Analog output vs digital output:

This is the first thing to consider. This depends on the interface between your system and the accelerometer. Generally, the voltage and acceleration of the analog output are proportional. For example, 2.5V corresponds to an acceleration of 0g, and 2.6V corresponds to an acceleration of 0.5g. Digital output typically uses a pulse width modulated (PWM) signal.

If the microcontroller you are using has only digital inputs, such as BASICStamp, then you can only select the digital output of the accelerometer, but the problem is that you have to take up an extra clock unit to process the PWM signal, and also for the processor. No small burden.

If you are using a microcontroller with an analog input, such as PIC/AVR/OOPIC, you can use the analog interface’s accelerometer very simply. All you need to do is add an instruction like “acceleration=read_adc()” to the program. And the speed of processing this instruction is only a few microseconds.

Number of measuring axes:

For most projects, two-axis accelerometers are already available for most applications. For some special applications, such as UAV, ROV control, three-axis accelerometers may be suitable for a bit.

Maximum measured value:

If you only need to measure the tilt of the robot relative to the ground, a ±1.5g accelerometer is sufficient. But if you need to measure the dynamic performance of the robot, ±2g should also be enough. If your robot will suddenly start or stop, you need a ±5g sensor.

Sensitivity:

In general, the more sensitive the better. The more sensitive the sensor is more sensitive to changes in acceleration over a certain range, the greater the change in output voltage, which makes it easier to measure and obtain more accurate measurements.

Bandwidth:

The bandwidth here actually refers to the refresh rate. This means how many readings the sensor produces per second. For applications where tilt angles are generally measured, a bandwidth of 50 Hz should be sufficient, but for dynamic performance such as vibration, you will need a sensor with hundreds of HZ bandwidths.

Resistance / Cache Mechanism:

For some microcontrollers, for A/D conversion, the connected sensor must have a resistance of less than 10kΩ. For example, Analog Devices’s analog accelerometer has a resistance of 32kΩ and does not work properly on PIC and AVR control boards. Therefore, it is recommended to read the controller manual carefully before purchasing the sensor to ensure that the sensor works properly.
 

Leave a Reply

Your email address will not be published. Required fields are marked *