KUKA iiwa Robot Safety Operation and Maintenance

KUKA iiwa Robot Safety Operation and Maintenance

Product positioning and system composition

In the field of collaborative robots, KUKA's LBR iiwa (Lightweight Robot Intelligent Industrial Work Assistant) has always been a representative product of seven axis redundant kinematic design. This series currently includes two models: LBR iiwa 7 R800 and LBR iiwa 14 R820, both of which consist of the following core components to form a complete robot system:

Robot (including mechanical structure and electrical device)

KUKA Sunrise Cabinet Robot Controller

KUKA smartPAD teaching pendant (referred to as KCP in the document)

connecting cable

System software and optional accessories

Its kinematic system is designed redundantly with 7 axes, mainly consisting of three parts: a 2-axis inline wrist located on the A6 and A7 axes, an aluminum joint module (with the drive unit built into the module), and a base frame as the robot base with an A1 interface at the rear. All motor power and control cables are internally routed, and all motor connections are designed with plug-in connections, which is also a significant feature that distinguishes lightweight robots from traditional industrial robots.

It is worth noting that each axis of LBR iiwa is equipped with multiple sensors: the axis travel sensor ensures that the axis operating range does not exceed the limit; Torque sensors prevent overloading of axle loads; Temperature sensors monitor the thermal limit of electronic components. Under unfavorable working conditions of long-term high demand for robot power and external temperature influence, temperature monitoring will automatically shut down for protection. After cooling, no additional measures are required to restart - this should be the first step in troubleshooting for thermal overload factors.

Horizontal comparison of core parameters between two models

During the selection stage, the following parameter comparison table can be directly used as a decision-making basis:

Parameter item LBR iiwa 7 R800 LBR iiwa 14 R820

Number of axes 7 7

Workspace volume 1.7 m ³ 1.8 m ³

Posture repeatability (ISO 9283) ± 0.1 mm ± 0.15 mm

Self weight approximately 23.9 kg, approximately 29.9 kg

Rated load 7 kg 14 kg

Maximum operating range 800 mm 820 mm

Protection level (IEC 60529) IP54 (same as IP54 for wrist) IP54 (same as IP54 for wrist)

Noise level<75 dB (A)<75 dB (A)

Installation hole mode C184 C216

Supporting Controller KUKA Sunrise Cabinet KUKA Sunrise Cabinet

The axis motion range of the two models is completely consistent: A1, A3, A5 are ± 170 °, A2, A4, A6 are ± 120 °, and A7 are ± 175 °. The difference is mainly reflected in the shaft speed under rated load: the A1/A2 axis of the iiwa 7 R800 can reach 98 °/s, and the A6/A7 axis can reach 180 °/s; while the iiwa 14 R820 has a larger load, with the A1/A2 axis at 85 °/s, the A4 axis at only 75 °/s, and the A6/A7 axis at 135 °/s.

In terms of environmental conditions, both models operate in environments with temperatures ranging from 5 ° C to 45 ° C, storage and transportation temperatures ranging from 0 ° C to 45 ° C, and air humidity ranging from 20% to 80%. The installation locations support three methods: ground, ceiling, and wall. Special attention should be paid to the fact that robots are not allowed to carry auxiliary loads, which is a significant difference from many traditional robots that can have auxiliary devices attached to their bases or columns.

Load capacity and center of gravity constraints

Load planning must simultaneously verify two dimensions: load mass and mass moment of inertia. The rated mass moment of inertia of both models is 0.3 kgm ², and the allowable mass inertia at the design points (Lx, Ly, Lz) is also 0.3 kgm ².

The load center of gravity is based on the flange surface of A7 axis: the nominal center of gravity distance of iiwa 7 R800 is Lxy=35 mm, Lz=60 mm; Iiwa 14 R820 has Lxy=40 mm and Lz=44 mm. The load curve corresponds to the maximum load capacity, and overloading can shorten the service life of the robot and cause motor and gearbox overload. Such applications must consult KUKA customer support in advance. In addition, the actual load capacity is also related to the type of media flange installed, and the media flange documentation needs to be consulted separately.

Foundation Load - Key Input for Installation Design

The most easily overlooked aspect in integrated design is foundation load verification. The maximum load value specified in the document (including the load and the inertial force of the robot's own weight) is as follows:

LBR iiwa 7 R800：

Vertical force F (v max): 524 N

Horizontal force F (h max): 240 N

Overturning moment M (k max): 310 Nm

Torque around axis 1 M (r max): 156 Nm

LBR iiwa 14 R820：

Vertical force F (v max): 541.2 N

Horizontal force F (h max): 228.4 N

Overturning moment M (k max): 281.6 Nm

Torque around axis 1 M (r max): 172.6 Nm

These maximum values must be used as the basis for designing the foundation dimensions, otherwise it may cause material damage. During installation, the machine frame is used to fix the components: 2 locating pins (6x12 for flat side locating pins and 6x12 for cylindrical locating pins, with a locating hole of 6H7) and 4 hexagon socket bolts - M8x30-8.8 (torque 23 Nm) for iiwa 7 R800 and M10x35-8.8 (torque 45 Nm) for iiwa 14 R820. They need to be gradually tightened in multiple stages diagonally to the specified value, and after running for 100 hours, they need to be re tightened with a torque wrench. To avoid positional deviation during machine replacement, it is recommended to always use positioning pins.

