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 supply information to the control system. The mechanical construction is composed of several components that are connected to each other by means of active joints. Active joints have drives to which the control system gains access in order to assign a task to the end-effector. The term 'robot' comes from the Slavic word for work.
The individual robot parts in the robolink® modular system
The robolink® modular system of igus® GmbH makes it possible to design robot arms individually. It contains a wide variety of individual parts that can be ordered and that make it possible to design robots for a large range of different tasks. They include the joints and the control system and, above all, connecting elements, drive units, tool adapters and elements for communication between the drives and the control system.
In order to remove mobile phone half-shells from a hazardous area of a machine with coolant spraying water, a robolink® articulated arm is used by a machine tool manufacturer.
robolink® Apiro and ReBeL are still in the development phase. But even now, it is evident that the future belongs to modular robot systems, service robots and collaborative robots
With the help of a robolink® D articulated arm, the Four Stars Engineering Systems GmbH is able to offer precisely that to its customers for the automated electrical testing of printed circuit boards.
The connecting elements structure the robot and make it stable. Their dimensions determine the range of the end-effector, e.g. gripper. The connecting elements include the connecting base and the connecting parts between the joints.
The connecting base is the substructure on which the robot arms are built. It carries the entire construction and the tool or the workpiece that is to be machined or positioned. igus® GmbH has designed the connecting bases to be correspondingly stable.
The connecting parts are box-type sections made of metal sheets and have mounts for the joints at their ends. The fork-shaped lower end enables a rigid connection to the output of one joint while the upper end enables flexible attachment for the input of the next joint.
Drive units for robots
In the robolink® modular system, stepper motors (NEMA motors) for direct driving of the joints are available. In a stepper motor, the movement of the rotor is controlled by means of an incrementally rotating electromagnetic field. A step is a very small angle through which the rotor can be turned. As the steps follow the electromagnetic field exactly, the position of the rotor is known at all times. Sensors for position feedback are not needed. A stepper motor can therefore be controlled very precisely. In the USA, the National Electrical Manufacturers Association (NEMA) has standardised stepper motors. In the standards, the connecting dimensions (flange dimensions) and the performance characteristics are defined for individual motors. The information provided by igus® GmbH regarding this type of motor refers to this standard.
Communication between drives and control system
Communication between drives and control system takes place by means of proximity switches and drive encoders, among other things.
A proximity switch or threshold switch monitors a changing physical variable and compares its value with a limit value. If this limit value is reached, the proximity switch triggers a switching process. When positions specified in advance are reached, changes of direction can therefore be initiated and movements can be stopped or induced. Proximity switches can also be used to switch a cooling or heating system 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 the drive units is determined by the position of the drive shaft or the speed. The control system reacts to the signals as programmed and causes the status to change correspondingly.
Tool adapters are the final link between robot arms and end-effectors. The products supplied by igus® GmbH include the robolink® D gripper adapter, among other things. It is composed of two parts. One part is for connection to the last connecting part of the robot arm. The other part is adapted for connection of the gripper. Grippers or vacuum suction units of the company SCHUNK or ABB, for example, can be attached here.