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 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 (x2)
  • Arm-updown (x2)
  • Neck-YES (x1)
  • Neck-NO (x1)

Cabling Improvements

• Cables are now better organized
• Added connectors inside the arm to disconnect motors easily for repairs
• Signals are color coded as follow (TODO ADD DOCUMENTATION)
  • Red
  • Green
  • Black
  • Yellow
  • Purple
  • Gray
  • White
  • Blue

Head Improvements

File:ReddyGravityCompensation.jpg

Motor controllers for head movement (YES-NO)

• 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.

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

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;
				
				//RAM LOC7 (PID + TRAPZ VARIABLES)
				
				short SpeedMax; //for Trapz 
				short AccelerationStep; //for Trapz, Speed
				
				
				//RAM LOC8 (TRAPZ VARIABLES)
				short InitPoint; //for Trapz
				short DestPoint; //for Trapz
				short NextPoint; //for Trapz
				
				
				//RAM LOC9 (CURRENT LIMIT)
				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;	

Future Improvements

• 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.

Documents

File:MotorControllerTuningWin32.zip