If you need make your 4WD robot car I suggest to start from this kit that include also 4 encoder.
On BangGood there is a similar kit that is this.
- For drive the motors I suggest to use this board (Adafruit Motor Shield) that mount the Arduino™ Uno V3 connectors.
- The official Arduino page concerning this board is here.
- The schematic of this board, in .PNG format is here.
- The schematic of this board, in EAGLE (CAD) format is here.
- Here there is: Understanding the Adafruit Motor Shield HW & SW
- ATTENTION: For use the Adafruit Motor Shield on STM32 NUCLEO board is necessary do a HW change on the Adafruit Motor Shield board.
For detail see the descriptions that are here.
- Here there is an example based on STM32-NUCLEO and L293D, all is made under the free mBed compiler.
- Here there is a nice mBed library for L293D
A simple example of to use the board is shown below.
- L293D data sheet is here.
- Operation Mode is here.
- Explanation on how to use L293D in Italian language are here.
On the board there is mounted 2 x L293D and 1 x 74HCT595N.
74HCT595N is use to reduce the number of pins necessary for drive the 2 x L293D.
- Here there is the 74HC595N datasheet.
Another board for drive the motors is this.
On Internet there are a lot of example regarding the use this kit, some are listed below.
For avoid the obstacles during the movement of your car robot I suggest this ultrasonic measuring sensor module (HC-SRF04).
For move the ultrasonic sensor I suggest the SG90 RC servo motor.
A kit for mounting ultrasonic measuring sensor and SG90 RC servo motor is here.