Dexter Er-2 Robotic Arm 2011-09-30

Dexter ER2 Robotic Arm

NEX Robotics Pvt. Ltd. 1 www.nex-robotics.com

DEXTER ER2 ROBOTIC ARM User Manual



Version 1.00 April 2011 Documentation author Sachitanand Malewar, NEX Robotics Pvt. Ltd.



Content of this manual is released under the Creative Commence cc by-nc-sa license. For legal information refer to: http://creativecommons.org/licenses/by-nc-sa/3.0/legalcode

Products electronics is static sensitive. Use the product in static free environment.

Read the user manuals completely before start using this product

Recycling: Almost all the part of this product are recyclable. Please send this product to the recycling plant after its operational life. By recycling we can contribute to cleaner and healthier environment for the future generations.



Index

1. Introduction

5

2. Hardware Setup and Driver Installation 7



1. Introduction Dexter ER2 Robotic Arm is a 5 Axis robotic Arm + Servo Gripper. It uses 7 metal gear servo motors with 15Kg/cm torque and two servo motors with 7Kg/cm torque. Robot Arm has 5 degrees of freedom which includes: Base rotation, Shoulder rotation, Elbow rotation, Wrist pitch and roll. Out of which Shoulder rotation, Elbow rotation, Wrist pitch have two 15Kg/cm torque servo motors in parallel for giving additional torque. Robotic arm comes preassembled along with the Servo control card, Servo motion profile generator GUI, 5V-25A, 12V-5A SMPS and Flex sheets with polar and rectangular coordinate systems for the robotic arm. Servo motion profile generator GUI is used for quickly generating servo motion profile for the robot. GUI can access each servo motor individually in real-time. We can select individual servo motors velocity. We can also generate, edit and play motion sequence (motion profile) using GUI.

Figure 1.1: Dexter ER2 Robotic Arm



1.1 Technical Specifications Mechanical Structure Vertical articulated Number of Axes 5 axes plus servo gripper Axis Movement Axis 1: Base rotation Axis 2: Shoulder rotation* Axis 3: Elbow rotation Axis 4: Wrist pitch Axis 5: Wrist roll

180 180 (Dual servos) 180 (Dual servos) 180 (Dual servos) 180

Maximum Operating Radius 320mm End Effecter DC servo motor based gripper with Parallel

finger motion Maximum Gripper Opening 55mm Hard Home Yes Actuators 5VDC servo motors Motor Capacity (axes 14) (7 motors) Motor Capacity (axes 5) Motor Capacity (gripper)

15Kg/cm 7Kg/cm 7Kg/cm

Total number of Servo Motors 9 Maximum Payload 50gms Weight 1.5Kg Ambient Operating conditions 240C (36104F) 10% to 90% relative

humidity Power 5V-10Amp; 12V-2Amp (SMPS) Control GUI for Servo Motion Profile Generation *For long life move shoulder (joint 2) in front 90 degrees region. To rotate in full 180 degrees remove two metals studs which are located between joint number 2 and 3. Important: Before using the robotic arm ensure that the robotic arm is kept in an area where lots

of free space is available. Before use mount the robotic arm using screws / nuts and bolts on the table. Read the product manual carefully before using Robotic Arm Do not keep arm in stretched position for more than few minutes at a stretch, else

servo motors will get damaged because of overheating. Kit contains: Dexter ER-2 Heavy Duty Robotic Arm Servo control card 5V-25A, 12V-5A SMPS Two flex sheets with polar and rectangular coordinate systems Documentation CD



2. Hardware Setup and Driver Installation 2.1 Setting up robotic Arm Robotic arm comes with two types of flex sheets for object positioning in polar or rectangular coordinate system. Setup flex sheet with the required coordinate system on the table and put the robotic arm in the middle circular area.

Figure 2.1: Flex sheets with polar and rectangular coordinate systems for the

Robotic Arm 2.2 Powering up the Robotic Arm Robotic Arm is powered by SMPS. It provides 5V DC for powering up the servo motors and 12V DC for powering electronics. Figure 2.2 shows the SMPS power supply for the robotic arm and figure 2.3 shows the power connector on the robotic arm.

