CN102621986A - Navigation control system based on vision and ultrasonic waves - Google Patents

Abstract

The invention relates to a navigation control system based on vision and ultrasonic waves, which comprises a caterpillar robot body, an ultrasonic ranging subsystem, a vision subsystem and a motion control subsystem, wherein the ultrasonic ranging subsystem is arranged in front of the robot, the vision subsystem is arranged over the robot, and the motion control subsystem is positioned above the robot. The ultrasonic ranging subsystem comprises ultrasonic transmitters, ultrasonic receivers and a signal processing circuit, and a plurality of transmitters and a plurality of receivers are distributed in an equally spaced mode. The vision subsystem comprises a CCD (Charge Coupled Device) camera, an analog-to-digital conversion circuit and a DSP (Digital Signal Processor) image processor, and the motion control subsystem comprises a DSP motion controller and corresponding peripheral circuits. Information processed by the vision subsystem and the ultrasonic ranging subsystem is transmitted to a fuzzy controller inlaid in the motion control subsystem, and the fuzzy controller outputs control information to control the motion of the robot. The system has the advantages that the advantages of visual navigation and ultrasonic navigation are combined, so the navigation accuracy is increased; as the DSP high-speed processor is adopted, the instantaneity and the expandability are increased; and the anti-jamming capability is enhanced through applying a fuzzy control method.

Description

A Navigation Control System Based on Vision and Ultrasonic

technical field

The invention belongs to the technical field of robot navigation and control, and relates to a crawler robot navigation control system based on vision and ultrasonic waves.

Background technique

Navigation technology is the key technology for mobile robots to realize intelligence and complete autonomy, but the accuracy and real-time performance of navigation still need to be further improved. Visual navigation has the advantages of wide signal detection range, complete target information, and high sensitivity. It is a main development direction of robot navigation. Among the visual navigation methods, the most widely used is the local vision-based navigation method that uses a vehicle-mounted camera installed on the robot. With this navigation method, the control equipment and sensor devices are mounted on the robot body, and high-level decision-making such as image recognition and path planning are all completed by the on-board computer. Image processing requires a lot of calculations, so poor real-time performance is a problem to be solved. In addition, when obstacles are not within the field of vision or the light is very dark, the visual navigation activities of the robot are limited; ultrasonic navigation has the characteristics of simple structure, fast information collection rate, and high time resolution. At the same time, ultrasonic sensors are not easily affected by weather conditions and ambient light. and other external environmental conditions. At present, ultrasonic navigation technology is mature and has been widely used in the perception system of various mobile robots. However, due to the defects of the ultrasonic sensor itself, there is a detection blind area, which makes it difficult to fully obtain the surrounding environment information of the robot. Different robot navigation sensors reflect the robot's navigation status from different aspects. In order to maximize the comprehensive use of these sensor information and avoid the blind spot of a single sensor, it is necessary to establish an appropriate multi-sensor integrated navigation system so that the robot can adapt to complex environments. Improve navigation reliability.

Contents of the invention

In order to overcome the shortcomings of the general robot navigation control system, such as low real-time performance, low navigation accuracy, and inflexible movement, the present invention provides a navigation control system based on vision and ultrasonic waves.

The technical solution of the present invention is: a navigation control system based on vision and ultrasonic waves, including a crawler robot body, ultrasonic ranging subsystems arranged in front left, front, and front right of the crawler robot, and a vision subsystem directly above , and the motion control subsystem located above the tracked robot.

The visual subsystem includes two CCD cameras and a DSP image processor. The two CCD cameras are installed directly above the crawler robot. When the crawler robot is walking, the camera collects video information of the road ahead in real time, and the video information passes through the analog-to-digital conversion circuit. Send it to the DSP image processor; the image processing algorithm in the DSP image processor processes the digital video information to obtain the navigation parameters, and then transmits the obtained navigation parameters to the motion control subsystem through the interface circuit.

