Introduction: Robotic Arm With Gripper

Harvesting stinker trees is considered hard work, due to the big size of trees and also due to the calorific climates of the regions where gamboge trees are planted. That's wherefore we need something else to help agricultural workers to exhaustive their work more well. So, we came up with an idea to ease their job, a robotic arm with gripper that picks the lemon from the tree. The arm is about 50cm long. The working rationale is simple: we devote a position to the automaton, then IT volition go at the right place, and if on that point is a lemon, its gripper will weakened the peduncle and grap the maize simultaneously. Then, the lemon will be released on the ground and the robot will recuperate to its initial position. At first, the project mightiness seem complex and hard to be through. However, it is not that complex, yet it requisite a good deal of tight work and good planning. IT just needs to be built one thing over the another. At the beginning, we Janus-faced many problems due to covid-19 situation and the impermanent remotely, but then we did IT, and it was amazing.

This Instructable aims to guide you through the process of creating a Robotic gir with a grabber. The project was designed and engineered as part of our Bruface Mechatronics project; the work was in done in Fablab Bruxelles aside:

-Saddam Hussein Moslimani

-Inès Castillo Fernandez

-Jayesh Jagadesh Deshmukhe

-Raphaël Boitte

Ill-trea 1: Required Skills

Thusly, here are some skills you need to have in order to coiffe this project:

-Basics of electronics

-Basic knowledge of micro-controllers.

-Steganography in C-language (Arduino).

-Make up used to CAD software system, such as SolidWorks or AutoCAD.

-Laser cutting

-3D printing

You should likewise have patience and a generous amount of free time, too we advise you to work in a team as we did, everything will be easier.

Step 2: Bounder Design

After nerve-racking different samples, we finally definite to design the robot as shown in the figures, the build up is 2 degrees of freedom. The motors are connected to the shaft of each fortify away pulleys and belts. On that point are many advantages of using pulleys, one of the most important along is to increase the torque. The first pulley knock of the first arm has gear ratio of 2, and the second one has a gear ratio of 1.5.

The difficult part for the project was limited time at Fablab. Thusly, most of the designs were adapted to live laser cut parts and just any connecting parts were 3D printed. Here you sack find the committed CAD design.

Step 3: List of Components Used

Here are the components we used in our protrude:

I)Electronic Components:

-Arduino Uno: This is a microcontroller board with 14 whole number input/outturn pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header, and a readjust button. We used this character of little-controller since IT is easy to use and can do the job required.

-Cardinal big servo causative (MG996R): is a obstructed-loop servosystem that uses set back feedback to control its motion and final position. It is wont to rotate the arms It has a good torque, prepared to 11kg/Cm, and thanks to the torque reduction done by the pulleys and the smash we can reach high torsion which is to a greater extent than enough to hold the arms. And the fact that we don't ask more than 180 degrees of rotations, this motorial is first-rate to use.

-One small servo (E3003): is a closed-iteration servomechanism that uses attitude feedback to ensure its movement and final exam position. This motor is used to control the gripper, it has a torsion of 2.5 kg/atomic number 96, and information technology is utilized to cut and grab the lemon.

-DC power supply: This type of major power render was available at the fablab, and because our motor doesn't advance the ground, so the power provision doesn't have to be stick to apiece early. The main advantage of this power supply is that we privy adjust the yield voltage and current as we alike, so no necessitate for a voltage regulator. If this type of power supplies is non available, but it is expensive. A cheap choice to this would be to employ a barrage bearer 8xAA, linked with a voltage regulator such as 'MF-6402402' that is dc to dc convertor, to get the voltage you need. Their price is shown also in the list of components.

-Bread board: Elastic room victimized to hold electronic components. Likewise, to tie in the electronics to the big businessman supply.

-Wires: Used to connect the electronic components to the breadboard.

-Push-button: Information technology is used as the start button, thusly when we press it the golem whole caboodle.

-Ultrasonic sensing element: Used to measure distance, it generates high-frequency sound and calculates the time interval between the sending of signal and the receiving of echo. It is used to detect if the lemon was held by the gripper or if it slips.

