Expert modelling and algorithm design for space missions

The complexity of each space mission presents unique technical challenges. Despite this, the levels of accuracy demanded in the space industry are probably higher than any other sector. Tessella’s expertise in systems engineering, mission analysis, control design, mathematical modelling and detailed analysis provides a unique combination of skills to develop accurate solutions to meet these challenges.

Tessella has built an enviable reputation for excellent technical support in the following main areas:

• Attitude and Orbit Control Systems (AOCS)
  Tessella’s capability covers all phases of the design:
  • Initial trade-offs and early hardware selection
  • Mode identification and requirements flowdown
  • Detailed mode trade-off and design
  • Guidance and control algorithm development and validation
  • Fault detection, isolation and recovery (FDIR) algorithms
  • Full modelling and simulation
  • Pseudocode-level software specification and implementation support
  • Automated tuning and export of flight databases
  • Expert support to hardware-in-the-loop testing
  • Launch and commissioning support
  • In-flight data analysis and performance optimization
• Entry, Descent and Landing System (EDLS) design and analysis

  Tessella’s analysis and modelling capabilities combine with our specialist expertise in parachute and airbag design to provide a valuable UK capability in this field. Specifically, we support the industry at three levels:

  • Parametric system-level sensitivity studies and trade-off analyses. The sizing and optimization of the parachutes, rockets and airbags can be studied comprehensively using our parametric analysis tools. Questions such as the sensitivity of the design mass to various input conditions and the optimal balance of parachutes against rockets can be explored.
  • Full multi-body simulation of descent sequences. The PASDA parachute sequence simulation tool, originally developed with ESA funding and now further extended by Tessella under license, provides highly detailed six-degree-of-freedom multi-body simulation capability of various descent sequences, including parachute deployment and inflation, front shield separation and complex aerodynamic wake effects.
  • Detailed design of parachutes and airbags. As one of the few companies with experience of designing a parachute and overseeing its manufacture and testing, as well as airbag design expertise, Tessella can provide expert support to parachute and airbag design, risk analysis and testing.
• Orbital dynamics and mission analysis
  The subtle changes in a satellite’s orbit, deliberate or otherwise, need careful analysis to ensure that the mission meets its requirements. Tessella’s modelling and orbital dynamics capabilities can be combined, where appropriate, with powerful software tools to give a general mission analysis capability. Tessella has developed a wide range of mission analysis tools, and also has expertise in industry-standard tools such as AGI’s STK.
• Pointing error analysis
  Tessella has amassed an unusually strong capability in this area. In particular, ESA’s recommended approach is encapsulated in the Pointing Error Handbook, originally written by staff now at Tessella. Based on that work, Tessella developed the Analytic Pointing Performance (APP) software tool for ESA. The tool allows pointing errors to be combined using a justifiable approach from statistical, frequency content and geometric viewpoints. Using a rigorous approach and avoiding unnecessarily conservative approximations reduces the level of over-design, and hence reduces cost.
• Hardware modelling
• Sensors (e.g. Sun sensors, gyros and star trackers)
• Actuators (e.g. reaction wheels, thrusters and magnetorquer bars)
• Deployment mechanisms and antenna drives
• Solar array drives
• Hi-fidelity simulations of mechanisms & controllers including non-linear effects such as stiction, backlash and non-linear frictions

This work is underpinned by staff with outstanding mathematical and engineering skills, and by Tessella’s leading expertise in:

• Control design and analysis
• Optimal estimation techniques
• Modelling and simulation
• Systems engineering
• Parametric trade-off studies