The Idea of Scorbot comes from the Hollywood famous movie ‘The Scorpion King’ starring by the retired star wrestler ‘The Rock’. The outlook of Scorbot is illustrated to a scorpion with 2 arm and a powerful and poisoning tail behind. Scorbot can perform some human like fighting movements for example right hand front punch, side punch, defend posture and etc (Scorpion Kung Fu seven styles). The scorpion’s stinger which is illustrated by a gripper is one of the weapons for fighting. For mobility, Scorbot is driven by two dc brush motor at the base and this allows Scorbot to move quickly, stably and effectively.
Scorbot is a semi auto robot which the mobility and body movements can be controlled through PC and PS2 controller wirelessly. There are three kinds of wireless communication protocols or device can be used to control Scorbot. They are Bluetooth protocol by using Cytron bluetooth starter kit (SKKCA), XBEE protocol by using Cytron XBEE starter kit (SKXBEE) and PS2 wireless controller protocol using Cytron PS2 Controller starter kit (SKPS).
Now, let’s see what Scorbot can do better than The Rock’s scorpion king!
This is the initial posture of Scorpion kung fu to show respect to its opponent and ready to fight! The scorpion tail is taken up and the stinger (gripper) is open to attack in any time! OK! Now let’s see how it perform the kung fu and how it is being built!
Scorpion kung fu first style – Scorpion two claw front punch!
Scorpion kung fu second style – Scorpion right claw sudden front strike!
Scorpion kung fu third style – Scorpion left claw sudden front strike!
Scorpion kung fu forth style – Scorpion right claw sudden right bite!
Scorpion kung fu fifth style – Scorpion left claw sudden left bite!
Scorpion kung fu sixth style – Scorpion stinger attack!
Scorpion kung fu seventh style – Scorpion defend!
Cytron Bluetooth starter kit (SKKCA) allows Scorbot to be controlled wirelessly through PC by using graphical user interface (GUI).
Cytron XBEE starter kit (SKXBEE) allows Scorbot to be controlled wirelessly through PC by using graphical user interface (GUI).
Cytron PS2 controller starter kit (SKPS) allows Scorbot to be controlled through wired or wireless PS2 controller.
The scorpion mobile robot graphical user interface (GUI) shown above is created for my ease to control Scorbot through PC via Bluetooth or Xbee communication. From the GUI, I can control the mobility, predefined movements of the body and even the position of all the servos by using keyboard or pc mouse (click the button on GUI). But, before that, i have to connect the PC to the virtual com port created by the wireless device. The rate of the data transferred is 115200kb/s.
For Bluetooth communication, a bluesoleil software is being used to connect the Bluetooth dongle with SKKCA and a virtual com port will be created. At the COM port area of the Scorbot’s GUI, select the created virtual COM port and clicks connect. Now, connection between Bluetooth dongle and SKKCA is ready.
For XBEE communication, a already predefined address of SKXBEE (source and destination address) must be plug to the pc in order to communicate with the SKXBEE on Scorbot. At the com port area of Scorbot’s GUI, search for the new created COM by the pc’s SKXBEE and clicks connect. Now, connection between two SKXBEE is ready.
Next, let’s go to the assembly process of Scorbot!
Figure above shows how the wheel is mounted on the dc brush motor using the coupling. The coupling is fit for any SPG model dc brush motor and the wheel from Cytron.
Next, locate the flexibot dc brush motor driver (FD04A) on the base and firm it together with the base. The rainbow cable is the signal cable from the driver to connect to PIC.
From the figure above, the left motor is connected to motor1 port at FD04A and right motor is connected to motor2 port. The yellow/green cable at the left side of FD04A is the power supplement cable to the driver. 12V is enough for the two dc brush motor to operate.
Bottom view of the circuit board. Jumper is used to link all the components with SK40B 40 pins PIC start-up kit.
The SK40B which is the brain of Scorbot is placed at the predefined location. The SK40B is removable.
Switch 1 (SW1) and switch 2 (SW2) are programmable buttons but the RESET labeled button is a fix function button to reset the PIC.
The figure above shows the IDC connector to link the I/O pins of PIC with the signal control pins of FD04A.
Connect the signal control pin of SC16A with the main board through 2510 connector and rainbow cable.
The wireless starter kit can be directly plugged to the connector at the main board shown above but to allow me to change the wireless device easily, I extend the connection to the top of Scorbot using rainbow cable.
Figure shown is the 6V regulator circuit set to generate 6V for the needs of the 11 servo motors.
After the main board is perfectly functioning, it is mounted on the base.
Scorbot needs two 7V above battery to power it up. One battery is for the circuit and dc brush motor and another 1 is for servo motor. 11.1V Li-Po battery is being chosen as the power source for Scorbot because it is light in weight and rechargeable.
The base of Scorbot is complete!!
Now, let’s go to the upper body of Scorbot. Scorbot contains 11 servo motors on Its body offers 9 degree of freedom ( 9 axis ) motion. The shape of the body is the combination of the servo with two types of servo brackets which are servo holder and U-joint. The end of its tail is the servo based gripper.
This is the driver for all the servo motors (SC16A). It is located at the back of the scorpion body. As you can see, all the servos are connected to it and the signal control pins are connected to the SK40B at the main board through rainbow cable.
This is the tail of Scorpion! The tail provide 2 degree of freedom with two servo motor and one servo motor for the gripper.
Figure shows the two DOF joint of the scorpion tail using two servo motor and few servo bracket.
The fierce Scorpion stinger (gripper)!
The gripper is operated by a servo motor inside.