Figure 2.2: SMPS power supply for the robotic arm



Figure 2.3: Power connector on the robotic arm

Figure 2.4: Home position of the robotic arm



Steps Involved in powering up the robotic arm

1. Mount the robotic arm on the table using screws or nuts and bolts 2. Bring the robotic arm in the home position slowly and carefully by hand as shown

in the figure 2.4. If robotic arm is in other state then it will try to regain is home position quickly. To avoid stress to the robotic arm bring it to the home position before powering it up.

3. Connect the power connector of the SMPS to the robotic arm as shown in the figure 2.3

4. Turn on the SMPS. 5. Robot will come back to its home position as shown in the figure 2.4.

Refer to figure 2.5. Green and Yellow LEDs indicate the 5V and 12V supply from the SMPS. Red LEDs marked by FUSE 5V and FUSE 12V shows the fuse status. If any of these Red LEDs are on then fuse is blown and you need to replace them before resuming the operation. If fuse are blown again then do the visual inspection for non working / damaged servo motor. If problem is not resolved then send the robotic arm back to the NEX Robotics for the servicing. Use 20Amp slow fuse for 5V and 2Amp slow blow fuse for the 12V. You can use this home position to replace the damaged servo motor with the new servo motor.



2.3 Servo Motor Control Card for the Robotic Arm

Figure 2.5: Control Card for the Robotic Arm

Control card for the Robotic Arm is based on ATMEGA640 microcontroller. It has connections for 9 servo motors. Figure 2.5 shows the various sections of the control card.



2.4 USB Driver installation and COM port identification 2.4.1 USB Driver installation Before using USB port we need to install the driver software for FT232 USB to serial converter. The software is located in the Software and Drivers \ CDM 2.06.00 WHQL Certified folder in the documentation CD or can also be downloaded from the NEX Robotics website.

Steps to install the drivers for USB to serial converter:

Step 1: Copy the driver installation folder on your PC from Software and Drivers \ CDM 2.06.00 WHQL Certified Folder in the CD.

Step 2: Connect the USB to serial converter cable between robot and the PC

Step 3: On connecting the device Found New Hardware message will appear in the taskbar tray and the following window opens.

Figure 2.6

Step 4: Check on the radio button No, not this time and then click on the next button.

Figure 2.7



The following window will appear.

Figure 2.8

Select the second option manually to install the drivers and click on next button. Step 5: Now check the second option and set the location of folder containing drivers E.g.(C:\CDM 2.06.00 WHQL Certified).

Figure 2.9



Step 6: On clicking next driver installation will begin.

Figure 2.10 Step 7: On successfully installing the driver following window will appear. Click Finish to complete the installation.

Figure 2.11

After installation of FT232 USB UART software, PC may ask for USB serial port software. To install this software follow steps 1 to 7 of USB serial converter software installation. Important: When using USB port for the communication, for proper operation first turn on the robot then connect USB cable between PC and the Robotic Arm. We have to follow this exact sequence because USB to serial converter chip is powered by USB. If any fault occurs then turn off the Robotic Arm, remove the USB cable and repeat the same procedure.



2.4.2 COM port number identification We need to specify the COM port number to the GUI from the drop down list as shown in figure 2.20. If many COM ports are active at the same time then you may have to identify COM port associated with the Robotic Arm. Follow the procedure described below to identify the COM port number. Step 1: Right Click My Computer and click on properties. System properties window will appear.

Figure 2.12

Step 2: Click on the Device manager in the Hardware tab.

Figure 2.13



Step 3: Expand Ports (Com & LPT) tree. COM Port number is mentioned in the parenthesis next to USB Serial Port. For example in the figure 2.14 COM3 is connected with the Robotic Arm via FT232 USB to Serial Converter.

Figure 2.14 FT232 connections shown in device manager

2.4.3 Changing COM port number Ideally COM port number should not be changed but if you still want to change it then follow the following steps.

Step 1: Right click on USB serial Port and select properties. In this case USB Serial Port (COM3).

Figure 2.15



Step 2: In the Port settings tab click on the Advanced button, the following window will appear.

