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| robotic:explorer [2021/07/30 07:32] – tony | robotic:explorer [2026/09/26 20:24] (current) – tony |
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| The corner infrared sensors are vulnerable to being displaced by collisions, and end up effectively inoperative. So some consideration needs to be made to protect them, eg mounting them so they do not protrude beyond the edge of the chassis, or adding a bumper/guard. Also there is a small amount of light that comes out the side of the LEDs, and that can muck up distance sensing, especially if the LED and phototransistor are touching. The LEDs are rated as 100mA maximum continuous current, as wired the circuit doesn't get anywhere near this, a 47Ω series resistor would still limit current to safe levels (nominally (5.0-1.4-0.2)/47=72mA, maximum (5.2-1.2-.2))/44=86mA), | The corner infrared sensors are vulnerable to being displaced by collisions, and end up effectively inoperative. So some consideration needs to be made to protect them, eg mounting them so they do not protrude beyond the edge of the chassis, or adding a bumper/guard. Also there is a small amount of light that comes out the side of the LEDs, and that can muck up distance sensing, especially if the LED and phototransistor are touching. The LEDs are rated as 100mA maximum continuous current, as wired the circuit doesn't get anywhere near this, a 47Ω series resistor would still limit current to safe levels (nominally (5.0-1.4-0.2)/47=72mA, maximum (5.2-1.2-.2))/44=86mA), |
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| ====== Software ====== | The infra-red corner sensors can either be read as digital or analog inputs. The Mr Tidy example code treats them as digital inputs - effectively making them fixed distance, very short-range sensors. The //Explorer// example code treats them as analog inputs - so although still short-range you can set a distance threshold. Both robot platforms that I've built with this board have had the wheels or tracks extending well beyond the explorer board, which cuts down their effectiveness as they really are only short range sensors, so I will have to build something with a smaller footprint. |
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| | Navigating and avoiding obstacles with the corner sensors has severe limitations: |
| | * Short range, <200mm |
| | * Background lighting can over whelm them (eg sunlight when outside) |
| | * They really only detect obstacles at their height, so low walls and overhangs are not detected |
| | * Narrow obstacles aren't detected |
| | * The colour of walls greatly affects how far away they are detected (eg dark not detected as easily as white) |
| | * The sensors are at 45º, so for example you can't easily tell whether an object is in front or to the side |
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| | In my example of this board, the repeatability of distance readings is quite good - with a spread of 4 values (ie +/- 2 about the mean) for stationary readings (both robot and environment not moving) for 3 out of the 4 sensors. The 4th sensor seems to vary more than twice as much, maybe one of the components (resistor, photo diode, photo transistor) is faulty. |
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| | ===== Software ===== |
| Despite the board having full H-bridge driver hardware, the example //Explorer// code (file dated 24/01/2011) assumes that the main drive motors are of the analog pulse-width driven, continuous rotation, servo type. That is they only require a single control line for forward, back and stop control. The example software for the "Mr Tidy" robot handles normal PWM DC motors, and has the same corner infrared collision detection hardware, but it also has a lot of other features and so requires a controller with a lot more I/O pins than an Arduino UNO. | Despite the board having full H-bridge driver hardware, the example //Explorer// code (file dated 24/01/2011) assumes that the main drive motors are of the analog pulse-width driven, continuous rotation, servo type. That is they only require a single control line for forward, back and stop control. The example software for the "Mr Tidy" robot handles normal PWM DC motors, and has the same corner infrared collision detection hardware, but it also has a lot of other features and so requires a controller with a lot more I/O pins than an Arduino UNO. |
