Introduction: Intelligent Feeding Arm for Humans - Not Only for Lazy

Requirement is the mother of invention

Automatic Moving Machines make us very Lazy.


Lot of home inventions and automation are done for people who cant able to done. But it makes persons physically well to gone lazy.

From where the thinking comes

In Hospital i found physically ill persons on bed cant able to take their food by their own hands. Some one want to feed them. Some times patients also don't like to be feed by others. Some times feeder want a long time to feed the patient. So if a robotic arm can feed then the patient who dont need other to feed and take long time to eat can take care by the robotic hand.

Here we want some mothers touch. If the patient don't hold the bowl and spoon can't able to know the heat of the food. So I plan to provide a temperature sensor and small fan. So if the heat is high it never feed, it switch on the fan and cool it. Once the temperature is up to eating level, then it stop the fan and take the soup in spoon. Wait for the person to eat. When the person eat it again take the food.

I feel its a simple plan. Usually like my previous projects Quote, 'I have only limited resource' so i can't able to use 3D printer to design the arm. I use light weight wiring pipes and micro servos. So i study a lot in this project, like counter weight to balance the load, create Pattern to take uniform output etc... Lets see all the steps including the errors like, make a long arm and then cut it, adding counter weight in the arm.

Step 1: Full Plan

1) Make a four servo robotic arm controlled by 9 g Micro servo.

2) In Arduino side, use a temperature sensor to find the temperature of the food. If the temperature is high then switch on the relay for the fan using arduino.

3) If the Arduino detect the temperature is normal then it switch off the fan and start feed.

4) In the spoon side want to use two spoons with top full spoon and bottom only center part of the spoon. if any one touch with mouth and both spoons join it is sense by arduino and the spoon again fetch food to eat.

5) Use separate switch for ON/OFF the whole sequence.

Step 2: Materails and Tools Required

Materials Required

1) 19mm PVC wiring pipe.

2) 19mm PVC wiring coupling

3) Hard plastic bottle for base.

4) Hard Bowl for base.

5) 9g Micro servo.

6) Arduino Uno.

7) Power Supply.

8) Screws and nuts.

9) Fan.

10) Small pump.

11) ON/Off Switch

12) DS18B20 Temperature Sensor

13) Wooden sheet for base.

Tools Required

1) Hacksaw.

2) Drilling machine.

3) Hot Glue Gun.

4) soldering iron, Lead, Paste.

5) Screw Drivers.

Step 3: Robotic Arm Plan

1) Before start the project i test the model with straw and safety pin.

2) So here i plan to use 4 servos for 4 axis movement.

Step 4: Make Straight Cutter for PVC Pipe

1) Pipes are want to cut straight, for that i am going to make a simple tool.

2) Take a Coupling and cut one end.

3) Insert it into the pipe and mark the distance in the pipe.

4) Now use the Hacksaw and cut the pipe. Now we able to cut it straight.


1) At first i cut 30 cm 2pieces and 10 cm 2 Pieces. At the end of the project reduce 30cm to 15 cm. Trim 10cm to connect with coupling.

Step 5: Make Tracing for Equal Marking

1) Make a tracer in paper to mark in all pipes for correct marking of Servo and its arm.

2) Roll a A4 paper in a PVC pipe.

3) Paste the ends.

4) Remove the paper from the pipe.

5) With the Servo size draw the lines in the paper. Also mark the center of the hole for drill.

6) Cut the paper for servo slot.

7) Now the pattern is ready for marking.

Step 6: Mark, Cut and Drill PVC Pipes

1) Now insert the pipe in to the marking paper and trace the servo outline and the center points for drill.

2) Remove the pipe and insert another pipe and mark in that pipe.

3) Now use knife and drilling machine cut and drill the pipe.

4) In the Servo arm fixing hole make a straight hole. So that we are able to insert the screw driver for join with servo.

Step 7: Fix Servo and Arm

1) Place a Arm over the hole we already drilled in the pipe.

2) Mark on both sides for screw.

