History of Radio Control
The first U.S. patent for a radio control device was issued to Nikola Tesla in 1898. Tesla demonstrated his invention to a crowd of onlookers at New York’s Madison Square Garden in the form of a radio controlled boat. The boat seemed to respond to verbal commands, however, Tesla was using his new invention to steer the vessel.
Other inventors were quick to match Tesla’s success, a French inventor developed a radio controlled torpedo in 1904, and in 1917 radio control was used successfully in an airplane by Archibald Low.
This new technology was quickly put to use during the First World War. Several countries used radio control to pilot aircraft as target drones. The drones were used to train anti-aircraft gunners. Britain used a Tiger Moth biplane named the Queen Bee at first but found it slow and cumbersome so they created a drone that was faster and more agile named the Queen Wasp.
The Russian army found a better use for radio control in the 1930’s and created their teletank groups. Comprised of a manned tank and a radio controlled tank the group could be used as an attack force. Radio control moved from target drones to an offensive weapon.
The technology at this point was best suited for large vessels and planes due to the size of the equipment and required batteries to power the receivers and motors. In the 1960’s transistors became widely used and allowed electronic equipment to shrink in size. It was this advancement that led to the formation of the radio control hobby.
Early consumer radio control equipment came in the form of a kit, one had to assemble the transmitter and receiver first, then it could be used in a plane or boat. The first of these systems were limited to a single channel. Typically they were used to control the rudder of what was formally a free-flight plane. The moveable rudder gave the pilot the ability to keep the plane in relatively contained area and added the thrill of actually controlling the plane.
Early commercial radio control units used relays and reeds to power escapement actuators. The controls were usually nothing more then a toggle switch. The toggle switch would act like an on/ff switch in the model.
The 1960’s rang in the era of the transistor and smaller equipment. A transistor based receiver could have more channels and take up less then 50% of the space of relay/reed based systems.
Multi channel systems became very popular in the 1970’s when proportional control was introduced. This allowed the movements to be proportionate to the movement of the control sticks. Typical radio controlled airplanes use a channel for ailerons, elevator, throttle and rudder with options for retractable landing gear and functional flaps. With additional channels other scale operations like bomb drops can be added.
Radio controlled cars and boats stay limited to 2 or 3 channels since they do not need much more then throttle and steering controls. Using more channels allows the hobbyist to equip there models with scale-like features that actually work.
Radio controlled helicopters have become very popular in the last few years and range from simple coaxial models to fully capable 3D crafts. The coaxial models use counter-rotating main rotors that eliminate the need for a tail rotor and make the craft easier to control. The aerobatic models have collective pitch control that allows the helicopter to fly inverted and perform unimaginable tricks. It is common to use a 2, 4, 6, or 7 channel radio control system with a helicopter, the more features, the more channels.
The most recent change in the radio control hobby occurred early in the 2000’s when 2.4 GHz spread spectrum technology was introduced. Prior to this change all radio control units needed to have matching crystals in the transmitter and the receiver. These crystals defined the frequency a radio set used. These sets are still used and sold today. The problem with this set up is that 2 pilots can not use the same frequency at the same time; the interference will make both models difficult or impossible to control. The spread spectrum technology eliminates the need for crystal sets and the interference problem.
Spread spectrum will scan the area for any frequencies in use and select a clear channel, the transmitter then synchronizes that channel with the receiver. Now several hobbyists can use their equipment at the same time without worrying about interfering with each other.
Besides spread spectrum, the single biggest advance in radio control has been battery technology. In the radio controlled hobby, NiCad batteries were the first rechargeable packs used in cars, boats and planes. These battery packs are rugged and can handle mild abuse, however, they are heavy and bulky. These attributes restricted their use in radio controlled aircraft. Nickel Metal Hydride (NiMh) battery packs were the next generation. These batteries are a direct replacement for NiCad packs. NiMh packs can be charged with the same equipment as NiCads and match the voltage exactly. NiMh packs are lighter then NiCad packs making them more attractive for aircraft.
The real advance came when Lithium Polymer (LiPo) batteries were introduced. These batteries have more voltage and amperage per cell than NiCad or NiMh cells. LiPo packs are more delicate then NiCad or NiMh packs and must be charged with equipment that is designed for LiPo packs. There is a risk factor with LiPo packs that doesn’t exist with other rechargeable battery packs, if mishandled LiPo pack will burst into flames.
Battery technology is also a major factor in large scale robots as well. Explosive Ordnance Disposal (EOD) crews rely on their robots to investigate and disarm roadside bombs and Improvised Explosive Devices (IED) in Iraq and Afghanistan. The EOD crews need as much battery life as possible to insure that they can complete their task. New innovative solutions have been developed that increase the battery life by 23% and allow batteries to be hot-swapped without needing to reboot the robot and loose valuable time.
There are radio control transmitters that allow the user to select any of the 60 frequencies allocated to the hobby. The model’s receiver still needs to be matched to the same frequency as the transmitter for the system to work. Synthesized receivers exist that allow the receiver to “listen” for a transmitter and set it’s frequency to match the transmitter. Using these 2 devices together also eliminates the need for crystals, however, it does not eliminate the interference problem.
As radio control equipment has improved its uses in the military has also increased. This technology allows personnel to handle dangerous objects from a safe distance and perform reconnaissance without exposing ones position to the enemy. The U.S. Military uses radio control helicopters and airplanes equipped with video cameras to see if there are enemy forces in the area. Radio controlled robots are used to investigate suspicious packages and defuse bombs.
Many companies that produce consumer electronics have produced specialized devices for military use; iRobot and Bobcat each make devices specifically for military use. iRobot produces the roomba robotic vacuum cleaner for commercial use and the Pakbot for the military. The Pakbot has tank-like treads that allow it to climb over rocks, a mechanical arm for retrieving explosive devices. Once the explosive device has been seized the unit can dismantle it via radio control.
With all this technology at hand the U.S. military, they are moving away from radio controlled devices and moving more towards devices using GPS satellite navigation. These devices remove any chance for human error/interference.
The military is not the only sector that uses radio controlled equipment for hazardous or cumbersome jobs. Bobcat has produced a radio control unit that can be attached to any of its skid steer units. This configuration allows an operator to guide equipment like wheel saws into position without the help of a second person.
RC Hall of Fame http://www.rchalloffame.org
A European Informational Website http://radiocontrol.eu/
Bobcat Company http://www.bobcat.com/loaders/remote_control