Robotic Arm

This project consists in a robotic arm that holds an LED fan as a tool. This LED fan will generate holographic pictures and the robotic arm porpouse is to follow the person looking at the hologram to keep the perfect angle to keep the holographic image.

Step 1: Gathering the Parts

For the creation of this proyect we need to gather the mechanical and electrical parts

For the mecanical parts we used 3D printing, laser cutting, aluminum extrusions, iron cast bearings and screws and bolts.

• 25 Black-Oxide Alloy Steel Socket Head Screw M5 55 mm
• 15 Black-Oxide Alloy Steel Socket Head Screw M5 20 mm
• 8 Black-Oxide Alloy Steel Socket Head Screw M3 10 mm
• 2 Black-Oxide Alloy Steel Socket Head Screw M2 10 mm
• 39 Metric Oversized Washer M5
• 35 Metric Medium-Strength Steel Hex Nuts M5
• 8 Metric Medium-Strength Steel Hex Nuts M3
• 5 Medium-Strength Metric Class 8.8 Steel Hex Head Screws M5
• 1 Ball Bearing R20 ½ in
• 1 AudioJack Male stereo 3 terminals 6.35 mm
• 1 AudioJack Feale stereo 3 terminals 6.35 mm
• 3 Stepper Coplers 30 x 40 mm
• 1 Aluminum Extrusion 3030 6 m
• 1 NEMA 23
• 1 Motor DC CHR-GM25-370
• 1 Endless Screw ½ in
• 2 ½ in Nut
• 2 Arduino Uno
• 1 Arduino H-Bridge Shield
• 1 LED strip WS2812BALL
• 1 Acrylic Sheet 3 mm 100 x 100 mm
• 1 Acrylic Sheet 6 mm 100 x 100 mm
• 1 Aluminum Sheet 6 mm 20 x 30 mm
• Cable
• 1 Power Source of 12 V
• 1 Bearing UCP201
• 2 Bearings UCL201
• 2 Bearings UCF201

Step 2: 3D Printing

The Following parts were 3D Printed on a RostockDelta for the bigger parts and a Zortrax M200 for the smaller more detailed parts, they can be diferentiated by the color ( Black Rostock , White Zortrax).

• Lateral Connector must be printed 4 times
• Angle Connector must be printed 2 times normal and 2 times mirrored
• Corner Connector must be printed 2 times normal and 2 times mirrored

Depending on the quality of your 3D Printer you may need to sand the interior of the pieces to make the fit

Step 3: LaserCut

All the laser cuts were realized in a 6mm acrylic sheet, only the V# ones, they were cutted in a 3mm acrylic sheet.

Step 4: Machining

Only one part is needed to be machined in this proyect as arcylic broke during further tests in the developement.

Step file is added for use in your convinience cnc or manual machining.

Step 5: Building the Base

Base Structure is build with only the 3D prints and aluminum extrusions.

The Aluminum extrusion must be cut in the next pieces

• 2 x 10 cm
• 2 x 45 cm
• 2 x 50 cm
• 2 x 10.4 cm (Internal Aluminum support)
• 2 x 18.6 cm (Diagonal support)

The diagonal supports with the internal extrusion must be the first ones to be built followed by the diagonal supports and then joining all the pieces together from the center.

Screws, nuts and washers can be added by drilling small 5mm holes into the 3D prints for extra stability.

Step 6: Building the Endless Screw

To build the Endless
Screw We used a 1 1/2 in hollow tube as a support this can be change by your preference or materials you had.

1. The motor and the coupler must be tightening to the endless screw
2. The part resulting from the last step must be screwed to the "Abrazadera de motor" the machined part
3. The tube is then added to "TubeSupport" in this step you can put both cylindrical supports as well as only one of them
4. At the end of the tube the TubeSupport3 the rectangular one must be added to put the acrylic supports that will resemble another part of the robot to keep symmetry
5. After the assembly of the acrylic parts a wall bearing must be secured in order reduce friction in the joint
6. Step number 5 can be avoided but the results may not be adequate

All the pieces are secured with M5 screws, nuts and washers

Step 7: Building the Fan

The Fan build will be described in 2 parts

• The Fan Propeller
• The Fan Mechanism

The Fan Propeller

• Starts by screwing together the "V#" .dxf in order creating an elongated propeller, in the middle part a M3 nut must be added.
• The LED strip must be cut to the size of the propeller and pasted with the adhesive it has
• 3 cables must be weld to the female Audio jack before introducing it to the fan holder, then the holder must be slide into the propeller and then screwed to it to increase the safety during operation.
• LEDs and the cables from the Audio Jack must be weld together

The Fan Mechanism

• The ServoHolder must be secured to the metal extrusion in order to secure the servo motor
• The FanHolder must be screwed to the acrylics that hold the DC motor and to the servo motor extension
• Then the DC motor must be introduced and screwed to the acrylics
• The coupler must be slide into the DC motor shaft and the Gear must be secured to the coupler (Instant glue can be used to insure a good contact)

Step 8: MainFrame

The main frame must be set in 2 parts

• The base system
• The axis

For the base we must screw the floor bearings to the base in the center, they will be slightly out of size by 10 degrees each one.

Then for the axis we must repeat the same steps as in the endless screw for the top bearing part

At the end we screw the 45-degree connector with the 10 cm extrusion.

Step 9: Electronics

For the electronics we used the following components

• 2 Arduino Uno
• 1 H-Bridge Arduino Shield with drivers in paralel to withstand the current of the motors
• 1 LED Strip of 3 Terminals
• 1 330 Omh Resistor
• 1 2.7k Omh Resistor
• 1 470 Omh Resistor
• 1 LM317 Voltage regulator
• 1 5V Diode
• 1 12V Power Supply
• 1 12 V DC motor
• 1 6 V DC motor
• 1 5 V Servomotor
• 1 NEMA 23 Stepper Motor

The stepper motor and the DC motors were controlled using the H-Bridge Shield

For the 6V motor we used an input of 8.5 Voltage to increase the velocity of rotation, we used the 12 V output and the Voltage Regulator as stated in the diagram.

The Led Strip was connected to the 5V output of the power supply, a diode was connected to protect the arduinos and a 330 resistor was weld on the signal input to prevent noice.

Step 10: Coding

For the Coding of the Robot we used 2 Arduinos and a H-Bridge Arduino Shield (Mentioned in the Electronics) The codes used for the control of the leds and the DC motor are found in the LEDs.ino file and the control of the xy axis and the z axis can be found in the Progra.ino

For the Coding we used a simple code based on a joystick control, the joystick value gets measured and averaged on a certain number of ticks, this gets the value to the control of the robot.

X of the joystick control de xy axis of the robot and Y of the joystick control Z of the robot.

Signaling of the arduino was sent to the H-Bridge shield to move the dc motor and the stepper.