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Tham khảo tài liệu 'mcgraw-hill - the robot builder's bonanza episode 2 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 686 EXPERIMENTING WITH TILT AND GRAVITY SENSORS FIGURE 41.3 A basic schematic diagram for using the Analog Devices ADXL150 singleaxis accelerometer. FIGURE 41.4 My prototype of the ADXL150 accelerometer which can be used for robotic tilt motion and vibration sensing. CONSTRUCTING A SINGLE-AXIS ACCELEROMETER ROBOTIC SENSOR 687 slowly move the sensor board in different directions adjust R2 and R4 for maximum voltage change. ADJUSTING THE SENSOR You will need to experiment with different settings to achieve the output you want for the application you have planned for the 150 As a level or tilt sensor position the ADXL150 so it points arrow up 1 g setting . Any tilt in any direction will then be registered as a negative-going voltage change. For this application you want a low-g scale so adjust R2 near its minimum and R4 near its maximum. As a movement sensor position the ADXL150 so it points arrow forward arrow to the front of the robot . For a slow robot a rather low-g scale is likely the best choice but adjust as you see fit. Some small robots turn and spin on their axis very quickly producing momentary forces of 2 or 3 g s As a shock or vibration sensor position the ADXL150 in the horizontal or vertical position as desired. Adjust the scale setting based on the sensitivity you need. If the robot is not supposed to be highly sensitive to minor bumps and grinds for instance set a high-g scale by increasing R2 and decreasing R4. CONTROL INTERFACE AND SOFTWARE Of course the schematic in Fig. 41.3 still needs to be interfaced to a computer or microcontroller via an analog-to-digital converter to do your robot any good. Chapter 29 Interfacing with Computers and Microcontrollers discusses in more detail how to use ADCs so we will dispense with that discussion for this project. If you plan to use your PC to interface to the ADXL150 for example you need just a basic ADC chip such as the ADC0804. You input a single analog voltage and the output is converted to eight data .
