Deltabot Sorting Machine Preparation

Deltabot Sorting Machine

Introductory Research

 

  1. Background :

Late this year I bought a delta 3d printer. I was fascinated by the design and mechanism, how it moves so dynamically by actuating its three arms.it accelerates and decelerates quickly maintaining the accuracy of the printing head position.

It made me think to study it and why not make my own delta robot. The occasion came up in this year’s project, I proposed the idea to my team and they liked it.

So we intend to make a deltabot with a different purpose than 3d printing, a pick and place machine sorting items according to different characteristics (color, weight…..)

2. The Delta Mechanism :

A delta mechanism is composed of three parts:

  1. The BASE:

A triangular shaped platform which houses the actuators in our case we chose stepper motors for their accuracy and repeatability, because all the weight resides in the base the arms of the robot can be very light reducing there inertia so they can accelerate very fast in an accurate way.

  1. The End-Effector:

A smaller triangular shaped platform which translates in the XYZ axis but stays parallel to the base platform, it also houses a suction device or a smell actuated arm to pick and drop the sorted items.

  1. The Arms:

Three symmetrical arms that move independently, Composed of an arm that is actuated from the base, a parallelogram acting as the forearm which is the connected to the end effector all its joints are ball joints. The parallelogram locks the end effector platform parallel to the base which is the difference between a delta bot and a Stewart platform and the ball joints give the end-effector the 3 Degrees of freedom DOF to move in the XYZ planes.

  1. Actuation Type Choice:

There is two types of actuation for these three arms either linear or revolute, common 3D printers use linear actuation, and industrial deltabot used for pick & place use revolute actuation. I chose the revolute actuation because it’s easier to make with minimal mechanical items and also cheaper as linear rods or wheels on aluminum profiles tend to be more expensive to buy than to directly drive the arms from the actuator.
 


3. Motion Study:

Only by rotating first part of the arms we are able to change the position of the end effector platform as shown in the figure below,

via GIPHY

Input 3 rotations è output 3 translations on the X Y and Z axis.

Check  https://sites.google.com/site/deltarobotberkeley/how-it-works 

Inverse kinematics was applied to determine the output angle of each servo for a desired position of the effector (xg,yg,zg). Each leg was solved individually. Cylindrical polar coordinates are used to take advantage of the circular symmetry. Each leg is projected into a 2D plane then basic geometry was used to determine the final servo output angle.

4. Design and Parts List

1. Mechanical Parts:
We will be needing a strong frame to support the weight of the motors and the base it needs to rigid and heavy to eliminate all the vibration when the arms are moving quickly so we can either use steel or aluminum profiles to make it.

For the Base and the end effector an acrylic (plastic) or a wooden board can be used

For the upper arm 3d printing the part can be easier as it’ll have many mounting points one side for the motor and the other side to connect the ball joint, if we don’t have access to a 3d printer we will be using acrylic.

For the parallelogram we need small rods need to be very light and 4 ball joints each.

The ball joint problem:
It may be difficult to find small ball joints (embout a rotule) on the market so we are not lucky we can make our own in a very clever way by combining two perpendicular pivot axes on the X and Y using 4 ball bearings.

The end effector will be equipped with an actuator to hold the items were picking preferably it’s a suction module but we can use a servo actuated gripper.

2. Electronics Components:

• As actuators we can use either servo motors or steppers I prefer steppers as they are more accurate in both position and acceleration, we need three in total
• If we are using steppers drivers are needed (DRV8825 or A4988)
• A microcontroller (an arduino Uno or Mega)
• Wires
• A color sensor
• Weight sensor

Essential parts List Proposal:

3 Stepper Motors NEMA17   Arm Actuator
3 A4988 3 Stepper Motor Driver
1 Arduino UNO Microcontroller board
12 Ball Joints  Mechanical joint linkage
1 TCS34725 Color sensor 1 Color sensor



I modeled the design on Fusion 360 and exported these renderings :


TunMaker at SOMEF

First of all i need to thank SOMEF for this opportunity and special thanks to my Supervisor Med Amine Chibani,Also all the members of the development & test team

Introduction

As a student engineer in Electro-Mechanics I had the opportunity for an internship at SOMEF which is the leader company in its field of business here in Tunisia, with products that varies from simple home switches to home automation and smart house implementation it presented for me a company that I need to visit and a chance to widen my professional experience.
So I applied and they accepted me in the department of development and testing, not going to go in all the details I just want to tell you about my project so here we go.


The Internship

Main task: Design and manufacture of an instantaneous current measurement module, able to visualize the values on the computer in real time

With my supervisor we detailed what the project was and its functionalities :

The module needs to be able to measure the current up to 5 A we chose the IC ACS712 for that,an LCD-1602 to display the values everything will be controlled by an ARDUINO-UNO, using its serial port we will relay the values and print them in real time on an excel-sheet.

My first challenge was to read the Data Sheet of the ACS712 to interpret the output signal according to the passing current, after finding the formula I had to write and test the program on the arduino and display it on LCD.
The Second Challenge was to find a reliable solution to visualize and save these values on Microsoft-Excel in order to draw the curve. For that I found PLX-DAQ which is a software add-in of the Parallax Data Acquisition Tool (PLX-DAQ) for Microsoft Excel Acquires up to 26 channels of data from a microcontroller and places them in the columns as soon as they arrive. PLX-DAQ provides easy analysis of spreadsheets of collected data.

After testing the features separately from reading ,  displaying on an LCD and the real-time acquisition of the values. All that remains was writing the program.

