Robot drives backwards and only in Right Stick Mode

Our Girl Scout Troop has completed building the VEX IQ Clawbot IQ according to the standard instructions and configuration. We have not yet installed the sensors. We have updated the Robot Brain with the latest firmware upgrade, (as of March 2015.) We have not attempted any customizations of the programming or joystick controls. As far as I am aware, we have a straight out-of-the-box build, and have plugged the motors into the Robot Brain ports that were indicated in the manual. We are attempting to use the standard, pre-installed Driver Control > Run program

Here’s what happens:

Prior to the firmware update, in Two Joystick mode, the robot only moved forwards in a clockwise direction. The jaw opened and closed, and the arm raised and lowered. After the firmware update, in Two Joystick mode, the Robot only moves backwards in a clockwise direction. The jaw opens and closes, and the arm raises and lowers. In Right Stick Mode, the Robot moves backwards in a straight line, and can turn both left and right, but it does not move forward. The jaw opens and closes, and the arm raises and lowers. In Left Stick mode, the Robot does not move, neither forward or backwards, but the jaw opens and the arm raises and lowers. When we reset to the Default settings, we go back to Two Joystick mode, with the same behavior as described above.

Please advise on how we should trouble-shoot this problem

Hi Girl Scout Troop 2653,

We’re sorry that you have encountered this issue. To help resolve this situation, we have a few questions:

When you mention that the robot drives forwards and clockwise or backwards and clockwise, are both the left and right sides of the drive train spinning? For example, when you are in 2-Joystick mode, please lift the Clawbot off the ground and push both joystick channels (A & D) up. Do both the left and right sides of the drive train spin?

If both the left and right sides of the drive are not spinning, please check the cables connecting these two sides. If a Smart Cable is loose/not fully inserted, or plugged into the wrong port, the built-in Driver Control program might only cause one motor in the drivetrain to work, which would cause the robot to drive forwards/backwards in a circle. Please ensure the cables are fully inserted into the Smart Motors and to the correct ports on the Robot Brain (the left side of the drivetrain is Port 1, the right side of the drivetrain is in Port 6). When the cables are fully inserted, you’ll hear a click sound. After you checked this, turn the Robot Brain off and on again. Did this resolve the problem?

If this did not resolve the problem where the robot drives forward/backwards in a circle instead of a straight line, please return to the Driver Control program. When the program is running, please press the Down button on the Robot Brain. This will show the Controller information screen. Please rotate both joysticks around - are the values for channel A, B, C, and D looking correct? The values should be very close to 100% when the joysticks are pushed to their maximum up, left, down and right directions.

If these joystick values are 100%, please press the Down button on the Robot Brain again. There will be one (or more screens if more than 4-devices are attached) that list all connected sensors and motors. If there are more than 4 devices connected, please press the Up and Down arrow buttons on the Robot Brain to scroll through them. Do you see your two drive train motors on Port 1 and 6 connected? When you push the joysticks on the Controller, do the motors (and speed values on the Robot Brain LCD) move as intended?

If not, please turn off your Robot Brain then first switch the cable to any motor(s) that do not show up on the robot brain with a cable that was working on a good motor, then test again. After this, please move the motor in question to a different port, such as the Arm or Claw motor port, then test again. During either of these tests, did a specific cable or motor appear to be the culprit?

If you have narrowed this down to a specific bad motor or cable, or if you have any other questions, then please contact our technical support folks at or by calling +1-903-453-0802 so we can help resolve the issue.


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