An electric gripper, also known as the electrical gripper, is a type of actuator that utilizes compressed air as power to grip a workpiece. An electric gripper was originated in Japan, and is now widely used across the globe.
In fact, the demand for electric grippers has been record high over the years, attributed to its efficient, powerful and fast nature. In the early days, electric grippers were very slow and fragile compared other similar sized pneumatic grippers. The rapid mechanical development over the years however has allowed the new generation of the electric grippers to perform on part with their counterparts, exceling in both the force and speed. They are also capable of providing much more data feedback compared to other pneumatics.
To see how an electric gripper works, we’ve broken the process down into four sections to better illustrate:
1. When an electric gripper is put to action, a robot control unit is used to send an input command to the gripper. This is typically done by pre-programing the so-called teach pendant by the operator. For most electric grippers, the command can be a group force, speed or position. Then, the robot in accordance to the communication protocols will send commands to the electric gripper using digital inputs and outputs.
2. The control module then drives the motor of the electric gripper upon receiving command from the robot. In most cases, the gripper module is consisted of a box sitting between the gripper and the controller, but can also be embedded in the gripper sometimes.
3. Next, the motor of the electric gripper will react to the signal, and the shaft will rotate based on the commanded force, speed and position. For the closed-loop control to be enabled, the feedback from the motor position should be at the gripper level in most cases. Until there is a change in the signal, the gripper will remain positioned and resist change.
4. Some electric grippers are also capable of sending certain parameters back to the robot control unit, and these parameters include jaw position, grip detection, speed and so on.
There are actually quite several reasons why many would prefer an electric gripper other robotic grippers:
1. Grip Detection:
Electric grippers are able to detect if a part has been picked up by using encoders. In some cases, this information will be delivered to the robot controller of the electric gripper. Being able to detect the grip is almost always mandatory for error-proofing in many applications. Also, doing this at the gripper level can prevent other sensors from being put in the loop, which greatly simplifies integration and reduce the relevant costs.
2. Grip Force and Speed:
It is entirely possible to control the grip force exerted by the gripper as the electric motor current is positively correlated with the torque it applies. This is also very beneficial for various applications, especially when handling parts that are relatively fragile.
3. Position Control:
The jaws of an electric gripper are controlled using encoded motors as well as the proper control scheme, while a full stroke would almost always be required for a conventional gripper. Electric grippers are designed with the flexibility where only minimum clearance and stroke is required to approach a part and pick it up, respectively.
4. No Air Lines:
Another big advantage of the electric gripper is its power-saving and easy-to-maintain nature compared to pneumatic, which is why many companies are starting to shift from pneumatic to the electric niche to lower operating cost. The cost of energy is also another reason attributing to such shift.
5. Clean Environment:
Electric grippers are perfect for applications that require a clean environment that isn’t prone to air leakage, the major cause for contamination.
Electric grippers are often used in applications where the environmental and atmospheric conditions are considered in ensure desirable workflow. As mentioned above, for applications that require a clean environment, such as medical and pharmaceutical settings, an electric gripper will be much preferred rather than a pneumatic gripper.
It has also been reported that there is an increasing number of collaborative robot users who are starting to lean toward electric gripers because of the superb control and adjustability they offer as opposed to the pneumatic counterparts. With the recent years of development, people are starting to see electric grippers’ improving capability of sensing parts more accurately, allowing them to work with very delicate parts by automatically adjusting the forces.
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