft encoders Allow for navigation techniques such as dead
reckoning. Feedback mechanism to control the forward
speed Used in conjunction with the LIDAR to create a
table of points that define a map of the environment
CAN protocolCAN protocol Implementing CAN protocol would allow the
microcontroller to communicate with the chair in the same way as the proprietary joystick. This could lead to more finely tuned control.
•Collision avoidance:•LIDAR
•Object Tracking:•Camera + Image Processing
•Chair Control:•Pulsed Feedback Control
•Behavior & Programming:• Target Following Mode, Supervisory Control Mode
DIO Module 5-Way Switch
At Rest Motion
Moving Motion
Decelerate
Accelerate
Turn left in place
Veer left
Turn right
in place
Veer right
Start movin
g forwar
d
Start moving backwar
ds
Forward pin
Left pinRight pinReverse pin