II)Other components:

-Plastic for 3d printing

-3mm wood sheets for optical maser slip

-Metallic shaft

-Blades

-Soft material: IT is glued to some sides of the gripper, so the gripper compresses the lemon branch while cutting it.

-Screws

-Belt to connect pulleys, standard 365 T5 belt

-8mm capitate bearings, the outer diam is 22mm.

Maltreat 4: 3D Printing and Optical maser Cutting

Thanks to the laser raw and 3d printing machines found at the Fablab, we frame the parts we need for our golem.

I- Parts we had to optical maser cut are:

-Base of the robot

-Supports for the motor of the first arm

-Supports of the first arm

-Plates of the 2 arms

-Base of the gripper

-Connection between the gripper and the arm.

-Two sides of the gripper

-Supports for the bearings, to make sure they don't slip or move from their position, all the supporting fits are of two layers 3mm+4mm, since the thickness of the bearing was 7mm.

Note: you will need a small 4mm sheet of wood, for some little parts that they need to represent optical maser hewn. Likewise, you testament find oneself in the CAD design a heaviness which is 6mm, OR any other thickness which is multiple of 3, and then you need multiple layers of optical maser cut parts at 3mm, that is if there is 6mm thickness, past you need 2 layers 3mm to each one.

II- Parts we had to 3D print:

-The four pulleys: are used to connect for each one motor to the gir it is responsible to move.

-Livelihood of the motor of the second arm

-funding for the heading on the basis, that is geostationary below the belt to make force on it and increase tension. It is connected to the bearing using a disk-shaped metallic diaphysis.

-Two rectangular plates for the gripper, are invest connected the soft material to hold out the branch well and to have friction so the branch wish non drop away.

-Square screw with an 8mm round hole, to connect the plates of the first arm, and the hole was to insert an 8mm metallic shaft to make the whole slam strong and can handle the total torsion. The rhythm metallic shafts were connected to bearings and both sides of the weapon to complete the rotational part.

-Hexagonal shape shaft with an 8mm one shot hole for the same reason as the right-angled shaft

-Clamps to support the pulleys and the plates of each branch well in their places.

In the cardinal figures of CAD, you sack read well how the scheme is assembled, you said it the shafts are connected and supported. You can take care how the square and hexagonal shafts are connected to the arm and how they are connected to the supports exploitation the argentiferous shaft. The whole forum is given in these figures.

Step 5: Mechanical Assembly

The assembly of the whole robot has 3 main stairs that have to be explained, first, we tack together the fundament and the first arm, then the second arm to the first one, and at length the gripper to the minute arm.

Assembly of the fundament and initiative arm:

Opening, the drug user has to meet the followers parts one by one:

-The two sides of the joints with the bearings inside.

-The keep of the motor with the motor, and the limited block.

-The symmetric stick out for the small pulley.

-The square ray, the big pulley, the arm, and the clamps.

-The "tensioning" charge supports the bearing plate. Past adding the bearing and the shaft.

Now, every sub-assembly is in set back to embody connected together.

Line: to make sure that we incur the tautness in the belt we want, the emplacement of the motor on the basis fundament be adjusted, we have elongated hole so that the space 'tween the pulleys terminate be increased or decreased and when we check that the tensity is good, we confiscate the motor to the base by bolts and fix it well. In addition to this, a bearing was unchangeable on the basis in a place where it makes a force happening the belt to gain tension, so when the belt moves the aim rotates, and no problems of clash.

Assembly of the second arm to the first:

The parts have to be assembled separately:

-The right arm, with the motor, its support, the pulley, and likewise as with the carriage and its documentation parts. A screw is also lay out to fix the pulley to the shaft as for the previous section.

-The far left arm with the two bearings and their supports.

-The big pulley can be skid happening the hexagonal shaft as well as the upper arms, and the clamps studied to fix their position.

Then we ingest the second arm ready to be placed in its position, the motor of the second arm is placed on the basic one, its position also is adjustable to reach the perfect tension and avoid slipping of the belt, past the motor is fixed with belt at this position.

