Days 1 - 7
Days 8 - 16
Robomagellan 2012 Build Diary - Day 17
I have a MaxBotix ultrasonic range sensor driver running on the MSP430G2553. This driver supports both the analog and pulse outputs of the sensor. The specific sensor used for the robot is the MB1000 - http://www.maxbotix.com/documents/MB1000_Datasheet.pdf
The sensor has max range of 95 inches to 118 inches (7.9 feet to 9.8 feet ) depending on the size of the object detected.
The robot will use 6 sensors total, 5 pointed forward and 1 pointed back.
The sensors are daisy chained using what MaxBotix calls "Simultaneous Operation". The TX of the first sensor goes into the RX of the next sensor. The 5 front facing sensors are daisy chained into 1 group, with the back facing sensor being in its own group. The back sensor is only used when the robot is going in reverse.
Each sensor takes approximately 50ms to make a measurement. With 5 sensors the maximum scan rate is 250ms. This may be a problem when running the robot, depending on how fast the robot ends up being.
If the 250ms ends up being too long of a scan period, the image below shows how to use four sensors instead of five and still get a full perimeter scan.
This sensor arrangement has a gap in the front close to the robot. This gap is 4 * (half the distance between sensors) in front of the robot. A gap of 4 inches between sensors will have a gap up to 8 inches in front of the robot.
The EMGRobotics Autonomous navigation Board arrived today.
I finished the MaxBotix analog and pulse drivers last night. These drivers support up to 6 sensors (4 analog, 3 pulse). The sensors can be organized into 2 banks. In addition to the drivers, I wrote some test code to output the sensor data through the serial port in ASCII hex. This will be used for testing.