Trajectory Generator (2025)

Trajectory Generator is a control voltage generator & signal router for the [Nonlinear] Dynamics system. Its primary functions include automated many-to-one crossfading, arbitrary triggered and cyclical control voltage generation, six to 96-stage envelope generation, and triggered and looping ramp generation on several simultaneous timescales.

Functional Explanation

As its name suggests, Trajectory Generator is designed to generate parametric trajectories, with many changes of direction and detours along the way. It is perhaps simplest to think of Trajectory Generator first as a six-stage/seven-breakpoint envelope generator. The a–g slide potentiometers determine the amplitude at each breakpoint; the Timebase parameter and associated control voltage input determine the envelope’s total timescale (from mere milliseconds to tens of seconds). A one-shot trajectory may be initiated (i.e. an envelope may be triggered) by sending any signal into the “single” input; upon detecting an input, the trajectory will immediately reset to the a value and gradually move toward the g value. One may also choose to initiate a cyclical trajectory; by pressing the yellow tactile switch or sending a signal into the cycle input, the trajectory will immediately reset to the a value and cycle through all stages indefinitely.

In these situations, the TB:traj output produces the Trajectory value, as determined by the seven breakpoints’ slide potentiometers. The TB:ramp output produces a descending ramp, which progresses from 5V at the beginning of the a stage to 0V upon reaching g. This ramp may be used as a trigger source, sychronizing other modules to the beginning of individual repetitions of the trajectory. The ramp may also be used as input for one of the [Nonlinear] Dynamics system’s many nonlinear voltage processors, such as the Random State Array or Voltage Mapping Array, allowing the creation of multiple simultaneous nonlinear trajectories at the same rate as Trajectory Generator’s own internal processes.

The somewhat erroneously named TB/7:sRamp output is a per-stage descending ramp output, which produces six descending ramps for every cycle through the primary trajectory. Of course, as with any descending ramp in the system, it may also be used as a discrete trigger or as a synchronization source for other continuous nonlinear shaping processes.

Repetitions and Curve Shaping

The n rept. parameter has several implications on Trajectory Generator’s global behavior. It determines the number of repetitions of the trajectory that occur when a new trajectory is initiated—either by discretely initiating a new trajectory or through cyclical trajectory generation. The number of repetitions varies from 0 to 15. The TB*n:Ramp output produces an ascending ramp, which progresses from 0V to 5V across the total group of repetitions. The corresponding trig output briefly goes high at the end of each total group of repetitions.

The time curve parameter allows for the generation of trajectories that gradually accelerate or gradually decelerate as they progress; the time curve is applied across a total group of repetitions, as determined by the n rept. parameter. For example, setting time curve fully counterclockwise, n rept. fully clockwise, and then discretely initiating a trajectory would result in sixteen cycles of the 7-breakpoint trajectory, starting relatively fast and continuously decelerating as they progress. Internally, this is achieved through time and amplitude multiplications of a single core ramp generator (surfaced to you, the user, as the TB*n:Ramp output), which is subjected to multiple modular processes and waveshaping to derive the remaining ramp and trajectory outputs. The time curve parameter simply applies exponential or logarithmic curve shaping to this core ramp prior to these additional shaping processes, creating the illusion of acceleration and deceleration. (Note, however, that the total timebase’s ramp output is tapped prior to the curve shaping process, and is always linear—making it a good candidate for further shaping using other nonlinear processors, as described above.)

The amp curve parameter is designed to compensate for the unusual exponential or logarithmic amplitude biases that can be introduced due to the nature of the ramp curve shaping introduced by the time curve parameter. In essence, amp curve allows the introduction of exponential or logarithmic biases to all of the stages, individually. The amplitude of each individual breakpoint remains constant regardless the amp curve setting; this setting applies specifically to the nature of the curve shape between individual break points.

Multiple Perspectives

Not least significant is the fact that each of Trajectory Generator’s breakpoint amplitude sliders features a complementary control voltage input. Patching into these inputs defeats an internal normalled connection to the potentiometer from a +5V reference; the slider then acts as an attenuator for the signal you have patched into the input. One may conceptualize this as being a means of voltage-controlling envelope stage levels. However, I would implore you to consider an alternative perspective: an “envelope” like Trajectory Generator is just a way of continuously crossfading between several fixed amplitude values in a specific order. If those amplitude values are made variable, it becomes clear that such a device may also be considered a specialized type of signal router—one which crossfades between several signals, one adjacent pair at a time. By patching dynamic and/or automated control sources to the breakpoint inputs, many unusual possibilities emerge.

Trajectory Generator’s strengths lie in its creation of many simultaneous related signals. It is possible to use it to coordinate complex multi-parametric modulation; and, given the relatively large number of nonlinear processors in the [Nonlinear] Dynamics system, the nature of such modulations can quite literally take many shapes.

Trajectory Generator is a concept/prototype developed primarily for personal use and is not available for purchase. As of May 2025, only five Trajectory Generators have been built.