CAN Protocol
The Allegro Hand designed with CAN specification 2.0.
Baud-Rate
The CAN communication baud-rate is 1Mbps.
Periodic Communication
The Allegro Hand control software attempts to communicate with the Allegro Hand at a regular control interval. Every 2 milliseconds, the join torques are calculated and the joint angles are updated.
CAN Frames
Arbitration Identifier
The Allegro Hand uses 11-bit standard arbitration identifier.
Message ID
Messages marked with RTR can be sent by host in remote frame, and the Allegro Hand will respond it.
Data Structure
Each message has different data filed format.
All multi-byte data structures in data filed uses little endian
Servo ON
Data Length = 0
This message does not have data field.
Servo OFF
Data Length = 0
This message does not have data field.
Set Torque Finger
Data Length = 8
Each finger has 4 joints. This message sets joint torque set-point. Torque set-point is 2 byte signed digit. Data field is composed as below.
Information
Data Length = 7
Information message is composed with hardware version and firmware version. The Allegro Hand sends this message when the host request by remote frame.
Hardware Ver. And Firmware Ver. Is 2 byte number.
Serial Number Read
Data Length = 8
Serial number can be retrieved using CAN interface. It is stored in ASCII characters. The Allegro Hand sends this message when the host request by remote frame.
Position Finger
Data Length = 8
Joint position is reported through this message format. The Allegro Hand sends this message when the host request by remote frame or report period comes. All values are represented as signed 2-byte integer.
Joint angle can be calculated by this equation
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Fingertip Pressure
Data Length = 8
Fingertip sensor data is reported through this message format. The Allegro Hand sends this message when report period comes. All values are represented as signed 4-byte integer.
Fingertip sensor data is expressed in pascal (Pa) units, indicating the pressure applied to the fingertip.
Pick
Data Length = 0
This message does not have data field. This message indicates that the Allegro Hand has been commanded to pick.
Place
Data Length = 0
This message does not have data field. This message indicates that the Allegro Hand has been commanded to place.
Error
Data Length = 2
Error message is reported through this message format.
The error code is displayed as a result of a bitwise OR operation for each situation, and its meaning is as follows.
If an error occurs, the LED on the back of the hand changes from green to red.