Neurostimulation Parameter Dithering for Sub-Step Pulse Control
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Solution Overview
Problem
Existing neurostimulation systems face limitations in resolution for controlling stimulation parameters, particularly for low-intensity therapies like DBS and VNS, due to hardware constraints, which can be costly to modify for improved resolution.
Innovation Solution
A system that enhances parameter resolution by dithering, interleaving higher and lower values of stimulation parameters at a calculated ratio to achieve finer resolution without modifying the hardware, using an external programming device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware resolution is increased to improve parameter control precision, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The system changes the state of stimulation parameter delivery by using dithering - rapidly alternating between two discrete hardware-resolvable values (higher and lower) to achieve an effective intermediate value. This transforms the delivery pattern rather than the hardware resolution, allowing sub-hardware resolution control through temporal modulation of parameter values.
Solution Approach 2:
The dithering process acts as an intermediary mechanism between the discrete hardware resolution levels and the desired continuous parameter values. By introducing this intermediate dithering layer, the system can achieve fine-grained parameter control without requiring the hardware itself to have higher resolution capabilities.
2Manufacturing precision
If hardware resolution is increased to achieve finer parameter control, then manufacturing precision improves, but ease of manufacture deteriorates
Solution Approach 1:
Instead of modifying the physical hardware to achieve higher resolution, the system creates a virtual resolution through software-based dithering algorithms. The control circuit generates a sequence of discrete values that copy or approximate the effect of higher resolution hardware, achieving the desired precision through computational methods rather than physical modifications.
Solution Approach 2:
The system changes how parameters are delivered by using temporal dithering patterns rather than changing the hardware resolution itself. By modulating the delivery timing and alternating between adjacent resolvable values, the system achieves effective sub-resolution control without any hardware changes, maintaining ease of manufacture while improving parameter precision.
3Measurement precision
If dithering is applied to achieve higher parameter resolution, then measurement precision improves, but device complexity increases
Solution Approach 1:
The dithering process employs periodic action by rhythmically alternating between higher and lower parameter values at calculated ratios. This periodic modulation creates an effective average value that represents the desired intermediate parameter setting, achieving high resolution through regular temporal patterns rather than complex continuous control mechanisms.
Solution Approach 2:
The system introduces dynamics by making the stimulation parameter delivery time-varying through dithering. Instead of delivering a static parameter value, the control circuit dynamically switches between adjacent values according to a dithering algorithm, creating temporal variations that encode fine-grained control information and achieve effective higher resolution.
4Productivity
If dithering mode is enabled to improve parameter resolution, then productivity of therapy customization improves, but loss of time for parameter processing increases
Solution Approach 1:
The dithering parameters and patterns are pre-calculated and stored in the control circuit before actual stimulation delivery. The system prepares the dithering sequences in advance based on the desired target parameter values, so that during therapy delivery, the pre-computed dithering patterns can be executed without real-time computational overhead, minimizing processing time delays.
Data Source
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AI summary
A system for delivering neurostimulation comprises a stimulation output circuit configured to deliver the neurostimulation according to stimulation parameters defining a pattern of neurostimulation pulses and including timers each independently operable to control timing of one or more pulses of the pattern of neurostimulation pulses. The stimulation output circuit sets a minimum step size for adjusting an adjustable parameter of the stimulation parameters. A system for delivering neurostimulation further comprises a control circuit configured to receive a value of the adjustable parameter and to control operation of the stimulation output circuit using the received stimulation parameters. Further, a control circuit is configured to perform parameter dithering when a dithering mode is enabled and the received value of the adjustable parameter is not available with the minimum step size. The parameter dithering performed by delivering neurostimulation pulses including a first number of pulses at a higher value of the adjustable parameter interleaved with a second number of pulses at a lower value of the adjustable parameter periodically at a period being a sum of the first and second numbers of pulses to produce an average value of the adjustable parameter that approximates the received value of the adjustable parameter. The higher value and the lower value are values available with the minimum step size for adjusting the adjustable parameter.