Figure 2.16

You can change the COM port number by clicking on the Com Port Number drop down list and select the appropriate number. Make sure the new COM port is not being used by any other device.



2.5 GUI installation for the Robotic Arm Servo motion profile generator GUI is used for quickly generating servo motion profile for the robot. GUI can access each servo motor individually in real-time. We can select individual servo motors velocity. We can also generate, edit and play motion sequence (motion profile) using GUI.

Figure 2.17: GUI for Robot Motion Profile Generation



2.5.1 Installation of the Servo Motion Profile Generator GUI on PC GUI is located in GUI folder in the documentation CD. Step1: Copy the Servo motion profile generator GUI folder from the documentation CD on the PC. Click on the setup.exe file to start the installation. Following window will appear.

Figure 2.18 Step 2: Click on the Next button to continue. Step 3: Browse the location where setup file should be installed or set the default location and click next button to start the installation. Step 4: When installation is successfully completed, click Close to exit.

Figure 2.19



2.6 Using Servo Motion Profile Generator GUI 2.6.1 GUI components

Figure 2.20

1. Comport selection: Select COM port corresponding to the robots USB port 2. Connect button: Used to establish communication with the robot 3. Exit button: Used to close the application. 4. Reset button: Resets the angle to 90 degree and velocity to 90 degree per sec. for all servo motors 5. All: Used to select all servo motors. 6. None: Used to unselect all servo motors 7. Lock: To lock the velocity of servo motors to a constant value. You can set the common velocity of all the servos in this scroll bar after pressing lock button. 8. Angle scroll bar: Used to select the desired angle of individual servo motor. 9. Velocity scroll bar: Used to select the servo motor velocity of individual servo motor. 10. Check/Uncheck box: Select individual servo motor which is to be used. 11. ADD: Used to generate the string for motion profile, for checked servo motors. 12. DELETE: It clears data from the motion profile editor box. 13. RAM: Used to load the generated motion profile string to the RAM memory of robot. 14. ROM: Used to load the generated motion profile string to the ROM memory of robot. 15. RUN: Execute loaded motion profile strings from the RAM memory of robot. 16. STOP: Stop the Robot, while in motion. 17. String Execution Time: Use this to allot single string execution time in milliseconds (ms). 18. Motion Profile Editor: Shows the generated motion profile strings from the checked servo motors from the real time servo control section of GUI.



19. Terminal window: Displays status of the motion profile data while being loaded on the robot. Note: To execute the motion profile strings from the RAM memory of robot press INT7 Switch (Boot Load Switch) on the robot. 2.6.2 Establishing communication between PC and the Robotic Arm 1. Fix the robot on the table firmly using screws or nuts and bolts. You may also use Flex sheet with polar or rectangular coordinate system. 2. Turn on Robotic Arm. Robot will move to its home position as shown in figure 2.4. Important: Bring the robotic arm in the home position slowly and carefully by hand as shown in the figure 2.4. If robotic arm is in other state then it will try to regain is home position quickly. To avoid stress to the robotic arm bring it to the home position before powering it up. 3. Connect USB cable between robot and PC. If you not installed USB drivers for the robot then you need to install them before using GUI. For USB driver installation, refer to section 2.4. If drivers are installed then Connect USB cable between robot and PC, wait for 5 seconds and start the GUI.

Figure 2.21: Servo Motion Profile Generator GUI



4. In the GUI select the correct COM port. If multiple COM ports appear then refer to section 2.4.2 for identifying the correct COM port number. Press Connect button. PC will start communicating with the robot. 2.6.3 Moving individual servo motors using Real Time Servo Control window GUI has 18 + 2 servo motors. Robotic Arm uses 1 to 6 servo channels. For number associated with each joint, refer to figure 1.1. As default GUI starts with all servo motors selected with default velocity set at 90 degrees per second and angle set at 90 degrees. You can move slider bar corresponding to any servo motor to move it. You can also change the velocity of the individual servo motor. To bring all servo motors to the home position press Reset button. You can also select or unselect all servos by pressing All or None buttons. If required you can select or unselect individual servo motors as required. If you want to keep same velocity for all servo motors then press Lock button and use slider bar above to set common velocity for all the servo motors. Important settings for the Robotic Arm

1. Select Servo numbers 1 to 6 in the Real Time Servo Control Window 2. If you are a new user then lock velocity of all servos and keep it at 20 degrees per

second. As you acquire more familiarity with the Robotic Arm, you can set different velocity for each servo motor.



