3 Getting Started
This section introduces the basic operation and development of the TRACER platform using the CAN bus interface.
3.1 Use and operation
Check
Check the condition of vehicle body. Check whether there are significant anomalies; if so, please contact the after-sale service personnel for support;
Check the state of emergency stop switches. Make sure both emergency stop buttons are released.
Start up
Emergency stop switch status. Confirm that the emergency stop buttons are all released;
Rotate the key switch (Q6 on the electrical panel), and normally, the voltmeter will display correct battery voltage and front and rear lights will be both switched on.
Shut down
Rotate the key switch to cut off the power supply;
Emergency stop
Press down emergency push button both on the left and the right of rear vehicle body;
Basic operating procedure of remote control:
After the chassis of TRACER mobile robot is started correctly, turn on the RC transmitter and select the remote-control mode. Then, TRACER platform movement can be controlled by the RC transmitter.
3.2 Charging
TRACER is equipped with a 10A charger by default to meet customers' recharging demand.
The detailed operating procedure of charging is shown as follows:
Make sure the electricity of TRACER chassis is powered off. Before charging, please make sure Q6 (key switch) in the rear control console is turned off;
Insert the charger plug into Q3 charging interface on the rear control panel;
Connect the charger to power supply and turn on the switch in the charger. Then, the robot enters the charging state.
3.3 Communication using CAN
TRACER provides CAN and RS232 interfaces for user customization. Users can select one of these interfaces to conduct command control over the vehicle body.
3.3.1 CAN message protocol
TRACER adopts CAN2.0B communication standard which has a communication baud rate of 500K and Motorola message format. Via external CAN bus interface, the moving linear speed and the rotational angular speed of chassis can be controlled; TRACER will feedback on the current movement status information and its chassis status information in real time. The protocol includes system status feedback frame, movement control feedback frame and control frame, the contents of which are shown as follows:
The system status feedback command includes the feedback information about current status of vehicle body, control mode status, battery voltage and system failure. The description is given in Table 3.1.
The command of movement control feedback frame includes the feedback of current linear speed and angular speed of moving vehicle body. For the detailed content of protocol, please refer to Table 3.3.
The control frame includes control openness of linear speed and control openness of angular speed. For its detailed content of protocol, please refer to Table 3.4.
The light control frame includes current state of front light. For its detailed content of protocol, please refer to Table 3.5.
Note[5]: This date only valid in custom mode
The light control frame includes light control mode and control openness. For its detailed content , please refer to Table 3.6.
The control mode frame include set the control mode of chassis. For its detailed content , please refer to Table 3.7.
Note 1， Control mode instruction
In case the RC transmitter is powered off, the control mode of TRACER is defaulted to command control mode, which means the chassis can be directly controlled via command. However, even though the chassis is in command control mode, the control mode in the command needs to be set to 0x01 for successfully executing the speed command. Once the RC transmitter is switched on again, it has the highest authority level to shield the command control and switch over the control mode.
The status position frame includes clear error message. For its detailed content , please refer to Table 3.8.
The chassis status information will be feed back; what’s more, the information about motor. The following feedback frame contains the information about motor:
The serial numbers of 2 motors in the chassis are shown in the figure below:
3.3.2 CAN cable connection
FOR WIRE DEFINITIONS, PLEASE REFER TO TABLE 2.2.
Note:The maximum achievable output current is typically around 5 A.
3.3.3 Implementation of CAN command control
Correctly start the chassis of TRACER mobile robot, and turn on FS RC transmitter. Then, switch to the command control mode, i.e. toggling SWB mode of FS RC transmitter to the top. At this point, TRACER chassis will accept the command from CAN interface, and the host can also parse the current state of chassis with the real-time data fed back from CAN bus. For the detailed content of protocol, please refer to CAN communication protocol.
3.4 Communication using RS232
3.4.1 Introduction to serial protocol
This is a serial communication standard which was formulated collectively by Electronic Industries Association (EIA) together with Bell System, modem manufacturers and computer terminal manufacturers in 1970. Its full name is called "the technical standard for serial binary data exchange interface between data terminal equipment (DTE) and data communication equipment (DCE). This standard requires to use a 25-pin DB-25 connector of which each pin is specified with corresponding signal content and various signal levels. Afterwards, RS232 is simplified as DB-9 connector in IBM PCs, which has become a de facto standard since then. Generally, RS-232 ports for industrial control only use 3 kinds of cables - RXD, TXD and GND.
3.4.2 Serial message protocol
Basic parameters of communication
Basic parameters of communication
The protocol includes start bit, frame length, frame command type, command ID, data field, frame ID, and checksum composition. Where, the frame length refers to the length excluding start bit and checksum composition; the checksum refers to the sum from start bit to all data of frame ID; the frame ID is a loop count between 0 to 255, which will be added once every command sent.
Protocol content
System status feedback command
[1]: The subsequent versions of robot chassis firmware version after V1.2.8 are supported, but previous versions need to be updated before supported.
[2]: The over-temperature alarm of motor drive and the motor over-current alarm will not be internally processed but just set in order to provide for the upper computer to complete certain pre-processing. If drive over-current occurs, it is suggested to reduce the vehicle speed; if over-temperature occurs, it is suggested to reduce the speed first and wait the temperature to decrease. This flag bit will be restored to normal condition as the temperature decreases, and the over-current alarm will be actively cleared once the current value is restored to normal condition;
[3]: The over-temperature protection of motor drive and the motor over-current protection will be internally processed. When the temperature of motor drive is higher than the protective temperature, the drive output will be limited, the vehicle will slowly stop, and the control value of movement control command will become invalid. This flag bit will not be actively cleared, which needs the upper computer to send the command of clearing failure protection. Once the command is cleared, the movement control command can only be executed normally.
Movement control feedback command
Movement control command
No.1 motor drive information feedback frame
No.2 motor drive information feedback frame
Lighting control frame
Lighting control feedback frame
Example data The chassis is controlled to move forward at a linear speed of 0.15m/s, from which specific data is shown as follows:
The data field content is shown as follows:
The entire data string is: 5A A5 0A 55 01 02 00 0A 00 00 00 00 6B
3.4.3 Serial connection
Take out the USB-to-RS232 serial cable from our communication tool kit to connect it onto the serial port at the rear end. Then, use the serial port tool to set corresponding baud rate, and conduct the test with the example date provided above. If the RC transmitter is on, it needs to be switched to command control mode; if the RC transmitter is off, directly send the control command. It should be noted that, the command must be sent periodically, because if the chassis has not received the serial port command after 500ms, it will enter the disconnected protection status.
3.5 Firmware upgrades
The RS232 port on TRACER can be used by users to upgrade the firmware for the main controller in order to get bugfixes and feature enhancements. A PC client application with graphical user interface is provided to help make the upgrading process fast and smooth. A screenshot of this application is shown in Figure 3.3.
Upgrade preparation
Serial cable X 1
USB-to-serial port X 1
TRACER chassis X 1
Computer (Windows operating system) X 1
Firmware update software
Upgrade procedure
Before connection, ensure the robot chassis is powered off;
Connect the serial cable onto the serial port at rear end of TRACER chassis;
Connect the serial cable to the computer;
Open the client software;
Select the port number;
Power on TRACER chassis, and immediately click to start connection (TRACER chassis will wait for 6s before power-on; if the waiting time is more than 6s, it will enter the application); if the connection succeeds, "connected successfully" will be prompted in the text box;
Load Bin file;
Click the Upgrade button,and wait for the prompt of upgrade completion;
Disconnect the serial cable, power off the chassis, and then turn the power off and on again.
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