Persistence through Reliable Perching (PEP)

Lead Research Organisation: Loughborough University
Department Name: Aeronautical and Automotive Engineering


Small Unmanned Aerial Systems (SUAS), enjoying the advantage of small size and low-weight, can be easily carried by end-users and rapidly deployed into different scenarios. However, multi-rotor, battery powered SUAS usually have the endurance of around 20 mins. In contrast, a common request for SUAS is the persistence of hours or more. Swarm Systems is developing a product for the growing market need of flying binoculars based on a Nano quadrotor platform (under 200g). Customers are specifically asking for a perch and stare capability to achieve persistence. However, perching using existing technology is very hit and miss. This Persistence through Reliable Perching (PEP) proposal has a goal of achieving greater than 99% reliability in perching on unprepared, outdoor locations in challenging weather conditions and taking off again. The PEP research approach includes: adding new passive and active sensors, creating soft sensors from combinations of existing sensors, researching a novel automatic abort using 'disturbance from internal model' techniques and innovating undercarriage design including multi-surface gripping. In particular, the Loughborough team will be responsible to develop the novel 'abort' flight control function to enable the SUAS to recover from unsuccessful perching in the presence of external disturbances such as wind gusts or contact with obstacles. A disturbance observer based on the quadrotor's internal model will be designed as a 'soft' sensor to provide estimates on abnormal external forces acting on the airframe together with normal sensors. The estimates will then be fed into a decision-maker to trigger the 'abort' flight mode, where a dedicated flight controller will be designed and optimised to perform this maneuver.

PEP project management will be led by an analysis of perching ground types and weather conditions. The final 1/3 of the project will be focused on improving where testing proves that reliability is poor. The Loughborough team will use its world leading indoor flight test facility (using Vicon system) to verify its algorithm and help the system integration of different algorithms into Swarm System's Nano quadrotor. A commercial goal is to add a key new capability to Swarm Systems product, enabling it to win export orders.

Planned Impact

The direct beneficiaries of this project will be participators in UAV communities. This project is able to provide a new control design tool for UAVs, which are often subject to external disturbances and need agile manoeuvres. We also believe that the effective dissemination of the research outcomes and methods of this project will pave the way for wide applications of the proposed control method in different domains (e.g. robotics, maritime vessels and general industrial control applications), which in turn will bring long term impact.

On the other hand, by closely working with the project partner Swarm Systems Ltd (SSL), it is envisaged that the following impact will be made through the company:

Customers: Presently, the utility of a Small Unmanned Aerial Vehicle (SUAS) is limited to around 20mins in all applications. With the proposed project, that utility can be expanded to many hours outdoors, which can extensively expand the range of applications. Furthermore, with solar re-charging, a new era in which SUASs can be outdoors for many days and weeks becomes possible.

Supply chain: SSL has a largely British supply chain. Manufacturing, assembly and dispatch takes place at Adapt EMS in the region of Hitchin, Herts. SSL licenses IP from some of its subcontractors. If sales grow rapidly, then more R&D will be subcontracted to companies and universities throughout the UK.

Imports: The MoD placed their first Flying Binoculars procurement with a Norwegian company. If SSL, with new capability such as PEP, wins the next MoD procurement then approximately £20m of equipment imports will be substituted.

Social impact: some jobs that are dull, dangerous and dirty will be substituted by a perching SUAS. Productivity will increase as mundane work is automated.

Environmental: PEP will contribute to their being higher safety levels in autonomous SUASs.


10 25 50
Description When landing a quadrotor on an unprepared field, unexpected objects on the ground may tip over the quadrotor and cause quadrotor crash if landing is not aborted in time. In this project, an disturbance observer based abort flight control framework is developed. This framework employs disturbance observers to estimate external forces and torques acting on the quadtotor. If an object getting in the way when the quadrotor is landing, the disturbance observer is able to detect the contact and suggest the controller to switch to abort flight model to increase the height preventing crash.
Exploitation Route Swarm Systems Ltd is developing a sub-250g micro quadrotor which needs to perch landing on unprepared field. The company will take the technique forward by integrating it with their quadrotor platform.
Sectors Aerospace, Defence and Marine

Description Autonomous Search for Chemical Release with a pocket-sized Drone [SceneSEARCH]
Amount £375,000 (GBP)
Funding ID ACC500113 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 09/2017 
End 10/2018
Description Swarm Systems Ltd 
Organisation Swarm Systems Ltd
Country United Kingdom 
Sector Private 
PI Contribution We provided the indoor flight test facility and modelling expertise to characterise the flight dynamics of Swarm Systems' nano quadrotor and created a high fidelity model for simulation study.
Collaborator Contribution Swarms Systems provided some detailed requirements on disturbance rejection control for their nano quadrotor platform, which helps to define the control structure.
Impact Detailed simulation model for Swarm Systems' nano quadrotor, which incorporates the interaction with physical environment.
Start Year 2017
Description Dstl Autonomy S&T Collaboration 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact The objective of this event is to identify collaboration and exploitation opportunities by bringing the Defence and Security autonomous systems enterprise together. The event presents latest research on defence and security autonomy and autonomous systems. Consequently, it aims to bring MOD's research into focus and bring low Technology Readiness Level (TRL) research, core research and the stakeholder community together. In the event, a presentation on Loughborough's recent research activities on autonomous systems was delivered. A poster regarding Disturbance Observer Based Control techniques was displayed.
Year(s) Of Engagement Activity 2017