Kaya Dynamixel XC430 motors showing error on joystick app

Autonomous Machines Isaac Isaac SDK + Isaac Sim
#1

I’ve got a new Kaya build assembled and a workstation up and running. The stereo dummy app worked, so I moved on to the joystick app and immediately encountered issues. I have modified the kaya_hardware.subgraph.json according to the XC430 + U2D2 interchangeability section.

2020-12-26 20:05:49.377 ERROR packages/dynamixel/gems/dynamixel.cpp@186: Error while reading register 23
2020-12-26 20:05:49.421 ERROR packages/dynamixel/gems/dynamixel.cpp@33: Dynamixel error (-3001): [RxPacketError] Unknown error code!

This is appearing in the logging output over and over again. In the Dynamixel Wizard I could confirm that the motors are moving so I think it’s a configuration issue. Any help would be much appreciated. I want to get this thing moving!

#2

As far as I can tell the Registry 23 is CURRENT_SPEED.

#3

Ok, this is what I can tell is happening so far. The error for register 23 is because it is trying to read 4 bytes from the ram table at position 128, which is the value for Present Velocity(aka CURRENT_SPEED in the kaya driver). The Dynamixel error (-3001) is COMM_RX_TIMEOUT := -3001 Status of Receive packet in the ::dynamixel::PacketHandler::getPacketHandler (https://emanual.robotis.com/docs/en/software/dynamixel/dynamixel_sdk/api_reference/cpp/cpp_packethandler/).

In the Dynamixel Wizard though I can query that location and get 0 when stationary and a value when moving the wheel, so I know it’s not the motor. I have no clue how to troubleshoot the connectivity issue though.

#4

I finally got this working. The baudrate needed to be set for the Dynamixel driver to k57600. Once that was done the joystick app was working for me.

#5

Did you modify the kaya_hardware.subgraph.json file to have it look like this? I ask because I was able to get my servos moving in joystick (although the robot continuously spins at the start, but after manipulating the joysticks it allows me to control it properly). However, the “Error while reading register 23” and the Dynamixel error (-3001) are still continuously showing up the entire time.

Additionally, when I do follow_me app, the robot just continuously spins (it will not engage in autonomous and I also continuously have the error messages always showing up.

{
“modules”: [
“dynamixel”,
“imu”,
“kaya”,
“realsense”,
“viewers”
],
“config”: {
“kaya_base”: {
“holonomic_to_wheels”: {
“max_linear_speed”: 0.5,
“max_angular_speed”: 2.0
}
},
“dynamixels”: {
“driver”: {
“tick_period”: “50 Hz”,
"baudrate": “k57600”,
"servo_model": “XC430”,
"port": “/dev/ttyUSB0”,
“servo_ids”: [3, 1, 2]
},
“isaac.alice.Failsafe”: {
“name”: “robot_failsafe”
}
},

Does anyone know either how to get the follow_me working or these error messages to go away?

#6

My u2d2 and my BMI160 were faulty. Once I replaced them my issues went away.