Final Presentation Prime Mobility Group Group Members: Fredrick Baggett William Crick Sean Maxon Project Advisor: Dr. Elliot Moore.

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