The ultrasonic ranging subsystem includes ultrasonic transmitters, ultrasonic receivers and corresponding circuits. When the crawler robot is working, three sets of ultrasonic transmitters continuously transmit ultrasonic signals to detect obstacles around the crawler robot. When receiving the echo signal, the ultrasonic receiver receives the echo signal and generates distance information to transmit to the motion control subsystem.

The motion control subsystem includes a DSP motion controller and peripheral circuits. The DSP motion controller receives the navigation parameters transmitted by the vision subsystem and the distance information transmitted by the ultrasonic ranging subsystem, and fuses these signals. Using fuzzy control method, two fuzzy control subsystems are designed. One is the fuzzy control subsystem based on the ultrasonic sensor, that is, according to the fuzzy input of the three sets of distance values transmitted by the ultrasonic distance measuring subsystem, the clutches of the left and right driving wheels of the crawler robot are continuously disconnected. A fuzzy controller is designed using time as the output quantity, and the controller is embedded in the motion control subsystem. The second is the fuzzy control subsystem based on the visual sensor, that is, according to the navigation parameters transmitted by the visual subsystem as the fuzzy input, the duration of the clutches of the left and right driving wheels of the crawler robot in the disconnected state is used as the output , and according to the pose of the tracked robot, design a fuzzy controller, and also embed the controller in the motion control subsystem. The designed two fuzzy controllers coordinate their work through a set value, and when at least one group of ultrasonic ranging subsystems obtains obstacle zone distances less than or equal to the set value, they enter the fuzzy control subsystem based on ultrasonic sensors; Otherwise, go to the visual sensor-based fuzzy control subsystem. The motion control subsystem generates a control signal according to the movement of the crawler robot, and the drive circuit processes the control signal, and then controls the control amount of the left and right driving wheels of the crawler robot in the next cycle, so as to realize the turning and straight running of the crawler robot and stop.

Compared with the prior art, the navigation control system provided by the technical solution of the present invention has the following beneficial effects:

(1) The present invention integrates visual navigation and ultrasonic navigation, integrates the advantages of both, and has the characteristics of high navigation accuracy, good reliability, and strong adaptability;

(2) The visual subsystem and the motion control subsystem all use DSP high-speed processors, which can solve the problem of low real-time navigation, and can also use the rich interfaces of the processor to expand the corresponding functions, improving the flexibility of expansion and upgrading ;

(3) The motion control subsystem adopts fuzzy control, and the fuzzy rule base comes from the experience of operators and experts, which is easy to operate, and improves the robustness and anti-interference of the system.

Description of drawings

Fig. 1 is the overall structural block diagram of the embodiment of the present invention;

Fig. 2 is the flow chart of the navigation control method of the embodiment of the present invention;

3 is a schematic diagram of the positional relationship between the crawler robot and the navigation path in the vision subsystem of the embodiment of the present invention;

Fig. 4 is the schematic diagram of the fuzzy control subsystem based on visual sensor of the embodiment of the present invention;

Fig. 5 is the schematic diagram of the fuzzy control subsystem based on the ultrasonic sensor of the embodiment of the present invention;

In the figure: 1 is the vision subsystem, 2 is the ultrasonic ranging subsystem, 3 is the motion control subsystem, 4 is the world coordinate system, 5 is the centerline of the navigation path, and 6 is the driving direction of the crawler robot.

