Friday, 18 March 2022

Tim's ESP32-CAM (Little R.O.V. Upgrades)

Tim's ESP32 R.O.V.

This is a little ROV using an ESP32-CAM Module.
There was an earlier version that was as simple as it gets for making an ROV with an ESP32-CAM.
This one has a couple of upgrades, it has a simple track system and has an arm which can hook on to things.

Components

ESP32-CAM and ESP32-CAM-MB

The main module for this is an ESP32-CAM Module.
You can now get an ESP32-CAM-MB (Mother Board) to easaly program this module.
Take a look at what you are buying when getting Mother Board, one of the above MB has only one switch, or the ESP32-CAM for that matter, there are several manufacturers of these Modules.
Check what camera comes with the module, the cameras orientation cannot be changed with firmware, it is fixed. I have done a blog on how to change the cameras orientation if needed,

Before the release of the Mother Board, you needed an FTDI programmer to upload your code.
Before I continue I want to talk about power to the ESP32-CAM, when the Camera is on it needs a lot of power. Depending on which FTDI Programmer you have to program the ESP32-CAM, you may need to use a separate Power supply for the ESP32-CAM, this ensures no brownouts after programming.
The Programmer I have has a jumper to switch the VCC between 3.3v and 5v, this does not change the voltage on the Data Pins, these remain at 3.3v.
On this Programmer the 3.3v comes from the FTDI Chip and does not have enough current to run the Camera.
So the jumper needs to be on 5v, this comes from the USB so the VCC is connected to the 5v on the ESP32-CAM.
The new Motherboard supplies USB 5v to the 5v Pin..

To program the ESP32-CAM, GPIO Pin IO0 needs to be connected to GND when Reset.
Some Motherboards have a switch for this.
I have done a small Modification to make it easy for those that don't have the switch.
I have soldered a small SMD Switch across the two pins.
I used to just put a jumper on these two pins when using the FTDI Programmer, but that cant be done with the Motherboard with only one switch. Without the modification you have to unplug the USB and plug it back in.

About the Motherboards, I have found that I can program and run the Serial Monitor with the ESP32-CAM Modules that came with the Motherboards, the older ESP32-CAM Modules that did not come with the Motherboards, I can only program, I cannot see the Serial from the ESP32-CAM Modules and the program does not run until I remove the ESP32-CAM Module from the Motherboard.

The Arduino code is in this ZIP File: ESP32-Cam_ROV_P.zip
The Arduino code has some options for how you want to Connect with Wi-Fi and which Camera Module you use.
Read the comments inside the code to set the correct choices.
I have put lots of comments in the code so you can see what does what.

Motors and Diver

The motors are the cheep Motor with Gears found by searching for: intelligent smart robot car.
Add about 70mm of cable with Female Dupont connectors on the end to the Motors.

I find it some times cheaper to by a kit, (one may be on offer) rather than by individual motors.
For example:
At the time of writing, two motors where advertised at £5.50 (no wheels), the kit was only £7.90 (has wheels and battery holder).
If you don't have a 3D printer, you could use this kit as a base for this type of project.

The driver for the motors will be a DRV8833 Module.
This is a 2 Channel DC Motor Driver Module Board 1.5A 3V-10V
I am using this driver because it uses less control pins (only 4) from the ESP32-CAM.

To PWM using fast decay, the PWM signal is applied to one xIN pin while the other is held low; to use slow decay, one xIN pin is held high.

PWM Control of Motor Speed
xIN1 xIN2 FUNCTION
PWM 0 Forward PWM, fast decay
1 PWM Forward PWM, slow decay
0 PWM Reverse PWM, fast decay
PWM 1 Reverse PWM, slow decay
The code for the Arduino is written for fast decay.

I like to colour-code the header pins, this helps me get it right when connecting things together.

Battery

I use Li-Po Batteries to power my projects, I will be using one 1200mAh battery.

I use these flat type because they are cheaper than the round bullet type and they fit better into projects.

Buck

I will be using a Step-Up DC-DC Buck to increase the voltage of the battery to 5v.
I found this Small DC-DC Step-Up Adjustable SX1308 2A module.
I have soldered wires direct to this module.
The easiest way to show how the wires are attached, is to do a fritzing of the this part of the circuit.
When soldering the battery wires to it, I kept the top right hole as it is shown open, so that I can fix the module in place with a small screw.
The above is laid out like it should be made. There is about 50mm of cable both sides of SX1308 Buck.
The Servo I am using is an SG90 Micro Servo with a single Horn
.

Hardware

Two Bearings: ID = 3mm OD = 10mm W = 4mm.
Width = 35mm, Length = 40mm, Height =12mm.
The weight is not essential if you just want the R.O.V. to just run around, I add the weight so that the R.O.V. has some mass when opening doors with it's hook.
Not essential, just to add a little grip to the treads on smooth floors while pulling something.
The cable I use is four or three way JR flat servo cable, There are many AWG sizes, I mostly use 22 or 26 AWG depending on the price.
I find the four way is good for when I use I2C devices,
The back side of the headers where it is soldered to the cables
is insulated using UV Resin. (or cheap Ultra Violet Fingernail Lacquer)

I start with a kit and refill it as needed.

Printed Parts

Frame.stl
or
Tread_A.stl (X16)
Tread_B.stl (X16)
The difference between Tread A and Tread B are the hole sizes, I wanted the screw heads all to be on the outside.

Assembly

I will assume you have made/attached all the necessary cables and connectors to all the electronic modules as shown previously.
All screws will be M1.7x6mm Self tapping Screws unless stated.

