RC Car Dynamometer
I designed and built this RC car dynamometer within my mechanical engineering internship at the Active Learning Labs at Harvard. It replaces an old and obsolete machine that was outdated and difficult to use. This will be used for years to come in a thermodynamics lab for a class at Harvard.
This device is relatively simple in concept--dynamometers are used to characterize motors, and in this case, it is used to quantify the work output of RC cars. In the lab, the input energy is compared to the work output of an electric and a gas powered RC car.
To find the amount of work produced by the cars, the only variables needed are the RPM and the calculated moment of the flywheel bar. To find RPM, I attached a magnet to the flywheel bar so that every rotation, a Hall Effect sensor would send an interrupt signal to a micro-controller. Combining that with the calculated moment of inertia from the flywheel bar, the rest of the data can be dynamically plotted and observed.
As far as the important physical aspects of this project, the flywheel bar was turned on a lathe out of 3 inch solid aluminum rod stock. Precise measurements were required to achieve interference fits with the bearings upon which it rotates. The brackets that hold the bearings were machined utilizing a CNC mill. To challenge myself, I wrote the G-code by hand, as it was a relatively straightforward set of circular patterns to cut. The board where the micro-controller is fixed was laser cut (along with some added decals representing the school). The rest of the aluminum frame was made of leftover materials from previous projects that were left in the shop.
This device is relatively simple in concept--dynamometers are used to characterize motors, and in this case, it is used to quantify the work output of RC cars. In the lab, the input energy is compared to the work output of an electric and a gas powered RC car.
To find the amount of work produced by the cars, the only variables needed are the RPM and the calculated moment of the flywheel bar. To find RPM, I attached a magnet to the flywheel bar so that every rotation, a Hall Effect sensor would send an interrupt signal to a micro-controller. Combining that with the calculated moment of inertia from the flywheel bar, the rest of the data can be dynamically plotted and observed.
As far as the important physical aspects of this project, the flywheel bar was turned on a lathe out of 3 inch solid aluminum rod stock. Precise measurements were required to achieve interference fits with the bearings upon which it rotates. The brackets that hold the bearings were machined utilizing a CNC mill. To challenge myself, I wrote the G-code by hand, as it was a relatively straightforward set of circular patterns to cut. The board where the micro-controller is fixed was laser cut (along with some added decals representing the school). The rest of the aluminum frame was made of leftover materials from previous projects that were left in the shop.