SILA Technology
Reliable, smooth movement
SILA actuators are compact and streamlined with reliable power and smooth movement. This is SILA-P8 lifting 6kN, the weight of 8 people or a small car – on air, without any mechanical support. The load is 1kN and the actuator is working at a 6x disadvantage. An external motor controller is being used to operate the actuator using a low voltage DC supply. Without transmission friction, bandwidth is only limited by the motor controller.
Simple, robust construction for low maintenance, consistent performance
This exploded view of SILA-P7 shows the actuator’s simple, scalable design and tightly-integrated, non-contact magnetic transmission. In operation, low voltage AC from the motor controller reaches the stator via slim cables running through a stiff central rod, causing the rotor to spin. The magnetic field generated by the spinning rotor then moves the stator assembly through the magnetic track without contact. SILA transmission has a 96.7% predicted steady-state efficiency, limited only by build accuracy.
With a relatively low part count and no highly stressed components, SILA actuators are resilient under off-axis loading, have no single point failure modes and no risk of jamming. If the actuator is overloaded it will restart once the overload is removed. With no transmission wear and no backlash, SILA high performance will be maintained consistently through use, simplifying AI control.
High power density
To increase power density, an in-running stator with high copper fill is used to maximise torque generation and the motor’s magnetic field is reused, removing weight and cost of gearing. Low voltage DC operation means that slimmer power cables can be used, further reducing weight and cost and less vulnerable to tensile and compressive stress on flexing.
Sustained high efficiency across the dynamic range and low losses
Despite claims for 90+% efficiency for conventional EMA technologies, 30% lower values are generally achieved in practice. To bench-mark SILA, WaveDrives purchased and tested a comparable leading planetary roller-screw, finding that SILA-P7 has 31% less mass, 8% less bulk, is 37% more efficient averaged over the human dynamic range and acts almost 3 times more powerfully at low voltages and speeds due to more efficient torque production and greater transmission efficiency.
Free and predictable backdrive
Low backdrive force results from actuator efficiency. The video shows SILA-P8 almost backdriving under its own weight, mounted off-power in a test frame normally used for force tests. Average backdrive force recorded for this unit 0.516kN. Significant energy is regenerated during backdrive, also reflecting SILA ultra-efficiency. Electromechanical actuators will backdrive in some circumstances but not predictably, dependent on factors such as the level of lubrication.Compliant motion
SILA actuators can work in parallel with no hard stops.Due to their compliant motion SILA actuators can work together to multiply force output. Mechanical comparators are rigid systems and generally not modular. Modularity offers power, footprint and reliability advantages.
Near silent operation
SILA has been designed for near-silent operation, which is primarily enabled by its non-contact, low loss transmission. Quiet operation can be mission-critical in domestic, industrial and defence contexts.Configurable and flexible
SILA is highly configurable to suit diverse applications. WaveDrives has developed digital models for optimising SILA magnetic arrays for force generated vs size/weight, stroke length, cogging vs compliance, braking and speed profile along travel. The SILA-P7 external back-shaft has been replaced by a closed unit in SILA-P8 onwards, enabling more resilient mounting of power and sensor cables and ingress protection; other configurations are available.SILA-P9: bionics example
Max force: 2.2kN
L x Ø 162 x 62 mm
Stroke: 44mm
Lifts ~ 2 people on a 48V supply
SILA-P7: evaluation unit
Max force: 1.55kN
L x Ø 205 x 62 mm
Stroke: 77 mm
Lifts ~ 1.5 people on a 48V supply
SILA-P8: electrification
[aerospace]
Max force: 8+kN
Lifts ~ 10 people on a 48V supply.
L x Ø 486 x 124 mm
Stroke: 162mm
Low lifetime-cost-of-ownership
SILA’s construction with simple low-cost parts is suited to automation for affordable setup and highly competitive unit costs, once in mass manufacture. Its compact streamlined form and slim low-voltage cabling give increased freedom of design and ease of integration for mobile product and system developers. Running costs are reduced due to actuator ultra-efficiency and light weighting. With high reliability, low complexity and no transmission wear, lubrication or coolant requirements, maintenance requirements are minimal. SILA is designed for very long life, with the end bearings that hold the actuator rod replaceable every 10 years for ease of remanufacture to production standard. These cost and carbon savings and design freedom support development of advanced actuated products and systems, for more competitive and sustainable value chains. WaveDrives is actively exploring low cost manufacturing methods, in particular state of the art and emerging methods for construction of magnetic assemblies with complex/subtle magnetic geometry, including post-construction magnetisation, additive manufacturing and UK sintering of recycled materials. long life, with the end bearings that hold the actuator rod replaceable every 10 years for ease of remanufacture to production standard. These cost and carbon savings and design freedom support development of advanced actuated products and systems, for more competitive and sustainable value chains. WaveDrives is actively exploring low cost manufacturing methods, in particular state of the art and emerging methods for construction of magnetic assemblies with complex/subtle magnetic geometry, including post-construction magnetisation, additive manufacturing and UK sintering of recycled materials.£ & C12 matters