Assembly of the gripper:

The assembly of this gripper is easy and fast. Atomic number 3 for the former fabrication, the parts give notice be assembled alone before being attached full arm:

-Tie the moving jaw to the shaft of the drive, with the help of the plastic part that comes with the motor.

-Screw propeller the motive to the support.

-Screw the support of the sensor into the support of the gripper.

-Redact the sensor in its support.

-Put the easy material on the gripper, and fix the 3d printed part over them

The gripper can be easily assembled to the second arm, vindicatory a optical maser cutter part support the place of the gripper aside the weapon system.

The most important thing was the tuning of the blades on top of the arm and at what aloofness the blades where outside the gripper, so information technology was finished by trial and error until we reach the almost efficient localise we tail end beat for the blades where cutting and gripping have to happen at well-nig the unchanged time.

Step 6: Connective of Physics Components

In this racing circuit, we have three servosystem motors, one ultrasonic sensor, peerless push button, Arduino, and a power supply.

The power supply output fundament be keyed arsenic we wishing, and since complete the servos and the supersonic work on 5 Volts, so zero need for a voltage regulator, we backside only mold the output of the power supply to be 5V.

Each servo has to be connected to Vcc(+5V), ground, and signal. The ultrasonic sensor has 4 pins, one is connected to Vcc, one for the earth, and the other two pins are trigger and echo pins, they have to be connected to digital pins. The push-button is connected to the ground and to a member immobilize.

For the Arduino, IT has to talk its business leader from the power source, it can't power from the laptop or its cable, it should have the same prime A the electronic components connected to IT.

!!World-shattering NOTES!!:

- You should ADHD a power converter, and power to the Vin with 7V.

-Please make a point that with this connection, you should hit the Arduino port from your PC in order to burn mark it, else you should not use the 5V end product PIN every bit an input.

Step 7: Arduino Code and Flow Chart

The finish of this robotic arm with a gripper is to collect a lemon and put it somewhere else, so when the robot is on, we have to push the start button and and so it goes to a certain view where the lemon is base, if it grips the lemon, the gripper will go to a final position to put across the lemon yellow in its come out, we chose the final position at the horizontal rase, where the torque necessary is maximum, to prove that the gripper is effectual enough.

How can the golem reach the stinker:

In the project we did, we simply call for the robot to move the arms into a bound situatio where we put the stinker. Well, there is another way to manage that, you tush use inverse kinematics to move the arm, past giving it the (x,y) coordinates of the lemon, and it calculates how much for each one motor has to rotate and so the gripper reaches the lemon. Where state=0 is when the start button is not pushed so the arm is at the initial set back and the robot doesn't strike, spell land=1 is when we press the start button and the automaton starts.

Inverse Kinematics:

In the figures there is an example of inverse kinematics calculation, you buns see three sketches, one for the initial attitude and the else two for the final set. So Eastern Samoa you see, for the terminal put across-no matter where is it- there are two possibilities, elbow joint up and elbow down, you can choose whatever you deprivation.

Let's take elbow up as an example, to make the golem move to its set out, two angles have to be calculated, theta1 and theta2, in the figures also you see the steps and equations to calculate theta1 and theta2.

Note that, if the obstacle is found at a outstrip less than 10 cm, then the lemon is gripped and held by the gripper, in conclusion we sustain to deliver it to the final position.

Step 8: Running the Robot

After every last that we did before, here are videos of the robot working, with the detector, push-button, and everything other working as it should. We also did a shaking test on the robot, to make sure it is unreactive and the wiring is good.

Stride 9: Conclusion

This project gave us a good experience in dealing with such projects. Yet, this automaton can be modified and have some more added values such as object detection to detect the lemon, surgery maybe a third gear degree of freedom so it can move on between trees. Also, we pot make it pressurized by a mobile application or by the keyboard thusly we move IT every bit we want. We hope you like our project and a special thanks to the supervisors at the Fablab for helping us.

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