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Sun, 18 Nov 2007
SRV-1 power consumption
We noticed that our prototype robots seemed to be running a long time between charges, so we finally took some measurements. We found that the robot was drawing only 220 milliamps from the 7.4V Li-ion battery pack while stationery but fully operational (i.e. transmitting video frames at full speed). With the robot moving on a flat surface, the overall consumption jumped to 400 milliamps.
As the robots are assembled with Li-ion battery packs rated at 2000 mAh (milliamp-hours) capacity, it is reasonable to expect operating time of 4-8+ hours off a single charge, depending on the amount of robot movement. This is comparable to the power consumption of the original SRV-1 with ARM7 and Zigbee.
In fact, the Blackfin and WLAN draw more current than the ARM7 + Zigbee combination, but the overall system efficiency is the same because we're using a Recom switching regulator to convert the battery's 7.4V to 3.3V with 90% + efficiency. The original robot used an inefficient LM7805 linear voltage regulator to dissipate the voltage drop from 7.4V to 5.0V as heat.
There are a variety of power save features available in both the Blackfin processor and the Matchport WLAN module that we have yet to explore. Just dropping the clock speed of the processor can make a substantial difference in consumption, and there are some similar adjustment that can be made to the Matchport. At the moment, the power consumption levels are not an issue, but we look forward to eventually experimenting with some power optimizations.
Posted Sun, 18 Nov 2007 10:54 | HTML Link | see additional stories ...
Updated support for SRV-1 Blackfin in RoboRealm
Roborealm.com has released an new version of software that includes updated support for the SRV-1 Blackfin robot and camera board. A description of the update is found here -
http://www.roborealm.com/help/Surveyor_SRV1b.php
along with a tutorial on object tracking here -
http://www.roborealm.com/tutorial/Surveyor_SRV1b_Trail/slide010.php
For those not familiar, RoboRealm is a very popular Windows-based programming tool that combines an extensive suite of vision processing modules with programmable robot control. The software is well supported and it's free !
Posted Sun, 18 Nov 2007 09:59 | HTML Link | see additional stories ...