3) Use a 2mm drill bit to drill the two hole.

4) Now put the arm inside the pipe and screw it with pipe.

5) Put the Servo through the hole on one side and allow the rotating side through opposite hole.

6) With out screw or glue its very tight, but for safety we want to glue it with hot glue gun.

Step 8: Fix the Links

1) Join the servos with its arm.

2) Simply put one joint over another and screw it through the hole.

Step 9: Make a Rotaing Base for Robotic Arm

1) Making a rotating base of robotics take some more time, because we cant able to fully load the servo. So i select a plastic bottle with long lid on the sides.

2) So the plan is bottle hold the weight and servo only rotate the lid.

3) Take the lid and remove the thread using knife, so that it never get tight and rotate freely.

4) Using a pipe paste a servo on the center of the bottle.

5) Paste the servo arm on the middle of the lid.

6) Now hot glue a 19mm pvc Coupling on the top of the lid.

7) Screw the lid servo arm with the servo in the bottle.

8) Now fix the Robotic arm with the rotating coupling and make two 2 mm holes in the coupling with robotic arm. Fix it with a screw.

Step 10: Change Arm Length

1) After Complete the arm I found the arm is very long (almost 3 feet) and its makes the servo more burden.

2) So cut the long 2 arms of the robotic arm. and remove a portion and join it again using a 19mm coupling.

3) The arm size from joint to joint is 15cm. Now the arm working fine. Only problem with first servo during lift from 0 pos or from 180 degree it not able to lift. Want to add a counter weight to correct it

Step 11: Wiring the Robotic Arm

1) Wiring the robotic arm is a plan where all the vcc and gnd want to loop and separate wire for signal.

2) so cut the female connector come with servo. Take two long wire for VCC and gnd. Pass all wires through the pipe. Take a separate wire from each servo (yellow-signal) with equal length up to base.

3) In the joints leave some wires for moving freely.

4) Cut the 2 supply wire and 4 signal wire in equal length and solder a single 8 male header pins(other 2 for spare and y servo want to connect).

Step 12: Shield Making

1) Making a shield for each projects separately is my principal.

2) So for this also i make a shield. But in this shield i fully use maximum digital pins and plan for future development.

3) In this shield i able to control 6 servos, 2 input circuit and 2 output relay module included (For future development).

4) Pins used in the shields are

1) Digital pins 3,5,6,910,11 are taken out and connected to a female header with extra two external VCC and GND for servo control. the external VCC and GND is joined using a 1000micro F capacitor to avoid servo from vibration.

2) 5 V relay module two nos is connected to the digital pins 2,4.

3) Input basic circuit using 10K ohms is connected to the digital pin 7,8.

Step 13: Complete the Robotic Arm

1) I need a ling base for my arm. I found a Blue color bowl match with the rotating base.

2) Hot glue the base with the bowl upside down.

3) Add a counter weight in the first arm back side. So that the servo can able to move the arm freely.

3) The bowl is very hard and weight so it make the robotic arm stand straight and it provide the house for Arduino.

4) Arduino with shield is kept inside the bowl.

5) For test temporarily i fix a spoon on the tip of the robotic arm by just drill (Feeding sensing spoon want to make).

Step 14: Servo Test Program

1) In this project i use 4 servos on pins 3,5,6,9.

2) In the Dot net program i use vertical and horizontal scroll bar with values 0 to 180.

3) On change the scroll bar the value in the scroll bar send to Arduino through serial port communication in and the servo move in the robotic arm.

4) On change the steps i note the degree for operation and in the full automation program i use that sequence to feed and stirrer.

Step 15: Arduino Programming


Servo - Default with arduino IDE.

One Wire - Click to download

DallasTemperature - Click to download


1) Using test program here i listed the position of servo with normal spoon.

2) With that position i create separate functions in Arduino.

3) Using serial port check the temperature.

