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ID : 2431

Engineering-design Notes for Robot Hands

Design a hand (end-effector) so that it will satisfy conditions (1) and (2) described below.

Strictly observe these engineering-design notes. Otherwise, the clamped sections of the robot unit will become loose, rattle or be out of position. In the worst case, the mechanical parts of the robot unit and the robot controller may be damaged.

Mass of Hand

The total mass of a hand or tool (including work-piece) should be less than the maximum allowable payload of the robot.

Be sure to include the mass of wirings and piping used for a hand or tool.

Total mass of hand or tool ≦ Max. allowable payload (incl.work-piece). (Mass of payload that you have preset)

Hand Center of Gravity

The center of gravity of a hand or tool (including work-piece) should be located within the range specified in Figure below.

Unit: mm

For each center of gravity position, figure out the speed based on the following graph.

For acceleration, use the value calculated by the formula below.

Acceleration (%) = (Speed/100)2 x 100

(The above setting is not required if you set the payload center of gravity and payload moment of inertia, and select Control set 3 of the Optimal speed control function.)

<Application sample>

  • To run the robot at 100% of the programmed speed and acceleration: Design so that the center of gravity of hand/tool is zero.
  • When the mass of hand/tool is 8 kg and the position of center of gravity is 85 mm, set the speed to 49% (acceleration: 24%) or less.

Moment of Inertia Around the T Axis

The moment of inertia of a hand or tool (including work-piece) around the T axis should be less than the maximum allowable moment of inertia around the T axis of the robot.

Hand's or Tool's moment of inertia around the T axis ≦ Max. allowable moment of inertia (incl.work-piece). (refer to the graph below).

Calculate the moment of inertia around the T axis according to the graph given below.

You may program the reduced ratio of the speed and acceleration individually within the range specified below. If you set the reduced ratio of the programmed speed only, the controller automatically calculates that of the acceleration according to the formula below.

Acceleration (%) = (Speed/100)2 x 100

(The above setting is not required if you set the payload center of gravity and payload moment of inertia, and select Control set 3 of the Optimal speed control function.)

<Application sample>

  • To run the robot at 100% of the programmed speed and acceleration: The moment of inertia around the T axis should be 0.01 kgm2 or less.
  • If the moment of inertia around the T axis is 0.12 kgm2: Run the robot at 29% or less of the programmed speed and at 8% or less of the programmed acceleration.
 

ID : 2431

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