KUKA KR C4 compact robot controller

KUKA KR C4 compact robot controller

KUKA KR C4 compact is a compact robot controller developed by KUKA Corporation for small industrial robots. It integrates high-performance control, modular design, and advanced security technology into a 19 inch chassis, suitable for various automation application scenarios. This article is based on the official technical document (Spec KR C4 compact V10), which comprehensively analyzes the system architecture, core components, security mechanisms, technical parameters, and planning and installation points of the controller, providing a detailed technical reference for system integrators, maintenance engineers, and technicians.

Chapter 1 System Overview and Modular Architecture

1.1 Composition of Industrial Robots

A complete KUKA industrial robot system consists of the following components:

Mechanical arm: The mechanical body of a robot, responsible for executing movements.

Robot controller: KR C4 compact control cabinet, realizing motion control, logic processing, and communication.

SmartPAD: A human-computer interaction terminal used for programming, operation, and diagnosis.

Connecting cables: including power cables, data cables, and smartPAD cables.

Software: KUKA system software (KSS) and various process software packages.

Options and attachments: External axes (linear units, positioners), process equipment, etc.

1.2 Overall structure of controller

The KR C4 compact controller adopts a modular design and is mainly divided into two units:

Control Box: Includes control PC, power management, safety logic, and communication interfaces.

Drive Box: Includes servo drive module, braking resistor, and power filtering unit.

This separated design is easy to install and maintain, and supports 19 inch rack installation or independent placement.

Chapter 2 Detailed Explanation of Core Components

2.1 Control PC (KPC)

The control PC is the computational core of the controller, responsible for running KUKA system software (KSS) and Windows operating system, realizing functions such as human-machine interface, program management, motion planning, monitoring, and network communication.

Depending on the hardware version, one of the following motherboards can be used to control the PC:

D3076-K: Provides 4 PCI slots for fieldbus cards, onboard 2 USB 2.0, 4 USB 2.0, DVI-I, and LAN (KONI).

D3236-K: Provides 2 PCI slots, onboard 2 USB 3.0, 4 USB 2.0, DVI-I, and LAN (KONI).

D3445-K: Provides 2 PCI slots, onboard 2 USB 3.0, 4 USB 2.0, DVI-D, DisplayPort, and LAN (KONI), supports external display connection through DP-VGA adapter.

All motherboards are pre configured and tested by KUKA, and users are not allowed to modify hardware configurations on their own, otherwise they will lose their warranty eligibility.

2.2 Small Robot Cabinet Control Unit (CCU_SR)

CCU_SR is the core component inside the control box, consisting of two parts:

CIB_SR（Cabinet Interface Board, Small Robot）： Provide functions such as safe input and output, contactor control, fan monitoring, temperature detection, etc.

PMB_SR (Power Management Board, Small Robot): Responsible for power distribution, battery management, power outage buffering, and load testing.

CCU_SR connects the drive box and RDC through the KUKA controller bus (KCB), and connects the smartPAD and external service devices through the KUKA system bus (KSB). Its main functions include:

Safe input/output (9 safe inputs, 4 floating-point outputs)

Quick measurement input (6 channels)

Power monitoring and battery backup

Internal temperature monitoring

Contactor drive and feedback

2.3 Drive Box

The drive box contains the following key components:

KPP_SR (KUKA Power Pack Small Robot): Provides DC bus voltage and braking energy management.

KSP_SR (KUKA Servo Pack Small Robot): A servo drive module that controls motor movement and braking.

Braking resistor: consumes regenerative energy.

**Mains filter * *: Suppresses conducted interference on power lines.

The drive box communicates with CCU_SR through the KCB bus, receives speed commands, and provides feedback on status information.

2.4 Cooling System

The controller adopts a forced air cooling design, and the control box and the drive box each have two independent fans for cooling. The air inlet is located on the front panel and sides, while the air outlet is located at the rear. It is strictly prohibited to install filter cotton in the ventilation opening, otherwise it will cause an increase in internal temperature and shorten the service life of the equipment.

Chapter 3 Security System Design

3.1 Safety Controller

The safety function of KR C4 compact is implemented by a safety controller integrated into the control PC. It is a software core independent of standard control programs, responsible for:

Cut off the drive power and brake

Monitor the braking ramp and static state

T1 mode speed monitoring (≤ 250 mm/s)

Evaluate safety input signals

Set secure output

The safety controller meets the requirements of ISO 13849-1 performance level d (PL d) and category 3.

3.2 Security Interface

The controller provides two optional security interfaces, but only one can be used simultaneously:

Discrete Safety Interface X11: Connected through a 50 pin Harting connector, it supports dual channel emergency stop, operator protection (safety door), enable switch, safety stop, and other functions. The input uses dynamic test pulses (test output TA_S/TA_S) to periodically detect whether the input circuit has failed.