Alok, Have your team put the ultrasonic sensor block within a time loop and also use a switch. That way you can make it either detect the object/wall correctly or have it quit the loop after specified time, whichever happens first. Sachin Aradhey #3629 Nanobots Harrisonburg, VA. On Fri, Nov 19, 2010 at 9:10 AM, Alok Jain <[log in to unmask]> wrote: > Hi! > My team realized that ultrasonic sensor is not consistent when used with > the wait block. Sometimes it seemed to be not stopping at all. I am talking > about big objects and the side wall. I did a little experiment and there > seems to be a difference of 15 cm (at power level 60). i.e. if I want the > robot to stop at 30 cm, it actually stops when distance is 15 cm. > I tried changing the sensor and also putting the sensor lower, but still > the same result. The reading in the sensor, when robot is stopped, shows up > correctly. It is only while stopping it is acting up. At power level 75 and > higher it totally misses the stop point. Did anyone else face this problem > in the past? Am I doing something wrong ? > Here are my questions: > > 1) how high should the Ultrasonic sensor be placed from the ground? > 2) Is there something I need to caliberate or change in the program ? > > My team is competing on Sunday, so any help is highly appreciated. > > Thanks, > Alok > > ------------------------------ > To UNSUBSCRIBE or CHANGE your settings, please visit > https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave > the list". > VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit > https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe. -- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list". -- VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe.