EtherDrive Motor Control System V2.0

Written by Pascal Stang | Updated: Friday March 17, 2006

Overview:

The EtherDrive Motor Controller is a multi-axis ethernet-based motor controller and driver system. It consists of controller and driver PCBs which operate together. A single controller may drive up to 6 motors (3 dual-channel driver cards, or 1 six-channel driver card).

System Level Features for V2.0:

6-axis full-featured motor control

Quadrature encoder input with index pulse (10MHz max)

Programmable PWM drive (13-bits resolution, up to 125KHz)

4-Quadrant differential motor current sensing (12-bit resolution, 15KHz)

Fast Ethernet communication (round-trip time: 124us)

Programmable PID and feedforward control at up to 10KHz/motor of:

Position (32-bits resolution)

Velocity (24-bits resolution)

Motor current (12-bits resolution)

Drive levels of 50V @ 20A per motor continuous (40A peak) using Dual Driver cards

Drive levels of 50V @ 3A per motor continuous (6A peak) using Hex Driver card

EtherDrive Controller V2.0
(Click for larger image)

EtherDrive Dual Driver V2.0 (two channel)
(click for larger image)

Harware Features

LPC2214 32-bit ARM processor @ 60MHz

10/100Mb/s ethernet interface

Dual RS-232 serial communication interface

6-axis motor control

6 Quadrature encoder counters

6 Programmable motor control PWM outputs (sign-magnitude or locked-antiphase mode)

6 Differential current-sensing inputs
-12-bit A/D, up to 10KHz per channel

Encoder connectors support std. Agilent HEDS 5-pin pinout or US Digital mini 4-pin pinout.

Emergency stop connector (4-pin molex)

8-channel 10-bit A/D general-purpose inputs

EEPROM for non-volatile storage of system, network, and motor control parameters.

Power input via DC jack or from driver boards.

LED indicators

Ethernet Link and Activity Status

4 System Status LEDs

Power LED.

Board Size: 5.0" x 3.0" x 0.7" (LxWxH)

Hardware Features

Dual-channel high-current motor driver
(drives 2 DC motors).

Discrete MOSFET driver stage

50V max motor voltage.

20A/channel rated current.

40A/channel peak current.

Integrated surge and spike protection

4-quadrant differential current-sensing outputs

Digital Logic Inputs:

3 digital control signals per motor.

May be configured for sign-magnitude or locked-antiphase (four-quadrant) drive.

PWM frequencies up to 250KHz

5V and 3.3V logic compatible.

LED indicators:

Bi-color motor drive LEDs.

Power LED.

On-board 12V regulator for drive electronics.

Auto-shutdown when controller is turned off.

Board Size: 5.0" x 3.0" x 1.1" (LxWxH)

Software/Firmware Features and Operation:

The EtherDrive Motor Controller standard firmware supports two modes of operation:
- Local Control Loop operation
  - Control loops calculated and executed locally by the on-board microcontroller.
  - Closed-loop rates of 100Hz - 15KHz depending on control requirements.
  - Operational modes include PID control of motor position, velocity, and current.
  - Motor commanding (control loop set points) are sent via ethernet UDP/IP or serial port.
  - Controller configuration and loop gains set via ethernet or serial port.
- Remote Control Loop operation
  - Control loops calculated remotely by off-board computer.
  - Closed-loop rates of up to ~6KHz (may be limited by host computer OS or usable network bandwidth)
  - Control loop procedure:
    - EtherDrive sends encoder and current feedback values to 'remote' control computer via ethernet UDP/IP packet
    - Remote computer computes desired control law
    - Remote computer sends motor PWM drive values to EtherDrive
    - Repeat.
  - Controller configuration set via ethernet or serial port.
Example client software is available to demonstrate operating the controller in each mode.
Custom operating modes can be designed to meet the needs of specific users or projects as needed.

Network Protocol Information:

Configuring and interrogating the EtherDrive Motor Controller
- The EtherDrive Motor Controller can be configured and interrogated over the network using by using EtherDrive Command/Reply Packets over UDP/IP. The format for commands and replies is the same.
- All EtherDrive commands are available via serial terminal or network.
- To issue a comand:
Commanding the Motors
- Once the EtherDrive Controller is configured and enabled, you can issue EtherDrive Motor Drive Commands via the network and operate in a closed-loop.
- To issue a motor command:

Information as of 7/14/2006.

