Circuit design of control system for vacuum cleaner robot

A cleaning robot is a type of service robot that can replace humans to clean rooms, workshops, walls, etc. This paper proposes a design scheme for a mobile cleaning robot used indoors. It has practical value. The main task of an indoor cleaning robot is to replace humans in cleaning work, so it needs to have a certain degree of intelligence. The cleaning robot should have the following capabilities: it can navigate by itself, detect walls, obstacles in the room and avoid them; it can walk through most of the room, detect the battery power and return to charge autonomously, and it should be compact in appearance, stable in operation, and low in noise; it should have a humanized interface for easy operation and control. In combination with the main functions of the cleaning robot, the hardware design of its control system is discussed.

Although traditional microprocessors such as the 51 series have a short development cycle and low cost, their real-time performance is poor and it is difficult to implement complex control algorithms. In addition, the data conversion speed of the added peripheral circuits is slow, so the performance of the robot cannot be fully utilized. Although the emergence of high-speed DSP makes the system modular and fully digital, its development cost is high. The ARM microprocessor with the same performance as DSP is rich in resources and has good versatility. Its main technical advantages are high performance, low price, and low power consumption. It is widely used in various fields. Therefore, it is a good strategy to apply ARM to robot control systems. LPC2210 is a Philips ARM7TDMI-S microprocessor with real-time simulation and tracking support. It uses a 3-level pipeline technology and can process instructions in parallel. Due to its very small size and extremely low power consumption, multiple 32-bit timers, PWM outputs and 32 GPIOs make it particularly suitable for industrial control and small robot systems, meeting the robot's requirements for controller operation speed. With LPC2210 as the core. Design a cleaning robot body system with simple structure and stable performance.

Infrared proximity sensor circuit design

The reflective photoelectric switch is composed of an infrared LED light source and a photosensitive element such as a photodiode or a photosensitive transistor. When there is an obstacle blocking the light, the light can be reflected back and the output is a low-level signal; when there is no obstacle blocking the light, the light cannot be reflected back and the output is a high-level signal. The short-range infrared proximity sensor of the vacuum cleaner robot consists of two identical infrared transmitting and receiving circuits. Each circuit can be divided into several parts, such as high-frequency pulse signal generation, infrared emission adjustment and control, infrared emission drive, and infrared reception. A 38kHz modulated pulse signal is obtained through a 38kHz crystal oscillator and a NOT gate circuit; the infrared transmitting tube (TSAL6200) is driven by a triode. The infrared light emitted by the transmitting tube is reflected by the object and received by the infrared receiving module. After being processed by the integrated circuit inside the receiving head (HS0038B), a digital signal is returned and input to the I/O port of the microcontroller, as shown in Figure 3. If the receiving head receives a 38kHz infrared pulse, it will return a low-level output, otherwise it will output a high-level output. By detecting the I/O port, the presence or absence of the object can be determined.

Two motor control system circuit designs

In low-power systems, DC motors have good linear characteristics and superior control performance, making them suitable for position and speed control. To achieve forward and reverse operation of a DC motor, you only need to change the polarity of the motor power supply voltage. The change in voltage polarity and the length of the running time can be achieved by the processor, while a drive circuit is required to provide the current for the normal operation of the DC motor.

The H-bridge drive circuit is a commonly used drive circuit. The two walking drive motors in this design are built with discrete power field effect transistors and freewheeling diodes, which are low-cost and easy to dissipate heat, as shown in the figure.

Use ARM7's P0.8 and P0.9 to control the motor. These two pins are PWM output pins that can control the speed of the motor. This part mainly ensures that the robot can move in a plane. At the same time, the wheel is equipped with an encoder to detect the distance traveled. The robot can turn by dead reckoning. Assuming that the number of divisions of the robot's photoelectric encoder is N; the number of pulses received by the controller is m; the diameter of the wheel is D; the distance between the two wheels is W, the distance the wheel moves forward can be calculated.