RoboteQ AX2550, AX2850 User Manual
AX2550/2850
Dual Channel
High Power
Digital Motor
Controller
User’s Manual
v1.7, February 1, 2005
visit www.roboteq.com to download the latest revision of this manual
©Copyright 2003-2005 Roboteq, Inc.
Revision History
Date Version Changes
February 1, 2005 1.7 Added Position mode support with Optical Encoder
Miscellaneous additions and corrections
April 17, 2004 1.6 Added Optical Encoder support
March 15, 2004 1.5 Added finer Amps limit settings
Enhanced Roborun utility
August 25, 2003 1.3 Added CLosed Loop Speed mode
Added Data Logging support
Removed RC monitoring
August 15, 2003 1.2 Modified to cover AX2550/2850 controller design
Changed Power Connection section
April 15, 2003 1.1 Added analog mode section
Added position mode section
Added RCRC monitoring feature
Updated Roborun utility section
Modified RS232 watchdog
March 15, 2003 1.0 Initial Release
The information contained in this manual is believed to be accurate and reliable. However,
it may contain errors that were not noticed at time of publication. User’s are expected to
perform their own product validation and not rely solely on data contained in this manual.
2 AX2550/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Revision History
AX2550/2850 Motor Controller User’s Manual 3
4 AX2550/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Revision History 2
SECTION 1 AX2500/2850
Quick Start 11
What you will need 11
Locating Switches, Wires and Connectors 12
Connecting to the Batteries and Motors 13
Using the Power Control Wire 14
Connecting the R/C Radio 14
Powering On the Controller 15
Button Operation 16
Default Controller Configuration 17
Checking and Changing Configurations 17
Connecting the controller to your PC using Roborun 18
Obtaining the Controller’s Software Revision Number 19
Exploring further 20
SECTION 2 AX2500/2850 Motor Controller Overview 21
Product Description 21
Technical features 22
SECTION 3 Connecting Power and Motors to the Controller 25
Connecting Power 25
Controller Power 26
Powering the Controller using the Motor Batteries 28
Using a Backup Battery 29
Power Fuses 30
Wire Length Limits 30
Electrical Noise Reduction Techniques 31
Power Regeneration Considerations 31
Overvoltage Protection 32
Undervoltage Protection 32
Using the Controller with a Power Supply 32
SECTION 4 General Operation 35
Basic Operation 35
Input Command Modes 35
Selecting the Motor Control Modes 36
Open Loop, Separate Speed Control 36
Open Loop, Mixed Speed Control 36
Closed Loop Speed Control 37
Close Loop Position Control 37
AX2500/2850 Motor Controller User’s Manual 5
Current Limit Settings 38
Continuous and Extended Current Limitation 38
Temperature-Based Current Limitation 39
Surge Current Protection 40
Regeneration Current Limiting 40
Programmable Acceleration 40
Command Control Curves 42
Left / Right Tuning Adjustment 43
Emergency Shut Down Using Controller Switches 45
Emergency Stop using External Switch 45
Inverted Operation 46
Special Use of Accessory Digital Inputs 46
Using the Inputs to Activate the Buffered Output 46
Using the Inputs to turn Off/On the Power MOSFET
transistors 46
Self-Test Mode 47
SECTION 5 Connecting Sensors and Actuators to Input/Outputs 49
AX2500/2850 Connections 49
AX2500/2850’s Inputs and Outputs 51
I/O List and Pin Assignment 52
Connecting devices to Output C 53
Connecting devices to Output D 54
Connecting Switches or Devices to Input E 55
Connecting Switches or Devices to Input F 55
Connecting Switches or Devices to EStop/Invert Input 56
Connecting Position Potentiometers to Analog Inputs 57
Connecting Tachometer to Analog Inputs 58
Connecting External Thermistor to Analog Inputs 59
Using the Analog Inputs to Monitor External Voltages 60
Connecting User Devices to Analog Inputs 61
Internal Voltage Monitoring Sensors 62
Internal Heatsink Temperature Sensors 62
Temperature Conversion C Source Code 63
SECTION 6 Normal and
Fault Condition LED Messages 65
Use of the LED Display 65
Motor Direction Status 66
Fault Messages 67
No Control 67
Emergency Stop 68
6 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Self-Test Display 68
SECTION 7 R/C Operation 69
Mode Description 69
Selecting the R/C Input Mode 70
Typical Wiring 70
Connector I/O Pin Assignment (R/C Mode) 71
R/C Input Circuit Description 72
Supplied Cable Description 73
Cabling to R/C Receiver using Full Opto-Isolation 74
Cabling to R/C Receiver with Partial Opto-Isolation 75
Powering the Radio from the controller 76
Operating the Controller in R/C mode 78
Reception Watchdog 79
R/C Transmitter/Receiver Quality Considerations 79
Joystick Deadband Programming 80
Command Control Curves 81
Left/Right Tuning Adjustment 81
Joystick Calibration 81
Automatic Joystick Calibration 82
Activating the Accessory Outputs 83
Data Logging in R/C Mode 84
SECTION 8 Serial (RS-232) Controls and Operation 87
Use and benefits of RS232 87
Connector I/O Pin Assignment (RS232 Mode) 88