2.6.4 Generating motion profile using motion profile generator and executing it on the robot To easily understand the process we are going to use a small example. In this example we are going to move axis 1 and gripper. 1. Follow all the steps of the section 2.6.2 and 2.6.3. 2. In this case keep String Execution Time at 5000 in the Motion Profile Properties window. We will see its purpose at the end of the example. 3. In the Servo Control Properties press Lock button and move velocity to 20 degrees per second. This will make all servos of the Robotic Arm move at 20 degrees per second.

Figure 2.22



4. Move Servo 1 to 65 degree, Servo 2 to 60 degrees and servo 3 to 70 degrees from the Real Time Servo Control window and press ADD button from the Motion Profile Properties window. It adds the following code in the Motion Profile Editor window. We will see its meaning at the end of the example. $ 1 5000 # 1 65 20 # 2 60 20 # 3 70 20 # 4 90 20 # 5 90 20 # 6 90 20 # 7 90 20 # 8 90 20 # 9 90 20 # 10 90 20 # 11 90 20 # 12 90 20 # 13 90 20 # 14 90 20 # 15 90 20 # 16 90 20 # 17 90 20 # 18 90 20 # 19 90 20 # 20 90 20 *

Figure 2.23



5. Move servo 4 to 70 degrees and press add. Following code will get added. $ 2 5000 # 1 65 20 # 2 60 20 # 3 70 20 # 4 70 20 # 5 90 20 # 6 90 20 # 7 90 20 # 8 90 20 # 9 90 20 # 10 90 20 # 11 90 20 # 12 90 20 # 13 90 20 # 14 90 20 # 15 90 20 # 16 90 20 # 17 90 20 # 18 90 20 # 19 90 20 # 20 90 20 *

Figure 2.24



6. Move all servos back to 90 degrees by slider bar and press ADD button. Following code will get added. $ 3 5000 # 1 90 90 # 2 90 90 # 3 90 90 # 4 90 90 # 5 90 90 # 6 90 90 # 7 90 90 # 8 90 90 # 9 90 90 # 10 90 90 # 11 90 90 # 12 90 90 # 13 90 90 # 14 90 90 # 15 90 90 # 16 90 90 # 17 90 90 # 18 90 90 # 19 90 90 # 20 90 90 *

Figure 2.25



2.6.4.1 Loading generated motion profile string in to RAM memory and executing The ATmega 640 have 8KB of RAM, If you are using this memory for storing the motion profile strings, Which will get erased after power OFF the Robot. To load the string in RAM, Continuing the step 6 from above section, 7. Press RAM button. It will load the generated motion profile displayed in Motion Profile Editor window in the robots RAM. After loading is successful robot will beep twice.

Figure 2.26

8. Now press RUN button, Robot will beep thrice at the beginning and it will start executing the generated motion profile. You can press STOP button if you want to stop in between.

Figure 2.27



Figure 2.28

2.6.4.2 Loading generated motion profile string in to ROM memory and executing The ATmega 640 have 4KB of internal EEROM, If you are using this memory for storing the motion profile strings, Which you can use even after restarting the Robot and run by pressing the INT7 i.e. BOOT switch. To load the string in ROM, Continuing the step 6 from above section, 7. Press ROM button. It will load the generated motion profile displayed in Motion Profile Editor window in the robots internal EEPROM memory of ATMEGA 640 Microcontroller. After loading is successful robot will beep twice.

Figure 2.29

8. Now press INT7 switch (boatload switch) on the robot, it will start executing the generated motion profile. Please refer the Figure 2.5 to know the INT7 switch (boatload switch) location on robot.



