Review on 🚗 VKmaker Smart Robot Car Chassis Kit with Speed Encoder, Ultrasonic Module, and Battery Box - New Avoidance Tracking Motor System 2WD. Includes Tutorial CD. by Jamar Gow

As others have pointed out, this kit isn't exactly perfect. You will be given all the parts you need to build this robot, but no part of the build will be an easy task. I would not recommend this kit for those new to Arduino or electronics. Nothing will work right out of the box. Someone with a little experience can turn this set into a fun working robot. At least you get a lot of good parts for the price in this set. First I'll cover some of the build issues I've encountered. Arduino and motor controller can be attached to acrylic with just two screws each. If you want more, you'll have to drill your own screws. I've decided against it for now, and it's holding up quite well. The battery compartment holds six batteries and only one hole fits the acrylic. I solved this problem by using velcro to hold the battery in place. The servo arm was already installed in the servo holder, but the screws were installed on the wrong side. The included instructions suggested "fixing" the screw through the center of the arm into the servo shaft, which would work, but I also decided to fix the screws that weren't properly adjusted. Despite all this hard work, you will still find that the screw holes in the acrylic don't quite line up with the screw holes in the base of the servo. Others point out that the instructions for connecting the motor controller are wrong. I noticed that with my set too. However, where others found the problem was that the analog pins had been renumbered to one, I decided to use digital pins and reserve the analog pins for future use with real analog devices. Once assembled, the last issue I had was the instructions for connecting a power switch between the Arduino and the motor controller. This isn't ideal since the Arduino board is always powered on after you install all the batteries. I cut the red power wire of the connected barrel and connect the switch right after the battery so that when the switch is pressed the entire robot turns on. Others have complained that the rear roller needs shims or is not quite aligned. It's funny, but this was the only piece of my kit that worked with no issues. Another reviewer, Perspicacious Consumer, commented that the ultrasound scanner was "crap". I agree. As for the included Arduino sketch, it stinks. This is very poorly written code that needs editing for the kit to work. At the very least, you'll either have to adjust the analog pin connections as mentioned earlier, or change the pin values in the sketch. As Astute Consumer pointed out, if you don't enable PWM by commenting out the AnalogWrite commands, your robot will run at full speed. I have hardwood floors in my house so I have to run the motors just above stall speed or the robot will 'fall' off, spinning the wheels in place and not catching traction. There is another big problem I have with my kit. No matter what tricks I tried, I couldn't get the left and right motors to work in sync, causing the robot to deviate from side to side. The kit includes shaft speed encoders, but for some odd reason it doesn't include the photo-optic speed sensors needed to read the encoders. I've ordered a couple of speed sensors and will update this review with my results once they're installed. Despite everything I mentioned above, this kit is pretty fun and I've already started writing my own library for it. It has a lot of potential and room for refinement and additions, but it will take a little know-how and perseverance to make it work.