Circuit Design of Embedded Robot Control System Based on Wireless Communication

RF cable can be customized for other specifications

Single chip microcomputer STM32L151CCU6

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Photocoupler

Wheeled mobile robot is an important part of robot research. It integrates mechanical, electronic, detection technology and intelligent control. It is a typical intelligent control system. The intelligent robot competition combines high technology, entertainment and competition, and has become a high-tech confrontation activity widely carried out internationally.

Wireless communication interface design

The system adopts the PTR2000 wireless communication data transceiver module produced by Xuntong. The circuit interface is shown in Figure 2. The module is based on the RF device nRF401 produced by NORDIC. It features: 1 with two channels to choose from, working at up to 20 Kb/s; 2 receiving and transmitting in one, suitable for duplex and simplex communication, thus communication More flexible; 3 small size, less peripheral components required, interface circuit is simple, so it is especially suitable for robot miniaturization requirements; 4 can be directly connected to the microcontroller serial port module, simple control; 5 strong anti-interference ability; 6 low power consumption, communication stability.

Design and implementation of ultrasonic ranging sensor

The two-way ultrasonic sensor is used to control the robot to avoid obstacles, and predicts the distance of the robot relative to the destination, and plays a navigation role, and the receiving portion is connected with the capture and timing pins of the microcontroller. The entire ultrasonic detection system consists of ultrasonic transmission, ultrasonic reception and single-chip control. The transmitting part is composed of a high frequency oscillator, a power amplifier and an ultrasonic transducer. After being amplified by the power amplifier, the ultrasonic wave is transmitted through the ultrasonic transducer.

Fig. 5 shows an ultrasonic oscillating circuit composed of a digital integrated circuit. The high-frequency voltage signal generated by the oscillator blocks the amount of direct current in the signal through the capacitor C2 and supplies it to the ultrasonic transducer MA40S2S. The working process: U1A and UlB generate a high-frequency voltage signal corresponding to the ultrasonic frequency, the signal is converted into a standard square wave signal by the inverter U1C, and then amplified by power, and the C2 is separated from the DC signal and then applied to the ultrasonic transducer. The MA40S2S performs ultrasonic transmission. If the ultrasonic transducer is applied with a DC voltage for a long time, its characteristics will be significantly deteriorated. Therefore, the AC voltage is generally subjected to DC removal. U2A is 74ALS00 NAND gate, control_port (control port) pin is the control port, when control_port is high level, the ultrasonic transducer transmits ultrasonic signal.

Fig. 6 shows an ultrasonic receiving circuit. The ultrasonic receiving transducer adopts MA40S2R, and the signal received by the transducer is amplified by the integrated operational amplifier LM324. After three stages of amplification, the sinusoidal signal is converted into a TTL pulse signal by the voltage comparator LM339. INT_Port is connected to the interrupt pin of the MCU. When the interrupt signal is received, the MCU immediately enters the interrupt and processes and judges the ultrasonic signal.

According to the functional requirements of the competitive robot, the overall design is carried out, and each function is modularized. The hardware block diagram of the control system is shown in the figure. The central processing unit uses a microcontroller structure to control the coordinated operation of peripheral devices. The steering gear controls the direction of motion of the robot; the drive motor motor uses a small DC motor with an output shaft equipped with a photoelectric encoder to drive the wheel rotation. The electromagnet acts as an actuator for the gripping of the robot. Two ultrasonic sensors, eight photoelectric detection inputs and eight switch detection interfaces are provided.