Gripping system
Gripping system describes the working organs of a robot . This includes actuators / effectors , but also necessary auxiliary equipment such as wrist axes, changing systems, joining aids, protective devices and sensor units .
Gripper
Gripping is a basic movement for grasping and holding and establishes the connection between the robot and the workpiece. The decisive factors for a secure connection are the type of active pairing and the number of contact levels. The effective pairing can be achieved via force, shape or material pairing. When a force pairing is used, the hold is created by exerting pressure on the workpiece surface. In contrast to this, when the mold is paired, it is held by enclosing the workpiece with the same shape. The transmitted clamping forces are very small with safe guidance. In the case of a material pairing, contact with the workpiece occurs through the use of adhesion . This process has so far been used to a limited extent by industry, although a change is becoming apparent here, especially with regard to micro-assembly .
Furthermore, the gripping systems can be used in
Subdivide systems. These effects can also be used in combination for greater flexibility of the gripping system. A scientific classification in the form of a construction catalog was found by the Institute for Construction Technology (IK, Braunschweig) and the Institute for Machine Tools and Manufacturing Technology (IWF, Braunschweig).
Mechanical grippers are available as single-finger, two-finger or multi-finger grippers in rigid, rigid-articulated or elastic designs. The mechanical gripper is driven mechanically, pneumatically or electrically. The pneumatic drive is very popular due to its easy handling. Due to its universal applicability, the human hand often serves as a model for mechanical grippers.
Pneumatic grippers work by picking up flat parts using the suction principle or by clamping the workpiece using the pressure principle. When using a suction cup, the surface of the workpiece must be smooth, clean, dry and impermeable to air.
Magnetic grippers are divided into permanent and electromagnetic grippers. Permanent magnet grippers are very simply built, but require additional equipment to strip off the workpiece. Electromagnetic grippers are picked up and released by switching the electrical energy on and off. When using magnetic grippers, there is a risk that several workpieces will be gripped.
Grippers can also be subdivided according to their design. These include
- Parallel-,
- Radial-,
- Angle-,
- Three-point or
- Suction cups.
Anthropomorphic claws
Novel drive principles such as flexible fluid actuators allow the development of lightweight and multi-link anthropomorphic grippers whose appearance, size and function come very close to the human hand. This is intended to allow flexible gripping and manipulation tasks to be performed in an unstructured and unpredictable environment. Their areas of application are hand prostheses as well as humanoid service robots.
Tools
Robotic tools are assembly or machining tools. These include u. a. Grinding machines, screwdrivers, drill spindles, glue guns, paint spray guns or spot welding guns .
Measuring tools
Measuring tools are sensors that convert a physical or chemical variable into a clearly usable, often electrical, signal. The measuring tools on the gripping system of a robot include:
- Strain gauges (DMS),
- Incremental encoder ,
- Acceleration sensors ,
- Image processing systems (BVS) and
- Proximity switch.
They help the robot to recognize the correct position and presence of the workpiece, to check that the workpiece is being processed correctly or to check the relevant processing parameters.
- see also: sensor
Joining aids
The robot uses joining aids for the correct installation of workpieces and when changing its own tools. Form elements and guides enable a reproducible approach with low tolerances to certain defined positions in the work area.
see also: RCC module
Exchange systems
Changing systems help with the flexible use of industrial robots . They consist of an upper and a lower part and must be coupled in a reproducible manner. Form elements for coarse and fine centering as well as locking elements are used for this purpose. With an exchange system, the IR can use different effectors to fulfill its tasks. General requirements for a change system:
- low dead weight
- low overall height
- modular construction
- self-locking locking
- very good repeatability
- Emergency release device
In addition to the mechanical connection, the elements for information and energy flow are also coupled at the same time. Depending on the area of application, changing systems can be equipped with media couplings (water, hydraulics, air), electrical signal connectors (fiber optic, data bus) and electrical power connectors .
Terms and characteristic properties are specified in DIN V 24603 / ISO 11593.
- see also: tool change system
safety devices
Protective devices are intended to prevent damage to the IR. This includes damage caused by collision and overload. Predetermined breaking points, locking clutches and disconnection safeguards are used. Should be achieved
- a fast, low-delay shutdown response
- an adjustable response sensitivity in as many directions as possible
- reproducibility of the movements after the protective device has responded without reprogramming
- a low net weight and
- a simple control-technical integration