Network Addressing and Support Details		Notes
Supported protocols	UDP, ICMP (ping), IP, ARP	Unit will respond to pings to IP address. No TCP support at this time. ARP table currently limited to 8 entries.
IP Address (default)	192.168.1.12	User-changable via serial port interactive terminal. User set value is non-volatile, stored in EEPROM.
Netmask (fixed)	255.255.255.0	User-changable, non-volatile setting.
Gateway (fixed)	192.168.1.1	User-changable, non-volatile setting.
Network Active Port Details		Notes
Echo	7/UDP	UDP Echo port. Packets sent to this port will be echoed to sender, payload unmodified.
Motor Control port	4900/UDP	Motor drive and feedback values passed via UDP packets on this port. See protocol info below.
EtherDrive Command port	4950/UDP	Configuration and instruction packets should be sent to this port. See protocol info below.
EtherDrive UART0 port	4960/UDP	Packets sent here will be relayed via UART0.
EtherDrive UART1 port	4961/UDP	Packets sent here will be relayed via UART1.

Motor Drive Command Format (send to Motor Control port)				Notes
Description	Byte Offset	Byte Length	Data Type	This packet is sent by the controlling host
Motor 1 Drive	0	4	signed int32	Drive command of zero indicates no net power to motor. Valid range and units of drive command depends upon control mode. If using direct PWM: In Locked-Antiphase mode, range is +/-(PWM period/2) In Sign-Magnitude mode, range is +/-PWM period Drive levels in excess of the linear range will be clamped at the extreme.
Motor 2 Drive	4	4	signed int32
Motor 3 Drive	8	4	signed int32
Motor 4 Drive	12	4	signed int32
Motor 5 Drive	16	4	signed int32
Motor 6 Drive	20	4	signed int32
Motor Feedback Format (received from Motor Control port)				Notes
Description	Byte Offset	Byte Length	Data Type	This packet is sent back to the host in response to a Motor Drive Command
Encoder 1 Position	0	4	signed int32	Encoder position feedback is read and refreshed for each motor feedback packet sent. Value indicated number of tics counted since last reset. Value will overflow in standard 2's-complement form upon reaching +/-2^31.
Encoder 2 Position	4	4	signed int32
Encoder 3 Position	8	4	signed int32
Encoder 4 Position	12	4	signed int32
Encoder 5 Position	16	4	signed int32
Encoder 6 Position	20	4	signed int32
Motor 1 Current	24	4	signed int32	Motor current values represent the latest available values at time of packet transmission. Value range is +/-2048. Current readings may only be accurate in locked-antiphase mode. Value = (ImotorRsenseGain2048) / Vref Imotor = (ValueVref) / (RsenseGain2048) where Gain is the A/D converter Gain setting = 1,2,4,5,8,10,20x and Vref is the A/D converter reference = 2.048V default and Imotor is in [AMPS] and Rsense is in [OHMS]
Motor 2 Current	28	4	signed int32
Motor 3 Current	32	4	signed int32
Motor 4 Current	36	4	signed int32
Motor 5 Current	40	4	signed int32
Motor 6 Current	44	4	signed int32
Motor 1 PWM	48	4	signed int32	Motor PWM values are those applied to the motor by the control algorithm that is currently in use.
Motor 2 PWM	52	4	signed int32
Motor 3 PWM	56	4	signed int32
Motor 4 PWM	60	4	signed int32
Motor 5 PWM	64	4	signed int32
Motor 6 PWM	68	4	signed int32

EtherDrive Command/Reply Format (sent to/from ED Command port)				Notes
Description	Byte Offset	Byte Length	Data Type
Command	0	4	signed int32	An EtherDrive command can be issued to change the way the EtherDrive system is configured or operating. A reply is returned for each command issued. The reply will be identical the command, but may have argument values changed to reflect the response or result of the command. NOTE: Processing of commands may interrupt closed-loop motor operation and should not be issued during critical motion control. It is recommended that motors be stopped before sending most commands.
Argument 0	4	4	signed int32
Argument 1	8	4	signed int32
Argument 2	12	4	signed int32
...	...
Argument N	4*N	4	signed int32