Cable configuration 89
Extending the RS232 Cable 89
Communication Settings 90
Establishing Manual Communication with a PC 90
Entering RS232 from R/C or Analog mode 91
Data Logging String in R/C or Analog mode 91
RS232 Mode if default 92
RS232 Commands Set 92
Set Motor Command Value 92
Set Accessory Outputs 93
Query Power Applied to Motors 93
Query Amps Consumed by Motors 94
Query Analog Inputs 94
Query Heatsink Temperatures 95
Query Battery Voltages 95
Query Digital Inputs 95
Read and Modify Controller Settings 96
AX2500/2850 Motor Controller User’s Manual 7
Apply Parameter Changes 97
Reset Controller 97
Optical Encoder Commands 97
Commands Acknowledge and Error Messages 97
Character Echo 97
Command Acknowledgement 98
Command Error 98
Watchdog time-out 98
RS-232 Watchdog 98
RS232 Accessible Parameter Table 99
Automatic Switching from RS232 to RC Mode 101
Analog and R/C Modes Data Logging String Format 102
Data Logging Cables 103
Decimal to Hexadecimal Conversion Table 104
SECTION 9 Analog Control and Operation 107
Mode Description 10 7
Connector I/O Pin Assignment (Analog Mode) 108
Connecting to a Voltage Source 109
Connecting a Potentiometer 109
Selecting the Potentiometer Value 110
Analog Deadband Adjustment 111
Power-On Safety 11 2
Under Voltage Safety 11 2
Data Logging in Analog Mode 11 2
SECTION 10 Closed Loop Position Mode 11 5
Mode Description 11 5
Selecting the Position Mode 11 5
Position Sensor Selection 116
Sensor Mounting 11 6
Potentiometer wiring 117
Using Optical Encoders in Position Mode 117
Sensor and Motor Polarity 11 7
Adding Safety Limit Switches 119
Using Current Limiting as Protection 120
Control Loop Description 120
PID tuning in Position Mode 122
SECTION 11 Closed Loop Speed Mode 123
Mode Description 123
Selecting the Speed Mode 123
8 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Using Optical Encoder for Speed Feedback (AX2850 only) 124
Tachometer or Encoder Mounting 124
Tachometer wiring 124
Speed Sensor and Motor Polarity 125
Adjust Offset and Max Speed 126
Control Loop Description 127
PID tuning in Speed Mode 128
SECTION 12 Installing, Connecting and Using the Encoder Module 131
Optical Incremental Encoders Overview 131
Recommended Encoder Types 132
Installing the Encoder Module 133
Connecting the Encoder 135
Motor - Encoder Polarity Matching 136
Voltage Levels, Thresholds and Limit Switches 136
Wiring Optional Limit Switches 137
Using the Encoder Module to Measure Distance 138
Using the Encoder to Measure Speed 139
Using the Encoder to Track Position 140
RS232 Communication with the Encoder Module 141
RS232 Encoder Command Set 142
Read Encoder Counter 142
Set/Reset Encoder Counters and Destination Registers 143
Read Speed 143
Read Distance 144
Read Speed/Distance 144
Read Encoder Limit Switch Status 144
Read / Modify Encoder Module Registers and Parameters 145
Register Description 147
Encoder Hardware ID code 147
Switch Status 148
Speed or Distance 1 or 2 148
Counter Read/Write Mailbox 148
Counter 1 and 2 148
Destination Register 1 and 2 148
Distance 1 and 2 148
Speed 1 and 2 149
Time Base 1 and 2 149
Encoder Threshold 149
Counter Read Data Format 149
Encoder Testing and Setting Using the PC Utility 150
Encoder Module Parameters Setting 151
Exercising the Motors 152
AX2500/2850 Motor Controller User’s Manual 9
Viewing Encoder Data 152
Updating the Encoder Software 152
SECTION 13 Configuring the Controller using the Switches 153
Programming Methods 153
Programming using built-in Switches and Display 153
Entering Programming Mode 154
Changing parameters 155
The Special Case of Joystick Calibration 155
Restoring factory defaults 155
Exiting the Parameter Setting Mode 156
Programmable Parameters List 156
SECTION 14 Using the Roborun Configuration Utility 159
System Requirements 159
Downloading and Installing the Utility 159
Connecting the Controller to the PC 160
Roborun Frame, Tab and Menu Descriptions 161
Getting On-Screen Help 162
Loading, Changing Controller Parameters 162
Controls Settings 163
Power Settings 164
Analog or R/C Specific Settings 165
Closed Loop Parameters 166
Viewing the Parameters Summary 166
Optical Encoder Operation 167
Running the Motors 167
Logging Data to Disk 170
Connecting a Joystick 171
Viewing and Logging Data in Analog and R/C Modes 172
Loading and Saving Profiles to Disk 172
Operating the AX2500/2850 over a Wired or Wireless LAN 172
Updating the Controller’s Software 174
Creating Customized Object Files 174
SECTION 15 Mechanical Specifications 177
Mechanical Dimensions 177
Mounting Considerations 178
Thermal Considerations 178
Wire Dimensions 179
Weight 179
10 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
SECTION 1 AX2500/2850
Quick Start
This section will give you the basic information needed to quickly install, setup and
run your AX2500/2850 controller in a minimal configuration. The AX2850 is a version
of the AX2550 controller with the addition of Optical Encoder inputs.
