{"id":11656,"date":"2025-10-19T23:26:07","date_gmt":"2025-10-19T22:26:07","guid":{"rendered":"https:\/\/dronesonen.usn.no\/?p=11656"},"modified":"2025-10-21T15:20:08","modified_gmt":"2025-10-21T14:20:08","slug":"pickmebot-week-8","status":"publish","type":"post","link":"https:\/\/dronesonen.usn.no\/?p=11656","title":{"rendered":"PickMeBot-week 8"},"content":{"rendered":"\n

Theo:<\/strong><\/h2>\n\n\n\n

This week, I managed to get the servo working. I did some troubleshooting with a multimeter and found that the issue was insufficient power to the servo. After connecting the servo to the driver board and powering it with a power bank, it started working. Once the arm is ready, I\u2019ll calibrate the servo and it will be able to move the box.<\/p>\n\n\n\n

Sondre:<\/strong><\/h2>\n\n\n\n

This week involved quite a bit of troubleshooting and debugging on my part. We finally received the BNO055 IMU module last week, and over the weekend Anette was able to solder the pin headers so it could be mounted on the robot\u2019s expansion board. My main goal this week was to get the IMU communicating reliably with the Micro:bit and integrate it into the robot\u2019s control system. <\/p>\n\n\n\n

Me and Anette connected the BNO055 to the Micro:bit Driver Expansion Board using the built-in I2C connector. The table below shows the pin mapping I used for this connection: <\/p>\n\n\n\n

BNO055 (IMU) <\/td>Micro:bit expansion board: <\/td><\/tr>
Vin <\/td>3v3 <\/td><\/tr>
GND <\/td>GND <\/td><\/tr>
SDA <\/td>SDA <\/td><\/tr>
SCL <\/td>SCL <\/td><\/tr>
PS0 <\/td>GND <\/td><\/tr>
PS1 <\/td>GND <\/td><\/tr>
ADR <\/td>3v3 <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

And the I2C connection on the driver expansion board is shown below.  
<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

When we first connected the IMU, it did not appear on the I\u00b2C bus. I expected to find it at address 0x28 or 0x29, depending on whether the ADR pin was set low (GND) or high (3V3). To verify the connection, I used an I2C scanner script that I generated with help from ChatGPT. When I ran the scan, only the motor driver\u2019s addresses appeared, meaning that the IMU was not responding at all. <\/p>\n\n\n\n

At this point, I suspected a hardware issue so I checked the power connections with Anette and Robin to confirm that the IMU was receiving voltage. Everything looked fine, which ruled out a power problem. Eventually I decided to swap the SDA and SCL lines, and that turned out to be the issue. After switching the connections, the IMU was successfully detected at address 0x29, confirming proper communication over I2C. <\/p>\n\n\n\n

To interface with the sensor, I installed the Adafruit BNO055 library via PlatformIO. This made the integration straightforward, as the library handles sensor initialization. <\/p>\n\n\n\n

I then uploaded a simple test program to confirm that the IMU was sending orientation data: <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Now I could see in the serial monitor that I got all the readings from the IMU:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

But the only one I was interested in was the heading. So next was to try to implement this in the code for the robot.  <\/p>\n\n\n\n

The idea I had with buying the IMU was that with an absolute heading reading I could use that to make it drive straight in the path. I also wanted it for turning since now it would no longer depend on turning for a set time but rather turning based on degrees.  <\/p>\n\n\n\n

Now that I had gotten readings from the IMU, I could start integrating it with the robot\u2019s navigation system. I reused the turning functions I developed last week, but instead of relying on the ultrasonic sensors to trigger course corrections, the robot now uses the IMU\u2019s heading data to detect and correct angular drift. <\/p>\n\n\n\n

To achieve this, I calculate the difference between the robot\u2019s current heading and its target heading using a simple formula that keeps the value within the range of \u2013180 degrees to +180 degrees. This difference, called diff, tells the robot whether it has rotated slightly left or right from its intended direction. By using symmetric thresholds, I can decide which rotation function to call:<\/p>\n\n\n\n