Now, come to the scorpion king arm! Each arm has 3 servo motor which provide 3 degree of freedom motion to the arm.
The combination of the first 2 servo motor is shown in figure above. They are likely to illustrate the shoulder of human.
This is the third servo motor of the arm which illustrate the elbow joint of human.
The servo allows the body of scorpion to rotate in one axis and it is like the waist of human.
The head of the scorpion is a servo motor which can turn right and left.
At last, to mount the upper body of the scorpion on the mobile base, another robot platform has been used as the supporting layer.
The upper part of Scorbot has been done, it is ready to combile with the base. A wireless device is mounted beside the scorpion tail and it link to the main board through cable.
Here come the new Scorpion king, The ScorBOT has borned!
What components actually used in ScorBot? Very simple, let’s look to the details!
CYTRON DC Gear Mobile Robot Base (HD-BSC-SPG-G)
This is the material I used as the base of ScorBOT and the supporting layer for the body of ScorBOT (servo and bracket). The base is ready with holes to mount the DC gear motor, caster and PCB stand.
CYTRON DC Gear Motor, Coupling and Wheels (is included in Robot Base)
Since Cytron’s product range also provides DC gear motor together with its coupling and wheels, this make me feel very convenient because by using the robot base, dc gear motor, coupling, wheels and caster, I can built up my ScorBOT base within few minutes! Hardware construction is always not an easy part for robot lover because it may need some expansive tools and machine to process. The DC gear motor I used is the SPG30-20K model with 185 R.P.M. The speed and torque of the motor is just enough for ScorBot.
CYTRON RC Servo Motor (C36S, C40R, and C55R)
11 servo motors are being mounted on every joint of ScorBOT body, and resulting in 9 degree of freedom motion. The capabilities of Cytron RC servo motor are fit for Scorbot to perform any body movement and posture.
CYTRON Servo Bracket (HD-SB-SH ) and (HD-SB-UJ )
It is good to hear that Cytron now provide two types of servo bracket for their servo motor which are servo holder and U joint. With the combination of these two type of brackets, any creative shape and joint can be assembled just like Scorbot.
CYRON enhanced 40 pins PIC start-up kit (SK40B)
The main controller I used in this project is the PIC16F877A microcontroller. In order to avoid possible soldering error and save development time, I choose to use the CYTRON SK40B as the basic circuit for this project. SK40B is a very useful start up kit for the PIC users especially for beginners because it provides all the basic elements required to operate the PIC microcontroller. The start-up kit comes with a 20MHz crystal oscillator, 5V regulator to convert supply voltage (usually 7-12V) to 5V (required for PIC), reset button to reset the PIC, 1 programmable push button, on/off switch for main power, UIC00A (CYTRON ICSP programmer) programmer port, RS232 hardware for serial communication to PC, DC adaptor socket for adaptor power input and an alternative 2510 connector for battery power input.
CYTRON USB ICSP PIC Programmer (UIC00A)
ICSP stand for in circuit serial programming which mean the process of writing the machine code to the microcontroller can be done on the circuit board without plugging out the microcontroller. The input of UIC00A is connected to the USB port of PC and the output is connected to the ICSP port of microcontroller. The SK40B PIC start-up kit do provide the ICSP programming port. The PICkit2 free version software is used to transfer the .hex file (compiled machine code) from PC to the PIC through UIC00A.
CYTRON 16 channels servo controller (SC16A)
In the robotic market nowadays, there are many servo controller had been designed for the convenient of servo motor driving. Cytron has now come out with a reasonable yet reliable servo controller for hobbyist. The SC16A provides 16 channels of independently servo driven port so the driver is more than enough for Scorbot which has only 11 servo motors. Since the driver can be connected to a pc and interface with user through a user friendly GUI, I can monitor the value of all the servos and position Scorbot easily.
CYTRON Flexibot Driver (FD04A)
FD04A is designed to drive 4 DC brush motor. The advantages of the driver are it supports 4 DC brush motor in bidirectional control, every port has independent PWM function to control the speed of motor, the control pins can be directly connected to the I/O of PIC and the driver is protected by over current. Since Scorbot has only 2 dc brush motor for mobility, the FD04A driver used is more than enough to use in this project.
CYTRON KC Wirefree Bluetooth Module Starter Kit (SKKCA)
As mention earlier, there are 3 method to control Scorbot which are Bluetooth communication, XBEE communication and PS2 controller wireless communication. SKKCA is a extremely convenient kit for Bluetooth user because it is ready to interface with 5V operate PIC microcontroller without any additional circuit. UART protocol is used to interface between PIC and SKKCA. Besides, the SKKCA is also able to connect to PC through USB port as wireless transmitter or receiver. With the SKKCA on Scorbot, I can now control the robot through the Bluetooth dongle or another SKKCA connected to PC.
CYTRON XBEE Starter Kit (SKXBEE)
SKXBEE provides XBEE communication protocol which is different with Bluetooth protocol. For me, XBEE based application is much more simple to develop compare with Bluetooth based application even through Bluetooth is more popular nowadays. XBEE has wider reception range and low power consumption compare to Bluetooth but the maximum data transfer rate is slower. Similar to SKKCA, SKXBEE is ready to interface to any 5V UART communication and also connectable to PC.
CYTRON PS2 Controller Starter Kit (SKPS)
The SKPS supports both wired and wireless PS controller. For Scorbot, wireless PS controller has been used to reduce the messiness from using cable. The interface to the SKPS is also the 5V UART at PIC. All the button and joystick of the PS2 controller is programmable. SKPS provide a very convenient method to control the mobility of robot.