Original, most unmanned aircraft is simple toy nevertheless. However, their flight ability had recently rise significantly, it is safer, stabler, easier that the drill that lets them accuses, make the application of their in actual life wider and wider also thereby.

 

The crucial factor that these ability raise was to use system of high-powered personal computer cable (MEMS) sensor, the sensor market in having man-machine consequently is rising in apace: According to Yole ” the sensor that uses at unmanned aircraft and robot ” report data, the sensor market growth that applies at unmanned aircraft and robot is driving, predict to will reach 709 million dollar 2021, arrived 2018 2021 compound year of increase rate for 12.4% .

 

The influence does not have the MEMS sensor of man-machine flight function

 

Unmanned function retains way quite stable, be held to accuse definitely by user essence, fly automatically perhaps, rely on inertial MEMS sensor. However, a few challenges that face without man-machine make its system design becomes complex: Motivation of insufficient perfect, system follows electric machinery calibration load differs and change, moving condition alternates quickly, or sensor introduces inaccurate information. These bring about fixed position possibly to process generation error, positional mistake appears when bringing about navigation finally, cause unmanned aircraft trouble even.

 

Should letting unmanned aircraft is a toy not merely, even “ is further upward ” , providing high-powered MEMS sensor and advanced software is indispensable. Of the high accuracy on advanced and unmanned aircraft inertial measure unit (IMU) , node of baric sensor, magnetometer, special sensor (ASSN) and the data between sensor is shirt-sleeve, have to its flight function mix directly the influence of materiality.

 

Get measure limitation and harsh environment and moving condition, be like temperature wave motion and vibration, promote new standard to the requirement of sensor. MEMS sensor must reduce these effects as far as possible, offer essence of life to allow reliable measurement.

 

The method that achieves outstanding flight performance basically has: Software is algorithmic (if sensor calibration and data are shirt-sleeve) , mechanical system is designed (if reduce vibration) , and the requirement according to unmanned aircraft manufacturer and sensor of demand choice MEMS. We pay close attention to MEMS sensor through key of a few example below.

 

System of boat appearance reference (AHRS) the “ heart ” that is unmanned aircraft, it includes inertial sensor, magnetometer and processing unit. AHRS but beforehand the advancing direction of appraise equipment, if boil,turn, the angle of a simple move or action and crab. The inaccuracy of sensor, be like error of deflection, sensitivity or hot drift, can cause directional error. Graph 1 showed directional error (angle of scroll, a simple move or action) concern with the function of accelerometer deflection, directional error is the biggest factor in sensor error catenary normally. For example, only the acceleration deflection quantity of 20 Mg will bring about equipment to appear 1 degree direction error.

 

Graph 1: The directional error that accelerometer deflection causes

 

Inertial measure unit (IMU)

 

IMU includes accelerometer and gyroscope, contain embedded processing program. This makes it can decide athletic contrail, include to linear moves and rotate.

 

The BMI088 of Bosch Sensortec is IMU of a 6 axes, have accelerometer of 16 low noise and gyroscope of 16 low drift. The technology of parts of an apparatus of this kind of high accuracy comes from high-end car sensor, because of this it can be in longer the slanting that keeps outstanding inside time buy and temperature stability, and have outstanding vibration rash club sex, make its make the good choice of unmanned aircraft.

 

Graph the 2 typical values that showed BMI088 follows temperature drift.

 

Graph 2: BMI088 is worth along with the model of temperature drift (acceleration and rate are 0)

 

The deflection limits in 10 Mg less than and gyroscope is less than the range that shows drift amount represents accelerometer deflection 0.5 Dps. In addition, BMI088 behavior expression and temperature show linear concern, and have lag appearance hardly. This makes BMI088 applies in unmanned aircraft and robot have appeal extremely.

 

Baric sensor

 

The high-powered baric sensor of the buy inside unmanned aircraft can measure height accurately, can use at height to control with the reading union of IMU. Baric sensor must decrease as far as possible external influence and error. Current, with other sensor, for example GPS and light shed union of sensor, range finding sensor to use, can raise systematic dependability and reduce position error.

 

The BMP388 baric sensor of Bosch Sensortec is used at providing high information, the control of ameliorable flight stability, height, function that take off and lands. This makes hold accuse to become easy to do without man-machine, can attract more extensive user accordingly.

 

The unmanned aircraft requirement to baric sensor the extreme is normally slashing. Even if suffers bad weather and air temperature effect, high precision also must be controlled inside strict tolerancepublic errand limits, along with time elapse additionally sensor must maintain the drift of low defer and very little to measure. BMP388 can satisfy these Yan Ke’s requirements, its are relative to precision + / – 0.08 HPa (+ / – 0.66 M) , 300 be in to the very precision between 1100 HPa + / – 0.5 HPa, low temperature coefficient is compensated (TCO) be less than 0.75 Pa/K normally. It has the sexual price that has appeal extremely to compare, power comsumption is low and enclose dimension minimum, it is 2.0mm X 2.0mm X 0.75mm only.

