DIY gripper motor selection

Hello, I am working on a college project for a gripper design for the UR3e robot. The scope is to create a gripper that can simply open and close.

Essentially, how can I connect a stepper motor to the i/o to control the motor that can open and close the gripper.

The problem i was facing was, am i able to take a 2,4 or 8 wire stepper motor and connect it to the robot for open and close command. I have found an m8 connect that can connect to the connector on the side of the last joint of the UR3e and has 8 leads at the end.

How can I connect that 8 pin connector to a stepper motor that can open and close my gripper.

Also, how will the UR3e know that an object has been gripped and to stop applying pressure and to keep holding the object until opened.

also can this be done with out Arduino

Here is the pinout of the tool connector (port on the side of the robot wrist). You’ve got 2 digital outputs, 2 digital inputs, and 2 analog inputs. So to close the gripper, you’d use one output, to open it, you’d use the other. As for determining if the object is closed or not, you can attempt to read the current out of the stepper into the analog inputs. You’d just have to account for inrush current. Otherwise high current draw should correspond to torqueing on the part (ie it’s gripped)

Alternatively, you can use the tool connector as a serial communication, though I confess I’m not familiar with that process.

Thank you for your response. so a 4 wire stepper motor would be 2 wires for power and ground and and the remaining 2 wires would be one for digital input and the other for digital output?

A stepper motor requires a stepper motor driver. It translates a clock signal and a direction signal into a sequence of motor winding activations. So you cannot directly connect a stepper motor to the robot.

you could use the digital outputs of the robot for signaling open or close until an input becomes active, indicating the gripper has grabbed something. Please note that the digital outputs are open collector (ground switching) and you need to translate open/close into a clock signal and a direction signal.

Nice job for an Arduino, since it has solutions for stepper motors and digital interfacing.

Good luck!