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8

Keyence has a useful comparison table: ╔════════════════════╦══════════════════╦══════════════════╗ ║ Item ║ Optical ║ Ultrasonic ║ ╠════════════════════╬══════════════════╬══════════════════╣ ║ Detectable target ║ Affected by ║ Unaffected by ║ ║ ║ colour/material ║ colour/material ║ ║ Detecting ...


6

There is actually no such thing as a 6-axis gyro; the correct term for this is "IMU", which stands for "Inertial Measurement Unit". An IMU is a device that combines several inertial sensors that measure the craft's orientation and position in space. The 6-axis IMU is a composite sensor, which contains two different types of 3-axis sensors on one chip. ...


5

TL;DR: The configurable scale ranges for the accelerometer, gyroscope, and magnetometer on the MPU-9250 IMU affect the maximum resolution and range of the reported values. As you increase the full-scale range setting, the maximum value/rate that can be reported by the IMU before the IMU is saturated increases, but the resolution of the value/rate decreases. ...


5

Is the shunt resistor usually mounted high-side (i.e. at the positive battery terminal), or low-side (at the negative terminal), and why? Does it matter? There should be no significant difference to the measurement if the shunt resistor is on the high or low side. As the resistor is in series the absolute voltage across, and current through, the resistor ...


4

The full scale range is the largest value that the sensor can report; this is usually a balance of sensitivity to word length. If you have 8 bits to report the value, how many deg/s do you make one bit? The more deg/s you use per bit, you can report a bigger full-scale value but you loose sensitivity as the minimum change reported increases. As an example, ...


4

The simple answer would be a potentiometer, as used for position feedback in a servo. You apply a voltage to the outer two contacts and measure the voltage at the moving, middle connection. The next step would be a rotary encoder. These should give you less friction and more accuracy, if you need it. A camera would require significant processing power, but ...


4

A three-axis gyro measures the speed of rotation in three-axis - pitch, roll, and yaw. A six-axis gyro is a slight misnomer, as it is a three-axis gyro with a three-axis accelerometer, which measures acceleration in three axes (x, y, and z). As it can measure the acceleration from gravity, these sensors can be used to determine which way is down relative to ...


4

TL;DR: it depends entirely on the situation in which you intend to use the sensors. According to this article, it is entirely dependent on your application. You’ve mentioned you want to use it for obstacle avoidance, but the environment in which you want to do this is important. IR sensors are easily affected by external conditions such as ambient light ...


4

You may want to take a look at dronecode.org, or their supported projects. Especially, PX4 (which was also mentioned in another answer): Getting Started with PX4 Autopilot guide PX4's Follow-Me Flight Mode MAVLink's Follow Me plugin You may also find some interest in some other open sourced drone projects, e.g. ArduPilot's Follow Me Mode. Another one ...


2

The PX4 open-source flight stack has made some progress on various forms of computer vision. While not exactly turnkey, it’s an active area of development and you absolutely can buy hardware that supports it as long as you’re comfortable getting your hands dirty setting up the software.


2

Using PM07 power management board from Holybro as an example. They use shunt resistor on the high side. Voltage across the shunt resistor is then fed into the Texas Instruments INA169 current sense amplifier. Gain and BW of the amplifier is set using an external resistor. I was designing my own power management board recently and had exactly the same ...


2

Sensitivity Barometers are quite sensitive, however "air pressure" is very much not consistent. Generally, you can expect about one meter accuracy, maybe a bit less, from a barometer, once it has been given time to settle. This is important to consider if your CanSat is falling quickly, especially if you have small pressure regulation holes The ...


2

i2c Yes. This is how flight controllers talk to the already available sensors on board*. The addition of barometer and magnetometer sensors (and any other sensors that these flight control softwares support natively) is, and should be, done via the i2c bus. Save some sensors like GPS which is generally UART (though i2c/SPI GPS chips may exist). USB Short ...


1

After reading relevant materials, i think I have find the answers for this question. Q1:Since AR drone2 is a proprietary system, this company didn't publish any documentation about the internal structure. Q2:According to my understanding and guess, the controllers will use the estimated states of AR drone2 and the estimated states may from EKF(I am not 100% ...


1

The RC Rates are just the multiplicator value the Aircraft will try to execute your inputs. The resulting speed (degrees/sec) are just estimates based on a typical hardware configuration, without a major effort, as this is very much dependent on the conditions the aircraft is in, the way the execution is carried out, and the hardware that actually does it. ...


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