MELFA robots and SafePlus functionalities

MELFA robots are classified as »Pick-and-Place« robots with up to 20 kilograms payload capacity. Beside fast and short movement cycles, MELFA robots also enable some other functionalities. Mitsubishi`s robots perform operations which mainly replace movement of human`s hand, somewhere they even work in human`s workplace. MELFA SafePlus functions enable collaboration of human and robot, together with force sensor robots are able to adapt to external forces and are able to learn movements.

Integration of robot vision with MELFA robots

Basic movements and functionalities of robots can be upgraded with robot vision. With help of robot vision robot are able to detect workpieces and to identify position of workpieces. Cameras, which enable integration of machine vision, capture positions and check quality of workpieces. Robot vision at conveyor tracking is typical application, where workpieces are coming differently positioned piece-by-piece on conveyor belt. On particular point pieces are scanned, while camera sends information about piece position and orientation. This way robot knows the “micro” position of piece on moving belt. Visualization of pieces is possible on computer or HMI panel, another possibility is to send captured photos to FTP server. Robot vision functionalities are upgrading basic functionalities of robots, when only basic robot movements between predefined reference points is not enough. By combining more known camera producers (Keyence and Cognex) and MELFA robots it is possible to reach high compatibility.

Force sensor enables soft robot movements and perception of environment

MELFA robots can be upgraded with Mitsubishi Electric force sensor. In a places where it is not possible to provide geometrical stability of reference point (eg. hole or workpiece) because of unfavorable conditions, possible crash to unwanted object and interruption of working process can happen. Force sensor is mounted between robot flange and robot gripper. Consequently it is possible to obtain information of forces which are affecting the robot gripper or forces of robot movements. By adding force sensor, robot obtain sense, which obtains two types of information: information about force of robot movements and information if robot is pressing on desired point. Main functions of force sensor are force control (robot is automatically pressing to workpiece or it serves as a spring), force detection (detection of force for the purpose of quality control) and log of force. Sensor is completely system supported with Mitsubishi robots. Sensor is connected with robot controller with SSCNET III optical communication.

MELFA SafePlus Safety functions

In flexible production environments it often happens that worker and robot work in parallel in the same time and in the same workplace (cell). The newest MELFA robot F series and  MELFA SafePlus technology enable speed limit, torque limit and limit of robot movements, when safety sensors are activated. Workers can work and operate near robot or robot cell.

Main functionalities of MELFA SafePlus robots are following:

Reduced Speed Control function limits maximum speed of robot to less than 250 mm/s, which enable continuation of robot movements with limited speed, when human is nearby. It is possible to define two safety speed levels, according to proximity of worker.

Second safety function limits reach of robot into working space, by which robot is prevented to operate in worker`s working place. When this function is turned ON, the system controls position of four points which are located on a robot arm. These four points can not exceed predefined plane in working place. Consequently robot can not affect into worker`s working place.

Function of robot arm torque control limits speed and movement of robot by limiting torque of servo motor in joints of robot. Combination of “intelligence” of robot and constant calculation of torque in servos guarantees that robot is stopped in case when predefined torque levels are exceeded. This function provides a shutdown of robot in case of robot collision with other human or object.

Above mentioned functions are enabled by data gained with vertical safety curtain and horizontal laser sensor. Data are transferred onto SafePlus control system, which limits robot movements in real time, and enables collaboration between human and robot.



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