Recherche de partenaires

Résumé

A South East UK University have developed an enhanced servo with distinctive advantages over current devices and very broad application domains. The technology offers significant, urgently needed benefits including reduced power usage and a mechanically held rotational position (rather than relying on the force of a motor). Partners sought from a broad range of sectors where servo technology is applied (below) to further develop and commercialise or license to manufacture the system.

Description complète

The new technology is a long-overdue enhancement of the well-established servo. Whilst the current in-market technology enjoys enormous popularity over a very wide range of applications, it can be demonstrated that the current technology has several key pitfalls which are undesirable in many of its deployments. The continued popularity of the current technology in many applications is sustained principally by the fact that there has been no suitable alternative to overcome these limitations.

The University now offers a replacement technology  an automatic latching servo - which retains the benefits and operational characteristics of the current technology, whilst at the same time offering a significant enhancement which brings a number of key, urgently needed benefits, described in the following section.

Limitations of the current in-market servos
1. The current servos are configured by a pulse-width-modulation signal which is translated by a control circuit into a rotational position. Changing the pulse width of the position-control pulse causes the servo to rotate to the new position. Correct operation requires that the position-control pulse is continuously supplied to the servo, even when the position is unchanged. The behaviour upon removal of the control pulse is actually undefined for most current devices, and the typical behaviour is to remove power to the motor  i.e. the servo does not hold its position. In some devices it is possible that unexpected but forced movement, such as rotation to one of the end-stops, results. In the typical case where the servo just becomes passive, the physical apparatus it is connected to is unconstrained and free to rotate under the influence of any external force applied.
2. The current servos suffer the same weakness of unconstrained movement as described in (1 above) if the power supply to the servo is removed.
3. The current servos power requirements when holding a fixed position is proportional to the amount of force applied by the connected physical apparatus.

The consequences of these limitations are numerous, and their relative importance depends on the application context, but include:
A. Upon loss of the position-control pulse the behaviour of the servo is often undefined and thus designers cannot be certain of outcomes unless they conduct specific tests with each servo model used in their design.
B. Upon loss of either the position-control pulse or the power supply the servo ceases to hold its desired position, allowing connected apparatus to be disturbed by external force. This could have safety implications, or at least can lead to incorrect system behaviour.
C. In the case of intermittent power loss the situation in (B above) could lead to mechanical oscillation, as the servo regains its desired position abruptly each time power is restored.
D. Under normal conditions, if a current servo is mechanically stressed it can cause mechanical bouncing as fights to regain its target position once disturbed.
E. Servos are a considerable power drain in a system and this is a particular concern for battery-powered equipment and can be a safety-issue for safety-critical equipment.

Aspects innovants

The enhanced servo automatically latches (locks) its position in the following circumstances; upon reaching its target position, upon loss of position-control pulse, and upon loss of power.
This leads to the following benefits:
1. The behaviour under power loss or signal loss conditions is defined and predictable  enhancing safety and/or usability.
2. The rotational position of the servo, and hence the connected apparatus, is held mechanically rather than by the force of the motor. This ensures that no power is used to hold the position regardless of the amount of external force applied, and prevents mechanical bouncing.
3. (2 above) also leads to potentially very high savings in power usage; and thus heat generated, which in turn prolongs the life of the servos. The reduced power usage also leads to longer operating times for battery powered equipment and reduces the cost of use.
4. The new servo is self-contained and is a direct replacement for current in-market devices, not requiring any application re-design.
5. In addition, new applications can take advantage of an additional feature in which the latching action can be disabled / re-enabled dynamically by a pair of special out-of-band command pulse signals.

The enhanced technology has been designed to operate with a wide range of servo parameters (gear ratio, torque, physical size) and therefore could be applied to an entire product range.

Expertise recherchée:

- Type of partner sought: Industry from most sectors using and developing servomechanisms, position control systems etc.

- Task to be performed by the partner sought: Further development, assistance commercialising, exclusive, or non-exclusive licencing to manufacture the devices.