Reddy Update

Schedule

Week 31, July 27 - August 1	Ordered new coupling for shoulder Fab. + installation of head mechanism for gravity assist (previous one had interference problems with other head parts) Assembly and installation of 1 motor PCB for neck Assembly and installation of the speaker PCB + support Final tuning of motor controllers Documentation (protocol)
Week 32, August 3 - August 9	Final tests & tuning
Week 33, August 10 - August 15	Schedule a meeting for robot exchange

Arm Improvements

To have better control of the arm (and neck) motors, we did the following :

• Change the Motor PCB to support
  • Temperature detector. A signal will be sent to the motor controller if the motor temperature is higher than 60 degrees celcius. Analog temperature value is also available.
  • Potentiometer feedback.
  • Motor power connection.
• Design a new PCB with support to 4 motors
• Communicate with the CAN bus already available on Reddy
• Allow position feedback from the RS-232 interface
• Create a tuning GUI for easier setup of the robot controllers

Motor PCB

Modified Servo Motors

Cable + Servo PCB	Servo PCB installed in housing	Final servo + cable + connector

Motor Controllers

• A new motor drive that can connect up to 4 motors have been designed.
• A new adjustable bracket for fixing the drive to the side of the robot have been designed.
• We installed two motor controllers (one on each side) to allow the modification of 8 motors. Motors modified are :
  • Arm-Elbow (x2)
  • Arm-Shoulder-Yaw (x2)
  • Arm-Shoulder-Pitch (x2)
  • Neck-Yaw (x1)
  • Neck-Pitch (x1)

Cabling Improvements

• Cables are now better organized
• Added connectors inside the arm to disconnect motors easily for repairs

 (TODO ADD DOCUMENTATION FOR CABLING)

• Signals are color coded as follow
  • Red
  • Green
  • Black
  • Yellow
  • Purple
  • Gray
  • White
  • Blue

Head Improvements

We added gravity compensation for the head to minimize power required for motors.

TODO Add description here

Motor controllers for head movement (Yaw + Pitch)

• Same motor controllers were used for the neck to add overheating protection and better feedback / control
• Internal servo potentiometers were used for position control.

Tuning the motor controller

A GUI was created to facilitate motor tuning.

Warning! This GUI is intended for Engineers at IntRoLab and changing control values can lead to indesirable effects. Assistance will be required before changing controller values.

[[Image::ReddyTuningGUI.jpg|600px|center]]

RS-232 protocol enhancements

• We added a CAN command to the RS-232 robot interface to allow direct communication with the motor controllers. The RS-232 robot interface now acts as a RS-232 to CAN bridge and bidirectional communication is now possible. This will allow feedback from the motor controllers (current, position, speed, etc.)

(RS-232 CAN COMMAND) <------------------------> (MOTOR DRIVE CAN INTERFACE)

CAN command format for RS-232 communication

Serial messages containing CAN commands will have the following stucture :

RS-232 Data Format (16 bytes total)

HEADER	CAN_MSG_PRI_MSB_CMD	CAN_MSG_TYPE	CAN_MSG_BOOT_RTR_LENGTH	CAN_MSG_CMD	CAN_MSG_DEST	CAN_MSG_DATA
(3 bytes)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(8 bytes)
header[0] = 'c' header[1] = 'a' header[2] = 'n'	We had to change the standard protocol here to address more than 256 bytes of internal memory of the motor controlers. MSB of the MSG_CMD will be stored here (3 bits max).	CAN_TYPE_EMERGENCY=0x01 CAN_TYPE_ACTUATOR_HIGH_PRIORITY=0x02 CAN_TYPE_SENSOR_HIGH_PRIORITY=0x04 CAN_TYPE_ACTUATOR_LOW_PRIORITY=0x08 CAN_TYPE_SENSOR_LOW_PRIORITY=0x10 CAN_TYPE_REQUEST_DATA=0x20 CAN_TYPE_USER2=0x40 CAN_TYPE_EVENTS=0x80	bit 0-3 = DATA_LENGTH (0-8) bit 4 = RTR bit 5 = Boot (READ=1/WRITE=0) bit 6 = Boot (EEPROM=1/RAM=0)	if (MSG_TYPE == REQUEST) CMD = RAM OFFSET FOR READ/WRITE endif if (MSG_TYPE == SENSOR_HIGH_PRIORITY) CAN_ACTUATOR_CMD_POSITIONS=0x90 CAN_ACTUATOR_CMD_CURRENTS=0x91 CAN_ACTUATOR_CMD_SETPOINTS=0x92 endif	0x01 = First controller 0x02 = Second controller	Wll depend on commands

Note: It is not essential to understand the structure of the CAN messages. Souce code will be provided to format the data correctly.

Motor Controller Variables

Motor controller internal variables can be represented like this :

typedef struct _SharedVariables
	{
		union {
			struct {
				unsigned char CtrlMode;
				unsigned char CtrlType;		
				unsigned char SetPointSource;	
				unsigned char PosMesSource;
				unsigned short ErrorCode;
				short SetPoint;
				short SetPointMax; //Maximum SetPoint
				short SetPointMin; //Minimum SetPoint
				short Current;
				short CurrentOffset;
				short ADCValue;
				short ADCOffset;
				short ICValue;
				short ICOffset;
				short ThermalState;	
				//CONTROL VARIABLES
				short Speed;//16 bit speed
				short Position; //16 bits position
				short Acceleration;
				//PID REF AND MES POINT
				short RefPoint; 
				short MesPoint;
				float pid_kp;
				float pid_ki;
				float pid_kd;
				float pid_error;
				float pid_error_accum;
				float pid_error_derivative;
				float pid_error_accum_max; //PID I value max limit (abs)
				short PIDOut;
				short SpeedMax; //for Trapz 
				short AccelerationStep; //for Trapz, Speed
				short InitPoint; //for Trapz
				short DestPoint; //for Trapz
				short NextPoint; //for Trapz
				short CurrentLimit; //unit = mA
				short PWM_CurrentLimit;
				short PWM_CurrentStep; //PWM increment
				unsigned char CurrentLimitActive;
				unsigned char EncoderBias; //Setting this to 1 will invert the encoder sign
				unsigned char MotorBias; //Setting this to 1 will invert motor polarity
				unsigned char padding[3];
			} __attribute__((packed));
			
			unsigned char m_data[];
		};
	} SharedVariables;


typedef struct _GlobalVariables
	{
		union {
			struct {
				
				//All control variables
				SharedVariables m_variables[4];
				