Note: After each power ON the data stored in EEPROM is getting erased, to avoid this we need to enable the EESAVE bit in the fuse setting of ATMEGA 640 microcontroller. Please read carefully the data sheet of ATmega640 microcontroller. While shipping the robot all the fuse setting is burned properly and tested all the motion profiles on Robotic arm. The above discussion on EESAVE fuses setting is for Knowledge purpose. 2.6.5 Error Messages wile loading motion profile strings GUI will give the two types of error messages. 1. Firstly, while loading the motion profile generated string in RAM or ROM of the robot, after pressing the RAM or ROM button, if the robot is not detected due to some loose connection of USB cable between Robot and GUI or robot is powered off unfortunately, the GUI will display the following message in terminal window.

Figure 2.30

2. Secondly, while loading the motion profile generated string in RAM or ROM of the robot, if string is more then 4000 byte, the GUI will display the error in terminal window.

Figure 2.31

Important: After pressing run button Arm will only respond to STOP command. In order to start again, first press Disconnect button on the GUI then press Reset button of the Robotic Arm. Now press Connect button on the GUI and start using application. If GUI is not responding to the commands then restart the GUI and Reset the Robotic Arm. If it is still not responding then close the GUI, unplug and plug the USB cable and repeat the same process.



When you are using Real Time Servo Control you can see the frequent blinking of the Red LED on the Servo Control Card. If Red LED is not blinking while using Real Time Servo Control then you have to repeat above steps. 2.6.6 Interpretation of the generated motion profile string In the exampled covered in the section 2.2.5 following motion profile strings were generated. $ 1 5000 # 1 65 20 # 2 60 20 # 3 70 20 # 4 90 20 # 5 90 20 # 6 90 20 # 7 90 20 # 8 90 20 # 9 90 20 # 10 90 20 # 11 90 20 # 12 90 20 # 13 90 20 # 14 90 20 # 15 90 20 # 16 90 20 # 17 90 20 # 18 90 20 # 19 90 20 # 20 90 20 * $ 2 5000 # 1 65 20 # 2 60 20 # 3 70 20 # 4 70 20 # 5 90 20 # 6 90 20 # 7 90 20 # 8 90 20 # 9 90 20 # 10 90 20 # 11 90 20 # 12 90 20 # 13 90 20 # 14 90 20 # 15 90 20 # 16 90 20 # 17 90 20 # 18 90 20 # 19 90 20 # 20 90 20 * $ 3 5000 # 1 90 20 # 2 90 20 # 3 90 20 # 4 90 20 # 5 90 20 # 6 90 20 # 7 90 20 # 8 90 20 # 9 90 20 # 10 90 20 # 11 90 20 # 12 90 20 # 13 90 20 # 14 90 20 # 15 90 20 # 16 90 20 # 17 90 20 # 18 90 20 # 19 90 20 # 20 90 20 *

In this set of commands $ represents the beginning of the each string. Number followed by the $ is string number like $1 or $4 etc. Followed by this we have number 5000 which is the String Execution Time. It sets the time interval after which robot will execute the next string. You can change this by moving the slider bar. It shows the time in milliseconds i.e. 5000 represents 5000 milliseconds or 5 seconds. Warning: While setting String Execution Time make sure that you give sufficient time for the execution of the particular motion. If time set is less then robot will simply skip the current motion and go to next motion. Some times it may result in damage to the servo motor. After the String Execution Time we have # 1 65 20. Here # acts as servo motor separator. First number followed by # represents the servo motor number. After servo motor number first digits separated by space indicates servo angle which can vary between 0 to 180 degrees and second set of digits separated by space represents servo motors velocity in terms of degrees per second. You can set servo motors velocity from 1 to 180 degrees per second. Each motion profile string is ended by symbol * 2.6.7 Using previously generated commands to play motions After generating complete motion you can copy it from Motion Profile Editor and paste it in note pad to save it. Do not copy it to word pad or word document as it may add its own characters in between. To use this saved motion profile copy it from the note pad and paste it in the Motion Profile Editor window. Finally to load this string and execute refer the above section 2.6.4 section You have to restart GUI and Robot after pressing RAM, ROM or RUN button to start with new application.



2.6.8 Application Examples: Some Robotic Arm motions are given as an Example in the documentation CD. It is located in the folder Servo Motion Profile Examples You can use them by following process explained in the section 2.6.7 & 2.6.4.

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