Cape of Stomping (deprecated)
The Cape of Stomping has been replaced by hand-wired protoboard capes with simpler functionality
The Cape of Stomping is a custom Beaglebone cape designed for the Beaglebone Black.
Stompy will use 9 BeagleBone Blacks fitted with Capes of Stomping. There will be one on each leg populated with 4 solenoid drivers and 3 string pot connections (third string pot is used to measure the compliant link deflection). Two will be located on the chassis for driving the hip yaw pistons. These two will be populated with 6 solenoid drivers and 3 string pot connections. The final BeagleBone will also be located on the chassis. It will be a bare-bones board with only 2 solenoid drivers, and will be used for controlling the pump bypass valves.
The cape contains:
- Solenoid drivers for controlling the hydraulic valves
- ADCs for reading in string potentiometer sensors
- Ethernet for communicating with Main Computer
An additional Cape will be produced for test purposes. The test Cape will have the current sensors for pressure transducers populated, and the voltage sense will not be used.
Each Joint Controller draws a maximum of 4A at 12V.
The Beaglebone Board runs on 5V. Each BeagleBone draws max ~400mA.
The solenoids run on 12V. Each solenoid draws 1.2A when powered. A maximum of 3 solenoids can be on at one time per Beaglebone, and a maximum of 18 solenoids can be on for the whole robot.
The Cape has a 12V Buck converter to ensure that the solenoid power is a consistent 12V. Expected battery voltage is around 14V.
This layout diagram has most of the correct dimensions, but the cutout on the left for the ethernet port and power plug are different than the cutouts used on the Cape of Stomping.
The PCB can be ordered from: https://oshpark.com/profiles/spark
There are two pumps driven by Stompy’s engine. One is twice the size of the other . Stompy’s computer will be able to bypass either or both of the pumps. During startup, both pumps will be bypassed. If at any time the robot is not moving, both pumps will be bypassed. The large or small pump can be enabled to get 1/3 or 2/3 of full flow rate, and both pumps can be enabled to get full flow rate. The control system will use the minimum needed flow rate at all times.
Beaglebone capes typically include an EEPROM chip to store configuration data. We don’t actually need this, and it won’t be implemented on the Cape of Stomping.
Implementation notes for EEPROM:
Adventures in BeagleBone Cape EEPROMs
NULLCape
Cape of Stomping Rev2
- Pick new resistor values for ADC dividers
- See Brett's email
- Done I think?
- Check 12V divider too
- Add jumpers for selecting real time processing pins or PWM pins
- add holes for power supply standoffs
- remove power supply
- Remove current sensors
Cape of Stomping PCB updates
- Space diodes out more
- Space FET's out more
- C12 pads should extend farther from the part
- Add polarity markers to giant surface mount cap footprints (C12, C13)
- Power connector footprint needs shape polarity mark
- Power connector needs room on sides for mating connector tabs
- J1 Solenoid connector footprint is wrong - far row of holes too close