There are more actions and functions to be implemented, and multiple sensors are required to detect the outside world and control the location, action, and operational status of the robot in real time. All tasks in the system are ultimately running on real-time operating system μC / 0S 1 II, but not only should consider the internal resources of the microcontroller, but also to see their portability and scalability. LPC2129 is a 32-bit ARM7TDMI-S microprocessor produced by Philips, embedding 256 kb high-speed flash memory, which uses 3-level pipeline technology, and performs finger, decodes, and execution, and can process instructions in parallel, improve CPU. Running speed. Since its size is very small, the power consumption is extremely low, strong anti-interference ability is suitable for a variety of industrial controls. 2 32-bit timing counters, 6-way PWM outputs, and 47 general I / 0 ports, especially suitable for industrial control and small intelligent robot systems for low environmental requirements. Therefore, the LPC2129 is selected as the main controller, and a smart robot control system is simple and stable performance.
Wireless communication interface design
The system uses the PTR2000 wireless communication data transceiver module produced by PTR2000. The circuit interface is shown in Figure 2. This module is based on Nordic's RF device NRF401, which features two channels to choose from. The operating rate is as high as 20 kb / s; 2 receive the emission and one, suitable for dual-labor and single work, thus communication Flexible; 3 small size, less peripheral components, simple interface circuits, is especially suitable for machine miniaturization requirements; 4 can directly pick the single-chip serial module, simple control; 5 anti-interference ability; 6 power consumption, communication stability.
Ultrasonic ranging sensor design and implementation
The two ultrasonic sensors are used to control the robots to avoid obstacles, and predict the relative destination distance of the robot, and the receiving portion is connected to the capture of the microcontroller and the timing pin. The entire ultrasonic detection system consists of ultrasonic emissions, ultrasonic reception, and microcontroller control. The transmitted portion consists of a high frequency oscillator, a power amplifier, and an ultrasonic transducer. After amplifying the power amplifier, ultrasonic transducer is transmitted by an ultrasonic transducer.
FIG. 5 shows an ultrasonic oscillation circuit composed of a digital integrated circuit. The high-frequency voltage signal generated by the oscillator is separated by the capacitor C2 and the ultrasonic transducer MA40S2S. It works: U1A and ULB generation The high-frequency voltage signal corresponding to the ultrasonic frequency, the signal becomes the standard square wave signal through the reverse device U1C, and then the power is amplified, and the C2 is applied to the ultrasonic transducer MA40S2S for ultrasonic transmission. If the ultrasonic transducer is a long time to reach the DC voltage, its characteristics will be significantly denied, so the AC voltage is generally separated from DC processing. The U2A is 74ALS00 and non-door, the Control_Port (Control Port) pin is the control port, when Control_Port is high, the ultrasonic transducer transmits an ultrasonic signal.
Figure 6 shows an ultrasonic receiving circuit. The ultrasonic receiving transducer employs MA40S2R, and the signal received by the transducer is enlarged by the integrated operation amplifier LM 324. After the three-stage amplification, the sinusoidal signal is converted into a TTL pulse signal by the voltage comparator LM 339. INT_PORT is connected to the single-chip interrupt pin. When the interrupt signal is received, the microcontroller immediately enters the interrupt and processes the ultrasonic signal.
Photoelectric detection module design
Design a photoelectric detection module that allows the robot to detect white guides on the ground. The photoelectric detecting circuit mainly includes an emission portion and a receiving portion, which is shown in FIG. The waveform modulation of the transmitted portion uses a frequency modulation method. Due to the fast response speed of the light-emitting diode, its operating frequency can reach a fewgottegate or more than ten megaw, and the modulation frequency of the detection system is within dozens to several hundred kilohertz, so the requirements can be met. The light source drive is mainly responsible for amplifying the modulated waveform to sufficient power to drive the light source. The light source adopts an infrared light-emitting diode with a high operating frequency, suitable for modulated light emission of waveforms.
The receiving portion receives the modulated light by a photosensitive diode to convert the optical signal into an electrical signal. This electrical signal is usually weak, and it is necessary to perform filtering and amplification. The amplification of the modulation signal is in the form of AC enlargement, and the modulated optical signal can be separated from the background light signal to provide convenience for signal processing. The modulation signal processing section identifies the amplified signal, and determines the characteristics of the detected object. Therefore, the nature of the module is separated from "DC", useful modulated optical signal from "DC", and useless background light signals to achieve anti-interference.
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