Blog #3 - Solar Powered Remote Controlled Lawn Mower

 

        Over the period of March 12th to March 26th of 2022 group 19 finished the last minor tweaks needed to complete the prototype of the our lawn mower. We added a second cutting motor and blade since with just one of them our cutting width was only 5.5 inches. The prototype mower is fully complete and is ready for the demo on the 28th. It can travel as far as 245ft at an average speed of 2.92 mph while the blades and all the other components are powered on. The fully assembled mower is shown below in Figure 1, and an overview of the mower with the solar panel removed labels the main components in Figure 2.

Figure 1: Fully assembled RC Solar Lawn Mower

Figure 2: Mower with panel removed

In terms of challenges or obstacles, implementing a second cutting motor and blade was definitely one. Since the first blade/motor was centered and had a hole cut for it already, working around that area and cutting two new holes for each cutting motor and blade was tricky. The cuts had to be precise since cutting too much would affect the overall structural integrity of the chassis, and cutting too little wouldn’t allow the motor/blade to sit properly in place. Another challenge we currently have is finding a way to house the small live feed camera. The camera itself reaches high temperatures just after a couple minutes of use, so mounting it down in some type of small box or with walls will be challenging. Doing so would prevent any grass from getting near the camera which could potentially cause the grass to light on fire. The team is contemplating removing the camera system from out design, since it is hard to implement and testing shows the mower is best operated with a direct line of sight.   

For the work period of March 27th to April 9th, we will be presenting our prototype for the demo day and getting necessary feedback from the instructor and our mentor. The prototype will then be updated according to the feedback we receive, if any. During this time we will work on addressing the issue with the camera system. We will also be working on the final technical report and technical report presentation/slides.

We have completed preliminary validation testing on the speed of the lawn mower. A measuring tape was used to measure a 50 ft distance and a stopwatch to measure the time it took for the lawn mower to travel that distance. The test was run 5 times to ensure repeatability and validity. As seen in Table 1, we ran 5 trials with the cutting motor off and 5 trials with the cutting motor on. The difference in the averages is negligible, hence we can conclude that having the cutting system on does not exert a penalty on the system. The speed of the lawn mower was then calculated using the Distance/Time formula:

50ft / 11.68s = 4.281 ft/s 

1 ft/s = 0.68181818 mph

4.281*(0.68181818) = 2.92 mph

                

Table 1: Time for the mower to travel 50 ft