Important Safety Warnings
The AX2500/2850 is a high power electronics device. Serious damage, including fire, may occur to the unit, motors, wiring and batteries as a result of its
misuse. Please review the User’s Manual for added precautions prior to applying full battery or full load power.
This product is intended for use with
Unless special precautions are taken, damage to the controller and/or power
supply may occur if operated with a power supply alone. See“Power Regeneration Considerations” on page 31 of the Users Manual.
What you will need
For a minimal installation, gather the following components
• One AX2500/2850 Controller and its provided cables
• 12V to 40V high capacity, high current battery
• One or two brushed DC motors
• One R/C to DB15 connector (provided)
• Miscellaneous wires, connectors, fuses and switch
rechargeable batteries
.
AX2500/2850 Motor Controller User’s Manual 11
AX2500/2850 Quick Start
Locating Switches, Wires and Connectors
Take a moment to familiarize yourself with the controller’s wires, switches and connector.
The front side (shown in Figure 1) contains the buttons and display needed to operate and
monitor the controller. The 15-pin connector provides the connection to the R/C or microcomputer, as well as connections to optional switches and sensors.
Program Set
Controller Configuration buttons
Connector to
Optical Encoders
(AX2850 only)
FIGURE 1. Front Controller Layout
At the back of the controller (shown in the figure below) are located all the wires that must
be connected to the batteries and the motors.
Controller Power
Power Control
Yellow
Reset
Operating Status
and Program LED
Display
Ground (-)
Black
Connector to Receiver/Controls
and sensors
(top)
Motor (+)
White
Motor (-)
Green
Motor 1
12 to 40V (+)
Red
Ground (-)
Black
12 to 40V (+)
Red
Motor 2
Motor(+)
Yellow or
White
Motor (-)
Green
FIGURE 2. Rear Controller Layout
12 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Connecting to the Batteries and Motors
Connecting to the Batteries and Motors
Connection to the batteries and motors is shown in the figure below and is done by connecting the set of wires coming out from the back of the controller.
Motor2
Motor1
Motor
Cables
+
-
+
-
Controller
Battery
Power Cables
Motor Battery
Fuse
12V to 40V
Optional
Power on/off
switch
Power Control
Wire
Notes:
- The Battery Power connection are doubled in order to provide the maximum current to the controller. If
only one motor is used, only one set of motor power cables needs to be connected
- Typically, 1, 2 or 3 x 12V batteries are connected in series to reach 12, 24 or 36V respectively
- The Power Control wire may be used to turn On and Off the controller, or to provide a separate and stable supply to the controller’s logic (See discussion below)
FIGURE 3. Electrical Power Wiring Diagram
1- Connect the two thick black wires to the minus (-) terminal of the battery that will be
used to power the motors. Connect the two thick red wires to the plus (+) terminal of the
battery. The motor battery may be of 12 to 40 Volts. There is no need to insert a switch on
Motor Power cables, although one is suggested.
Avoid extending the length of these wires as the added inductance may cause damage to the controller when operating at high currents. Try extending the motor wires
instead since the added inductance on this side of the controller is not harmful.
The two red wires are connected to each other inside the controller. The same is true
for the black wires. You should wire each pair together as shown in the diagram
above.
2- You may leave the yellow Power Control wire and the thin black wire unconnected, or
you may connect them to a power switch. If left floating, protect these wires from touching
any metallic part of the controller or chassis.
Refer to the chapter “Connecting Power and Motors to the Controller” on page 25 for
more information about batteries and other connection options.
3- Connect each motor to one of the two output cables pair. Make sure to respect the
polarity, otherwise the motor(s) may spin in the opposite direction than expected
AX2500/2850 Motor Controller User’s Manual 13
AX2500/2850 Quick Start
Important Warning
The controller includes large capacitors. When connecting the Motor Power Cables,
a spark will be generated at the connection point. This is a normal occurrence and
should be expected.
