AGV/AMR Fleet Maintenance Manual: Wheel Replacement, Sensor Calibration, Battery Conditioning and Charging System Check

1. Scope of Application and Purpose

This manual covers scheduled and unscheduled maintenance procedures for Autonomous Mobile Robots (AMRs) and Automated Guided Vehicles (AGVs) used in industrial manufacturing. The main goal is to ensure uninterrupted operation, extend the life of the equipment and maintain maximum operational efficiency. Regularly performing these procedures is critical to prevent unplanned downtime, optimize fleet performance and reduce operating costs. The manual is intended for use by technical personnel, service engineers and those responsible for the reliability of equipment at manufacturing enterprises. Maintenance should be carried out in accordance with the manufacturer's recommendations, or if signs of wear or malfunction are detected.

2. Precautions

CAUTION! Before starting any maintenance work on AGV/AMR MANDATORY follow lockout/tagout procedures (Lockout/Tagout - LOTO) in accordance with local safety standards and requirements of DSTU EN 1037:2003 (Machine Safety. Prevention of Unexpected Start). This includes turning off all power sources (electrical, hydraulic, pneumatic) and blocking them. Ensure that all stored energies (eg capacitors, springs, lifted loads) are discharged or captured.

WARNING! Use appropriate personal protective equipment (PPE), in particular: protective glasses (DSTU EN 166:2017), protective gloves (DSTU EN 388:2017), protective shoes (DSTU EN ISO 20345:2016) and protective clothing. When working with batteries, additionally use a protective face shield and acid-resistant gloves.

WARNING! Avoid working with electrical components in a wet environment. Always check for no voltage with a certified multimeter before touching electrical circuits.

WARNING! When lifting the AGV/AMR, use only specialized lifting devices with the appropriate load capacity and follow the manufacturer's instructions. Always place stands or supports under raised equipment.

3. Necessary Tools and Materials

4. Pre-sales Inspection of AGV/AMR

Carry out the following inspection before starting any maintenance work.

5. Step-by-step Service Procedure

5.1. Replacement of wheels

1. Preparation and Lockdown:
   1. Move AGV/AMR to designated service area.
   2. Activate the LOTO procedure: turn off the AGV/AMR, disconnect the battery, lock the main switch. WARNING! Check the absence of voltage with a multimeter at the main electrical terminals.
   3. Secure the AGV/AMR to prevent it from moving unintentionally.
2. AGV/AMR lifting:
   1. Determine the lifting points according to the manufacturer's instructions.
   2. Raise the AGV/AMR with a jack/lift until the wheels are completely off the surface. Avoid lifting by suspension elements or sensors.
   3. Install support stands under the AGV/AMR, ensuring its stable position. Carefully lower the AGV/AMR onto the stands. WARNING! Never work under equipment supported only by a jack.
3. Dismantling the Old Wheel:
   1. Using a suitable wrench, unscrew the wheel mounting bolts/nuts. For example, for wheels with a diameter of 150 mm, fastening M12, the typical tightening torque is 70-80 N·m. It may be necessary to keep the shaft from turning.
   2. Carefully remove the wheel. Pay attention to the arrangement of washers, bushings, bearings.
   3. Clean the axle and seat from dirt and old grease with a lint-free cloth.
4. Installing a New Wheel:
   1. Check the new wheel for defects. Make sure the bearings (if separate) are installed correctly and lubricated with an appropriate grease (eg NLGI 2 lithium grease).
   2. Install the wheel onto the axle in the correct order of components.
   3. Tighten the mounting bolts/nuts by hand.
   4. Using a torque wrench, tighten the bolts/nuts to the manufacturer's recommended torque. For a typical AGV with wheels with a diameter of 150-250 mm, M16 fasteners, the recommended tightening torque is 120 N·m ± 5 N·m. Follow the star pattern for even tightening if there are 4 or more bolts. Do not overtighten the bolts, this may damage the thread or deform the wheel.
   5. Visual control: the wheel should rotate freely without backlash and jamming.
5. Completion:
   1. Carefully lift the AGV/AMR, remove the support stands and lower it to the floor.
   2. Put away the tools, clean the work area.

5.2. Calibration of Sensors

This procedure is critical for the accurate navigation and safety of the AGV/AMR. Calibration is performed after replacement of sensors, mechanical damage or if navigation errors occur.

1. Preparation:
   1. Place the AGV/AMR on a flat, clean surface in a calibration area free of obstructions and strong electromagnetic fields.
   2. Connect the diagnostic PC/laptop to the AGV/AMR via the appropriate interface (Ethernet, USB, CAN) and run the calibration software.
   3. Ensure that the AGV/AMR battery voltage is at least 80% of nominal.
2. Lidar calibration:
   1. Clean the scanning surface of the lidar with a lint-free cloth moistened with an optical cleaner. Avoid scratching the surface.
   2. In the software, select the lidar calibration option.
   3. Typically, the system will suggest placing calibration marks (known landmarks) at certain distances and angles from the AGV/AMR. Follow the software instructions very carefully.
   4. Perform the scanning procedure. The software will automatically calculate the corrections.
   5. Check the reading: the expected value of the distance to the object is 2000 mm, the actual value should be in the range of 1995-2005 mm (tolerance ±0.25%).
   6. Save the calibration settings and reboot the AGV/AMR system.
3. Camera Calibration:
   1. Clean the camera lenses.
   2. Use a calibration checkerboard or special templates placed in front of the cameras at a certain distance.
   3. Run the camera calibration software. The system will determine the distortion and correct the lens parameters (focal length, distortion).
   4. Check the image quality: no "fish eye", clarity throughout the field of view.
   5. Save the calibration settings.
4. Ultrasonic Sensor Calibration:
   1. Clean the sensor surfaces from dirt and dust.
   2. Place the test object (e.g. metal plate) at a known distance (e.g. 500 mm) in front of each sensor.
   3. In the software, check the readings of each sensor. They must correspond to a known distance with a tolerance of ±2%.
   4. If necessary, perform offset or sensitivity correction according to the manufacturer's instructions. Avoid over-sensitivity, which can cause false positives.
   5. Save the settings.
5. Test Calibration:
   1. Run the AGV/AMR in test mode.
   2. Test its ability to follow a route, detect obstacles and stop at set points.
   3. Visual control: AGV/AMR must move smoothly, without false stops or deviations from the trajectory.