Fit the Camera Mount Vertical to the Base, with two screws.
Fit two Battery Support, with four screws.
Fit Hook Mount, with two screws.
Fit Servo to Servo Mount, with two screws.
Fit Horn to Servo, with one screw (The one that came with it).
Fit Servo Arm to Horn of Servo, with two screws and washers.
Fit Servo Assembly to Base, with two screws.
Fit both Wheel Brackets to the Motors, with two M3x25mm Allen Cap Head Set Screws.
One mirrored to the other.
Fit both Wheel Brackets with Motors to the Base, use four screws.
Fit Axle Bracket to underside of Base, use two screws.
There is two versions of this, one has mount holes central, the other has holes off-set, using the off-set version enables the slack to be taken out of the track when it loosens with use.
Fit the two Bearings to both of the Idle wheels. (One of each in each wheel)
Fit both Idle Wheels to the Rear Axle, use two M3x10mm Self Tapping Screws.
Fit the Rear Axle Assembly to the Axle Bracket, use two screws.
Fit the two Drive Wheels, I used the two screws that came with the motors.
If you didn't get screws then two M1.7 may do.
Fit a Weight to the underside using the Weight Support, use four screws.
Fit the Hook to the Hook Support and the Servo Arm, use three screws.
Fit the DRV8833 Module with the Motor Driver Bracket, use two screws.
Fit the SX1308 Module, using one screw.
Fit the Re-Set Bar. This just slides over the Camera Mount Vertical.
Depending of the orientation of the ESP32-CAM, this aids pushing the Re-Set Button if the Re-Set Button ends up at the bottom.
Fit the ESP32-CAM Module.
The ESP32-CAM Module should just slide inside the two slots of the Camera Mount Vertical.
Make up two sets of Track.
Each Track is made up of eight Tread A and eight Tread B, with sixteen screws.
Make sure the Treads pivot around the screws, don't over tighten the screws.
If you want to add foam pads to the treads, it is a good time to do this now.
Fit the Tracks to the R.O.V.
Easiest method is to remove the Drive Wheels, assemble and re-fit the Drive Wheels. 
Time to connect some cables.
It should be just a matter of plug things together if the cables shown previously have been made.
Reference: Tims_ESP32-CAM_ROV_Power_Module.fzz, while connecting the cables from the SX1308 Module.
Bring the cables from the Motors up through the hole between the two Battery Supports, plug them onto the DRV8833 Module.
From the SX1308 Module, take the Cable
and plug it onto the DRV8833 Module.
Make sure of the correct polarity.
Take the Cable DRV8833 IN1 & IN2, also the Cable DRV8833 IN3 & IN4 and plug these onto the DRV8833 Module.
Next fit the Power Cable that goes to the ESP32-CAM.
Then fit the Cables for POI 2, PIO 14, PIO 15 and PIO 13 on the ESP32-CAM.
The Servo Plug goes to the Pins for the Servo.
It is best left unplugged until the first time it is switched on and has been adjusted.
Instruction comes later.
Now fit the Battery.
I haven't fitted a switch, to turn it on and off, connect and dis-connect the battery.

There are some checks to do the first time you connect it up.
First you will need to connect to the ESP32-CAM with your Wi-Fi device.

A Wi-Fi Device = Mobile Phone, Laptop, Tablet, PC or similar.

Depending on you choice of Wi-Fi connection in the Arduino Firmware.
The choices of Wi-Fi connection are:
  • Access Point
  • Local Network
"Access Point"
This is not connected to your local network, you connect to the Network of the ESP32-CAM.
This means you can connect to it with your Mobile Wi-Fi Device any ware you are.
You change the Wi-Fi your Device is connected to, to the ESP32-CAM Wi-Fi.
Then open a browser on your Device to the IP of the ESP32-CAM control page. (may be
)
Have your serial monitor connected when you re-set the module to confirm correct IP Address.

"Access Point Password"
This is same as above, but you need a password to connect to the Wi-Fi.
It currently is: 2468

"Local Network"
This is, both you and the ESP32-CAM, connects to your local network.
You will need to give the SSID (name of your network) and the password required to gain access to your network.
You can connect to the ESP32-CAM from any devices browser that is connected to your network.
Open a browser to the IP of the ESP32-CAM control page. (may be 192.168.0.46)
Have your serial monitor connected when you re-set the module.

When connected with your web browser, the web page should look like this:
The LED Slider turns on the LED at a percentage of it's full power, it does not go full power there is no need.
The LED is designed as a flash, so it should only be on full for brief amount of time.
The Buttons do the movement, so the first test is to check that the motors go in the right direction.
Push the Forward Button, check that both motors rotate forward.
If any of the Motor run in the wrong direction, then that motors plug needs to turned around. This is the plug that is on the end of the cables from the Motor.
The Speed Slider sets the speed at which it moves.
The Servo Slider moves the Arm up and down.
The Servo will probably need to be adjusted the first use.

Servo Adjustment

  • Unscrew the screw holding the Servo Horn in place.
  • Pull the Servo Horn away from the servo.
  • Plug in the Servo Cables to the Servo Connector.
  • Connect to the ESP32-CAM with your browser.
  • Try the Slider for the Servo, the servo should move.
  • Set the Servo to Zero Degrees.
  • Re-Fit the Servo Horn so that the Servo Arm is in the following position.


You should be all set to go roving about with your Remotely Operated Vehicle (R.O.V.)

To open and get through doors I made a little ring that can be fixed to the bottom of the doors.

Here is the video again:

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