Using the Power Control Wire
The AX2500/2850 includes a DC/DC converter that will generate a 12V internal supply from
the main +12 to +40V battery. As a result, the controller will turn On as soon as its Battery
Wires (thick red and black wires) are connected to the battery.
In order to turn On and Off the controller without the need for a bulky and expensive
switch or relay on the high current wires, the AX2500/2850 uses a Power Control wire to
enable or disable the internal DC/DC converter. When left unconnected, the DC/DC converter is On. When grounded, the DC/DC converter is Off.
The Power Control wire can also be used to feed a separate supply to the controller so that
it will continue to operate if and when the main batteries’ voltage dips below 12V. The table
below shows the various functions of the Power Control input. See “Connecting Power”
on page 25 for more details on the use and operation of the Power Control signal.
TABLE 1. Use of Power Control wire
Power Control input connected to Action
Floating Controller is On
Ground Controller is Off
Separate 12V to 40V supply Controller is On. Controller will draw power from
the Power Control wire if main battery voltage
dips below 12V.
Connecting the R/C Radio
Connect the R/C adapter cables to the controller on one side and to two or three channels
on the R/C receiver on the other side. The third channel is for activating the accessory outputs and is optional.
When operating the controller in “Separate” mode, the wire labelled Ch1 controls Motor1,
and the wire labelled Ch2 controls Motor2.
When operating the controller in “Mixed” mode, Ch1 is used to set the robot’s speed and
direction, while Ch2 is used for steering.
See “R/C Operation” on page 69 of the User’s Manual for a more complete discussion on
R/C commands, calibration and other options.
14 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Powering On the Controller
Channel 3
Channel 2
Channel 1
Pin 1
15
FIGURE 4. R/C connector wiring for 3 channels and battery elimination (BEC)
This wiring - with the wire loop uncut - assumes hat the R/C radio will be powered by the
AX2500/2850 controller. Other wiring options are described in “R/C Operation” on page 69
of the User’s Manual.
Important Warning
Do not connect a battery to the radio when the wire loop is uncut. The RC battery
voltage will flow directly into the controller and cause permanent damage if its voltage is higher than 5.5V.
3: Channel 1 Command Pulses
4: Channel 2 Command Pulses
6: Radio battery (-) Ground
7: Radio battery (+)
8: Channel 3 Command Pulses
8
9
Wire loop bringing power from
controller to RC radio and
to optical isolators
Connecting the optional channel 3 will enable you to turn on and off two accessory outputs. See “Connecting Sensors and Actuators to Input/Outputs” on page 49 and “Activat-
ing the Accessory Outputs” on page 83 of the User’s Manual.
Powering On the Controller
Important reminder: There is no On-Off switch on the controller. You must insert a switch
on the controller’s power wire as described in section“Connecting to the Batteries and
Motors” on page 13.
To power the controller, center the joystick and trims on the R/C transmitter. Then turn on
the switch that you have placed on the Battery Power wire or on the Power Control wire.
If the R/C transmitter and/or receiver is powered off, the display on the controller will alternate the letters spelling “no ctrl” to indicate that it is On but is not receiving a control signal.
AX2500/2850 Motor Controller User’s Manual 15
AX2500/2850 Quick Start
FIGURE 5. “no control” scroll message indicates no valid R/C signal is present
Turn the R/C transmitter On. The “no ctrl” scrolling message will disappear and the display
will show steady patterns depending on the motors’ selected direction.
Move the joystick on the transmitter to activate the motors to the desired speed and direction.
See “R/C Operation” on page 69 of the User’s Manual for a detailed description of the
many features and options available in the R/C mode.
Button Operation
The AX2500/2850 has three buttons: Set, Program and Reset. These buttons are not
needed for normal operation, as the controller is immediately operational upon power up.
The Reset button will restart the controller. This button is recessed and you will need a
paper clip to press it. Reset is also accomplished by turning the controller’s power Off and
back On.
The Set and Program buttons have the following functions depending how and when they
are pressed:
TABLE 2. AX2500/2850 Buttons Function
Prog and Set button status Function
Press and hold Program alone during reset or power up Enter the Programming Mode.
Press and hold Set alone during reset of power up Enter Self-Test mode. See “Self-Test
Mode” on page 47 of the User’s Manual
Press and hold Program and Set together during reset or
power up
Press Program while Programming Mode Accept previous parameter change and
Press Set while in Programming mode Change value of selected parameter
Press Program pressed alone during normal operation No effect
Press Set alone during normal operation No effect
Press Program and Set together during normal operation Emergency stop
Reset configuration parameters to factory
default
select next parameter
16 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Default Controller Configuration
Default Controller Configuration
Version 1.7 of the AX2500/2850 software is configured with the factory defaults shown in
the table below. Although Roboteq strives to keep the same parameters and values from
one version to the next, changes may occur from one revision to the next. Make sure that
you have the matching manual and software versions. These may be retrieved from the
Roboteq web site. See “Configuring the Controller using the Switches” on page 153 of the
User Manual for a complete configuration parameter list and their possible values.
