CN101324430A - Binocular odometry based on similarity principle - Google Patents

Abstract

The invention belongs to the field of mobile robots and provides a novel binocular distance measurement method. The hardware of the distance measurement method mainly comprises two cameras with different focal lengths, an image acquisition card, a camera control motor and a main control computer. The distance and the size calculation formula of the object to be measured can be deduced according to the similar principle of triangle and the relation equations of focal length, object distance and image distance. The two cameras with different focal lengths are used for imaging the object to be measured to obtain images with two different scales, the main control computer calculates the different size of the object to the measured in the two images according to corresponding algorithm, and the two different sizes are substituted in the calculation formula to obtain the distance and the size information of the object to be measured. According to the method, a robot can have the effect of telescope and wide-angle lens to improve the depth and the wideness for detecting the world. According to the principle and formula of the method, the distance information of the object can be calculated without measuring the image distance, thus obviating the use of a displacement sensor and lowering the cost.

Description

Binocular telemetry based on the principle of similitude

Technical field

The invention belongs to the intelligent mobile robot field, proposed a kind of novel binocular telemetry.

Background technology

Realize the autokinetic movement of intelligent mobile robot, just be unable to do without path planning and keep away barrier in real time, and a gordian technique of keeping away barrier in real time is exactly to measure the distance of robot to barrier exactly.Distance-finding method commonly used at present mainly is divided into initiatively range finding and passive ranging two classes.

(1) initiatively range finding

Initiatively telemetry is to send energy by specific device, and the information that the range measurement system basis reflects is come the distance of Measuring Object, and it mainly comprises reflected energy method, ultrasonic time method etc.The reflected energy method needs specific apparatus to launch a branch of light (normally near infrared light or laser) to shine the testee surface, and instrument receives the energy of reflection light of testee simultaneously, judges the distance of testee according to the energy of reflection light that receives; The ultrasonic time method is measured a branch of ultrasound wave and is judged tested distance from the time that is transmitted into the reflected back instrument.Initiatively the advantage of telemetry is to be subjected to external environmental interference less, its shortcoming is to need extra energy emitters, has increased equipment cost, and have may need energy transmission medium (as the ultrasonic time method), affected by environment bigger, limited its use occasion.

(2) passive ranging

The passive ranging method is the distance of coming Measuring Object according to the signal (as light signal) that testee itself sends, it usually and machine vision interrelate, mainly comprise stereoscopic vision telemetry, monocular telemetry, angle measurement passive ranging method etc.The stereoscopic vision telemetry is to copy a kind of distance-finding method of human use's binocular perceived distance, and the difficult point of this method is to select rational matching characteristic and matching criterior, with the assurance matched accuracy, and makes the degree of depth and the range in the robot perception world limited; The monocular telemetry satisfies certain condition " mask " by introducing in optical system, make the optical transfer function of imaging system form a series of cycles that change with the zero point target object distance dependent, this method requires target object to have the low spatial frequency characteristic, needs exact instrument to measure image distance information simultaneously; Angle measurement passive ranging method is a kind of distance-finding method that units concerned of USN propose, and by twice angle measurement realizes range finding to target, this method requires the platform acceleration not to be zero.

As seen above-mentioned various active range findings and passive ranging method all exist certain shortcoming or deficiency.

The objective of the invention is:

Distance-finding method for intelligent mobile robot provides a kind of low cost, high precision, is easy to realize can improve the degree of depth and the range in the robot perception world simultaneously.

Technical scheme of the present invention is:

Based on the binocular telemetry of the principle of similitude, its hardware mainly comprises two camera, image pick-up card, camera control motor and main control computers that focal length is different.Two different cameras of focal length carry out imaging to a testee, obtain two images that yardstick is different, and image pick-up card sends to main control computer with two images, goes out the different size of testee in two images by corresponding algorithm computation.Again according to the leg-of-mutton principle of similitude, and the relation formula of focal length, object distance and image distance just can calculate the distance and the dimension information of testee.

Advantage of the present invention is:

Novel binocular telemetry based on the principle of similitude can adopt two cameras that focal length is different in application, can make robot have telescope and wide-angle lens simultaneously, improves the degree of depth and the range in the robot perception world.According to the principle formula of this method, need not measure image distance and just can calculate the range information of object, thereby save the use of displacement transducer, reduced cost.By a series of experiment, also verified this method precision height, be easy to realize.

Description of drawings

Fig. 1 is the schematic diagram of novel binocular telemetry

Fig. 2 is the structured flowchart of novel binocular range measurement system

The number in the figure explanation

(1) digit sequence:

1-lens one; 2-lens two; 3-binocular camera shooting head; 4-camera steer motor code-disc; 5-code-disc revolution; The 6-main control computer; 7-motion planning control system; The 8-movement instruction; The 9-motion motor; 10-visual information; The 11-image pick-up card.