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| The infra-red corner sensors can either be read as digital or analog inputs. The Mr Tidy example code treats them as digital inputs - effectively making them fixed distance, very short-range sensors. The //Explorer// example code treats them as analog inputs - so although still short-range you can set a distance threshold. | ===== Examples ===== |
| | {{:robotic:explorer:dsc_0220a.jpg?400|Turbo explorer}} |
| | |
| | Used to control a 3 wheeled robot testbed //[[:robotic:turbo|Turbo Explorer]]//. |
| |
| ====== References and Additional Resources ====== | ====== References and Additional Resources ====== |
| * [[http://www.dagurobot.com/miniature_servo_magnetic_clutches|Miniature servo Magnetic clutches]] | * [[http://www.dagurobot.com/miniature_servo_magnetic_clutches|Miniature servo Magnetic clutches]] |
| * [[https://web.archive.org/web/20130127120828/http://letsmakerobots.com/node/32198|Miniature servo Magnetic clutches]] | * [[https://web.archive.org/web/20130127120828/http://letsmakerobots.com/node/32198|Miniature servo Magnetic clutches]] |
| =====Rover 5===== | ===== Rover 5 ===== |
| * {{robotic:explorer:explorer_instruction_manual.pdf|Explorer instruction manual}} | * {{robotic:explorer:explorer_instruction_manual.pdf|Explorer instruction manual}} |
| * {{robotic:explorer:rover5_arduino.zip|Explorer example Arduino code}} | * {{robotic:explorer:rover5_arduino.zip|Explorer example Arduino code}} |
| * [[https://web.archive.org/web/20140708040248/http://letsmakerobots.com/node/36521|Understanding the "Explorer" PCB]] | * [[https://web.archive.org/web/20140708040248/http://letsmakerobots.com/node/36521|Understanding the "Explorer" PCB]] |
| * [[http://www.dagurobot.com/Robot_Chassis/Rover_5_chassis_with_0_encoder_accessories|RS011-2/0]], [[http://www.dagurobot.com/Rover_5_chassis_with_2_encoders_accessories|RS011-2/2]], [[http://www.dagurobot.com/Rover_5_chassis_with_4_encoders_4motors|RS011-4/4]] versions of Rover 5 chassis | * [[http://www.dagurobot.com/Robot_Chassis/Rover_5_chassis_with_0_encoder_accessories|RS011-2/0]], [[http://www.dagurobot.com/Rover_5_chassis_with_2_encoders_accessories|RS011-2/2]], [[http://www.dagurobot.com/Rover_5_chassis_with_4_encoders_4motors|RS011-4/4]] versions of Rover 5 chassis |
| =====Mr. General, related platform with similar hardware===== | ===== Mr. General, related platform with similar hardware ===== |
| * (https://sites.google.com/site/daguproducts/home/tutorials/understanding-mr-general) | * (https://sites.google.com/site/daguproducts/home/tutorials/understanding-mr-general) |
| * [[http://www.dagurobot.com/Mr_General?search=RS002&category_id=0|RS002]] | * [[http://www.dagurobot.com/Mr_General?search=RS002&category_id=0|RS002]] |
| * {{robotic:explorer:understanding_the_mr._general_-_attachments.zip|Understanding the Mr. General - attachments}} | * {{robotic:explorer:understanding_the_mr._general_-_attachments.zip|Understanding the Mr. General - attachments}} |
| * http://www.arobose.com/docs/Mr.General_Instruction_manual.pdf Mr. General instruction manual | * http://www.arobose.com/docs/Mr.General_Instruction_manual.pdf Mr. General instruction manual |
| =====Mr. Tidy, related platform with similar hardware===== | ===== Mr. Tidy, related platform with similar hardware ===== |
| * (Has the same corner sensors and PWM main motors) | * (Has the same corner sensors and PWM main motors) |
| * [[https://sites.google.com/site/daguproducts/home/Software/Mr_Tidy_MkII_Sample_Code_V3.zip|Mr Tidy MkII Sample Code V3]] | * [[https://sites.google.com/site/daguproducts/home/Software/Mr_Tidy_MkII_Sample_Code_V3.zip|Mr Tidy MkII Sample Code V3]] |
| * {{https://www.robotshop.com/media/files/PDF/manual-rs008.pdf|Mr. Tidy manual}} | * {{https://www.robotshop.com/media/files/PDF/manual-rs008.pdf|Mr. Tidy manual}} |
| |
| =====Playful Puppy user guide===== | ===== Playful Puppy user guide ===== |
| * {{http://www.arduino-direct.com/docs/PuppyRobotUser-guide.pdf|Details how to assemble pan-tilt bracket and servos}} | * {{http://www.arduino-direct.com/docs/PuppyRobotUser-guide.pdf|Details how to assemble pan-tilt bracket and servos}} |
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| =====IR Compound Eye===== | ===== IR Compound Eye ===== |
| * [[https://robottini.altervista.org/diffident-robot|Using the "compound eye" with an Arduino processor (including code)]] | * [[https://robottini.altervista.org/diffident-robot|Using the "compound eye" with an Arduino processor (including code)]] |
| * [[https://web.archive.org/web/20140212152707/http://letsmakerobots.com:80/node/10822|Cheap homemade IR compound eye]] | * [[https://web.archive.org/web/20140212152707/http://letsmakerobots.com:80/node/10822|Cheap homemade IR compound eye]] |
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