Engineering Notes by Oriental Motor

Improve Gripping Operation with Multiple Torque Limit Settings (VIDEO)

[fa icon="calendar"] Jan 15, 2019 1:00:00 PM / by Johann Tang

Johann Tang

Robotic grippers are typically used to grip parts for transport.  The driving force behind a gripper can be pneumatic, hydraulic, or electric.  Which type is best for gripping?

The answer depends on the application requirements and the size of the load.  While the high power from hydraulic and the cost-effectiveness from pneumatics may be appealing to some, electric motors should be considered for their consistency, efficiency, easy maintenance, and built-in driver functions.

In this post, we will explain how a torque limit function makes brushless motors a highly viable solution for grippers.

 CHALLENGE:   Gradually increase gripping force to securely grip load 

Gripper with pneumatic

Conventional Gripper


Equipped with a penumatic device on the gripper, it grips the load and transports it to the next process.

 

Problems with Pneumatic Grippers


While transporting a heavy load of a certain mass, the gripper may drop the load due to inconsistent gripping force.

 SOLUTION:   Use the Torque Limit function to gradually increase gripping force 

The Torque Limit function can be used to decrease or increase the torque of a motor incrementally by a percentage of the motor's rated torque.  It is available on a number of Oriental Motor's closed-loop motor systems.

Gripper with BLE2-1

Practical Application Example


The Torque Limit function delivers optimized multi-level gripping force to gradually increase gripping force of a gripper and securely grip a load without damaging the load.

How It Works


Torque of a motor can be increase or decreased by the amount of current flowing through its windings.  The Torque Limit function monitors and controls motor current in order to limit torque.

How To Use


  • Prior to operation, digitally set the data for required torque limit settings with either the front panel of the driver or the MEXE02 support software.
  • Start the motor and lightly grip the load with a low torque limit setting.  When the set torque limit is exceeded by the motor, the TLC output will turn ON.  
  • Once the TLC output turns ON, switch to a high torque limit setting.
  • If the TLC output remains ON, it means that the load is securely gripped, so the transporting process can be started.

 Timing Chart - Torque Limit Function

Torque limit

With 16 different speed and torque limit settings, the same BLE2 Series brushless motor and driver can be configured for various loads. *

*With  closed-loop stepper motor systems, up to 256 settings are offered.

BLE2 Series driver and motor

Learn More

Output Power 30 W, 60 W, 120 W, 200 W, 400 W
Torque Limit Setting Range*1 0~300%
Max Number of Settings 16
Torque Limit Accuracy*2 ±10%
Speed Control Range*3 80~4000 r/min

*1: The value when the rated torque value is 100%.
*2: An error up to a max. of approximately ±10% (at rated torque and rated speed) may occur between the setting value and generated torque due to the setting speed, power supply voltage
and motor cable extension length.
*3: The BXⅡ Series with a speed control range of 2~4000 r/min is also available.

 

Here's a demo video that introduces BLE2 Series brushless motor and driver, the Alarm Monitor function, and the Torque Limit function.

Need help with an application?

Contact Tech Support

Topics: Torque Limit (Push Motion), Robotics, Speed Control, VIDEOS, BLDC Motors

Johann Tang

Written by Johann Tang

Johann Tang is a Product Specialist at Oriental Motor USA Corp. with over 15 years of knowledge and experience supporting applications of various types of electric motors, gearheads, actuators, drivers, and controllers.