5.3. Conditioning Batteries

Regular conditioning extends the life of batteries and maintains their optimal capacity.

1. Inspection and Cleaning:
   1. Perform LOTO procedure for AGV/AMR.
   2. Open the battery compartment. Inspect the batteries for visible damage, swelling (for Li-Ion), leaks (for Pb-Acid), terminal corrosion. WARNING! If electrolyte leakage or significant swelling is detected, stop working immediately and contact a specialist.
   3. Clean the terminals and surface of the batteries from dust and corrosion with a lint-free cloth and electrical contact cleaner. Do not use abrasive materials.
   4. Check the reliability of all connections.
2. Conditioning procedure (for Li-Ion):
   1. Connect the battery to a specialized charger with cell balancing function.
   2. Do a full charge cycle, then a discharge cycle to the minimum allowable level (usually 20-30% to extend life), then a full charge cycle again. This will help balance the battery cells.
   3. Monitor battery temperature during cycles. It should not exceed 45°C. The optimal temperature for charging/discharging is 20-25°C. Avoid rapid charging/discharging unless absolutely necessary.
   4. Check the battery capacity after conditioning. It should be within 90-100% of the nominal for a new battery.
3. Conditioning Procedure (for Pb-Acid):
   1. Check the electrolyte level in each cell and add distilled water to the indicated level if necessary.
   2. Complete a full charge/discharge cycle. Use a charger with a desulfation function if the battery shows signs of sulfation.
   3. Measure the density of the electrolyte in each cell after it is fully charged. It should be in the range of 1.26-1.28 g/cm³ at 25°C. Uneven density indicates a problem with the cell.
   4. Monitor the voltage of each cell. It should be the same.
4. Completion:
   1. Install the battery back into the AGV/AMR ensuring a secure connection.
   2. Close the battery compartment.
   3. Put the tools away.

5.4. Checking the Charging System

An efficient charging system is the key to the reliable operation of the entire AGV/AMR fleet.

1. Visual Inspection:
   1. Inspect the charger, charging stations, cables and connectors for mechanical damage, cracks, melting, corrosion. WARNING! Any damage to cables or connectors may cause a short circuit or fire.
   2. Check the charger vents for obstructions.
   3. Make sure the status indicators on the charger are working correctly.
2. Electrical Parameter Check:
   1. Perform LOTO procedure for charging stations if necessary. CAUTION! Work with high voltage with extreme caution.
   2. Using a multimeter, measure the input voltage of the charger (for example, 230 V AC ±10%).
   3. Connect the charger to the AGV/AMR battery.
   4. Measure the output voltage and current of the charger while charging. For a typical Li-Ion AGV battery of 48V, the charging current can be 20A. Check that these values ​​match the charger and battery specifications. Significant deviations indicate a malfunction of the charger or battery.
   5. Check the voltage at the battery terminals while charging. It should gradually increase and reach the nominal value (for example, 54.6 V for 14S Li-Ion).
   6. Monitor the temperature of the charger and battery during the full charge cycle. Excessive heat (over 60°C for the charger, 45°C for the battery) is a sign of a malfunction.
3. Communication check (if applicable):
   1. If the charger supports communication (CAN, Ethernet), check its operation using the diagnostic software.
   2. Make sure that the charging status, temperature and voltage data are transmitted correctly.
4. Functional Test:
   1. Unplug the AGV/AMR from the charger.
   2. Ensure that the AGV/AMR correctly recognizes the state of charge and displays the correct battery level.

6. After-Service Checklist

7. Troubleshooting Guide

8. Recommended Maintenance Schedule

9. Directory of Spare Parts

The use of original or certified replacement parts is mandatory to preserve the warranty and ensure the reliability of the AGV/AMR. Refer to UNITEC's electronic catalog for complete listing and ordering.

To order and get a detailed overview of the range of spare parts, please visit our UNITEC electronic catalog.

10. Links

• DSTU EN 1037:2003 Machine safety. Prevention of unexpected start.
• DSTU EN 166:2017 Means of individual eye protection. Technical requirements.
• DSTU EN 388:2017 Protective gloves against mechanical damage.
• DSTU EN ISO 20345:2016 Personal protective equipment. Protective shoes.
• DSTU ISO 6789:2017 Manual dynamometric tool. Requirements and test methods.
• DSTU EN 61010-1:2014 Safety requirements for electrical equipment for measurement, control and laboratory use. Part 1. General requirements.
• DSTU EN 60947-5-1:2018 Low-voltage switching equipment and control devices. Part 5-1. Control and switching devices. Electromechanical control devices.
• ISO 3691-4:2023 Industrial trucks — Safety requirements and verification — Part 4: Driverless industrial trucks and their systems.
• Operation and maintenance instructions from the AGV/AMR manufacturer (OEM Documentation).