By: Oscar Ramirez (MST)
Edited and Approved By: Jesus Enriquez (Project Manager)
– Introduction & Conclusion
One of the challenges that we had to come up with was coming up with creative way to get the Velociraptor to perform a static walk. Adding to this challenge we needed to control and implement this static walk through the Arxterra app. With the help of our MST engineer, our team was able to come up with a way to control the DC motors that drive the Velociraptor through a “Move” command on the Arxterra app.
Requirement L2-7: The Velociraptor shall be able to perform a static walk
Requirement L2-5: The Velociraptor shall use the Arxterra Android or iPhone Application and/or control panel to control the Velociraptor
Testing the “Move” Command
One of the first telemetry commands that we implemented for Velociraptor was the “MOVE” command. The MOVE command controls both the speed and direction of DC Motors A or B on the 3DoT Board. The 3DoT Board uses the TB6612FNG motor driver that can drive two DC motors and control their speed, direction, and even brake. The braking feature can be very useful, especially considering the balance issues with biped robots. The movement speed of the motor is also important to our design since we are using the Theo Jansen walking mechanism that requires a fair amount of control to keep the robot balanced. As far as the direction, it will not be used for our design since it is not practical for the DC motors to go in opposite direction. After testing the MOVE command on CoolTerm and verifying that the board received the command, I moved on to physically testing the move command by setting up the HM-10 Bluetooth sensor and the TB6612FNG on a breadboard. For prototyping purposes I used the Arduino UNO as the micro-controller and used a 9V battery as the main power source for the motor and Arduino UNO.
Figure 1: Arduino UNO breadboard setup with the HM-10 and TB6612FNG
Once synching to the HM-10 with the Arxterra App I used the Joystick layout to send a move forward command to the Bluetooth sensor that then relayed that command to the MCU and back out through the PWM pin and analog pin. Once confirming that the MOVE command worked through simulation and testing we were ready to proceed to the next step in our design.
Figure 2: Sending a “move forward” command on the Arxterra app
Through testing, we were able to successfully send bluetooth telemetry commands through the Arxterra app. It was convenient for our design in that we were able to control the speed of the DC motors which is necessary for a design like the Velociraptor. It is recommended that this be one of the first tests or tasks to complete when doing the velociraptor project since there will need to be a ton of testing for moving the legs/walking which is the most critical to making successful project work.