MicroPilot - World Leader in Professional UAS Autopilots
World Leader in Professional UAS Autopilots

Articles | FAQs | Manuals | White Papers | Infographics

Infographics

 


All infographics are fair use for educational and encyclopedic purposes. Do not delete logo or crop images.

Communication errors
 
When two devices communicate, data can be lost due to communication errors. Either the original message is lost or the acknowledge is lost. The sending computer cannot determine if the original message was lost or the acknowledge was lost. As a result device A no longer knows the state of device B.
   
Multipathing 2
 
Multipathing causes large position errors and occurs when the signal from a GPS satellite does not take a straight path from the satellite to the receiver. Inside a city, a satellite could be blocked by one building but bounce off another.
 
Dual Frequency RTK
 
Carrier phase GPS (also known as RTK) uses the carrier wave to increase the position accuracy. Unfortunately this method provides many locations. By using two frequencies dual frequency RTK simplifies determining which position is correct.
   
Hysteresis
 
Hysteresis is a characteristics of most sensors. For example when a pressure sensor goes from measuring a low pressure to measuring a high pressure it will give different output than when it goes from a high pressure to low pressure.
   
Underfill
 
Normally chips on a circuit board are held onto the board by the solder that connects them to the board electrically. Underfilling a chip glues the chip to the circuit board improving reliability.
   
Thermal Expansion
 
Changes in temperature cause the chips and boards to expand at different rates. This causes stress on solder joints and could cause them to break.
   
trueHWIL vs. quasiHWIL
 
A quasi hardware-in-the-loop simulator exchanges sensor values and servo positions with an autopilot using a CAN bus or serial port. The quasiHWIL simulator changes how the autopilot’s software executes. MicroPilot's trueHWIL electronically simulates sensor inputs so autopilot software executes as if it is in flight.
   
Gravity's effect on Asymmetric clipping
 
Gravity will offset the zero point of a z-axis accelerometer by 1G. This means that vibrations clip 1G earlier in one direction than they do in the other. This results in large accelerometer offset or DC bias.

Gravity makes Asymmetric clipping much worse.
   
Non-Linear Response
 
With an ideal accelerometer, the positive and negative portion of a vibration cancel each other. Real accelerometers do not have perfectly linear response. This non linear response changes the size of the positive and negative so that they no longer cancel. The result is a small DC offset or bias.
   
Multipathing
 
Multipathing occurs when instead of traveling straight from the GPS satellite, the signal bounces off a building or ground. Multipathing can cause a sudden jump in position of hundreds of meters or more.
   
Decrabbing
 
In order to counteract the sideways drift caused by a crosswind on landing a UAS will crab into the wind on final approach. In order to align the wheels with the runway, the UAS’s autopilot must remove the crab or “de-crab”. The UAS uses its rudder to create sideslip that cancels the crab angle.
   
Asymmetric Clipping
 
All accelerometers have a maximum value that they can measure. Any accelerations that exceed this maximum are clipped at the maximum. Since the maximums are slightly different for positive and negative accelerations they clip at different values. As a result, the positive and negative portions of vibration no longer cancel and a DC offset or bias results.
   
   
GPS Signal Rebroadcaster
 
Limitation of GPS signals rebroadcasters; GPS rebroadcasters are a useful tool when you need your GPS to lock indoors. They will not give you an accurate position as they change the path the signals take from the GPS satellite to the GPS receiver.
   
Sculling Error
 
Angular vibration combined with an out of phase linear vibration on perpendicular axes results in an acceleration offset in the axis perpendicular to the two vibrating axes. Sculling error is at its maximum when the two vibrations are 90 degrees out of phase. Sculling error is not measured by the sensor as it is a mathematical effect arising from the body to world translation.
   
Coning Error
 
Angular vibration combined with an out of phase linear vibration on perpendicular axes results in an acceleration offset in the axis perpendicular to the two vibrating axes. Sculling error is at its maximum when the two vibrations are 90 degrees out of phase. Sculling error is not measured by the sensor as it is a mathematical effect arising from the body to world translation.