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Test Tools Motor and Pneumatic Subsystems Aimi Abe-Lafond Sarah Kirke Natalia Sydorenko
Intro § This seminar will teach you all about our secret tools that help us on the go, and help to prevent most tricky situations § Some of the tools we use in PEP are Digital Clamp On Ammeter, portable pneumatics tester, and a battery tester; they have all had an important role in problem solving on our team § Hope you all enjoy this presentation and learn at least one thing you didn’t know before.
Pneumatic Tools Portable Pneumatic Tester / Air Source § Complete portable, First Battery powered § 120 psi air to fill or leak test robot high pressure system § 60 psi air source to power robot main pneumatic supply “buss” or circuits § 2 electric switch controlled pneumatic solenoids to control up to 2 air cylinders § Pneumatic parts are all from past kits or as of last year FIRST Choice for free (even the compressor). § Dead standard FIRST Robots published pneumatic circuit with low & high pressure gauges, overpressure release, pressure switch, regulator, reserve tank etc § Compressor auto shuts off at target pressures without the use of a CRio to monitor pressure switch. Instead it uses a 40 amp 12 v relay from www. thesource. ca part #2750226
Portable Solenoid Test Box § Used to drive our standard pneumatic solenoids so we can test or problem solve a pneumatic circuit right from the IO port on the CRio § Since most FIRST pneumatic solenoids are “double ended” (have 2 electric solenoid valves, one to extend a air cylinder, another to retract the same air cylinder, our tester has two independent driver circuits, one with a red wire and red led, the other with a green wire and led. § Note our team has standardized on 12 v solenoids (so our tester has a small 12 v battery inside it - 4 x 3 v lithium cells in series). Another common solenoid voltage is 24 v so be certain what you have § Need a air supply to test your circuit ? Use our portable pneumatic tester / air supply
Electrical Tools High Power Battery Load Tester § Applies a high load (100+ amps) on a battery to measure how low the voltage droops. § If the battery voltage droops below an expected value, that is evidence the battery is either not fully charged or is aging, or has reduced capacity or is other wise possibly defective. § Good to check on batteries FIRST batteries that are 3 years or older (or newer batteries if you suspect they are damaged). Fully charge them before testing § The (car battery) load tester can be purchased from Canadian Tire or Princess Auto among other sources. The unit we will demo is on sale from Princess Auto a couple of times a year for $20. § Buy a light duty tester (not a super heavy duty one) as car batteries are at least 3 times the size of FIRST batteries (50 amp-hour+ versus 18 A amp-hour)
Battery Beak Battery Analyser § Designed specifically for the FIRST Battery. § Plugs into standard battery connector § Used to check the battery’s voltage, estimate how fully charged the battery is and shows how much the battery voltage droops with small loads (1 amp, or 18 amps). § Keep in mind the FIRST main breaker trips at 120 amps § Available from Andy Mark (AM-0995) $120 § Not cheap, easy to lose, easy to have “walk off” at the regionals. We are still evaluating its usefulness
Servo Tester (Speed Control Driver) § A Servo Tester outputs PWM signals that can drive standard FIRST speed controls (Victor, Jaguar, Talon) via a standard PWM cable. Note a Spike is not a PWM device) § Available from local hobby shops, Andymark, Ebay & sites like www. hobbyking. com where they can be less than $10. § A servo tester needs a ~ 5 v DC power supply to power it. We used 4 AA rechargeable batteries (1. 2 v each). § Every servo tester we have tried could only drive one Victor. If you want to drive 2 or more (like a 2 CIM transmission), you need a special PWM “driver” cable (onboard amplifier). One source is www. vexrobotics. com parts # PWM-DRIVER $14. 95 § Be warned to set the servo tester rotary knob to ½ rotation before turning it on as that is the pwm value for neutral (0 power) for FIRST controllers. § Your speed controller still needs 12 volts to power it. A powered up but disabled robot will have 12 volts
DC Digital Clamp-on Amp Meter § Measures the DC amps going through any circuit. Essential to check that motors are not overloaded or already damaged § Totally non-invasive. Just clip around either but not both of the red or black power lines of the device you want to measure (including a battery cable if you want. Clip-on and measure in a few seconds. § WARNING – 90% of Clamp-on Amp meters (especially cheap ones) can NOT measure DC amps. They only measure AC amps which is of no use on a DC powered robot. Check the specs carefully before buying. § Available from electronic stores, Ebay. Active Electronics has a model UT 203 by Uni-T for $99. (Ebay $38. ) § Note the 2015 Power Distribution Board is expected to have onboard amp measuring, displayable on a computer screen. But of course your robot and software must be complete and working.
Motor Driver / Tester § Allows you to power a specific motor (or 2) without any robot wiring, power distribution etc to test the correct operation of a motor subsystem. Detects stalls, overcurrents, etc. § Connects directly to motor of interest (via alligator clips). § Finger controlled variable speed “throttle” button. Reversible Switch § 60 amp meter to provide visual warning of excessive current draw. 40 amp inline autoreset breaker for over current protection. Powered by a standard FIRST battery § Speed controller comes out of any 12 v+ battery operated drill. Ours were from Dewalt 12 volt drills we had taken the transmissions out of (bought on Ebay). § Rest of the parts can be acquired at electronics store like Sayal, Active Surplus, A 1.
Portable Laptop Inverter § Ever had long waits in the lineup to the field or have to wait and wait while Karthik goes on and on announcing at the start of a match and wonder if your laptop battery is going to run out (in the middle of a critical semi-final match) ? § We use an “off the shelf” 12 v DC to 120 V AC “inverter” powered from a FIRST battery to the laptop AC adapter to charge the laptop while we wait for our match (even in the lineups or at the driver station or long testing sessions in the gym). § Our laptop is now always fully charged no matter where we are (assuming the field team plugged it in)! § Laptop AC chargers are usually 60 -90 watts so you need an inverter that is at least 100 w but we would recommend the next size up which is usually 250 watts or 300 watts § Canadian Tire has a range of them and they are on sale pretty well every few weeks, for as little as $35 for 250 watts
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