GPS-Guided Parachute Steers Falling Objects Home

Every day over one hundred weather balloons are launched daily in the US alone. Worldwide that number increases to over one thousand. These balloons have the mission of drifting into the atmosphere to collect data on the temperature, humidity, and pressure utilizing a device known as a radiosonde which relays that information wirelessly back to Earth. Ultimately, these balloons will reach a bursting altitude in which the balloon will pop and the radiosonde will parachute back down to Earth. Ideally these devices are found and re-used for future tests. However, the reality is that only around 20% of these devices are actually found and returned, costing the government thousands of dollars. One maker may very well have the perfect solution for having all those devices returned autonomously to known locations.

The R2Home robot is a steerable parachute that can help guide objects to desired landing points. The device consists of three main components. First is the drogue chute. This is a small parachute that is first to be deployed when an object is in freefall. The second component is the steerable parachute (wing chute). After the drogue chute slows down the device to a terminal velocity, the steerable parachute will deploy and be used to steer the device towards its destination. The third main component is the body that house the electronics and mechanics.

The automatic deployment of the parachutes is achieved through a combination of a barometer and an altitude sensor which allows an approximation of vertical speed. The drogue chute is first to deploy, slowing the device to its terminal velocity. Next, the wing chute, which steers the device is deployed. The process is accomplished through a clever mechanism which uses the drogue chute as an extraction force for the wing chute. As the drogue chute is deploying it pulls the wing chute out of its deployment bag. When the terminal velocity is reached, both the drogue chute and wing chute are both deployed. To prevent the drogue chute from interfering with the wing chute, a collapsible drogue chute is used, allowing the wing chute to take over and guide the device home.

To control the device a Teensy 4.1 board is used. The Teensy acts as the brains of the system constantly monitoring the sensors, the included GPS module, and ultimately controlling servos which steer the wing chute. In addition, the GPS module is used to determine the desired destination and the real time direction of the device. Using that information an error direction is calculated and used to determine whether the device needs to steer straight, turn left, or turn right. The entire device is built and assembled into a 3D printed housing and powered using a LiPo battery.

The device was tested by using a drone to lift it 100m high and 100m away from a central location and then dropping the device. This was done from four different directions with each test proving successful. The device always guided itself back to within a few meters of the desired central landing location. Future improvements to the device include adding a feature to allow it to choose to land in multiple “safe zone” locations, and testing it from higher altitudes. In fact, the creator hopes to someday achieve a flight altitude of 30km using the device.