Purpose In the industry, can reduce manpower and

improve efficiency can contribute to the restoration of some

functions lost by handicapped people medical assistance Do not need any one to help in 24 hours

Motivation The handicapped people doesn’t accept an

assistive arm onto the wheelchair , because they feel like being assimilated to a robot.

Manus® arm

Handicapped people takes the control of the mobile robot and move the platform wherever he wants and can also use the manipulator.

GLOBAL DESCRIPTION

It is made of two parts :○ 1. the wheelchair equipped with a standard PC

and an interface screen and a joystick for control .

○ 2. the mobile robot

equipped with two

omnidirectional

vision sensors

and a Manus® arm.

This robotic assistance will be used in:○ Automatic mode: track and follow a wheelchair

autonomously without holding up the wheelchair.

○ Remote mode: Standing

close to the wheelchair

in order to be

manually controlled.

(this mode the

arm can be used )

THE OMNIDIRECTIONAL VISION

What is omnidirectional vision ? A : Use only one camera, with a rotation motion

, in order to sweep a large space.

Disadvantage : the camera’s movement takes

time.

extend two classes of omnidirectional vision systems :

1. the systems made of a mirror and a camera are called 『 catadioptric systems 』 .

2. a classical camera with a fish-eye lens ,

such mountings are called 『 dioptric

systems 』 .

THE AUTOMATIC TRACKING

The main goal is to enable the mobile robot to track a wheelchair with no mark-up and no particular equipment onto the wheelchair.

The omnidirectional vision is used in two different ways :

○ 1. The free space map○ 2. The tracking

The free space map the two omnidirectional sensors are used as

goniometric sensors and compute distances of the different verticals parts called natural landmarks

Correspondences between angles from the left sensor to the rightsensor for objects situated at different distances from the mobile robot.

The tracking As the wheelchair is not equipped with any

particular mark-up, we have to track it as it is, so we use the CAMShift algorithm which perform a tracking by using an image of the object to track.

What is CAMShift?

A: Continuously Adaptive Mean Shift

CAMShift

Architecture○ CAMShift是Mean Shift 的改良版○ CAMShift 會更新每次搜索的範圍 , 更適合在連

續的影像中作物件追蹤 Step

○ 轉換 HSV 色彩空間○ Back Projection○ Mean Shift○ CAMShift

CAMShift ’s Step

轉換成 HSV 色彩空間○ 取得色彩直方圖

CAMShift ’s Step Back Projection

CAMShift ’s Step

Mean Shift○ 計算中心點○ 旋轉的角度

CAMShift ’s step

CAMShift○ 將新得到的搜尋視窗，當

作第三步驟的初始搜尋視窗。如此重複的執行，就可以達到連續追蹤物件的效果。

選擇要追蹤的物體

建立物體的色彩直方圖

計算得到整個場景的反向投影圖

搜尋視窗對準物件的中心

重新對場景搜尋

CAMShift ’s defect

背景過度複雜或是有類似顏色的時候效果會降低。

物體本身就很複雜，導致辨識困難或誤判。

The tracking _ Initialization of the CAMShift In order to init the CAMShift, we need images

of the wheelchair.○ compute the subtraction between the background

and the current image.

RESULTS

CAMShift :

www.youtube.com/watch?v=6rcTz1IuPGw&feature=related

Manus® arm :

www.youtube.com/watch?v=LBUyiaAPCcY