				//additional (global) variables
				unsigned char m_ESTOPEnabled;
				unsigned char m_WriteEEPROM;
				short m_loopTime;
				unsigned char m_padding[4];
				
			} __attribute__((packed));
		
			unsigned char m_data[];
		};//union
	} GlobalVariables;	

Notes :

• Understanding the structure of the controller is not required for normal operation.
• The structure GlobalVariables represents the memory organization of the motor controller. You can see that it contains control variables (SharedVariables structure) for 4 motor axis.
• Using the CAN protocol, we can access each variable and read/write its value.
• The GUI was designed for easy tuning of those variables by our engineers.

New Joints Configuration

 TODO : Update Servo Ranges

Updated Reddy Joints Configuration

Motor controller id=0x01	Motor controller id=0x02
Motor 0 = Left Arm Shoulder Pitch Range: Motor 1 = Left Arm Shoulder Yaw Range: Motor 2 = Left Arm Elbow Range: Motor 3 = Head Yaw ("NO") Range:	Motor 0 = Right Arm Shoulder Pitch Range: Motor 1 = Right Arm Should Yaw Range: Motor 2 = Right Arm Elbow Range: Motor 3 = Yead Pitch ("YES") Range:

Useful Examples

Those examples will probably contain all you will need to do to operate the robot.

Read all positions from the motor controller

The computer sends this to the RS-232 server (Remote request) :

Read all positions from the motor controller RS-232 Data Format (16 bytes total)

HEADER	CAN_MSG_PRI_MSB_CMD	CAN_MSG_TYPE	CAN_MSG_BOOT_RTR_LENGTH	CAN_MSG_CMD	CAN_MSG_DEST	CAN_MSG_DATA
(3 bytes)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(8 bytes)
header[0] = 'c' header[1] = 'a' header[2] = 'n'	CAN_MSG_PRI_MSB_CMD=0	CAN_TYPE_SENSOR_HIGH_PRIORITY=0x04	bit 0-3 = 8 bit 4 = RTR = 1 bit 5 =1 (not used) bit 6 =1 (not used)	CAN_ACTUATOR_CMD_POSITIONS=0x90	0x01 = First controller 0x02 = Second controller	CAN_MSG_DATA[0-7] (ignored)

Serial Message Sent:

• serial_message[0] = 'c'
• serial_message[1] = 'a'
• serial_message[2] = 'n'
• serial_message[3] = 0x00
• serial_message[4] = 0x04
• serial_message[5] = 0x78
• serial_message[6] = 0x90
• serial_message[7] = 0x01 or 0x02
• serial_message[8] = (ignored)
• serial_message[9] = (ignored)
• serial_message[10] = (ignored)
• serial_message[11] = (ignored)
• serial_message[12] = (ignored)
• serial_message[13] = (ignored)
• serial_message[14] = (ignored)
• serial_message[15] = (ignored)

The RS-232 server responds (response to remote request):

Read all positions from the motor controller RS-232 Data Format (16 bytes total)

HEADER	CAN_MSG_PRI_MSB_CMD	CAN_MSG_TYPE	CAN_MSG_BOOT_RTR_LENGTH	CAN_MSG_CMD	CAN_MSG_DEST	CAN_MSG_DATA
(3 bytes)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(1 byte)	(8 bytes)
header[0] = 'c' header[1] = 'a' header[2] = 'n'	CAN_MSG_PRI_MSB_CMD=0	CAN_TYPE_SENSOR_HIGH_PRIORITY=0x04	bit 0-3 = 8 bit 4 = RTR = 0 bit 5 =1 (not used) bit 6 =1 (not used)	CAN_ACTUATOR_CMD_POSITIONS=0x90	0x01 = First controller 0x02 = Second controller	CAN_MSG_DATA[0-1] LSB, MSB Position motor 0 CAN_MSG_DATA[2-3] LSB, MSB Position motor 1 CAN_MSG_DATA[4-5] LSB, MSB Position motor 2 CAN_MSG_DATA[6-7] LSB, MSB Position motor 3

Serial Message Received :

• serial_message[0] = 'c'
• serial_message[1] = 'a'
• serial_message[2] = 'n'
• serial_message[3] = 0x00
• serial_message[4] = 0x04
• serial_message[5] = 0x68
• serial_message[6] = 0x90
• serial_message[7] = 0x01 or 0x02
• serial_message[8] = Motor 0 Position LSB
• serial_message[9] = Motor 0 Position MSB
• serial_message[10] = Motor 1 Position LSB
• serial_message[11] = Motor 1 Position MSB
• serial_message[12] = Motor 2 Position LSB
• serial_message[13] = Motor 2 Position MSB
• serial_message[14] = Motor 3 Position LSB
• serial_message[15] = Motor 3 Position MSB

Additional Notes

• Single 12V power supply could be useful for direct connection to Pioneer robots. A 12V-->8.5V DC-DC (100W) converter is required for this operation. This item can be ordered at Vicor. 8.5V batteries would then be useless.