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Self Balancing Scooter The Key To Control
Nov 06, 2017

Self Balancing Scooter The key to control

We know that the car to go, of course, is the realization of two wheels turning. The control of the wheel is a technology alive. The wheel is driven by two motors via a gearbox, so motion control of the wheel can be achieved by controlling the motor speed. Motor motion control is achieved by controlling the current on the motor coil. Controlling the motor current controls the output torque (force) of the motor.

But who controls the motor?

In simple terms, when our fingers stood wooden sticks, the sticks moved forward, and we ran forward to counteract the tendency of the sticks to fall. But can not run too fast, otherwise the stick will fall backward. This time we are through the eyes to see the angle and speed down the stick to control their speed and direction of running.

Since the self-balancing car is also through the "eyes" to see the car's state Caixing, self-balancing car attitude and angular velocity measurements become the key to control. Measuring self-balancing car attitude and angular velocity can be achieved with accelerometers and gyroscopes. They are the "eyes" of self-balancing cars.

Now let's take a look at these two things:

(1) Acceleration sensor

Acceleration sensors measure the acceleration caused by the earth's gravitational attraction or object motion. Only need to measure the acceleration in one of the directions, you can calculate the vehicle inclination. For example, using the X-axis acceleration signal, the car is upright, the fixed accelerometer in the X-axis horizontal direction, the output signal is zero bias voltage signal. When the car is tilted, the acceleration of gravity g will be formed in the X-axis acceleration component, causing the axis output signal changes.

However, during actual vehicle operation, the acceleration caused by the movement of the self-balancing vehicle will generate a large interference signal superimposed on the above measurement signal, so that the output signal can not accurately reflect the real inclination. Therefore, attitude information required for upright control can not be completely obtained by the acceleration sensor. .

(2) Angular velocity sensor - gyroscope

Gyroscopes can be used to measure the angular velocity of an object. Since the balance car mounted gyroscope, can measure the angular velocity of the car tilt, the angular velocity signal integral processing can get the car inclination. However, due to the gyroscope itself has a certain noise, if it has been integral, it will cause tilt drift. Therefore, the posture information required for upright control can not be obtained separately by the gyroscope.

The two sensors mentioned above are both individually accurate and stable in dynamic conditions, but the two sensors are complementary, ie accelerometers, which work better under static conditions and the gyroscope is used under dynamic conditions , The effect will be better. At this point, an algorithm is needed to effectively fuse the two signals in order to obtain accurate pose information.

Fun self-balancing car using a self-developed variable compensated fuzzy Kalman filter algorithm to achieve effective attitude data fusion, you can get in the high dynamic state of the stable and accurate attitude information.