Index
| description
|
A
| RISC Microcontroller ATmega8 (16MHz)
|
B
| RISC Microcontroller AT90S4433 (8MHz)
|
C
| Comparator LM339
|
D
| Accelerometers (SMD) ADXL202
|
E
| RS232 interface converter
|
F
| 2, 5V-switching regulators 78SR105VC
|
Topview of the current circuit
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ATmega8 (16MHz, Master): This controller replaced the AT8535 because it can be driven at 16MHz, for a better servo control. An additional operation is the communication with the Slave-礐 via the SPI-Interface.AT90S4433 (8MHz, Slave): This 礐 is used to realise the Torque-Feedback. The prepared PWM-Signal from the servomotors is beeing processed and this data gets transfered to the Master-礐 via the SPI-Interface.LM339: These comparators prepare the fuzzy PWM-Signal from the servomotors to a clear digital signal that can be processed by the Slave-礐. A rough overview is given in the chart below.
TFB Measurement
The given example is valid for the used Sanwa-Servos. For the S-71 the REF-Voltage has to be connected to the noninverting and the motor signals to the inverting inputs of the comparators. The PWM Output-Signal for the Slave-礐 is independent of the torque direction, because the open collector outputs of the comparators realise a wired OR-Gate. So the Slave-礐 has to process the low periods of this signal.
Blockdiagram
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Software
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To improve balancing, four force-sensors were added on each foot. Illustration is done by direct display of data next to each sensor and grafically via a circle within each footplate. This illustration points if the forces are uniformly distributed and the center of gravity is within the footplalte(s). If not the servo positions have to be changed regarding this force distribution. The control of the calfs got extended by two slidebars. Like in the previous versions each servo can be controlled directly or both servos via the new slidebars to lean forward or sidewards.