The robolink® modular system - Individual parts of robot arms

Robots consist of the mechanical construction (robot arm, manipulator), the tool at the end of the robot arm (end effector), the control system and measuring points (sensors) that provide information to the control system. The mechanical construction is made up of several components that are connected to each other by active joints. Active joints have drives that the control system accesses in order to assign the end effector its work task. The term robot is derived from the Slavic word for labour.

The individual robot parts in the robolink® modular system
The robolink® modular system from igus® GmbH has a modular structure and enables the customised design of robot arms. It contains a large number of individual parts that can be ordered, making it possible to realise a wide variety of tasks with a robot. In addition to the joints and the control system, this primarily includes connecting elements, drive units, tool adapters and elements for communication between the drives and the control system.

Applications with robolink® industrial robots

Connecting elements
The connecting elements provide the robot with support and structure. Their dimensions determine the reach of the end effector, e.g. gripper. The connecting elements include the connection base and the connecting parts between the joints.

The connection base forms the foundation on which the robot arm is built. It carries the entire construction and the tool or workpiece that is to be processed or positioned. At igus® GmbH, the connection bases were designed to be correspondingly stable.

The connecting parts are box sections made of sheet metal, which are fitted with mounts for the joints at the ends. The fork-shaped lower end enables a rigid connection to the output of one joint, while the upper end allows the movable mounting for the input of the next joint.

Drive units for robots
Stepper motors (NEMA motors) are available in the robolink® modular system for direct drive of the joints. In a stepper motor, the movement of the rotor is controlled by a stepwise rotating electromagnetic field. A step is a very small angle through which the rotor can be rotated. As the steps follow the electromagnetic field exactly, the position of the rotor is known at all times. Sensors for position feedback are not required. A stepper motor can therefore be controlled very precisely. The National Electrical Manufacturers Association (NEMA) has standardised stepper motors in the USA. The standards specify the connection dimensions (flange dimensions) and the performance characteristics for individual motors. The specifications of igus® GmbH for the motor type refer to this standard.

Communication between drives and control system
Communication between drives and the control system takes place via proximity switches and drive encoders, among other things.

A proximity switch or threshold switch monitors a variable physical variable and compares its value with a limit value. If this limit value is reached, the proximity switch triggers a switching operation. In this way, changes of direction can be initiated and movements stopped or initiated when predefined positions are reached. A proximity switch can also be used to switch cooling or heating on or off, for example.

Drive encoders detect the current status of drive units and convert this information into a signal that can be processed by the control system. The status of drive units is determined by the position of the drive shaft or the speed. The control system reacts to the signals as intended by the programme and causes the status to change accordingly.

Tool adapter
Tool adapters form the final chain link between the robot arm and the end effector. The igus® GmbH product range includes the robolink® D gripper adapter. It consists of two parts. One part is intended for connection to the last chain link of the robot arm. The other part is adapted to the connection of the gripper. For example, grippers or suction cups from SCHUNK or diagram can be connected there.

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