TABLE 3. AX2500/2850 Default Settings
Parameter Default Values Letter
Input Command mode: (0) = R/C Radio mode I
Motor Control mode (0) = Separate A, B, speed control, open loop C
Amp limit (5) = 105A A
Acceleration (2) = medium-slow S
Input switch function (3) = no action U
Brake/Coast (0) = brake when idle b
Joystick Deadband (2) = 16% d
Exponentiation on channel 1 (0) = Linear (no exponentiation) E
Exponentiation on channel 2 (0) = Linear (no exponentiation) F
Left / Right Adjust (7) = no adjustment L
Checking and Changing Configurations
Any one of the parameters listed in Table 3, and others not listed, can easily be changed
either using the controller’s buttons or your PC with the Roboteq Configuration Utility.
The example below shows how to use the buttons to select and change the Motor Control
mode from “separate” to “mixed”. See “Configuring the Controller using the Switches” on
page 153 of the User’s Manual for a complete list of all the AX2500/2850’s parameters and
their meanings.
Press & hold Prog
Program mode entered
Restart
after 10 seconds
Press and hold the Prog button for 10 seconds while
resetting or powering on the controller
After 10 seconds, the controller will enter the programming mode and flash alternatively the current parameter (I= Input Mode) and its value (0= R/C mode).
AX2500/2850 Motor Controller User’s Manual 17
AX2500/2850 Quick Start
Press Prog to select
next parameter
Press Set to select
next value for parameter
Press Prog to store change
and select next parameter
Reset controller
to exit
Press the Prog button to move to the next parameter
(C= Motor Control Mode) and its value (0= Separate)
Press the Set button to change the parameter’s value
(1= Combined)
Press the Prog button record the change and move to
the next parameter (A= Amps limit) and it’s value (2=
75A)
Press the Reset button or power off/on the control to
restart the controller using the new parameters.
Connecting the controller to your PC using Roborun
Connecting the controller to your PC is not necessary for basic R/C operation. However, it
is a very simple procedure that is useful for the following purposes:
• to Read and Set the programmable parameters with a user-friendly graphical inter-
face
• to obtain the controller’s software revision and date
• to send precise commands to the motors
• to read and plot real-time current consumption value
• Save captured parameters onto disk for later analysis
• to update the controller’s software
18 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Obtaining the Controller’s Software Revision Number
FIGURE 6. Roborun Utility screen layout
To connect the controller to your PC, use the provided cable. Connect the 15-pin connector
to the controller. Connect the 9-pin connector to your PC’s available port (typically COM1).
Apply power to the controller to turn it on.
Load your CD or download the latest revision of Roborun software from
www.Roboteq.com, install it on your PC and launch the program. The software will automatically establish communication with the controller, retrieve the software revision number and present a series of buttons and tabs to enable its various possibilities.
The intuitive Graphical User Interface will let you view and change any of the controller’s
parameters. The “Run” tab will present a number of buttons, dials and charts that are used
for operating and monitoring the motors.
Obtaining the Controller’s Software Revision Number
One of the unique features of the AX2500/2850 is the ability to easily update the controller’s operating software with new revisions downloaded from Roboteq’s web site at
www.roboteq.com. This is useful for adding features and/or improving existing ones.
AX2500/2850 Motor Controller User’s Manual 19
AX2500/2850 Quick Start
Each software version is identified with a unique number. Obtaining this number can be
done using the PC connection discussed previously.
It is also possible to get the controller to display the software version number by following
these simple steps
• Disconnect the power from the motor batteries
• Press and hold the Set button while powering or resetting the controller
The LED will display a sequence of two numerical digits and an optional letter separated by
dashes as shown in the examples below.
FIGURE 7. Press and hold “Set” to display version number and enter self-test
After these digits are displayed, the controller will attempt to power the motors as part of
the self test mode (see “Self-Test Mode” on page 47 of the User’s Manual for a more
detailed explanation). This is why the motor’s battery must be disconnected. After about
30 seconds, the software revision number will be displayed every 30 seconds.
= Software version 1.7
You will need to reset, or power down and up, the controller to exit and resume normal
operations.
Now that you know your controller’s software version number, you will be able to see if a
new version is available for download and installation from Roboteq’s web site, and which
features have been added or improved.
Installing new software is a simple and secure procedure, fully described in “Operating the
AX2500/2850 over a Wired or Wireless LAN” on page 172 of the User’s Manual.
Exploring further
By following this quick-start section, you should have managed to get your controller to
operate in its basic modes within minutes of unpacking.
Each of the features mentioned thus far has numerous options which are discussed further
in the complete User’s Manual, including:
• Self test mode
• Emergency stop condition
• Joystick calibration
• Using Inputs/Outputs
• Current limiting
• Closed Loop Operation
• Software updating
• and much more
20 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
SECTION 2 AX2500/2850
Motor Controller
Overview
Congratulations! By selecting Roboteq’s AX2500/2850 you have empowered your-
self with the industry’s most versatile and programmable DC Motor Controller for
mobile robots. This manual will guide you step by step through its many possibilities.
Product Description
The AX2500/2850 is a highly configurable, microcomputer-based, dual-channel digital speed or position controller with built-in high power drivers. The controller is
designed to interface directly to high power DC motors in computer controlled or
remote controlled mobile robotics and automated vehicle applications.
The AX2500/2850 controller can accept speed or position commands in a variety of
ways: pulse-width based control from a standard Radio Control receiver, Analog
Voltage commands, or RS-232 commands from a microcontroller or wireless
modem.
The controller's two channels can be operated independently or can be combined to
set the forward/reverse direction and steering of a vehicle by coordinating the
motion on each side of the vehicle. In the speed control mode, the AX2500/2850
can operate in open loop or closed loop. In closed loop operation, actual speed measurements from tachometers or optical encoders are used to verify that the motor is
rotating at the desired speed and direction and to adjust the power to the motors
accordingly.
The AX2500/2850 can also be configured to operate as a precision, high torque
servo controller. When connected to a potentiometer coupled to the motor assembly, the controller will command the motor to rotate up to a desired angular position.
Depending on the DC motor's power and gear ratio, the AX2500/2850 can be used
to move or rotate steering columns or other physical objects with very high torque.
The AX2500/2850 is fitted with many safety features ensuring a secure power-on
start, automatic stop in case of command loss, over current protection on both
channels, and overheat protection.
AX2500/2850 Motor Controller User’s Manual 21
AX2500/2850 Motor Controller Overview
The motors are driven using high-efficiency Power MOSFET transistors controlled using
Pulse Width Modulation (PWM) at 16kHz. The AX2500/2850 power stages can operate
from 12 to 40VDC and can sustain up to 120A of controlled current, delivering up to
4,800W (approximately 6 HP) of useful power to each motor.
The many programmable options of the AX2500/2850 are easily configured using onetouch Program and Set buttons and a 7-segment LED display. Once programmed, the configuration data are stored in the controller's non-volatile memory, eliminating the need for
cumbersome and unreliable jumpers.
The AX2850 is the AX2550 controller fitted with a dual channel optical encoder input module. Optical Encoders allow precise motor speed and position measurement and enable
advance robotic applications.
Technical features
Fully Digital, Microcontroller-based Design
• Multiple operating modes
• Fully programmable using either built-in switches and 7 segment display or through
connection to a PC
• Non-volatile storage of user configurable settings. No jumpers needed
• Simple operation
• Software upgradable with new features
Multiple Command Modes
• Radio-Control Pulse-Width input
• Serial port (RS-232) input
• 0-5V Analog Command input
Multiple Advanced Motor Control Modes
• Independent operation on each channel
• Mixed control (sum and difference) for tank-like steering
• Open Loop or Closed Loop Speed mode
• Position control mode for building high power position servos
• Modes selectable independently for each channel
Automatic Joystick Command Corrections
• Joystick min, max and center calibration
• Selectable deadband width
• Selectable exponentiation factors for each joystick
• 3rd R/C channel input for weapon and accessory output activation
Special Function Inputs/Outputs
• 2 Analog inputs. Used as
22 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Technical features
•Tachometer inputs for closed loop speed control
•Potentiometer input for position (servo mode)
•Motor temperature sensor inputs
•External voltage sensors
•User defined purpose (RS232 mode only)
• One Switch input configurable as
•Emergency stop command
•Reversing commands when running vehicle inverted
•General purpose digital input
• Up to 2 general purpose outputs for accessories or weapon
•One 24V, 2A output
•One low-level digital output
• Up to 2 general purpose digital inputs
Optical Encoder Inputs (AX2850 only)
• Inputs for two Quadrature Optical Encoders
• up to 250khz Encoder frequency per channel
• two 32-bit up-down counters
• Inputs may be shared with four optional limit switches per channel
Internal Sensors
• Voltage sensor for monitoring the main 12 to 40V battery system operation
• Voltage monitoring of internal 12V
