https://wiki.robotika.sk/robowiki/index.php?title=Measurements_of_NXT_motors&feed=atom&action=history Measurements of NXT motors - Revision history 2024-03-29T05:33:22Z Revision history for this page on the wiki MediaWiki 1.30.0 https://wiki.robotika.sk/robowiki/index.php?title=Measurements_of_NXT_motors&diff=1687&oldid=prev Palo: preklep 2006-12-03T23:43:31Z <p>preklep</p> <table class="diff diff-contentalign-left" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr style="vertical-align: top;" lang="en"> <td colspan="2" style="background-color: white; color:black; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: white; color:black; text-align: center;">Revision as of 23:43, 3 December 2006</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l48" >Line 48:</td> <td colspan="2" class="diff-lineno">Line 48:</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The NXT output signals seem to be able to eliminate overshoot, and other ugly effects seen</div></td><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>The NXT output signals seem to be able to eliminate overshoot, and other ugly effects seen</div></td></tr> <tr><td class='diff-marker'>−</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>in the RCX motor plots. The RCX oscillates its motor output on 500 <del class="diffchange diffchange-inline">kHz </del>in both firmwares.</div></td><td class='diff-marker'>+</td><td style="color:black; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>in the RCX motor plots. The RCX oscillates its motor output on 500 <ins class="diffchange diffchange-inline">Hz </ins>in both firmwares.</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>&lt;br&gt;&lt;br&gt;</div></td><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"><div>&lt;br&gt;&lt;br&gt;</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'>&#160;</td><td style="background-color: #f9f9f9; color: #333333; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #e6e6e6; vertical-align: top; white-space: pre-wrap;"></td></tr> </table> Palo https://wiki.robotika.sk/robowiki/index.php?title=Measurements_of_NXT_motors&diff=1674&oldid=prev Palo at 17:56, 1 December 2006 2006-12-01T17:56:47Z <p></p> <p><b>New page</b></p><div>We have been curious how do actually the signals that control the NXT motors<br /> look like. The NXT output cable has 6 wires:<br /> <br /> MA0, MA1 - &quot;PWM&quot; output signals to actuators<br /> GND, POWERMA - optional power source for embedded devices<br /> TACHOA0, TACHOA1 - internal rotation sensors<br /> <br /> The MA0, MA1 are compatible with the RCX's motor, so they are not any<br /> kind of control signal to a servo motor, they are simply connected to<br /> two poles of a DC motor so that they can drive it forward or backward<br /> depending on changing polarity.<br /> <br /> When the motor is running full-speed, the MAX signals are simply connected<br /> to ground and battery voltage to drive the motor maximum speed. When the<br /> motor strength is decreased, the power is supplied in impulses with length<br /> proportional to the desired power:<br /> <br /> [[Image:nxt_motor_50_percent.png | NXT motor running half speed]]&lt;br&gt;<br /> Plot of the MA signal when NXT motor is running half speed (50%).<br /> &lt;br&gt;&lt;br&gt;<br /> <br /> [[Image:nxt_motor_75_percent.png | NXT motor running 75% speed]]&lt;br&gt;<br /> Plot of the MA signal when NXT motor is running 75% speed.&lt;br&gt;<br /> (note that the drive is supplied when the signal is low; <br /> the other MA signal is always high). Similarly, the signal looks<br /> the same, just inverted for 25% power.<br /> <br /> '''So the frequency of oscillations generated by NXT is 8kHz'''.<br /> <br /> And it is possible to drive the old RCX motors using these outputs and<br /> the conversion cable supplied by LEGO.<br /> <br /> It can be interesting to compare these measurements to signals generated<br /> by RCX: we look at both the standard firmware and BrickOS firmware. Those<br /> signals look like this:<br /> <br /> [[Image:rcx_motor_rcx_motor_nqc_57_percent.png | RCX motor running on power 4 out of 7 with standard firmware (and NQC program)]]&lt;br&gt;<br /> RCX motor running on power 4 out of 7 with standard firmware (and NQC program).&lt;br&gt;<br /> &lt;br&gt;<br /> <br /> [[Image:rcx_motor_rcx_motor_brickos_50_percent.png | RCX motor running on half of full power with BrickOS firmware]]&lt;br&gt;<br /> RCX motor running on half of full power with BrickOS firmware.&lt;br&gt;<br /> &lt;br&gt;<br /> <br /> [[Image:rcx_motor_rcx_motor_brickos_75_percent.png | RCX motor running on 3/4th of full power with BrickOS firmware]]&lt;br&gt;<br /> RCX motor running on 3/4th of full power with BrickOS firmware.&lt;br&gt;<br /> &lt;br&gt;<br /> <br /> The NXT output signals seem to be able to eliminate overshoot, and other ugly effects seen<br /> in the RCX motor plots. The RCX oscillates its motor output on 500 kHz in both firmwares.<br /> &lt;br&gt;&lt;br&gt;<br /> <br /> Finally, once we had an oscilloscope on, we also looked at the signal on the RCX's activated<br /> light sensor, it looks as follows (with BrickOS firmware):<br /> <br /> [[Image:rcx_light_brickos.png | RCX active light sensor sampling]]&lt;br&gt;<br /> RCX active light sensor sampling.&lt;br&gt;&lt;br&gt;<br /> <br /> It appears that the sampling frequency is about 6.5 kHz.</div> Palo