Detailed ways:

(1) The working principle of the present invention is: after the crawler robot starts to work, the vision subsystem and the ultrasonic ranging subsystem start to coordinate work simultaneously. During the moving process of the crawler robot, the CCD camera of the vision subsystem (installed directly above the crawler robot) collects video information of the road conditions in front of the robot in real time, and converts the video information into digital signals through the analog-to-digital conversion circuit. Send it to the DSP image processor (using TMS320DM642 chip) for information processing to obtain navigation parameters, and transmit the information obtained by the visual subsystem to the motion control subsystem through the UART serial port of the DSP (using TMS320C2812 chip) motion controller; at the same time The ultrasonic ranging subsystem also works together. The ultrasonic resonance frequency generating circuit and the conditioning circuit generate ultrasonic signals and transmit them from the ultrasonic transmitter. The ultrasonic echo receiving and processing circuit receives and processes the ultrasonic signals reflected by obstacles. The signal obtained by the ultrasonic ranging subsystem is transmitted to the motion control subsystem through the digital input interface of the DSP motion controller. So far, it works in two ways, the ultrasonic ranging subsystem and the motion control subsystem are one way, this way works when at least one set of ultrasonic detection obstacle distance is less than or equal to the set value, the designed ultrasonic based The fuzzy control subsystem of the sensor obtains the duration signal of the clutch of the left and right driving wheels in the disconnected state, and controls the clutch to disconnect after being processed by the corresponding drive circuit, thereby controlling the moving state of the crawler robot; the vision subsystem and the motion control subsystem The system is the other way. When the obstacle distances detected by ultrasonic waves are greater than the set value, the designed fuzzy control subsystem based on visual sensors can obtain the time duration signals of the clutches of the left and right driving wheels in the disconnected state. The crawler robot is controlled by this signal to move.

(2) The fuzzy controller based on the visual sensor constructed in the present invention, its input is navigation parameters: heading angle ψ _W and lateral deviation ρ, and the output control quantity is steering control u ₁ . The lateral deviation ρ is negative if it is _located on the left side of Z _W , and positive _{if ρ is} located on the right side of Z _W ; 90°]. Define the domain of discourse of the heading angle as 7 levels {-3, -2, -1, 0, 1, 2, 3}, and the language variable as 7 levels {NB, NM, NS, O, PS, PM, PB }, the quantization factor is controlled by fuzzy control parameter optimization. The lateral deviation is also divided into 7 levels, but not evenly distributed, the quantitative level is {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5}, and the linguistic variable is 7 bin {NB(-5), NM(-2.5), NS(-1), O(0), PS(1), PM(2.5), PB(5)}. The output variable steering control u ₁ is the degree of control on the steering direction of the working machine. It is divided into 7 gears {LB, LM, LS, O, RS, RM, RB} by the description language. LB, LM, and LS all represent left steering. Respectively represent left steering for 1.8s, 1.3s, 0.8s; O means keep the current driving state without turning; RS, RM, RB all represent right steering, respectively represent right steering for 0.8s, 1.3s, 1.8s.

The fuzzy controller uses the experience of operators and experts to compile fuzzy control rules, as shown in the following table:

Table 1 Fuzzy control rules based on visual sensor

The fuzzy controller adopts the center of gravity method to realize fuzzy judgment, and obtains the fuzzy control decision table, which is stored in the fuzzy controller based on the vision sensor. During real-time control, the navigation parameters obtained by the vision subsystem in real time are checked in the decision table to obtain the control quantity u ₁ .

(3) The fuzzy controller based on the ultrasonic sensor that the present invention builds, its input amount comes from the obstacle distance that three groups of ultrasonic sensors detect in front of the crawler robot, right in front, and right in front, and take the smaller value in each group as The distance value of the sensor group, the output control quantity is the steering control u ₂ . The fuzzy input distance variable is 5 levels {very close (CLOSE), near (NEAR), middle (MED), far (FAR), very far (VFAR)}, and the output variable steering control u ₂ is divided into 7 levels by description language {NB , NM, NS, O, PS, PM, PB}, NB, NM, and NS all represent left steering, respectively representing left steering for 1.8s, 1.3s, 0.8s; O represents maintaining the current driving state without turning; STOP represents Stop; PS, PM, and PB all represent right steering, respectively indicating that the right steering is maintained for 0.8s, 1.3s, and 1.8s. The summarized fuzzy control rules are as follows:

Table 2 Fuzzy control rules based on ultrasonic sensor

The fuzzy controller adopts the maximum degree of membership method to realize fuzzy judgment, and obtains the fuzzy control decision table, which is stored in the fuzzy controller based on the ultrasonic sensor. During real-time control, the distances of the three groups of obstacles obtained by the ultrasonic control subsystem in real time are checked in the decision table. Calculate the control quantity u ₂ .

