Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [velocity]

Velocity is a vector quantity referring to the rate at which an object changes its position.

Velocity is a vector quantity referring to the rate at which an object changes its position. Something that is oscillating back and forth might be described as having zero velocity. Even though it is in motion, it is not (on average) changing position.

If a person were to walk two steps forward and take one step back every 10 seconds, and repeat this process, their velocity could be described as one step forward per 10 seconds. Because velocity is a vector, the direction is important. "Forward" in the previous example is the direction, but could be applied to terms such as "voltage increase" or "traveling east."

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In theory, is the position derived from accelerometer absolute?

I recently found multiple research papers that say that in theory double integral of accelerometer data gives a position of the device. Does that refer to absolute position (like the one given by a GPS)? or for example starting position and then…
Maja
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How to measure propagation velocity through a trace on a pcb?

With a pcb in hand, how to measure the propagation velocity of a path from point A to point B, with accuracy in the picoseconds range?
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Most small / cost effective way to detect changes in altitude?

I want to make a device, which when placed on someone skiing or snowboarding, will be able to tell whether that person is sliding down the slope. The problem is two-fold. I must first detect whether the device is moving. Then, I must know whether…
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How do I determine the curve of the transmission output on a torque-angular velocity graph for a DC motor?

I'm doing a homework problem that involves motor characteristic graphs. For this problem, I have a motor with stall torque of 8 N-cm and a no-load angular velocity of 80 rad/s. The motor powers a 4-wheel drive robot that requires an input of 60 N-cm…
suhh_drude
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Doppler shift velocity sensor

Any reasonable priced (sub 20$/100) ways to directly measure indoors velocities between around 0.1 and 15m/s? Its main purpose would be to reduce speed drift for a 9DOF device (acc/gyro,magnetometer), so I believe only 1D will do. Now since it's…
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Estimation of swimmer's velocity from IMU sensor

I am dealing with the problem of estimation the swimmer's velocity. In the same time data from IMU sensor and tethered system are acquired. Data from tethered system are reference data. From IMU sensor acceleration, angular velocity and strength…
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Torque control of a BLDC motor

Please forgive my lack of perfect electronics knowledge. I am here to learn. I understand I am clearly missing and misunderstanding something important. The aim of this question is to find out what it is that I am missing and study it further. My…
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Confused on MOSFET terms (velocity limited, mobility limited, constant mobility)

So we're learning about transistors, but we don't much of the physics behind how they work (yet) so these terms are quite strange to me. The models we've used are "velocity limited", "mobility limited", and "constant mobility". In some models, the…
sciencectn
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A speedometer like chip

Is there a device which acts like an accelerometer but only measures absolute velocity? I could integrate the accelerometer's output but errors quickly accumulate and cause problems. Preferably the device is available in a MEMS based chip and is low…
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Does a phototransistor have a minimum focal window? - Velocity Measurement of High Speed Object

My goal is to measure the velocity of a moving object that has several different changes in velocity throughout the actuation. I am planning on using a phototransistor to detect black and white lines that are taped to a moving object that has a peak…
Nicholas Myers
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Brushless DC motor problems at high velocities

For a project we use a brushless DC (BLDC) motor. Everything works fine until we tried to reach high velocities. I will first explain my setup, and than explain our problems using some graphs. Unfortunately I don't have enough points to put al my…
ProjectM
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Phase velocity non-TEM transmission line

Assuming that a transmission line operates in a TEM or quasi-TEM mode, the phase velocity can be determined from the line parameters (R,L,C,G per meter assuming the RLCG model of a transmission line). Because $$V_p = \frac{\omega}{\beta}$$ and from…
waves
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Most accurate way to obtain angular velocity from a IMU sensor

I have been using a BNO055 sensor (9° dof IMU) for a project which will use angular velocity to move the mouse cursor on a PC screen. So far, I have gotten quaternion output from the sensor and been able to convert it to angular velocity in a couple…
Zhelyazko Grudov
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How is Gyro drift error related to error in velocity and position?

While reading about IMU on wikipedia I found this about its disadvantages: "A constant error in attitude rate (gyro) results in a quadratic error in velocity and a cubic error growth in position." How is Gyro drift error related to error in velocity…
alt-rose
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How to choose proper power supply for 8 servos on Adafruit shield with Arduino Uno controller

I use Adruino Uno micro-controller powered with USB 5V from PC and Adafruit 16-Channel 12-bit PWM/Servo Shield on it with 1000uF capacitor, powered with 6V 2A power supply. Seems like it is not correct power source. Need your help to choose single…
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