The quadruped robot in this project simulates the gait of a dog and simply realizes the function of moving forward.
This is the first time to do such a complete thing, including PCB board welding, shell design, and python development. It feels like I have stepped on a lot of pitfalls.
First use Lichuang EDA standard print PCB and place an order, free times every month~
The USB power supply in the lower right corner is useless because the eight-way servo requires a large current, but the maximum USB power supply of the computer is only 500mA. This was only learned later.
In addition to the raw materials shown in the BOM list at the bottom of this project description, we also purchased some necessities:
Eight MG90 servos
One PCA9685PW chip
Several M2.58 round head cross screws
Several M2.58 nuts
Several M1.78 self-tapping screws
Several M340 nylon columns
Several M312 flat head cross screws
Several M2.512 hexagon socket screws
Several M2.510 hexagon socket screws
Several M2.512 anti-loosening screws
One 5mm hexagonal thin wrench
An inner hexagonal wrench
900M-T-SK small soldering iron tip
A 200W heating plate
Lead-free low temperature solder paste 20g
Cut a piece of acrylic shell
Excluding screws, nuts, various tools and solder paste that can be reused, and excluding the BOM list purchased with Lichuang coupons, this project costs about 150 yuan.
There are also some tools that are required, the list I use is as follows:
Yihua 936 adjustable constant temperature soldering station and its soldering iron tip
Curved tip stainless steel tweezers
UV223 flux paste
White Monkey 63 solder wire
Phillips screwdriver
VC820L multimeter
Water mouth pliers
I already have the pin header and battery, just use them
It was my first time to solder chip components. Even with a small blade, it was still difficult to solder, especially several 0402 capacitors. I had to replace several boards. Finally, I used the heating plate and solder paste. It felt much more comfortable and was done in one step.
After welding, you need to carefully check the continuity of the circuit (use the buzzer setting of the multimeter) to prevent accidents after powering on...
As well as the connection between each pin and the pad, it seems that it is easy to solder.
There are also 0402 patches and this kind of very small ones, which are easy to connect to the tin and cannot be seen, so you need to test them more. There was a lot of soldering oil left by the flux on my board, which blocked my view and needed to be wiped with board cleaning water.
After soldering the chip components, it is more convenient to leave the rest to the soldering wire.
Weld the board and install it into the case after testing and if there are no problems.
Although the acrylic shell is made according to the official one, after assembly, it seems that there are openings in some places to facilitate plugging in wires, buttons and other operations, so you should adjust the design of the shell according to the board you drew. 3D printing is more flexible, and you don’t need to make boxes, but I don’t know how to design yet...
For the installation of the dog legs, we also refer to the official installation directions. Dog legs can be divided into knee and elbow styles. I don’t know much about this aspect.
Because I don’t know anything about Linux and have no experience in firmware development before, I didn’t write the firmware program myself. Just use the existing DAP-LINK, use the serial port on it, burn the officially provided firmware into the main control chip, and then use Pycharm and Yuanqipai plug-in to program the dog-leg action.
Since the battery used was not good enough, it could not carry the current of the eight-way servo. After reducing the servo, the dogleg was able to run normally. It was determined that the problem was with the battery. In addition to replacing the battery with large power supply current and the shell design, this project also has a lot of room for improvement. In addition, due to the powerful main control function of the ITCAST-HI3861 module and the firmware development based on Hongmeng system, it also provides a favorable foundation for the addition of subsequent functions.
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