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Introducing a Person Avoidance System for Tello


Well-known member
Jan 7, 2019
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Once you have a realtime person detection system and a person distance estimation, how easy is to make a Person Avoidance System for our Tello?
Very easy!
Here the code:

// Start person avoidance if the detected person is at less than 300 cm
if (estimatedDistance <= 300) {
//Slow down longitudinal speed (Sr)
Sr = 30*((int) estimatedDistance-100)/(200)+10;

//Decide to which side avoid the person
if(err_x_angle_value_deg<0) {
//Set lateral speed
Sx = 35;
} else {
//Set lateral speed
Sx = -35;
// Stop the drone if the detected person is at less than 100 cm
if(estimatedDistance<100) {

} else {
// No person is detected, set longitudinal speed and stop lateral speed
Sx = 0;

Here the demo:

Here the Android App:

Here the App Quick Guide:

a. Drone connection
a0. Power on your Tello (and the wifi extender if present)
a1. Put your smartphone in Aero mode
a2. Activate Phone wifi and connect to Tello (or extender) wifi

b. App Setup and Video management
b0. Start Tello Vision 1D
b1. Read and give ok to the Safety Warning
b2. Press 1.COMM to connect the App to Tello
b3. Press 2.VIDEO to start video live preview and recording
After a few seconds live view will appear on the screen
b4. Press VID OFF to stop video recording at the end of the flight

c. Tello Takeoff and height setting
c0. Press 3.TKOFF to Takeoff
c1. Press GO UP/GO DWN and STOP to set Tello vertical position
c2. Press LAND when you need to land

d. Autopilot modes
d0. SPOTLIGHT: Tello rotates to center detected person position
d1. FOLLOW: Tello rotates to center and goes back/forward to maintain setpoint distance wrt detected person
d2. ORBIT: Tello orbit around detected person
d3 PROFILE: Tello translates left/right to center and goes back/forward to maintain setpoint distance wrt detected person
d4. SEARCH: used with SPOTLIGHT/FOLLOW/ORBIT puts Tello in rotation until a person is detected.
d5. PARTY: Tello mission is to find persons and take pictures of them

e. Flight Results
e0. Recorded Videos are saved on the DOWNLOAD phone folder
e1. Selfie and autosaved pics are saved on the PICTURES phone folder
e3. Press STATS to see some object detection and tracking statistics

f. Person Avoidance System
f0. Press GO CCW and rotate Tello toward the desired cruise direction
f1. Press STOP or GO CCW again to stop Tello Rotation
f2. Press GO FWD* to move Tello forward.
f3. If Tello detects a person at less than 3m Tello slows down and starts to avoid the person
f4. Press STOP or GO FWD* again to stop Tello.

Have fun!


New member
Dec 27, 2019
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Nice to see people are still developing things for the Tello, thanks for your contributions! The app seems pretty cool, I've downloaded it & I look forward to testing it out.
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Reactions: pgminin

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