Appendix E
Glossary
1 sections · about 2 minutes
Back-EMF — voltage generated by a spinning motor that opposes the applied voltage; proportional to speed, and the reason stepper torque falls off at high speed.
Bresenham / DDA — an integer algorithm for distributing steps evenly over time across multiple axes; the basis of fixed-rate multi-axis step generation.
Chopper — the switching circuit that regulates winding current by rapidly switching the supply on and off.
CoolStep — Trinamic's automatic current reduction based on the StallGuard load measurement.
DH parameters — Denavit–Hartenberg; the four-parameter convention for describing each link of a serial manipulator.
DIAG — TMC2209 output pin signalling a stall or a driver fault.
DTCM / ITCM — Data and Instruction Tightly Coupled Memory; the fast, deterministic, cache-free RAM on the Cortex-M7.
Full step — one of the 200 natural positions per revolution of a 1.8° stepper.
Hold current — reduced current applied to a stationary motor to limit heating.
IFCNT — TMC2209 counter that increments on each successful UART write; how you confirm the UART is working.
Jacobian — the matrix relating joint velocities to end-effector velocity.
Jerk — rate of change of acceleration; unbounded in a trapezoidal profile, bounded in an S-curve.
Kinematic decoupling — splitting six-DOF IK into a position problem and an orientation problem, made possible by a spherical wrist.
Load angle — the angular lag between the rotor and the driving magnetic field; what StallGuard indirectly measures.
Microplyer — TMC2209 feature that interpolates incoming steps up to 1/256 microstepping internally.
Microstep — a subdivision of a full step produced by driving the two phases with intermediate currents.
MRES — the CHOPCONF field selecting microstep resolution.
Pose — position and orientation together; six numbers.
Singularity — a configuration where the arm loses the ability to move in some direction; the Jacobian loses rank.
SpreadCycle — Trinamic's current-regulated chopper mode; better dynamic response and high-speed torque.
StallGuard — Trinamic's sensorless load measurement, reported as SG_RESULT.
StealthChop — Trinamic's voltage-mode PWM; near-silent, lower dynamic response.
TCOOLTHRS — the velocity threshold that gates StallGuard and CoolStep; commonly forgotten.
TCP — Tool Centre Point; the point on the tool whose pose you control.
TSTEP — TMC2209 measurement of the time between steps; larger means slower.
VREF — analogue current-reference input; interacts with IRUN via the i_scale_analog bit.
Sources
- PAROL6 Documentation — Robot Specifications
- PAROL6 Documentation — General Concepts
- PAROL6 kinematic structure (Hackaday.io project log)
- PAROL6 Desktop Robot Arm — GitHub
- Source Robotics — PAROL6
Register details, datagram formats, and current formulas should be confirmed against the current Trinamic/Analog Devices TMC2209 datasheet. Teensy 4.1 pin assignments should be confirmed against the PJRC pin card for your board revision.