EtherDrive Motor Controller Commands				Notes
General and Test Commands
Description	Cmd	Arg0	Arg1
Help	'?'	.	.	Print commands to terminal
Encoder Monitor Test	'e'	.	.	Prints encoder values to terminal.
Current Monitor Test	'a'	.	.	Prints current-feedback values to terminal.
Config Commands
List Config	'l'	.	.	Prints currently active configuration to terminal.
Read Config	'r'	.	.	Loads the configuration stored in EEPROM and makes it current.
Write Config	'w'	.	.	Writes the current configuration to EEPROM.
Revert Config	'R'	.	.	Reverts all settings to factory defaults.
Network Commands
Ethernet MAC Status	'd'	.	.	Prints Ethernet MAC state for debug.
Ethernet PHY Status	'q'	.	.	Prints Ethernet PHY state for debug.
Send UDP packet	'u'	string	.	Sends broadcast UDP packet on command port with user-entered string as payload.
Set IP address	'n'	IP	.	Set EtherDrive Controller IP address, IP=XXX.XXX.XXX.XXX
Set IP address	's'	IP	.	Set EtherDrive Controller subnet mask.
Set IP address	'o'	IP	.	Set ErherDrive Controller gateway address.
Generate MAC addr	'H'	.	.	Auto-generates semi-random ethernet MAC address. Each controller must have a unique MAC address to function together on a network.
Set network motor-drive timeout	'T'	time [ms]	.	Sets the timeout between loss of motor drive communication and automatic disabling of the motors. If network-based motor drive communication begins but is interrupted for more than <time> milliseconds, the motors will be automatically disabled.
Motor Commands
Drive Motor	'g'	motor#	P	Drives the selected motor to drive power P. If a control mode is enbles, this input is passed as the input to the control law.
Enable/Disable Motors	'm'	mode	.	mode=0: Motor drivers OFF (open-circuit) mode=1: Motor dirvers ON
PWM Mode	'p'	mode	.	mode=0: Locked-Antiphase PWM mode=1: Sign-Mangitude PWM
PWM Period	't'	period [tics]	.	Period is specified in tics (1 tic = 20ns*2^N). Maximum period is 4095 tics. Periods less than 10us may not function correctly in current-control mode.
PWM Prescaler	'v'	N	.	Divides the PWM rate by 2^N. Default is N=0, or no division.
Current-Sense ADC Mode	'B'	mode	.	Set the motor current-sense ADC to the proper mode for the type of feedback: mode=0: Current feedback signal is bipolar mode=1: Current feedback signal is unipolar
Current-Sense ADC Gain	'G'	gain-idx	.	Set the motor current-sense ADC gain: gainidx=0: ADC gain = 1x (recommended for 6-ch driver) gainidx=1: ADC gain = 2x gainidx=2: ADC gain = 4x gainidx=3: ADC gain = 5x gainidx=4: ADC gain = 8x gainidx=5: ADC gain = 10x (recommended for 2-ch driver) gainidx=6: ADC gain = 16x gainidx=7: ADC gain = 20x
Control Mode	'i'	mode	.	mode=0: Disable, command voltage directly mode=1: Enable, command motor current mode=2: Enable, command motor position
PID Controller Settings
Set Proportional Gain	'P'	motor#	Kp	Sets the Proportional gain for the selected motor [units TBD]
Set Integral Gain	'I'	motor#	Ki	Sets the Integral gain for the selected motor [units TBD]
Set Derivative Gain	'D'	motor#	Kd	Sets the Derivative gain for the selected motor [units TBD]
Integral Windup Max	'W'	motor#	k	Sets the value limit on the PID integral error term [units TBD]
PID Output Max/Clamp	'M'	motor#	k	Sets the maximum output magnitude of the PID controller. Outputs greater than this will be clamped.
PID Output Deadzone	'Z'	motor#	k	Sets the PWM output magnitude below which the PID output will be clamped to zero.
I/O Commands
Read Aux ADC	'A'	ch#	.	Reads the voltage on the requested channel of the aux ADC (JP19). Results are 0-1023 over a range of 0-3.3V.
Set Aux I/O Port Dir	'C'	bitval	.	Sets the in/out direction of the aux I/O port pins (JP19). Each of the 8 pins are individually configurable, and correspond to the 8-bits in the bitval argument. For each pin, a '0' bit indicates input and a '1' bit indicates output.
Set Aux I/O Port Out	'O'	bitval	.	Sets the output value of the aux I/O port pins (JP19). Each of the 8 pins are individually set by the corresponding bit of the 8-bit bitval argument. For each pin, a '0' bit indicates output 0V and a '1' bit indicates output 3.3V.
This command list is subject to change.

Available to current customers via support site:

Firmware updates
Precise capabilities and specifications
Additional commands
Schematics
Mechanical drawings
To enter Support, click here.

Written by Pascal Stang | Updated: Friday March 17, 2006