The working process of the present invention is described above with specific implementation as an example. Of course, the present invention is not limited to the above embodiments. According to the above-mentioned description, relevant staff can perform various tasks within the scope of not departing from the technical thought of the present invention. changes and modifications. The technical scope of the present invention is not limited to the contents of the description, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. one kind based on vision and hyperacoustic navigation control system; It is characterized in that: this system comprises the crawler frame human body; Be arranged on caterpillar type robot left front, dead ahead, right front the ultrasonic ranging subsystem and directly over vision subsystem, and the motion control subsystem that is positioned at caterpillar type robot top; The guidance path that said crawler frame human body is used for providing according to vision subsystem moves, and realizes keeping away in real time barrier thereby detect caterpillar type robot barrier on every side according to the ultrasonic ranging subsystem in the motion process.

2. as claimed in claim 1 based on vision and hyperacoustic navigation control system; It is characterized in that said crawler frame human body turning, keep straight on and stop to move and coordinate control by the clutch coupling of caterpillar type robot left and right sidesing driving wheel, the action of clutch coupling is controlled by corresponding hydraulic cylinder automatically.

3. as claimed in claim 1 based on vision and hyperacoustic navigation control system; It is characterized in that vision subsystem comprises two ccd video cameras, two analog to digital conversion circuits and a DSP image processor; Two ccd video cameras are used for gathering in real time the video information of caterpillar type robot the place ahead road conditions, and the video information of being extracted is sent to the DSP image processor behind analog to digital conversion circuit; The DSP image processor is handled the gained video information and is obtained guidance path and navigational parameter.

4. as claimed in claim 1 based on vision and hyperacoustic navigation control system; It is characterized in that said ultrasonic ranging subsystem comprises ultrasonic transmitter and ultrasonic receiver and signal processing circuit; Transmitter is launched ultrasonic signal continuously and is surveyed caterpillar type robot dead ahead, left front, right front whether barrier is arranged, and ultrasonic receiver receives echoed signal that barrier reflects and it is transferred to signal processing circuit; Signal processing circuit is handled received signal and is obtained range information, sends this range information to motion control subsystem then and controls caterpillar type robot and keep away barrier.

5. as claimed in claim 1 based on vision and hyperacoustic navigation control system; It is characterized in that said motion control subsystem comprises DSP motion controller and peripheral circuit, the range information that navigational parameter that said motion control subsystem is used for providing based on said DSP image processor and ultrasonic ranging subsystem provide is controlled caterpillar type robot and is independently walked and keep away barrier;

Said motion control subsystem is divided into based on the RACS of ultrasonic sensor with based on the RACS of vision sensor; All adopt fuzzy control method; When the obstacle distance that has at least one group of ultrasonic ranging subsystem to obtain is less than or equal to setting value; Employing is about to the fuzzy input quantity of range information conduct of the barrier of said three groups of ultrasonic ranging subsystems detection, the design fuzzy controller based on the RACS of ultrasonic sensor; With the duration of clutch coupling under off-state of two driving wheels about said caterpillar type robot as output quantity, through control this time control caterpillar type robot turning, keep straight on and stop; The obstacle distance that obtains when three groups of ultrasonic ranging subsystems is during all greater than setting value; Employing is based on the RACS of vision sensor; Be about to said navigational parameter as fuzzy input quantity; The design fuzzy controller, with the duration of clutch coupling under off-state of two driving wheels about said caterpillar type robot as output quantity, through control this time control caterpillar type robot turning, keep straight on and stop.

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