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Difference between revisions of "Vorpal The Hexapod Troubleshooting Guide"

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(Gamepad Won't Control Hexapod)
(Servos Can't Lift Hexapod or are Sluggish)
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{{float_box|{{VCH Quick Links}} }}
 
{{float_box|{{VCH Quick Links}} }}
 
==Servos Can't Lift Hexapod or are Sluggish==
 
==Servos Can't Lift Hexapod or are Sluggish==
 +
Symptions:
 +
* Vorpal can't stand up, servos seem to struggle.
 +
* Vorpal can stand up but during walking it successively loses height, getting lower and lower over time.
 
Possible causes include:
 
Possible causes include:
 
* Batteries are low or dead.  Recharge the batteries.
 
* Batteries are low or dead.  Recharge the batteries.
* Too much friction on servo bearing. Make sure your 3D printed models are cleaned up, especially the little hemisphere on each servo mount on the chassis. This hemisphere is the bearing opposite the servo shaft, and if it has drips or other defects there may be too much friction for the servos to move smoothly. Sandpaper any areas that look misshapen or rough, or put a drop of silicone grease on the hemisphere.
+
* Improper surface: Vorpal is designed to work on reasonably smooth surfaces such as tile floor, wood floor, smooth table top, desk top, etc. It will not work on most carpets. There are "carpet feet" being developed by some Makers which may solve this in the future.
 +
* Too much friction on servo bearing. Make sure your 3D printed models are cleaned up, especially the little hemisphere on each servo mount on the chassis, and also the little hemispherical hole in the leg hinges. This hemisphere is the bearing opposite the servo shaft, and if it has drips or other defects there may be too much friction for the servos to move smoothly. Sandpaper any areas that look misshapen or rough, or put a drop of silicone grease on the hemisphere.
 +
* Legs out of adjustment. If the legs are adjusted such that Vorpal "rides too low" then the amount of torque required to walk increases and the legs may not be able to keep up with the requirements of the walking gait selected. Put the robot in ADJ mode (turn the dial fully counterclockwise to STOP, then slightly clockwise until the knees go out straight). Now, it's not always possible to make the servo horns come out totally straight from the body due to the way servo horns are manufactured. But, if you can't make it come out 90 degrees straight, it's better for the horn to be a little too clockwise than to be a little too counterclockwise. Too clockwise will make the leg lift the robot body a tiny bit higher, which is fine, but too much counterclockwise will make the robot ride "low" and stress the servos more.
 +
* Bad servo. If one or more servos are bad, the other servos may struggle to lift the robot's weight fast enough to keep up while walking. If a servo is obviously bad (chattering excessively, or clearly not pulling its fair share of the load) then that's the probable culprit.
 +
 
 
==One Servo Doesn't Work==
 
==One Servo Doesn't Work==
 
Most likely causes include:
 
Most likely causes include:

Revision as of 13:55, 24 November 2017

Vorpal Hexapod Quick Links:

Servos Can't Lift Hexapod or are Sluggish

Symptions:

  • Vorpal can't stand up, servos seem to struggle.
  • Vorpal can stand up but during walking it successively loses height, getting lower and lower over time.

Possible causes include:

  • Batteries are low or dead. Recharge the batteries.
  • Improper surface: Vorpal is designed to work on reasonably smooth surfaces such as tile floor, wood floor, smooth table top, desk top, etc. It will not work on most carpets. There are "carpet feet" being developed by some Makers which may solve this in the future.
  • Too much friction on servo bearing. Make sure your 3D printed models are cleaned up, especially the little hemisphere on each servo mount on the chassis, and also the little hemispherical hole in the leg hinges. This hemisphere is the bearing opposite the servo shaft, and if it has drips or other defects there may be too much friction for the servos to move smoothly. Sandpaper any areas that look misshapen or rough, or put a drop of silicone grease on the hemisphere.
  • Legs out of adjustment. If the legs are adjusted such that Vorpal "rides too low" then the amount of torque required to walk increases and the legs may not be able to keep up with the requirements of the walking gait selected. Put the robot in ADJ mode (turn the dial fully counterclockwise to STOP, then slightly clockwise until the knees go out straight). Now, it's not always possible to make the servo horns come out totally straight from the body due to the way servo horns are manufactured. But, if you can't make it come out 90 degrees straight, it's better for the horn to be a little too clockwise than to be a little too counterclockwise. Too clockwise will make the leg lift the robot body a tiny bit higher, which is fine, but too much counterclockwise will make the robot ride "low" and stress the servos more.
  • Bad servo. If one or more servos are bad, the other servos may struggle to lift the robot's weight fast enough to keep up while walking. If a servo is obviously bad (chattering excessively, or clearly not pulling its fair share of the load) then that's the probable culprit.

One Servo Doesn't Work

Most likely causes include:

  • The servo has gotten unplugged from the servo controller. Open up the hexapod by removing the screws holding down the electronics caddy and check the wiring.
  • The servo has a frozen gear. Occasionally when a servo goes to its maximum position it may get stuck there. You will know this is true if the servo won't move easily even with power off. You can usually fix this by turning power OFF, then gently applying pressure to the servo in the direction you would expect it to move until it "unsticks". If the same servo keeps getting stuck, you should replace it.
  • The servo has gone bad (either gears are broken or wiring is damaged). There are several possible causes for this, but in any case the only fix is to replace the servo.

One Servo Jitters Constantly

  • This typically means the servo has gone bad and its electronics are not responding properly. First check to make sure the servo's wire is completely inserted in the servo controller, but if that looks ok the only fix is to swap the servo.

Gamepad Won't Control Hexapod

  • Make sure the battery is charged in the gamepad.
  • Make sure the hexapod dial has been turned to BT (Bluetooth mode).
  • Make sure the gamepad is turned on and you see lights through the cover.

If you see lights through the holes in the center of the cover, observe the blinking pattern. Here's what the blinks mean:

  • NOT CONNECTED: When the Bluetooth modules are not connected, there will be a fast, steady blink.
  • IN THE PROCESS OF CONNECTING: When they first start to connect, they will blink slowly at first, then will go dark for a couple of seconds. This process will only take about 5 seconds.
  • CONNECTED: When they are properly connected, then there will be a 2 second pause followed by two quick blinks, and this will repeat over and over as long as there is a connection.

The next few sections explain what to do in each of these situations.

Lights indicate connection is good, but robot not responding

This could be because you've not hooked up the wires properly on the Bluetooth module, either the one on the robot or the one on the gamepad. Carefully check connections.

There could be a general issue with the robot. See if it works in DEMO mode. If DEMO mode doesn't work, you probably have an electrical issue and need to check all connections. It is possible you have a bad component (Arduino or Servo controller) and need to contact support@vorpalrobotics.com.

Lights never show a connection

If the Bluetooth modules are not paired after about 10 seconds (two seconds dark followed by two quick blinks), then the possible issues are:

  • If your gamepad has never worked, you may have wired the transmit and receive wires backwards on either the hexapod, or the gamepad, or both.
  • If you have several hexapods, make sure you're using the correct gamepad that's matched with your hexapod. If need be, open up the gamepad and the hexapod and check the labels on the Bluetooth modules, make sure the labels match. If the labels are different, the two modules won't auto-pair and connect. You may have mixed up modules when building several robots.

No lights at all

If you do not see any lights at all in the center of the gamepad, then:

  • Your Bluetooth module may not be getting power, check wiring, especially the VCC and GND connections.
  • The gamepad battery may be low or dead.