We are currently working (while we finish the control APPs of the blimpduino) in the SCARA robotic arm. The point of posting this on the web is to ask you for comments/ideas and any feedback. As we are still at this developing stage, we have time to re-think some aspects/features of this robot. A powerful, fast and reliable arm is the basic of modern robotics so… we wanted to “create” one but using regular “MAKER´s World” elements like NEMA17 motors, affordable electronics and common ancillary elements (GT2 timing belt, steel rod, aluminium tubes). The idea: create a very fast but precise robotic arm you can bring into existence using your own 3D printer.

This robotic arm is based on the awesome MPSCARA (by Williaty. Thanks Tyler for the ipt files!). We have modified almost everything but the main frame.

 

The current state of the robotic arm. Above: mounting the electromagnet and the medium size forearm

The advantages of this robotic arm:

  1. Affordable
  2. Easy to modify 
  3. You can create your own add-ons /actuators/ arms: adapters and 3D layouts have been create.
  4. Scalable
  5. Customizable 
  6. WIFI controllable

Mayor changes:

  • Motors placement
  • New center of gravity
  • The Z axis has been shifted looking for less torque forces during accelerations
  • Reduced friction
  • Aluminium structure were possible
  • Less expensive timing belts (shorter), but enlarging the working area
  • Different gear ratios for improved precision
  • Cables hidden inside the arms/structure

New ARM addon: Vacuum suction cup. Testing

New ARM addon: Electromagnet (12V, 500 mA): Currently working.

New ARM Addon: Vertical and horizontal Gripper (based on the Mantis gripper by 4ndreas). Horizontal version working. Designing Vertical version

Features:
  • 5 Degrees of freedom
  • Controllable from any smartphone via jjrobots free APP (currently can be controlled using basic commands using the app available at Google play)
  • Controllable via “queue of commands” from the computer/tablet/smartphone
  • Google blockly controllable
  • The kinetics behind a SCARA arm is way simpler than any other robotic arm/ alternative. This brings the possibility to easily understand how this robot works and create simple code to control it. A Cartesian XY+Z coordinate system is the natural approach to move its “hand”. We will create (beside the control APP/software) the “programming bricks” for everyone to control this robot in a simple way

Above: just calculating some tangents/ atan is enough to know the location of the robot´s “hand” (X and Y coordinates shown on the left top). In this case a “right handed elbow” robot has been simulated.

The control APP will display a similar (but better 😛 ) “working area screen” so you can move the arm just tapping on it and control the actuators as you please.

*This simulator window may not display properly on smartphones/tablets

 

The arm has been placed on top of the “control” platform which is carrying two stepper motors. The Z axis rod has been moved closer to the motors, modifying the center of gravity (now the motors weight is balancing the arm). Sudden UP+DOWN movements do not generate torque + vibrations.

 

Gears with guides for the timing belt keeping the pulling forces in the axis.
The Mantis gripper´s clamp closes around a point 4.1 cms away from the end of the forearm, making the positional calculations easier.
Metal gears servos used for the gripper. Precise and fast but strong enough to lift or move the load. The electromagnet actuator is capable of lifting up to 400 grams (some tests still have to be carried out here)
SOME VIDEOS OF THE ROBOT

Testing speed and accelerations: How much a 3D printer arm can handle? You will be surprised! 🙂

Two degrees of freedom for the gripper (we are currently working in a vertical gripper version). Metal gears servos for added precision and sturdiness

The Z axis movement has to be FAST.  A slow arm is not as… useful (nor cool) as a fast (but accurate) one.

The structure has to be sturdy but keeping a large working area.

January 2018 UPDATE

The frame is almost finished. We have been testing the HORIZONTAL and VERTICAL clamp. It is easy to switch from one to another. You just only have to rotate the support part 90 degrees. The control APP will have an option (a check-box) to let the code knows the current robotic arm configuration. Why two version of the clamp? The idea is to give this robot as much versatility as we can, not limiting its capabilities grabbing stuff. Once the vision system is working it should be able to pick almost any object not depending on its shape.

 

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