From Gizmag: Researchers at Siemens have created a new prototype electric motor specifically designed for aircraft that weighs in at just 50 kg (110 lb) and is claimed to produce about 260 kW (348 hp) at just 2,500 RPM. With a quoted power five times greater than any comparable powerplant, the new motor promises enough grunt to get aircraft with take-off weights of up to 1,800 kg (2 ton) off the ground...
... As a result, the new aircraft electric drive system achieves a claimed weight-to-performance ratio of 5 kW per kilogram. This ratio is an exceptional figure – especially if compared to similarly powerful industrial electric motors used in heavy machinery that produce less than 1 kW per kilogram, or even to more efficient electric motors for vehicles that generate around 2 kW per kilogram... (full article)
Recent servo motors are equipped with the encoder of 20 bits (1,048,576 steps) which has a very fine resolution. Because of this, errors due to the encoder installation accuracy have a huge effect on stopping accuracy.
IPR Robotics offers a wide range of servo-driven 7th axis linear rails for industrial robots. These rails come in ten different sizes and are constructed from modular high strength extruded aluminum sections to handle payloads of 100 kg to 1600 kg or from steel to handle 2000 kg payloads. This variety of rail sizes allows each application to be sized correctly, controlling the space required and the price point. The drive train design of these rails utilizes helical gear-racks and is proven over 10 years to be repeatable and reliable, even in tough foundry applications.