(2) letter series:

The AB-testee; The length of h-testee; The distance of u-testee to two lens; O ₁The center of-lens one; O ₂The center of-lens two; f ₁The focal length of-lens one; f ₂The focal length of-lens two; A ₁B ₁The imaging of-AB scioptics one; A ₂B ₂The imaging of-AB scioptics two; v ₁The image distance of-lens one imaging; v ₂The image distance of-lens two imagings; h ₁The yardstick of-testee scioptics one imaging; h ₂The yardstick of-testee scioptics two imagings.

Embodiment

Introduce the principle of work of this novel telemetry at first in detail:

The schematic diagram of novel binocular vision telemetry as shown in Figure 1.In Fig. 1,, draw following equation according to the leg-of-mutton principle of similitude:

$\frac{h_1}{v_1}=\frac{h}{u}=\frac{h_2}{v_2}---\left(1\right)$

By (1) Shi Kede: $v_1=\frac{h_1{v}_2}{h_2}---\left(2\right)$

Relation formula by focal length, object distance and image distance gets:

$\left\{\begin{array}{c}\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="A20081000064400061.png"\; state="\{\{state\}\}">f</figure-callout>}}_1}=\frac{1}{u}+\frac{1}{v_1}\\ \frac{1}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="A20081000064400061.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}=\frac{1}{u}+\frac{1}{v_2}\end{array}\right.---\left(3\right)$

(2) formula and (3) formula are put in order, obtain the computing formula of object distance:

$u=\frac{f_1{f}_2(h_1-h_2)}{h_1{f}_2-f_1{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20081000064400061.png"\; state="\{\{state\}\}">h</figure-callout>}}_2},$ Work as f ₁≠ f ₂The time (4)

And obtain testee size calculation formula:

$h=\frac{h_1{h}_2(f_1-f_2)}{h_1{f}_2-f_1{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20081000064400061.png"\; state="\{\{state\}\}">h</figure-callout>}}_2},$ Work as f ₁≠ f ₂The time (5)

(1), in (2), (3), (4) and (5) formula:

The length of h-testee AB, in the corresponding diagram 1 | AB|; The U-testee is to the distance of lens, in the corresponding diagram 1 | AO ₁|; h ₁The yardstick of-testee scioptics one imaging, in the corresponding diagram 1 | A ₁B ₁|; h ₂The yardstick of-testee scioptics two imagings, in the corresponding diagram 1 | A ₂B ₂|; v ₁The image distance of-lens one imaging, in the corresponding diagram 1 | A ₁O ₁|; v ₂The image distance of-lens two imagings, in the corresponding diagram 1 | B ₂O ₂|; f ₁The focal length of-lens one; f ₂The focal length of-lens two.

Introduce the embodiment of this telemetry in application below:

In actual applications, can use the different camera of two focal lengths, at first will know the focal distance f of two cameras as two lens ₁And f ₂, obtain the size h of two camera imagings again by corresponding algorithm ₁And h ₂, just can calculate the distance and the dimension information of testee.

Can design binocular vision system as shown in Figure 2.Two cameras 3 are by driven by servomotor, and its visual angle can reach 360 °.Servomotor is equipped with code-disc 4, and what be used for calculating camera waves angle and luffing angle.Vision 10 information that image pick-up card 11 transmits camera reach main control computer 6 and carry out pre-service, merge information such as code-disc revolution 5 again, after software processes, obtain command adapted thereto, vehicular motion planning control system 7 sends movement instruction 8 according to these instructions to motion motor 9, with the motion of control robot.

Claims (1)

1. the hardware of this telemetry mainly comprises two camera, image pick-up card, camera control motor and main control computers that focal length is different.According to the leg-of-mutton principle of similitude, and the relation formula of focal length, object distance and image distance can be derived the computing formula of testee distance.

$u=\frac{f_1{f}_2(h_1-h_2)}{h_1{f}_2-f_1{h}_2},$ Work as f ₁≠ f ₂The time

And obtain testee size calculation formula:

$h=\frac{h_1{h}_2(f_1-f_2)}{h_1{f}_2-f_1{h}_2},$ Work as f ₁≠ f ₂The time

Utilize two different cameras of focal length that a testee is carried out imaging, obtain two images that yardstick is different, image pick-up card sends to main control computer with two images, go out the different size of testee in two images by corresponding algorithm computation, in the computing formula with these two different size value substitutions derivations, just can obtain the distance and the dimension information of testee.

Images