Engine deceleration determination method/system for updating a control parameter

A control system for determining an updated value of a control parameter (dES/dt.sub.UPDATED) indicative of the rate of change of rotational speed (ES) of a vehicular internal combustion engine (E) in a vehicular automated mechanical transmission system during conditions of reduced fueling of the engine, said transmission system comprising a fuel throttle-controlled engine (E), an operator-set fuel throttle device (P), a multiple-speed change-gear mechanical transmission (10) having an input shaft (16) and an output shaft (90) adapted to drive vehicular drivewheels, said input shaft drivingly connected to said engine by a master friction clutch (C) and a control unit (106) for receiving input signals, including an input signal (ES, IS) indicative of input shaft or engine rotational speed and an input signal (THL) indicative of operator's setting of the throttle device and for processing said signals in accordance with predetermined logic rules to determine control parameters and to issue command output signals to transmission system actuators, including means for controlling fueling of the engine and means (70) for controlling shifting of the transmission, said transmission system performing dynamic upshifts from an engaged ratio into a target gear ratio in a sequence of operations, all without disengagement of the master clutch and regardless of operator's setting of the throttle device, said dynamic upshifts comprising:

• (a) a predip operation wherein fueling of the engine is manipulated to allow disengagement of the engaged gear ratio;
• (b) after confirmation of disengagement of the engaged gear ratio, a synchronizing operation wherein fueling of the engine is reduced, allowing engine rotational speed to decrease toward the synchronous speed for engagement of the target ratio (ES=IS=OS*GR.sub.T);
• and
• (c) after achieving substantial synchronous rotational speed of said engine and causing engagement of said target gear ratio, a throttle recovery operation wherein fueling of the engine is caused to be controlled by sensed operator setting of said throttling device;
• said control system characterized by:
• means for, during the predip operation, sensing engine speed;
• means for sensing initiation of said synchronizing operation, and upon sensing initiation of said synchronizing operation, means for causing sensed engine speed to equal engine speed initial (RPM.sub.A), and means for starting a timing sequence;
• means for sensing initiation of the throttle recovery operation, and upon sensing initiation of said throttle recovery operation, means for causing engine speed to equal engine speed final (RPM.sub.B), means for sensing elapsed time from starting of said timing sequence;
• and
• means for determining the updated value of the control parameter as a function of the difference between engine speed final and engine speed initial and of the elapsed time.