AnkleHardwareSpec2007Sep
From DIDEAS Wiki
State Machine (Master) Controller
- 25.32V max supply voltage
Off board interfaces
Switch Input
- external logic switch input for mode control
External Serial Communication and ISP
- Ability to support a variety of attached serial devices: wired RS-232, Bluetooth, 802.11, and ISP.
- 1Mbaud (max) RS-232 level ASYNC serial with power (Tx, Rx, RTS, CTS)
- Power for external devices: 5V and Vbat (with 0.25amp self resettable fuse)
- ISP signals (PGC, PGD, MCLR) - allows external programming
- signals: Vbat, Vcc5, GND, Tx, Rx, RTS, CTS, PGC, PGD, MCLR
power / data to Motor Controller
- logic level ASYNC 2-wire serial between master and motor controller CPUs
- logic level output to motor controller fault pin to disable PWM
- logic level input for motor controller alert status
- battery power from motor controller
- low current path to battery for voltage monitoring
- ??? board to board stacking connector (more reliable that wires)
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
- Thermo resistor with opamp follower placed very close to XY axis IMU
Supply Voltage Monitor
- (better than) 1% accurate measurement of battery voltage (prevent over-voltage during regen)
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
- ability to reprogram SM Controller over ASYNC serial
- 2 DMA controllers run the two ADC units at 12 bits, 400 KHz total sample rate
- Input capture measures PWM period of magnetic rotary 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, estimates orientation
- reads motor controller status (motor current, 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 (permanently) short motor leads when primary power absent or if some sort of system failure
Off board interfaces
Motor position sensor
- 5V quadrature with index (single ended)
- hall effect sensor
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+
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)
io count
AD
- 2 for motor current
- 1 for 5V supply monitor
- 1 for battery current
- 1 for supply voltage
- 1 or 2 for temperature
- 1 for 5V supply monitor
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