RC Robot

I have been busy over the last couple of months with a new project. Due to my lack of imagination I am calling it the RC Robot. The aim of the project was to build a sturdy, reliable mobile robot platform to use for future development. I am a bit of a purist and don’t really consider a remote controlled vehicle a robot. However, to start with I wanted to make the robot remote controlled, as I thought this would be a good fun place to begin.  I have every intention of developing this project and adding autonomy at a later date. I also vowed to use some of the many parts that I have accumulated over the years of robot building, basing the drive system around some 12-24V brushed gear motors that I have a number of from a previous project. I also wanted to document the build in the form of a series of Youtube videos.

I kicked off the project by designing the drive assembly. As mentioned, the motor/gearboxes were in my parts box and are 12-24V como drills units, geared at 30:1. These were still a bit quick for my needs so I designed and built a simple gearbox, complete with bearings for support of the output shaft. I initially attempted to design and build a belt drive system, but for various reasons abandoned this in favour of using gears. I decided to use SLA batteries for this project and two 12V, 2.1Ah batteries in series gives a good solid 24V to work with. Check out the below video for a breakdown of the design and initial testing.

 

 

The next step of the project was to add some electronics to drive the two motors. An L298 based motor driver was ideal for the job. Add in some HC-05 bluetooth modules and an Arduino or two and I had myself a way to remotely control the speeds of the motors using a joystick. Part 2 below shows the development and testing of the electronics system along with circuit diagrams.

 

 

Once confident that the drive assemblies and electronics were up to the task, the next job was to design and fabricate the robot chassis itself. Some 2mm aluminium sheet served as a sturdy chassis plate for the robot and a strong castor was selected to serve as the 3rd wheel. My initial design for the base plate and the mounting for the castor was disappointing and not particularly aesthetically pleasing. After 3D printing a fancy castor mount I was much happier with the look of the robot. Part 3 of the video series covers the chassis build process and the first tentative test drive before the electronics were properly mounted.

 

 

The next job was to take the electronics from prototype breadboard to a more permanent stripboard circuit, ready for mounting to the robot. All of the required electronics were mounted to the top plate of the robot and the final wiring completed ready for the first proper test run!! It was a sunny day and I had a fun hour test driving the robot in the sunshine. Part 4 shows the results of the test drive and an appraisal of the robots performance.

 

 

During the initial test run I found that the robot was a bit of a handful to control. I had the controls set up for a skid steer type arrangement, with the raw joystick values being sent to the robot and converted into motor speeds with very little additional processing. Whilst great fun and a good challenge, I wanted a bit more control of the robot when manually driving it. I decided that encoders would help the situation by allowing for some closed loop control of motor speeds. I knocked up some homemade incremental encoders to allow the motor speeds to be measured and set about adding these to the robot. Part 5 is a more tutorial type video to show you how I added encoders to the robot.

 

 

And this brings us right up to date. I have promised myself to update this blog a bit more often, particularly when I have a new video to share. Stay tuned as I have just finished work on the controller and will have a new video to share very soon.

If anyone reading this would like more information on any of my robots, please feel free to leave a comment, either here or on the Youtube video and I will always do my best to help.

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Hi, I'm Jim. Read what I write and I'll write more to read.

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