4) The Function name and whats the output and action is listed in the spread sheet.) With that plan i created the program. The sequence is

a) While power on the servo move to home position from default posiition.

b) after place the bowl and ON the start switch.

c) Temperature is measured and if the temperature is greater than the given value (i give 50). The fan switch on and the Stirrer function works.

d) If the temperature is less than or equal to given value. Then fan is switch OFF and the arm move to start position and pick up the soup from the bowl and bring near to mouth position.

e) if the soup in the spoon is drink by us it activate the switch in the spoon and arm again move to start position. Other wise it wait.

e) At any time if switch is off the arm back to start position and then to home position.


Step 16: Basic Feed Test

1) With out the Automatic sequence first i tested only the feed sequence. It working fine and want to change some code after finishing to make it smooth run.

Step 17: Circuit Panel

1) Want to select a panel to keep all the circuit together and not visible to all. A large space available under the robotic arm.

2) So i keep all the circuits inside the bowl.

3) Fix the on/off switch on the side of the Robotic arm.

4) Let all other wires temperature sensor, Power wire, Fan control wire come out through holes in the bowl.

5) Now the Robotic arm is fully finished. Want to make the feeding spoon.

Step 18: Make Spoon With Sensor

1) Make a spoon start with the selection of spoon. It must be weight less and strong.

2) I found a plastic spoon which cost only 0.15 Dollar.

3) Its very long so i cut to the required level.

4) Hot Glue the spoon with the Robotic arm after remove the test spoon.

5) Now want to make a relay like arrangement (NC - normally close) to sense that taken soup is drunk by the parson.

6) So cut the spoon (I use for test), only the to portion to side, So that it match the bottom of the feeding spoon.

7) Make a seasaw like arrangement as shown in the figure and paste two small plain pcb soldered with wire both in the tip of top and bottom spoon.

8) Test it with the multimeter, due to front portion weight more it shows continuity on normal feeding stage and when lift with lips it shows open position.

Step 19: Wooden Base

1) Even though base bowl is heavy weight we also want to fix it in a weight less ling wooden piece. It also never allow the circuit to come out while shift.

2) We already provide holes for power cable and sensor cable in the bowl.

3) So cut the wood piece for Robotic arm and soup bowl and screw the robotic arm with the base wood.

Step 20: Make Fan for Cooling

1) Lot of fan readily available in market. But i want to make a color full one.

2) U even control a 230V AC fan with this circuit. But i only use a 5 V DC fan.

3) 5V dc motor, Fan blade, Waste Plastic lid ( from liquidator), a rod from old PC mic with stand (it is able to bend in any direction and angle.

4) Pass wire through the road and solder with the motor. Hot glue the lid with the rod and insert the motor in to the lid.

5) Fix the fan blade to the motor.

6) Make holes in the wooden base and screw the fan base with the wood base. For Safety hot glue it also.

7) Now we able to change the position of the fan. Move it to the position where its arm never affect the Robotic arm movement.

Step 21: Bowl Holder With Sensor Slot

1) Make a bowl holder which hold the bowl and make the bowl contact with the Temperature sensor tip.

2) Use card board to make holder.

3) First make 4 round of almost 6 cm radius (because my bowl base if 5 cm radius).

4) Take two and remove the center with the radius of 4 cm, Make a slot in the ring so that its allow the sensor wire to come in.

5 )Take another two and take 5 cm (some units greater than 5cm so the that bowl sit in) radius.

6) Now paste all the rings together in the order of two 4 cm inner ring in the bottom and two 5 cm inner ring over that.

Step 22: Finishing Touch

1) Even all working fine. We want to give a finish touch by adding color.

2) Remove all the arrangement from wooden base and paste color paper over the wooden board.

3) After dry again screw it in the board and paste the Bowl holder in the correct position.

Step 23: Stirrer Test

Step 24: Feed Test

Step 25: Feeding Video

Step 26: In Full Action

See the Arm with full action. Details of function listed in the top of the video.

Its a very long journey for this Project. Lot of Lessons learned. Vote for me if you like this project.

Thanks You Very Much For Watching.

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Make It Move Contest 2017

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