• Temperature sensors on the heat sink of each power output stage
• Sensor information readable via RS232 port
Low Power Consumption
• On board DC/DC converter for single 12 to 40V battery system operation
• Optional backup power input for powering safely the controller if the motor batteries
are discharged
• Max 200mA at 12V or 100mA at 24V idle current consumption
• Power Control wire for turning On or Off the controller from external microcomputer
or switch
• No power consumed by output stage when motors are stopped
• Regulated 5V output for powering R/C radio. Eliminates the need for separate R/C
battery
High Efficiency Motor Power Outputs
• Two independent power output stages
• Dual H bridge for full forward/reverse operation
• Ultra-efficient 2.5mOhm ON resistance (RDSon) MOSFET transistors
• 12 to 40 V operation
• High current 8 AWG cable sets for each power stages
• SmartAmps Automatic current limitation
•120A up to 15 seconds (per channel)
AX2500/2850 Motor Controller User’s Manual 23
AX2500/2850 Motor Controller Overview
•100A up to 30 seconds
•80A extended
•High current operation may be extended with forced cooling
• 250A peak Amps per channel
• 16kHz Pulse Width Modulation (PWM) output
• Auxiliary output for brake or clutch
• Heat sink extruded case
Advanced Safety Features
• Safe power on mode
• Optical isolation on R/C control inputs
• Automatic Power stage off in case of electrically or software induced program fail-
ure
• Overvoltage and Undervoltage protection
• Regeneration current limiting
• Watchdog for automatic motor shutdown in case of command loss (R/C and RS232
modes)
• Large, bright run/failure diagnostics on 7 segment LED display
• Programmable motor acceleration
• Built-in controller overheat sensor
• Motor temperature sensing and protection
• Emergency Stop input signal and button
Data Logging Capabilities
• 13 internal parameters, including battery voltage, captured R/C command, tempera-
ture and Amps accessible via RS232 port
• Data may be logged in a PC, PDA or microcomputer
Sturdy and Compact Mechanical Design
• Built from aluminum heat sink extrusion with mounting brackets
• Efficient heat sinking. Operates without a fan in most applications.
• 7” (178mm) long (excluding mounting brackets) by 5.5” wide (140mm) by 1.8”
(40mm) high
• -20o to +70o C operating environment
• 3.3 lbs (1500g)
24 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Connecting Power
SECTION 3 Connecting
Power and
Motors to the
Controller
This section describes the AX2500/2850 Controller’s connections to power sources and
motors.
Important Warning
Please follow the instructions in this section very carefully. Any problem due to wiring errors may have very serious consequences and will not be covered by the product’s warranty.
Connecting Power
The AX2500/2850 has 2 sets of Ground (black) and Vmot (red) power cables and a Power
Control wire (yellow):
The power cables are located at the back end of the controller. The various power cables
are identified by their position, wire thickness and color: Red is positive (+), black is negative or ground (-).
The power cables to the batteries and motors are shown in the figure below.
AX2500/2850 Motor Controller User’s Manual 25
Connecting Power and Motors to the Controller
Controller Power
Power Control
Ye l l o w
Motor (+)
White
Motor (-)
Green
12 to 40V (+)
Red
Motor 1
FIGURE 8. Controller rear plate and power wiring
Ground (-)
Black
Ground (-)
Black
12 to 40V (+)
Red
Motor(+)
Ye l l o w or
Motor 2
(top)
Motor (-)
Green
White
Controller Power
The AX2500/2850 uses a flexible power supply scheme that is best described in Figure 9.
On this diagram, it can be seen that the Control Logic requires a stable 12V supply, while
the Power Output stage that drives the motors can tolerate a very wide voltage range.
Because of its wide operating voltage range, the Power Output stage is wired directly to
the Main Battery.
The control logic is connected to both the DC/DC converter as well as the Power Control
wire. If the voltage applied to the DC/DC converter’s input is lower than the 12V needed for
its proper operation, the Control Logic will stop unless the Power Control wire is connected to a separate 12V power source. The diode circuit is designed to automatically
select one power source over the other. The diodes will let through the source that is
higher than the other.
The Power Control input also serves as the Enable signal for the DC/DC converter. When
floating or pulled to above 1V, the DC/DC converter is active and supplies the AX2500/
2850’s control logic, thus turning it On. When the Power Control input is pulled to Ground,
the DC/DC converter is stopped and the controller is turned Off.
All 3 ground wires (-) are connected to each other inside the controller. The two main battery wires are also connected to each other internally. However, you must never assume
26 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Controller Power
that connecting one wire of a given battery potential will eliminate the need for connecting
the other. Malfunction or even damage may occur if one wire is assuming the load of all
two.