The standard length of the connecting cable is 4 meters, with options of 1 meter, 3 meters, 7 meters, and 15 meters. The maximum length should not exceed 15 meters. When laying, the bending radius of the data cable should not be less than 45 mm, and mechanical stress and joint pulling should be prevented. It can only be installed indoors, with a temperature range of 263 K (-10 ° C) to 343 K (+70 ° C). If necessary, it should be laid in metal pipes and additional electromagnetic compatibility (EMC) measures should be taken.

Safety Function System and Stop Reaction

The safety functions of LBR iiwa are divided into two categories: safety oriented functions for personnel protection (meeting EN ISO 13849-1 category 3, performance level PL d, and SIL 2 of EN 62061) and non safety oriented functions for machine protection.

The permanently defined security features include:

Emergency stop device (equipped with an emergency stop button on smartPAD as standard, Sunrise. OS 2.4 can be configured with external emergency stop as local emergency stop input)

Enabling device (3 three-stage enabling switches on smartPAD: not pressed/neutral/fully pressed dead position)

Operator safety signal (monitoring physical protective devices such as safety doors)

External emergency stop, external safety stop 1 (path keeping type), external enabling device, external safety operation stop

Typical stop reaction logic:

Trigger condition T1/T2/CRR mode AUT mode

Enable switch release safety stop 1 (path hold) -

Press the enable switch to the bottom (panic position) for safe stop 1 (path maintenance) -

Press local emergency stop safety stop 1 (path hold) safety stop 1 (path hold)

Safety controller malfunction, safety stop 1, safety stop 1

Safety door open (operator safety) - Safety stop 1 (path maintenance)

It should be noted that the 250 mm/s deceleration in T1 mode does not belong to the safety level deceleration in the standard safety configuration. If the application requires safety level speed monitoring, Cartesian speed monitoring must be configured through the KUKA Sunrise. SafeOperation option. In addition, the soft limit switch is only for machine protection and does not have safety oriented properties.

Stop distance data and hazardous area design

The stopping distance is the core data for planning hazardous areas (hazardous area=workspace+stopping distance). The document provides the measured reference values for STOP 0 (Class 0 stop) according to Appendix B of DIN EN ISO 10218-1, under the conditions of elongation l=100%, program multiplier POV=100%, and maximum load:

LBR iiwa 7 R800 STOP 0：

Axis stop angle (°) Stop time (s)

A1 5.193 0.182

A2 5.092 0.212

A3 8.091 0.166

A4 7.538 0.114

LBR iiwa 14 R820 STOP 0：

Axis stop angle (°) Stop time (s)

A1 5.742 0.188

A2 5.998 0.200

A3 9.323 0.198

A4 3.162 0.092

Three engineering points that must be kept in mind: firstly, data is based on single axis motion, and overlapping axis motion may result in longer stopping distances; Secondly, these average values obtained from experiments and simulations should be re measured under real working conditions in practical applications (which can be triggered by safety monitoring to stop and analyzed using a Data Recorder for trajectory data); Thirdly, brake wear is related to operating mode, application, and the number of STOP 0 triggers. It is recommended to check the stopping distance at least once a year.

Dangerous areas must be protected by physical protective devices (gratings, light curtains, safety fences, etc.) that meet EN ISO 14120 standards; If there is no physical protection, the EN ISO 10218 cooperative operation requirements must be met, and there must be no cutting or squeezing danger points in the loading and unloading area.

Key points for transportation, start-up, and daily operation and maintenance

Transportation specifications: Under the transportation packaging method, the transportation positions are A1=0 °, A2=25 °, A3=0 °, A4=90 °, A5/A6/A7=0 °, and the outer dimensions of the packaging are 1180 × 780 × 560 mm. Under the transportation box method (optional), all axes are zeroed, and the box size is 1450 × 480 × 340 mm. The lifting points are located between A2 and A3 and between A4 and A5. Before transportation, the tools must be removed and the connecting cables must be unplugged. After delivery, transportation fasteners such as nails or screws must be removed first.

Pre startup functional testing checklist:

All emergency stop device function tests (after pressing, the teaching pendant must display an emergency stop message without any error prompts)

All enable switch function test (release triggers stop)

Enable switch panic function test (press to the bottom to trigger stop)

SmartPAD Key Switch Function Test

Security oriented output shutdown capability test

Brake Testing - When conducting a risk-free assessment, default requirements can be followed: brake testing should be performed on each axis during start-up and re commissioning, and daily execution during operation

Maintenance and troubleshooting: The robot does not require planned maintenance when used for its intended purpose. Only solvent-free and water-soluble cleaning agents can be used for cleaning, and steam, refrigerant, and high-pressure cleaning equipment are strictly prohibited. The standard process when a malfunction occurs is: turn off and lock the controller (such as adding a padlock) → hang a warning sign → record the fault → troubleshoot and perform a functional test. Attention during maintenance: After the controller is powered off, some components may still have voltage exceeding 60 V for several minutes, during which operation is strictly prohibited; Replacement parts must use new parts with the same order number or equivalent parts approved by KUKA.

Shutdown, storage, and disposal: The long-term storage environment must be dry and dust-proof, avoid temperature fluctuations and condensation, and avoid direct sunlight; When scrapped, aluminum/steel structural components, copper cables, steel fasteners, and PUR cable sheaths must be classified and disposed of. Joint modules and electronic components must be scrapped as a whole and cannot be disassembled.

Service support information preparation

When contacting KUKA customer service, it is recommended to prepare the following information to significantly shorten the troubleshooting cycle: fault description (including duration and frequency), model and serial number of the robotic arm/controller/energy supply system, system software version, KRCDiag diagnostic package (V8 and above system software), existing Sunrise projects and applications, external axis information used, etc. For system software with versions lower than V8, software archiving is required.