Inertial Measurements Unit

 

System Description:The main parts of the system are the four gyroscopes and an Inertial Measurement Computer, together called the Inertial Measurement Unit (IMU). The four gyroscopes will be oriented to produce data representing the rocket's relative position, pitch, and high and low sensitivity roll rate. The IMU is an embedded system board. The IMU needs to gather and process the data produced by the gyroscopes, and then pass this data on to the Telemetry Stack (TM) (see Figure 1). The processor on the IMU must also run the timing of the onboard filters.

 

Firmware Description: The microprocessor on the IMU samples the signals being sent to the IMU board from the gyroscopes approximately every one millisecond. Each gyro sends two signals, one representing its rate, and the other its temperature, for eight total signals. The signals from the gyroscopes will be in analog form; therefore, the firmware uses the analog-to-digital converter (ADC) on the microprocessor chip to convert the signals to digital form. After ten samples, the program serially transmits the average of all the signals to the TM in a packet, approximately every 10 milliseconds. The program must also generate a steady four-kilohertz oscillating signal for use by filters on the IMU board. Three LEDs are available for use as status indicators.