 

Besides improvement besides TCO, still a variety of elements can raise integral precision: Relative to noise, stability and precision, very precision. Arrive from awakward toy high accuracy aircraft, current and unmanned aircraft applies what medium latent capacity surmounted engineers to envisage in industry and commercial innovation.

 

Magnetometer

 

Magnetometer resembles is compass, can be course of unmanned aircraft establish according to earthly magnetic field. The BMM150 of Bosch Sensortec of no less than, be the digital magnetometer of a 3 axes.

 

BMM150, combine BMI088 IMU, can offer 9 freedom to spend (DoF) solution, use at course estimation and navigation. BMM150 can maintain good performance inside very wide temperature range, have 16 resolution and fight ability of strong magnetic field (the sensor deflection that provides stability without magnetization) , because and rather than often suits unmanned aircraft to apply, and can the workload that utmost ground reduces place of calibration sensor deflection to need.

 

Special sensor node

 

Special sensor node (ASSN) it is to show the intelligence with compositive height passes move part line implement, it can many sensor compositive in enclosing body, deserve to have programmable small controller. It passes an induction to use the solution that offers agile and low power comsumption for motion.

 

For example, the BMF055 of Bosch Sensortec is an ASSN, it is compositive the small controller of accelerometer, gyroscope, magnetometer, 32 Cortex M0+ that can handle software, and the output end of each sensor. BMF055 and photograph of aligning treatment software are united in wedlock, can use as AHRS. This parts of an apparatus uses 5.2mm X 3.8mm X 1.1mm small-sized enclose, saved valuable space and weight. This sensor offerred unifinication to enclose to do not have man-machine application. Graph 3 demonstrated BMF055 to apply mediumly in unmanned aircraft, its regard aligning treatment as unit and compositive sensor confluence is algorithmic.

 

Graph 3: BMF055 (ASSN) apply in the AHRS in unmanned aircraft

 

Signal processing and software

 

Besides each sensor, the signal that we still can understand unmanned aircraft handles the systematic sketch map of integral structure, and compositive sensor reading and the software that control wants.

 

Graph the functional module that the 4 consumptive level that showed a pattern use at different signal processing in unmanned aircraft. Left row shows for each sensor, the kind states the software of its derive handles a function on the right side of, if directional processing and flight control are algorithmic. The sensor of blue-black diamonds is implementation indoor the sensor with the optimal and stable indispensable control that does not have man-machine with the toy, gray diamonds expresses optional sensor, can use at expanding the flight outdoor and automatic boat nod navigation function.

 

Graph 4: Consumptive level handles sketch map without the signal of man-machine

 

all sorts of sensor compositive an organic whole, hand-in-hand travel data is shirt-sleeve, can execute the software function such as aligning treatment on chip directly. Besides MEMS sensor, bosch Sensortec still provides the software of sensor data confluence that is used at aligning treatment, the function includes the pretreatment of data of sensor calibration, sensor and aligning treatment. To unmanned aircraft manufacturer, this can reduce the complexity of project and software significantly, reduce needless risk and shorten the product appears on the market time.

 

However, manufacturer still needs to be the mechanical design of unmanned aircraft and dynamical system, offer the software of themselves and special code, control the use of loop and specific function for example.

 

Typical unmanned aircraft function

 

Let the MEMS sensor technology that innovation sees in light of us how be united in wedlock with software photograph, realize function of contemporary and unmanned aircraft. Now, the toy that even if is low cost does not have man-machine, have complex function generally also. Above all, through using the output of IMU, stabilizer can maintain unmanned aircraft the level. Pass compositive the data that comes from baric sensor, can maintain unmanned aircraft height and position changeless. For example, in toy application, it is controallable unmanned aircraft undertakes retroflexioning when height is changeless. The result is to hold the practice that charges division to need to spend so much hour no longer to master hold basically accuse, and can reduce the risk that produces accident collision significantly.

 

It is unmanned aircraft with the data confluence of GPS module outdoors flight adds a few interesting functions, for example, fly between dot of a few boat automatically, and “ returns —— of domestic ” function unmanned function is returned quite automatically and safety descends to position of rest.

 

Other and novel function still includes ” of “ orbit mode or “ to follow my mode ” , unmanned aircraft can rotate around specific feature or can follow independently a person. With photograph union of photograph resembling a head, hold when accusing division to be able to take unmanned aircraft ” taking a walk in “ , see oneself from inside ” of “ bird’s eye view, perhaps interact through gesticulation and unmanned aircraft.

 

Unrestrained and far -ranging holds the post of me to swim

 

As the development of robot, semiconductor and current MEMS sensor technology, the precision that promotes ceaselessly especially and miniaturization, adumbrative in future unmanned remote control aircraft will gain ground more. From weather or air contaminant monitor, the management of domestic animals, safety or express system strengthen real play or content couplet network to next generation (IoT) platform, the plane of high-tech and the effect that in having man-machine to live daily in ours, produce are mainer and mainer, and sensor of rich world MEMS will cast powerful “ heart ” for them.