Power Regulator V2

1. Overview

The power management unit is designed by Weston Robot for mobile robot applications. It has the following features:

• Stable and low output ripple for all output channels
• All ports are fused for protection of both battery and connected devices
• Supports soft-start to avoid current surge during startup
• Temperature monitoring and regulation with active fan cooling
• The output ports can be controlled individually (on/off) for finer boot sequence control
• Output voltage and current feedback via CAN/RS485 communication port

2. Specifications

Power Module

Port	Voltage	Current (Max)	Power	Fused
Main input	18-32V	20A	/	20A fuse
Output - 19V	19V	8A	150W	10A fuse
Output - 12V	12V	10A	120W	15A fuse
Output - 5V isolated	5V	4A	20W	Resettable
Output - 12V isolated	12V	3.3A	40W	Resettable
Output - extension	Input voltage	/	Limited by total power	/

Control Module

Port	Protocol	Function
CAN	CANopen	monitoring and control, firmware upgrade
RS485	/	firmware upgrade (backup), future extension

3. Hardware Setup

3.1 Startup and Operation

LED Status Indicators

Version	V2.1		V2.2
State	Red LED	Green LED	Red LED	Green LED
Initialisation	ON	ON	ON	ON
Calibration	OFF	OFF	ON	ON
Operational	OFF	BLINKING	OFF	BLINKING
Firmware Upgrade	BLINKING	OFF	BLINKING	OFF

Startup Sequence

• Upon start up,
  • [V2.1]: Both red and green LEDs light up for about 2 seconds during initialization. Both LEDs then switch off for another 2 seconds, indicating the regulator is calibrating.
  • [V2.2]: Both red and green LEDs light up for about 18 seconds while initialization and calibration takes place.
• After calibration, the unit enters operational state, with the red LED turned off while the green LED blinks.
• During firmware upgrades, the green LED turns off while the red LED blinks.

3.2 Output Connection

The output ports of the power module are exposed with Molex Megafit connectors. For each port, 2 or 4 channels are provided. Note that the channels are interconnected internally, thus the total power consumption should not exceed the power ratings of the port.

Note: The operation of the fan is dependent on the state of the 12V channel, it will operate only when the 12V channel is on. The fan will be switched on once the temperature reaches 28°C, with fan speed reaching a maximum when the temperature rises to 45°C and above.

4. Software Setup

The power regulator uses CANopen to communication with a computer. The CANopen driver for the power regulator is supported by wrp_sdk since version 1.0.0.

• If you want to interact with the power regulator from your C++ program, you need to install the SDK.
• If you only need to monitor and control the power regulator with a GUI, you just need to install the widget.

4.1 Install SDK

Follow the instructions to install the latest SDK.

Install dependencies

sudo apt-get install -y software-properties-common 
sudo add-apt-repository ppa:lely/ppa && sudo apt-get update
sudo apt-get install -y pkg-config liblely-coapp-dev liblely-co-tools

Install the SDK

Please add the debian repository to your apt-get source list first. Refer to this guide for more details.

sudo apt-get install wrp_sdk

4.2 Install the Widget

Please make sure you have added the debian source.

# 1. install wr_regulator_widget dependencies
sudo apt-get install libgl1-mesa-dev libglfw3-dev libcairo2-dev

# 2. install the package 
sudo apt-get install wr_regulator_widget

Once finished the installation, you can find the executable of the widget at /opt/weston_robot/bin/regulator_widget.

/opt/weston_robot/bin/regulator_widget/wr_regulator_widget

Run the widget and you should see the GUI like this:

5. Configuration

Setting Default State for Channels

By default, all the output channels are disabled after the power regulator is powered on for safety purpose. Nevertheless, depending on your application, you may want to have a different initial state for the output channels. For example, if your main control computer is powered by the 19V channel, you would want this channel to be on by default, only after which you can control the power sequence of other channels from your control computer.

The default state is stored in non-volatile storage ROM. Thus, once set, the settings would persist.

Install dependencies

python-can can be used to set default state for channels,

pip3 install --user canopen python-can

Configure python-can to use your CAN adapter through its configuration file. On GNU/Linux, the configuration looks similar to this:

cat << EOF > ~/.canrc
[default]
interface = socketcan
channel = can0
bitrate = 500000
EOF

Next, bring up the CAN interface on the PC.

sudo ip link set can0 type can bitrate 500000
sudo ip link set up can0
sudo ip link set can0 txqueuelen 1000

Configure with Python scripts

You can customize the default output state of each channel to be ON or OFF upon power up.

The example code below demonstrates how to set all output channels to be ON by default.

Note that you will have to finish the configuration steps in Section 5 to execute the code below successfully. And you also need to modify the path of the eds file ("EDS" variable) from the SDK.

import canopen
import os
import time

EDS = <your-path-to-eds> // eg. /opt/weston_robot/share/wrp_sdk/eds/westonrobot/regulator/regulator_v2.1.eds
NODEID = 30

network = canopen.Network()

network.connect()

node = network.add_node(NODEID, EDS)

print("----------------------")
print("Initial Output state:")
print("----------------------")
print("19V {}".format(node.sdo['Output state'][1].raw))
print("12V {}".format(node.sdo['Output state'][2].raw))
print("Isolated 12V {}".format(node.sdo['Output state'][3].raw))
print("Isolated 5V {}".format(node.sdo['Output state'][4].raw))

print("----------------------")
time.sleep(1)
print("Setting Output command (1:on, 0:off):")
print("----------------------")
node.sdo['Output command'][1].raw = 1
node.sdo['Output command'][2].raw = 1
node.sdo['Output command'][3].raw = 1
node.sdo['Output command'][4].raw = 1
node.store() # store into ROM 
# node.restore() # restore ROM
network.disconnect()