Keywish Hummer-Bot-2.0 Instruction Manual page 68

8, Supporting the following 2 detection methods: 1, continuous detection; 2, controlled intermittent
detection;
9, Distance data format: using mm as the smallest data unit, double byte 16 hexadecimal transmission;
10, Temperature data format: using Celsius degree as the smallest unit, single byte hexadecimal
transmission;
11, Light data format: single byte 16 hexadecimal transmission; the value is big when it is dark, small
when it is bright;
12, Working temperature: 0℃~+100℃
13, storage temperature: -40 to +120 degrees Celsius
14, Size: 48mm*39mm*22mm (H)
15, The size of fixing holes: 3*Φ3mm; Gap:10mm
3.2.4.3 Working Principle
1. Steering gear
The control signal enters the signal modulation chip by the receiver channel, gets the DC bias voltage.
The steering gear has a reference circuit which generates a reference signal with a period of 20ms and a
width of 1.5ms. Comparing the obtained DC bias voltage with the voltage of the potentiometer and
obtaining the output voltage difference. Finally, the positive and negative output voltage difference in the
motor driver chip decide the positive and negative rotation of motor. When the speed of motor is certain, the
cascade reducer gear will drive potentiometer to rotate so that the voltage difference is reducing to 0, the
motor will stop rotating.
When the control circuit receives the control signal, the motor will rotate and drive a series of gear sets,
the signal will move to the output steering wheel when the motor decelerates. The the output shaft of
steering gear is connected with the position feedback potentiometer, the potentiometer will output a voltage
signal to the control circuit board to feedback when the steering gear rotates, then the control circuit board
decides the rotation direction and speed of the motor according to the position, so as to achieve the goal. The
working process is as follows: control signal→control circuit board→motor rotation→gear sets deceleration
→steering wheel rotation→position feedback potentiometer→control circuit board feedback.
The control signal is 20MS pulse width modulation (PWM), in which the pulse width varies linearly
from 0.5-2.5MS, the corresponding steering wheel position varies from 0-180 degrees, which means the
output shaft will maintain certain corresponding degrees if providing the steering gear with certain pulse
width. No matter how the external torque changes, it only changes position until a signal with different is
provided as shown in Fig.3.2.27. The steering gear has an internal reference circuit which can produce
reference signal with 20MS period and 1.5MS width, there is a comparator which can detect the magnitude
and direction of the external signal and the reference signal, thereby produce the motor rotation signal.
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