For the circuits he asked me to make a shield housing the LCD screen for the arduino and input for the measuring circuit. The second circuit had one power input and three USB outputs with the ACS712 in the middle of it to measure the passing current.
To make the circuits I used Autodesk EAGLE here’s some pictures:


And I used my CNC to make the PCB’s and I had an acceptable result.

tunmaker
tunmaker

Now that circuits are made I needed a box for them so I made one using Autodesk fusion 360 for modelling and 3D printed them on my KOSSEL DELTA

And here’s the project Done :





DIY Speed Ball

Hand-Crafting The Speed Bag:

Handmade Speed Ball
Handmade Speed Bag

This was the perfect summer project for me affordable and with much use. I never owned a speed bag or trained with it in the gym but it is fun and awesome.




Anyway materials used:

– Cheap industrial leather if you can afford quality go for it =)

– Glue

– Heavy string for leather

– Normal string

– One shoe string

– Scissors and needles big and small ones

NB:

-As the leather wasn’t thick I didn’t need to put holes in it before stitching

-Choose your colors nicely I went with my theme black and red =)

Let’s Start

DIY Speed Ball Template
DIY Speed Bag Template

Use the template or draw one yourself to mark the pieces were going to cut. We will need 6 of them and for the bottom draw a regular hexagon (six equal sides with six equal angles of 120 degrees between each side).and a rectangle of 8*40 cm which will be the attachment.

Now that all our pieces are ready use scissors to cut them leaving us with 8 pieces in total.

Next thing glue the sides by pairs it’s better to use wood glue but you’ll have to wait longer that’s why I used this type but it is messy and hard to clean.

Next we will start sewing the pieces with a typical two needles saddle stitches leaving a bit on less than 1cm free to join the bottom piece and more on the top for tightening string.

Now we glue the 3 pairs together and we start sewing like before with one left half open leaving enough room so we can put the ball later.

Almost done looks complete but we still have to do a little more touches.



Holding the pieces for stitching like that makes it easier and faster and use those laundry things to attach the pieces while they dry works like a charm

Use normal string to make the loops for the string and I added 3 washers on each side of the opening to protect the leather from the string as I couldn’t find proper ones for leather when I find them I ll change them for the looks and professionalism .

The only thing left now is the piece that will attach the ball to the swivel. I made it a little bit far from the swivel so don’t make the gap too big also the rectangular piece is folded in half making it 4*40 and it is sewed with saddle stitches drawing a rectangle for a strong bond from both sides.

We Are DONE put the ball inside pump air and it looks alive. This is not obligatory but I added bits of fabric in the upper gap to shape the looks.

 Have fun boxing this summer and share the knowledge

 

PCB Drilling Station

How to make a PCB Drilling station

mini drill

Making a mini drilling station is better than buying one. Why? Well making one is easier and it’s much affordable than you think.I use it to drill my  PCB’s which is the main purpose but then I realized that it is even capable for drilling plywood and plastic which is useful for small projects.

Materials used:

  • — 1 cm thick sheet of plywood
  • — scrap piece of wood
  • — Scarp piece of MDF
  • — Two stainless steel rods (10 mm diameter)
  • — Two springs
  • — 4 x O screws
  • — zip ties
  • — 30 V motor (I got it from an old printer with its power adapter and switch to power it)
  • — 4 x small L joints
  • — GLUE: two parts epoxy and wood glue
  • — Some small screws
  • – Tools:
  • — Jigsaw or normal saw
  • — chisel
  • — Screwdriver
  • — hand drill (with small bits and a 10 mm drill bit)
  • — Sand paper for the wood



The Plans


plans

 

The Base Structure :

Use the included schematics to retrace two pieces for the top and bottom and two more for the sides to a sheet of plywood.

I used my table mounted jigsaw for this cut but a normal saw would do.

Now sand the edges and mark and drill the holes for the steel rods later.

Using a Scrap of MDF as the base I assembled it with the L joints making everything square as possible.

The Slider :

It is composed of three pieces :

– 1 x the slider

– 2 x Motor holders

I cut it to length mounted it  to the vice pre-drilled with a 5 mm drill bit then completed at 10 mm theses two holes need to be straight and parallel to each other as possible as they are the guides of the steel rods if you have a drill press use it unfortunately I don’t but it worked just fine. Next carve two slots for the motor holder which I did with a saw and the chisel then sanded it

Now the motor holders retrace them on the plywood and make sure to know the diameter of the motor you’re using for the inner hole and cut them. After that to make it easier and to make them as identical as I can I glued them together with little drops of superglue (they need to be detached later) and made the inner hole

Now use glue and screws to assemble the three pieces and were done almost.

Make a quick test to see if everything fits together and mark the shaft of the motor to see where it will drop and drill that hole on the MDF base.

Assembly :

I painted everything white it looked nice i was so happy at this point =) Added the O screws for the spring and were ready to assemble. Put the motor in place and strap it with zip ties keep them loose for now until we finish the assembly.

put the steel rods make sure everything is aligned, perpendicular…(eye bowling) and tighten the zip ties , mix two parts epoxy and glue the steel rods to the top and bottom pieces and the drilling station is ready.

How To mount Drill Bits To The Motor:

To fit drill bits to the motor. I took the wire connectors removed the silicone plastic around it then loosen the screws and put it aside for now.

take the drill bit (in the video i showed you a 1 mm bit) wrapped it with paper tape until it fits snugly inside the connector now with two parts epoxy mixed glue it to the connector , Quickly before it dries join it to the motor and turn it on while its turning using a screwdriver push it until its perfectly aligned and doesn’t wobble around tighten the screws and check again when it looks straight carefully remove it and let it dry.



WHEN the epoxy dries start drilling some holes.

Complete Build Videos and Using It :