How to replace the motor power cables on MiR500 and MiR1000

This guide describes how to replace the motor power cables on MiR500 and MiR1000. This cable can be worn down if it has hung too low and dragged along the ground. If you have not already mounted a pair of cable clips inside the robot to keep the cable raised, it is highly recommended to do so. Refer to the how-to guide How to mount motor power cable clips for MiR500/MiR1000 for the order number for the clips and instructions for mounting.

The motor power cable runs through the entire robot, going from the motor carrier board to the rear relays and the motors beneath the robot. For this reason, the robot must be partially disassembled to access these areas. Use the image below as a reference for where the cables should be after the old ones have been replaced. The blue path indicates where CAB-52 should run, and the red path is for CAB-78.

Things you’ll need

• Flat-head screwdriver

• A 4 mm Hex screwdriver

• A 43 Nm torque wrench with a 17 mm six-point socket

• A pair of wooden beams to levitate the robot

• Power drill with assorted hex bits

• CAB-78 and CAB-52 power cables for MiR500 and MiR1000 motors

• Loctite 2400 threadlocking adhesive, or other adhesive with same properties (see Loctite 2400 specifications)

Before replacing the power cables

Step 1: Turn off the robot, and disconnect the battery. To disconnect the battery, open the rear compartment, and turn the Battery disconnect switch to the Off position.

Step 2: Remove the top module. See the newest version of your robot's top module user guide.

Removing the side compartment hatch

Step 1: Turn the two screws 90˚ with a flat-head screwdriver, and pull open the hatch.

Step 2: Remove the compartment hatch. To do this, disconnect the status light cable, and turn the two hinges in the bottom corners.

Removing the front compartment hatch

Step 1: Press the two buttons on the front hatch, and pull open the hatch.

Step 2: Remove the compartment hatch. To do this, disconnect the status light cable, and turn the two hinges in the bottom corners.

Step 3: Turn the two levers 180°, and pull out the electronics drawer.

Removing the corner shield

Step 1: Press the Emergency stop button on the corner shield you are going to remove. After reassembling, remember to release the button again.

Step 2: Remove the four screws from the corner shield using a 4 mm Hex screwdriver.

Step 3: Disconnect the cables plugged into the corner shield. Mark which cables should be plugged into which sockets, or take a picture to make sure you plug in the cables correctly when reassembling the robot.

Step 4: Remove the corner shield. It may require some force to disconnect the shield from the corner bumper. Pull it downward firmly to remove it from the bumper.

Pulling out the bogie arm

Step 1: Raise the robot above ground, and use a piece of wood or other firm material to keep it lifted. The drive wheel must not be in contact with the floor.

Step 2: Remove the bogie bolt, using a 17 mm wrench.

Step 3: Pull out the wheel and bogie arm slightly. Pull out the bogie arm enough to make it possible to gain access behind the wheel gearing.

Step 4: Disconnect the motor power cable labeled CAB-78 on the right side and CAB-52 on the left side. If you are not able to reach this far into the robot, you will need to unplug any other cables that prevent you from pulling the bogie far enough out.

• The motor power cable is connected to the motor. The socket is an L-shaped socket, located next to the Hall sensor cable.
   

• The list and image below identifies the brake and encoder cables that may need to be unplugged to be able to pull the bogie arm out further.

  1. Brake feedback cable

  2. Brake power cable

  3. Motor encoder cable
     

  

Removing the rear maintenance hatch and battery

Step 1: Press the two buttons on the rear hatch, and pull open the hatch.

Step 2: Press the two buttons on the battery hatch, and pull it down.

Step 3: Disconnect the battery by pulling out the cable in the top connector.

Step 4: Press down the button at the end of the battery rail, and pull the battery out of the robot.

Replacing the motor power cables on MiR500 and MiR1000

Step 1: Remove the zip ties and the cable holders as shown in the images below. Note the location of the cable ties, and which cables are bundled together, as you will need to place new cable ties with the new power cable in the cable bunch.

Step 4: Locate the motor controller carrier board, and unplug CAB-052 and CAB-78. Plug in the new cables so that CAB-078 goes to the right side, and CAB-052 goes to the left side of the robot.

Step 5: Pull the old power cables out of the cable chain, and pull the loose ends through to the center compartment. Replace the positions occupied by the old cables with the new ones, and loosely fit new cable ties to keep the cables together but still enable you to adjust the cables' positions. The cable leads all the way to the K4, K5, and K6 relays located next to the battery rail.

Step 6: Unmount the relays from the DIN rail by pulling the top of the relay away from the rail at a downwards angle.

Step 7: Pull the relay connector ends of the new power cables through to the relays.

Step 8: Connect the new relay wires one at a time. Each wire is labeled in a format where the relay it connects to it written first followed by the terminal number. For example, K4-2 is the label of a wire that connects to the second terminal in the K4 relay. New wires replace old wires with the same label.

Step 9: Double-check that the wires are correctly connected, and then mount the relay back on the DIN rail.

Step 10: Lead the final end of the cable behind the bogie, and connect the Phoenix connector to the motor power socket. The image below identifies the two sockets on the motors.

• If you have cable clips mounted in your robot, make sure to attach the power cable to the clips.
  
• If you don't have motor cable clips mounted, MiR highly recommends ordering them so you can keep the motor cable raised from the ground. If the cable drags across the floor, the damage may result in a robot that cannot drive correctly.

Step 11: Once you have connected the new cable to the motor, pull out the old cable completely and remove it from the robot.

Testing the robot

Step 1: Place the battery back in its compartment at the rear end, and reconnect it. Be careful not to pinch any cables or wires when reinserting the battery.

Step 2: Reconnect any cables you have unplugged from the motor or brakes, and push the bogie back into place.

Step 3: Screw on the bogie bolt, apply Loctite 2400 to the bolt, and tighten it to a torque of 43 Nm with a torque wrench. Mark the bolt with a marker again to indicate that it has been properly tightened.

Step 4: Close the battery hatch, and reconnect the battery by flipping the switch to the On position.

Step 5: Release all Emergency stop buttons.

Step 6: Run the robot through some tests. These tests could include:

• Running missions with robot positions going from position A to B.

• Activating the emergency stop button to check that the wiring is working.

• Driving the robot and turning corners both in Manual and Autonomous modes.

Reassembling the robots

To reassemble the robot, you must reattach the side, front, and back hatches and screw the top cover back on. Complete the disassembly steps in the opposite order to reassemble these parts of the robot.

Related material

How to mount motor power cable clips on MiR500 and MiR1000