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.