Low bandwidth setting

Description

Bandwidth is not set to very low value, causing data is being heavily filtered. The lowest bandwidth setting is 25Hz, which causes heavy data filtering. Values may seem to be constant when viewed with rostopic.

Diagnosis

On new C-turtle release, current bandwidth setting value can be viewed with diagnostics. The best way to view diagnostics is with pr2_dashboard.

On older systems, the bandwidth value is only available to controllers. Older software also defaulted to lowest bandwidth setting.

Solution

Upgrade software. Also, there might be a controller that is changing bandwidth value.

Accelerometer interrupt stays asserted

Description

The accelerometer has been know to go into bad state where it always interrupt stays asserted. The interrupt notifies controller that a new sample is available. If interrupt stays asserted, the controller board to constantly read from accelerometer data believing it has a new sample.

Diagnosis

Gripper firmware only buffer 4 most recent samples. When data is viewed with rostopic there is always 4 new samples instead of an average of 3.

header: 
  seq: 14080967
  stamp: 
    secs: 1282097599
    nsecs: 640504013
  frame_id: l_gripper_motor_accelerometer_link
samples: 
  - 
    x: -9.04359375
    y: -3.2572265625
    z: -0.843046875
  - 
    x: -9.04359375
    y: -3.2572265625
    z: -0.843046875
  - 
    x: -9.04359375
    y: -3.2572265625
    z: -0.843046875
  - 
    x: -9.04359375
    y: -3.2572265625
    z: -0.843046875

New diagnostics software will use the sample counter to monitor the accelerometer sampling rate. When the issue occurs the sampling rate will be around 40kHz. The diagnostics will produce the warning Bad accelerometer sampling frequency.

Cause

Older software and firmware would allow invalid bandwidth setting that would trigger this issue. Even with newer firmware and software, this still sometimes occurs. This is still under investigation.

Solution

The current solution is to power-cycle to right/left arm with the problematic gripper accelerometer. This can be easy be done through the dashboard by selecting Disable then selecting Enable. The software will need to be restarted after power-cycling.

Accelerometer values don't change (much)

Description

When viewing or plotting accelerometer data there does not seem to much high frequency content.

Cause

There's a couple possible causes for this

• Low bandwidth setting causing data to be heavily filtered.
• Accelerometer interrupt stays asserted. Effectively causing sample accelerometer data to be read many times.