Gear Shift Control Examples

Note: Refer HERE for a general overview of Gear Shift Control.

Note: Refer HERE for a detailed explanation of Gear Shift Control settings (or click on a setting listed below).

H Pattern Gearbox With Clutch Switch

This arrangement uses a pedal box mounted switch that is activated by the driver pressing the clutch. The switch is wired to a Digital Input. Typically the switch would become Active at the point where the clutch disengages. Some adjustment may be required to find the exact point at which the switch should become active.

As a Digital Input will be used to start the gear shift sequence, Start Shift Mode must be set to Digital Input. Up Shift Digital Input must be set to the digital input wired to the clutch switch. Down Shift Digital Input must be set to OFF as there is no means by which up and down shifts can be directly distinguished on an H pattern gearbox. This will start the shift sequence when the clutch switch is active for longer than Start Shift Validation Time.

Two gear shift types can be distinguished. If a shift is started while Throttle Position is greater than Drive/Overrun TP then a Driven Up Shift will be requested otherwise an Overrun Down Shift will be requested. Make sure that Throttle Position does not go below TP Low Lockout otherwise a TP Lockout will occur rather than a shift request. Set TP Low Lockout to 0 to ignore the TP lockout condition. If only full power up shifts are required TP Low Lockout can be set higher (eg 80%) to prevent gear shift requests when not near full throttle.

Throttle blipping can be used with Overrun Down Shifts. To disable throttle blipping, either set Drive/Overrun TP to 0 or set the entire Overrun Down Shift Throttle Trim table to zero.

There are two ways in which the shift sequence can be ended:

·After a fixed amount of time - End Shift Mode must be set to Time. The time that the shift sequence will last for is set in the Driven Up Shift Torque Reduction Time and Overrun Down Shift Torque Increase Time tables.

·When the clutch is released - End Shift Mode must be set to Digital Input. The shift will end when the clutch is released. Note that if the clutch is held for longer than Max Shift Time the shift will be ended.

When using a clutch switch it is important to set Speed Lockout to a suitable value to prevent a shift sequence starting when the clutch is pressed while the vehicle is not moving.

Sequential Gearbox with Strain Gauge Lever

This arrangement uses a strain gauge type sensor mounted on the gear lever or in the gear knob. A signal conditioned strain gauge is required (eg 0-5 V output, 2.5 V unloaded) such as the Hollinger gear knob. The signal from the strain gauge must be wired to an Analog Input.

The strain gauge must be correctly installed. To check this first watch the runtime value for the Analog Inputs signal voltage. Ensure that the lever is correctly orientated by ensuring that maximum signal change occurs when the lever is pushed and pulled in the direction of a gear change. There should be minimal signal change when the lever is forced at right angles to the direction of normal gear shifting.

The strain gauge lever must be calibrated. Note the voltage from the strain gauge when the lever is in its unloaded state. Enter this voltage as Gear Lever Force Offset. Set Gear Lever Force Gradient to achieve the required force. Monitor Gear Lever Force and ensure it reads near zero when the lever is unloaded and positive force when pulled in the up shift direction and negative force when pushed in the down shift direction. Note that it is not necessary (or sometimes even possible) to calibrate the actual lever force. As long as a good range is chosen (eg +/- 100 N when pushed much harder than a normal shift).

Set Gear Lever Force Up Shift Force and Gear Lever Force Down Shift Force to appropriate starting values. These will need to be adjusted after some testing.

Set Start Shift Mode to Gear Lever Force (Seq). This will result in a shift request occurring when Gear Lever Force goes above Gear Lever Force Up Shift Force or below Gear Lever Force Down Shift Force for longer than Start Shift Validation Time.

This arrangement can detect all four shift types. If a shift is started while Throttle Position is greater than Drive/Overrun TP then a Driven Up Shift or Driven Down Shift will be requested otherwise an Overrun Down Shift or Overrun Up Shift will be requested. Make sure that Throttle Position does not go below TP Low Lockout otherwise a TP Lockout will occur rather than an overrun shift request. Set TP Low Lockout to 0 to ignore the TP lockout condition. If only full power up shifts are required TP Low Lockout can be set higher (eg 80%) to prevent gear shift requests when not near full throttle.

Only Timed End Shift Mode can be used in this arrangement as there is no way to detect the end of shift (in this example no gearbox gear position sensor is installed). Gear Position Sensor End Shift Mode could be used if a gear position sensor was installed. Refer to the following example for using a gear position sensor.

Throttle blipping can be used with Overrun Down Shifts and Overrun Up Shifts. To disable throttle blipping, don't set an output to blip solenoid and set the Overrun Up/Down Shift Throttle Trim tables to all zeroes.

Sequential Gearbox Gear Position Sensor

This arrangement uses an analog sensor fitted to the gear shifter barrel to indicate gear position. Using this sensor it is possible to achieve full closed loop gear shifting (ie shift ends when the next gear is properly engaged). It is possible to use either the gear position sensor or a strain gauge lever to indicate a driver shift request. This example shows how to use the gear position sensor. Refer to the previous example for how to initiate shifts from a strain lever.

The Gear Position Sensor must be configured and calibrated. The sensor must be wired to an Analog Input and Gear Detection (in the Chassis and Body folder) must be correctly configured using the 'Analog Position Sensor' Gear Detection Mode with the 'Source' setting set to the correct Analog Input.

To calibrate gear position, move through the gears while observing the voltage on the Analog Input. While doing this make sure the gears fully engage. Under Chassis and Body->Gear Detection, set Gear Detection Mode to Analog Position Sensor. Set each gear and voltage pair as required. The Voltage Tolerance (+/-) setting is critical. This is used by Gear Shift Control to determine when the gear has fully engaged (Gear Position Sensor End Shift Mode only).

Set Start Shift Mode to Gear Position Sensor to indicate that shift requests come from movement of the gear position sensor. When the gear position sensor voltage changes by more than Start Shift Voltage Threshold from its normal in gear voltage, an up shift request (if going towards a higher gear) or down shift request (if going towards a lower gear) is generated.

There are two ways that shifts can be ended with a gear position sensor:

·After a fixed amount of time - End Shift Mode must be set to Time. The time that the shift sequence will last for is set in the Driven Up/Down Shift Torque Reduction Time and Overrun Up/Down Shift Torque Increase Time tables.

·When the next gear engages (closed loop) - End Shift Mode must be set to Gear Position Sensor. The shift will end when the gear position sensor voltage goes within Voltage Tolerance (+/-) of the expected next gear voltage. Note that if the next gear is not detected as engaged within Max Shift Time the shift will be ended.

Throttle blipping can be used with Overrun Down Shifts and Overrun Up Shifts. To disable throttle blipping, either set Drive/Overrun TP to 0 or set the entire Overrun Up/Down Shift Throttle Trim tables to zero.