Revision as of 17:16, 7 September 2007

Master (state machine) Controller

• 25.2V max supply voltage

Off board interfaces

Switch Input

• external logic switch input for mode control

External communication and ISP

• 1Mbaud MAX RS-232 level ASYNC serial with power
• Want the abiltiy to support a varitify devices, including wired RS232, Bluetooth, and 802.11
• signals GND, Tx, Rx, 3.3V, Vbat (0.25amp resettable fuse)
• Might want this header to have ISP signals, PGC, PGD, MCLR

Motor controller interface

• Bring battery power from motor controller
• TTL level ASYNC serial between master and motor controller CPUs (1Mbaud max)
• Signals: BAT+, GND, TX, Rx, DigOut, DigIn
• Use board to board stacking ???
• Motor controller ISP signals??? (PGC, PGD, MCLR)

Ankle Angle ???

• quadrature encoder (5V single ended) [GND, 5V, ChA, ChB, NDX to dsPIC QEI inputs]
• or magnetic rotary encoder (such as AS5045 family) [GND, 3.3V, PWM to dsPIC IC timer]

Strain, SEA, Motor Temp, Supply current

• 4 analog inputs to CPU, DC to 500 Hz analog bandwidth
• 1 x 10k thermo resistor (requires opamp follower), AGND and signal
• 2 x strain gauge bridges (high gain INA326), AGND, SG+, SG-, bridge reference
• SG bridge reference voltage through 0.1% resistance from AVCC5
• 1 x analog input for SEA hall sensor board (no voltage or current amp required) : 3.3V, AGND, signal

On board sensors

Ambient Temperature

• Place very close to XY axis IMU
• 10K SMT with opamp follower

Supply Voltage Monitor

• 1% accurate

IMU

• One SPI device, and (upto) 3 analog rate gyro signals

• 3axis (SPI) accelerometer LIS3LV02DQ
• Z axis rate gyro ADXRS300 (analog) or ADIS16100 (digital)
• XY axis (analog) rate gyro IDG300
• Note: XY is in circuit board plane, Z axis is normal to circuit board plane

software

• 2 DMA controllers run the two ADC units at 12 bits, 400 KHz total sample rate
• Input capture measures PWM period of magnetic rotory encoder
• QEI captures encoder position
• DMA controller sends/receives SPI to digital accelerometer
• Main code loop runs at 500 Hz
  • decimation of analog inputs
  • reads ankle position
  • reads IMU, calculates orientation
  • reads motor controller status (motor current, supply current / voltage, motor position, status)
  • processes external communication interface

Motor Controller

• support for Maxon EC30-48V [305015] with 500 CNT MR ENCODER [225778]
  • EC30-48V specs : L=65.3uH, R=386mohm, SpeedConst=346 rpm/volt, TorqueConst=27.6mNm/A
  • Required maximum RPM : 7500

• 25.38V abs max supply voltage
• suggested design using 30V MOSFETs, 35V bulk caps, and 35V DC-DC converter
• 2 phase current sensors (ACS712-20amp, 1.2mohm)
• Ability to (indefinitely) short motor leads when primary power absent or if some sort of system failure

Off board interfaces

Motor position sensor

• quadrature with index 5V (single or differential? )
• hall effect sensor 5V (may require pullups)

power / data to Master Controller

• ASYNC serial to UART
• TTL input to dsPIC fault pin to disable PWM
• TTL output for status
• "direct" connection to Bat+
• common (GND)
• Might want this header to have motor ISP signals going to local digital IO

• logic level ASYNC 2-wire serial between master and motor controller CPUs
• logic level input from SM Controller to /FLTB to disable PWM
• logic level output to alert SM Controller alert status
• battery power to SM controller
•  ??? board to board stacking connector (more reliable that wires)

On board sensors

• 2 current sensors

software

• master will periodically send ASCII commands to command current and mode
• controller will respond with status (encoder position, supply voltage, actual current, temperatures)
• ability to reprogram Motor Controller over ASYNC serial

io count

analog (6)

• 2 for motor current
• 1 for 5V (AVcc5/2) supply monitor
• 1 for battery current
• 1 for supply voltage
• 1 or 2 for temperature

digital (21 max)

• 6 PWM output
• 2 fault IOs
• 2 ASYNC serial
• 3 for ISP
• 3 for encoder
• 3 for motor hall position sensor
• 2 for LEDs

Mechanical

• dimensions