Mot1(-)
Mot1(+)
Channel 1 MOSFET Power Stage
Microcomputer &
MOSFET Drivers
Channel 2 MOSFET Power Stage
9.5V min
13V max
DC/DC
5Vmin
40V max
ENABLE
10.5V min
40V max
5Vmin
40V max
VBatt Vmot
GND
Power
Control
&Backup
GND
GND
VBatt Vmot
Mot2(+)
Mot2(-)
FIGURE 9. Representation of the AX2500/2850’s Internal Power Circuits
TABLE 4. Effect of Power Control under various voltage conditions
Power Control input is
connected to
And Main Battery
Voltage is Action
Ground Any Voltage from 0V to 40V Controller is Off
Floating Below 9V Controller is Off
Floating Between 9V and 10.5V Controller Logic is On
Power Stage is Disabled (undervoltage condition)
Floating Between 10.5 and 40V Controller is On. Drawing power
from Main Battery
Power Stage is Active
10.5V to 40V Lower than Voltage on Power
Control input - or Off
Controller is On. Drawing power
from external source (backup
battery)
Power Stage is Active
10.5V to 40V Higher than Voltage on Power
Control input
Controller is On. Drawing power
from Main Battery
Power Stage is Active
AX2500/2850 Motor Controller User’s Manual 27
Connecting Power and Motors to the Controller
Powering the Controller using the Motor Batteries
The AX2500/2850 included a DC/DC converter to generate the internal 12V required for its
operation. The diagram on Figure 10 show how to wire the controller to a single battery circuit and the two options for turning the power On and Off. The diagram shows two
switches, although switching either one alone will power the controller Off.
In a typical configuration, it is recommended that the Motor Power be always applied and
that the Controller’s Power be controlled using a switch on the Power Control wire (yellow).
When the controller is Off, the output transistors are in the Off position and no power is
drawn on the Motor Power battery.
For safety reasons, however, it is highly recommended that a way of quickly disconnecting
the Motor Power be provided in the case of loss of control and all of the AX2500/2850
safety features fail to activate
Note, however, that eventually the motor batteries will get weaker and the voltage drop
below the level needed for the internal DC/DC converter to properly operate. For all professional applications it is therefore recommended to add a separate 12V (to 40V) power supply to ensure proper powering of the controller under any conditions.
Important Warning
Unless you can ensure a steady 12V voltage in all conditions, it is recommended that
the battery used to power the controller’s electronics must be separate from the one
used to power the motors. This is because it is very likely that the motor batteries
will be subject to very large current loads, which may cause the voltage to eventually
dip below 12V as the batteries’ charge drops. The separate backup power supply
should be connected to the Power Control input.
Important Warning
On versions of the AX2550 with PCB revision number lower than 5.2, the backup
power supply applied on the Power Control wire must NEVER EXCEED 13V. Permanent damage may otherwise occur. PCB revision number can be found on the sticker
on the case’s bottom.
28 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
Controller Power
Swich on
Power Control
Swich on
Main Battery
(optional)
Controller
2 x 12V Batteries = 24V
3 x 12V Batteries = 36V
Notes:
- Only one switch is actually needed to turn On/Off the controller. If either one is used,
the other can be omitted.
FIGURE 10. Powering the controller from the Motor Batteries
Using a Backup Battery
To ensure that the controller will always be operational, regardless of the charge left in the
main battery, it is recommended to add a 12V backup battery connected as shown in
Figure 11.
Motor
Cables
Motor2
Motor1
-
+
-
+
Controller
Battery
Power Cables
Power Control
Fuse
12V to 40V
Motor Battery
Wire
On
Off
12V
Controller
Battery
FIGURE 11. Power wiring using a two-battery system
AX2500/2850 Motor Controller User’s Manual 29
Connecting Power and Motors to the Controller
Make sure that your motors have their wires isolated from the motor casing. Some
motors, particularly automotive parts, use only one wire, with the other connected
to the motor’s frame.
If you are using such a motor, make sure that it is mounted on isolators and that its
casing will not cause a short circuit with other motors and circuits which may also
be inadvertently connected to the same metal chassis.
Power Fuses
For low Amperage applications (below 30A per motor), it is recommended that a fuse be
inserted in series with the main battery circuit as shown in the Figure 11 above.
The fuse will be shared by the two output stages and therefore must be placed before the
Y connection to the two power wires.
Automotive fuses are generally slow and the following values are recommended depending on the desired level of protection. It should be noted that the current values listed will
apply to the sum of the current drawn by each channel. Practically, a fuse will be of limited
effectiveness. In very high current application (80A or more per channel), it will simply not
be possible to find a fuse with the necessary Amps rating and speed needed to provide
adequate protection. In such situation, the fuse may be just as well omitted keeping in
mind that the controller’s current limiting circuit may not be able to protect it against short
circuits and other abnormal situations.
TABLE 5. Fuse selection table
Desired Current Protection (total for
Channel 1 + Channel 2) Fuse
120A 100A
100A 80A
80A 60A
60A 50A
50A 40A
40A 35A
Important Warning
Fuses are typically slow to blow and will thus allow temporary excess current to flow
through them for a time (the higher the excess current, the faster the fuse will blow).
This characteristic is desirable in most cases, as it will allow motors to draw surges
during acceleration and braking. However, it also means that the fuse may not be
able to protect the controller.
Wire Length Limits
The AX2500/2850 regulates the output power by switching the power to the motors On
and Off at high frequencies. At such frequencies, the wires’ inductance produces undesir-
able effects such as parasitic RF emissions, ringing and overvoltage peaks. The controller
30 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005
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