Post by thread:[PIC]:how to use acceleration sensor for motion co

need to control two dimension movement, speed and distance. or may be even rotation movement. how good sensor is needed? 0.01 mg , from analog device, enough? acceleration sensor should works, theorically. any example? site? BR, -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Hi, I have posted some questions on the area of acceleration sensor some months ago and gain a lot of knowledge from other piclisters. For searching purpose, the subject of the thread is [EE]:Tilt Sensor. A two axis accelerometer are basically used to detect both dynamic acceleration (vibration) and static acceleration (gravity). As such, a dual axis acceleration can be use to detect vibration, tilting, and acceleration. I have given up on searching for a tilt sensor solution because accelerators are very expensive. ADXL202 is expensive and fragile. You can check also the accelerators from Memsic, but they are also very expensive (USD14.50). As for the rotational sensor, piclisters has suggested on using a optical encoder or ball bearing potentionmeter or electrolytic tilt sensor. Have yet to get some samples on that. Perhaps you can consider these for rotational sensor. There could be others which I do not know. Rgds, Pang Subject: [PIC]:how to use acceleration sensor for motion control? need to control two dimension movement, speed and distance. or may be even rotation movement. how good sensor is needed? 0.01 mg , from analog device, enough? acceleration sensor should works, theorically. any example? site? BR, -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

Hello I'm building a small robot and was planning to build a tilt sensor that should measure acceleration to. I only have the idea I haven't done any testing yet. The idea is to make a small pendulum with a ferrite bead as the weight. Near this will be a coil that is part of a tank circuit of an oscillator as the ferrite bead swings near or farther from the coil the frequency will change and I will keep track of it with one of the timer inputs on a PIC. The pendulum may need to be dampend. I once saw a small scale that had it's beam dampend by having a small copper plate attached to the beam swing near 2 small magnets this would cause eddy currents in the copper and dampen the beam movment. Regards Jim {Original Message removed}

Hi Jim If I can suggest an alternative. Small tube with a magnetic ball bearing held loosely in the middle between two soft springs. At one or both ends [resolution} is positioned a linear hall effect IC. the output of which varies with distance from a magnet. This will produce a single axis accelerometer, response will be a direct result of spring force and damping can be provided by filling the tube with a light oil, viscosity to suit. Mike ----- Original Message ----- From: "Jim" <.....james3162KILLspam.....WORLDNET.ATT.NET> To: <EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU> Sent: Wednesday, July 10, 2002 4:00 PM Subject: Re: [PIC]:how to use acceleration sensor for motion control? > Hello > I'm building a small robot and was planning to build a tilt sensor that > should measure acceleration to. > I only have the idea I haven't done any testing yet. The idea is to make a > small pendulum with a ferrite > bead as the weight. Near this will be a coil that is part of a tank circuit {Quote hidden}> of an oscillator as the ferrite bead > swings near or farther from the coil the frequency will change and I will > keep track of it with one of the timer > inputs on a PIC. The pendulum may need to be dampend. I once saw a small > scale that had it's beam > dampend by having a small copper plate attached to the beam swing near 2 > small magnets this would > cause eddy currents in the copper and dampen the beam movment. > > Regards > Jim > > > {Original Message removed}

Jim Just to add to my last you might want to look at Analog's ADXL202 or ADXL05/50 Mike ----- Original Message ----- From: "Jim" <james3162spam_OUTWORLDNET.ATT.NET> To: <@spam@PICLISTKILLspamMITVMA.MIT.EDU> Sent: Wednesday, July 10, 2002 4:00 PM Subject: Re: [PIC]:how to use acceleration sensor for motion control? > Hello > I'm building a small robot and was planning to build a tilt sensor that > should measure acceleration to. > I only have the idea I haven't done any testing yet. The idea is to make a > small pendulum with a ferrite > bead as the weight. Near this will be a coil that is part of a tank circuit {Quote hidden}> of an oscillator as the ferrite bead > swings near or farther from the coil the frequency will change and I will > keep track of it with one of the timer > inputs on a PIC. The pendulum may need to be dampend. I once saw a small > scale that had it's beam > dampend by having a small copper plate attached to the beam swing near 2 > small magnets this would > cause eddy currents in the copper and dampen the beam movment. > > Regards > Jim > > > {Original Message removed}

{Quote hidden}> -----Original Message----- > From: Mike Pink [SMTP:KILLspammjpinkKILLspamkingstag.com] > Sent: Thursday, July 11, 2002 8:46 AM > To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU > Subject: Re: [PIC]:how to use acceleration sensor for motion control? > > Hi Jim > > If I can suggest an alternative. > > Small tube with a magnetic ball bearing held loosely in the middle between > two soft springs. At one or both ends [resolution} is positioned a linear > hall effect IC. the output of which varies with distance from a magnet. > This > will produce a single axis accelerometer, response will be a direct result > of spring force and damping can be provided by filling the tube with a > light > oil, viscosity to suit. > > Mike > I think you may have to use a bar magnet, the magnetic field would change and even reverse as the ball bearing rolled! Regards Mike -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics