Welcome time
environment
Humidity 5% ~ 98% (non-condensing).
Working temperature ..................................... -20℃ ~+50℃
Storage temperature .................................... -40℃ ~+60℃
weight
Gyroscope host .................................................15kg (excluding total station)
Size (width× height)
Gyroscope host
Reliability ... MTBF ≥ 400 hours, MTTR≤30 minutes.
life
Directional mode
The degree of automation is automatic
I. Introduction
As an inertial measurement device, gyroscope is the core component of inertial navigation, inertial guidance and inertial measurement system, which is widely used in military and civil fields. Traditional gyroscopes are large in size, high in power consumption, susceptible to interference and poor in stability. Recently, analog devices, Inc. of the United States introduced a new type of rate gyroscope chip, ADXRS, which is only 7mm×7mm×3mm in size and adopts BGA-32 packaging technology. This package is at least 65,438+000 times smaller than any other gyroscope with similar performance, with a power consumption of 30mW and a weight of only 0.5g, which can well overcome the traditional gyroscope. The angular velocity detection gyroscope composed of ADXRS chip can accurately measure angular velocity, and in addition, it can also be used to measure angle, and the experiment has achieved good results.
Second, the principle and structure of gyroscope
ADXRS series gyroscopes are manufactured by analog devices, Inc. of the United States, and adopt the patented technology of integrated microelectromechanical systems (iMEMS) and BIMOS technology, and are internally integrated with angular rate sensors and signal processing circuits. Compared with any gyroscope with similar functions, ADXRS series gyroscopes have the advantages of small size, low power consumption, good shock resistance and vibration resistance.
1, coriolis acceleration
ADXRS series gyroscopes use coriolis acceleration to measure angular velocity, and the principle of coriolis effect is shown in figure 1. Suppose someone is standing near the center of the rotating platform, and his speed relative to the ground is represented by the length of the arrow 1 If you move to a certain point on the outer edge of the platform, its speed relative to the ground will increase, as shown by the long arrow in figure 1. The rate of tangential velocity caused by radial velocity increases, which is Coriolis acceleration. Let the angular velocity be half of the Coriolis acceleration of W, and the other half generally comes from the change of radial velocity. The sum of them is 2wv. Coriolis acceleration of 2Mwv must be applied to the rotating platform, and people will receive equal reaction force. Forced production. If the human mass is m and the platform radius is r, then the tangential velocity is wr. If people move along the radial direction R at the speed V, a tangential acceleration wv will be generated, which only has
Gyroscope uses Coriolis effect to measure angular velocity by using resonant mass elements similar to those when people move outward or in a rotating platform. Fig. 2 shows the complete micromechanical structure of the ADXRS series gyroscope, which measures the displacement of the resonant mass element and its frame due to Coriolis effect through the capacitance detection element connected to the resonator. These capacitance detection elements are all beams made of silicon material, which intersect with two groups of static silicon beams attached to the substrate to form two capacitors with equal nominal values. Displacement caused by angular velocity produces differential capacitance in the system. If the elastic coefficient of the spring is K2wv·m and the total capacitance is C2wv, it is proportional to the angular velocity. This relationship has good fidelity in practical application, and its linear error is less than 0. 1%. MC/gK, the spacing between silicon beams is g, the differential capacitance is /K, and the displacement caused by reaction force is
2. The structure and circuit realization of gyroscope.
The dimensions of the ADXRS series gyroscopes are 7mm×7mm×3mm, and BGA-32 packaging technology is adopted. There are two models, namely ADXRS 150 and ADXRS300. Their functional circuits are exactly the same, the only difference is that the range of the former is 150 /s, and the range of the latter is 300 /s ... Figure 3 shows the internal circuit structure and peripheral circuit of the ADXRS300, in which the peripheral circuit is mainly composed of capacitors and resistors.
Pin AVCC is connected to 5V supply voltage, and the pump capacitor of 22nF is used to generate a pump voltage of 12V for some circuits. The measured angular velocity is output in the form of voltage at the RATEOUT pin, and the output voltage is 2.5V at 0 /s s. A resistor RoutADXRS300 is connected in parallel between the RATEOUT and SUMJ pins, and the frequency of-3dB is determined by the following formula: and the capacitor Cout, thus forming a low-pass filter for limiting.
fout = 1 / (2 π？ Collapse? ( 1)
For RoutΩ//rextadxrs300 from the outside, the range of Rout180Ω in the internal circuit can be 300 °/ s, which can be increased by 50% by providing rout 300kω resistor between RATEOUT and SUMJ pins, but this requires a reset circuit. The zero point of a resistor RnullRATEOUT connected to the SUMJ pin is 2.5V, but when the angular motion range is asymmetrical, the calculation is as follows: connect a resistor in parallel to the ground or the positive pole of the power supply, and increase the range when the angular motion is symmetrical, for example, connect a resistor in parallel, so as to adjust the angular rate response bandwidth. A resistor Rext is connected in parallel, so Rout= 180k is
Rnull = (2)
Where v null 0- the output voltage with zero angular velocity when uncorrected,
V null 1- requires zero voltage after correction.
If you get an Rnull5V power supply. If it is negative, the resistor Rnull is grounded; positive value