Servocore 2-motor walker circuit

  
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There is an advantage in using continuously active PWM signals. The main reason is that the asynchronous frequencies of the PWM core and microcore can sometimes result in a forshortened PWM pulse. The Sevo reconizes this as a command for a new positions and twitches toward that position. This makes the motion somewhat jerky on the original uServo4 c
Servocore 2-motor walker circuit - schematic

ircuit. In this application the microcore is actually used as a quasi- bicore. The microcore outputs are connected through 4 diodes to give the equivalent of master / slave bicore waveformsbut withindividual control of the rising and falling phaseangles. Since that can be used for turning a conventional " bicore " walker (but not the uServo walker), this techniquemay be exploited in other walker applications as well. Normally the microcore generates 4 individual pulses from Nv 1 - Nv 4. The master / slave bicore waveforms are two ovelapping quadrature waveforms. The translatorsynthesizes the bicore waveforms in two parts using diodes D3 - D8 to OR the microcore outputs. During forward motion theoutput of Nv 1isnot used So when Nv 1 is active, the PWM pulses for both S1 and S2 are not influenced through diodes D3-8. and the PWM s generate thelongestpulses driving bothservos to CCW. When Nv 2 is activeit controls duration of the first half of the S1 CW position, Nv 3 sets the second half of CW forS1 and the first half of CW for S2. Nv 4 controls the second half of CW for S2. Ifthe outputs of Nv 1and Nv 3 can be alternately selected, that would provide a 180 degree phase shift of the PWM signals required to reverse the walker. The microcore to bicore diode networkalsopart ofthe reverse circuit to selectwhether the rear legs lead or lag by 90 degrees and therefore reverse the walker. The reverse circuit is a multiplexerto...



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